Date   
OSCILLOSCOPE LEADER 4081= KENWOOD CS-5135 DOES NOT CHECK THE BRIGHTNESS OF THE T

quinoarango@...
 

Dear Foristas, I am grateful in advance for some collaboration with this LEADER 4081 analog oscilloscope equal to the KENWOOD CS-5135. With failures with the brightness control, I have the service manual.
Initially, when it was turned on, it took time to appear the stroke and when it appeared in 10 or 15 minutes, it did not let the brightness control.
Initially, the operating voltages were checked, being all normal, note that when starting the ignition did not show high voltage, the high voltage section was checked and an isolated high-speed diode was found at one of the ends due to oxidation, in the Inten adjust circuit consisting of VR401, coming into operation correctly.
The surprise came after armed and covered when a light was heard when a diode or resistance was broken, leaving the oscilloscope with excess brightness in the stroke and without intensity control this does not work.
The X74-1490-00 card was checked thoroughly to see if something burst or burned I want to emphasize that no burning smell was felt, everything being in normal condition.
Diode by diode, resistance by resistance, transistor by transistor, capacitors all manually with the ohmmeter were checked in detail, making different tests to verify the optimal state of each component, finding everything normal including the pot that controls the Focus intensity and astigmatism.
The approach works normal and astigmatism control. It just does not control the brightness or intensity. Attached scheme and photo of the failure presented.
I reiterate thanks for any suggestions.
Download link service manual https://we.tl/t-x3dRSxH1ET

Re: Risetime calculator (in tekwiki)

 

Hi Everyone,
Before getting caught up in the concept of an analog computer take a step back to consider what an analog is. It is something that is similar to something else; the two are said to be analogous.

THE RISETIME CALCULATOR IS AN ANALOG COMPUTER BASED ON LOGARITHMS
The risetime calculator is a simple, but clever, analog computer that relies on an analogy between the angle of the dial on each pot and the resistance of the pot at that angle. This in turn relies John Napier's discovery of logarithms, which he first published in 1614. Logarithms are a method to multiply two numbers together by adding their exponent. Anyone familiar with a slide rule knows the C and D scales on a slide rule are logarithmic and not linear. The A and B scales increase twice as fast as C and D because they represent a number times itself or the square of a number. If I wanted to multiply 7 times 5 I simply had to add together the logarithm of 7 (in base 10) to the logarithm of 5 (in base 10). The log (short for logarithm in base 10) of 7 is 0.845. The log of 5 is 0.699. 7 x 5 = log 7 + log 5 = 0.845 + 0.699 = 1.544. If we look up the number whose log is 1.544 it is our answer: 35. Commonly available 10" slide rules are accurate to 2 or 3 decimal places. This is accurate enough for an enormous variety and number of calculations so they were widely used until the introduction of mechanical and then electronic calculators.

HOW IT WORKS
If the three pots on the left side of the risetime calculator have a logarithmic taper and the current coming out of each was added together the sum would = A + B + C. That's not what we want. We want A*A + B*B + C*C. To do that the taper has to change logarithmically but twice as fast as an ordinary logarithmic taper. If the first pot's taper increases twice as fast as an ordinary logarithmic taper the current that comes out of it will be analogous to A*A. The same taper used for the second pot will produce a current analogous to B*B, and the third pot will produce a current analogous to C*C. Now if we sum together the currents coming from the three pots we will get A*A + B*B + C*C. Our next step is to find the number, using the pot on the right side, whose current equals the sum of the 3 pots on the left side. The minimum current from a pot on the left side will be when it is counterclockwise representing 1. 1*1 = 1, and the log of 1 is 0 so there would be 0 units of current coming out of the pot. If the pot were set to 10, then 10*10 = 100 and the log of 100 is 2. So there would be 2 units of current coming from the pot. The currents are summed from all three pots and the total can range from 0 to 6 units of current. With the meter we have to balance (or null) the current on the left side with an equal current from the right side knob. There is no need to take the square root of the left side provided we square the right side instead. So on the right side we can use one more pot as long as it has the same taper as the other three pots. We can even use the same scale. One small drawback to doing this is there exists the possibility that if all three risetimes happen to be greater than 5.773nSec you won't be able to balance the bridge since the total risetime will be larger than 10nSec.

ANALOG VS DIGITAL OSCILLOSCOPES
High quality oscilloscopes strive to present an accurate analog of the voltages or currents in a circuit being probed. Until recently all of the oscilloscopes in the world were analog and there was no need to use the word analog to describe them. I am absolutely certain no one gave that word a second thought until another way to make an oscilloscope became possible in the 1970s. Suddenly it was important to distinguish whether the oscilloscope made every attempt to present you with a wiggly line on a CRT that was an analog of what was happening in the circuit you were measuring or if what you saw looked like a connect the dots page from a coloring book.

How closely the analog displayed on the CRT compared to the actual potential in the circuit being measured was an indication of the quality of the instrument. Enormous amounts of money were spent over 100+ years to insure the trace on the CRT was an accurate analogue of the voltage in the circuit. The result was something that could be within +/-1%. Today there are two kinds of oscilloscopes. One important attribute distinguishes analog oscilloscopes from digital oscilloscopes.

* The representation on the CRT of an analog oscilloscope is a CONTINUOUS analog of the signal being measured (except for sampling plugins). One advantage of an analog oscilloscope, as long as you use it within its specified limits, is the representation on the CRT has a high likelihood of being a good analog of the signal being measured.

* The representation on the display of a digital oscilloscope is a SERIES OF DISCRETE DOT PAIRS that may (or may not) appear to form one or more patterns that humans will assume, sometimes erroneously, are continuous and then they might conclude it is an analog of the signal being measured. The interpretation of the pattern of dots on a digital oscilloscope requires a detailed understanding of how the samples are taken, how the samples are displayed, the type of sampling used, and the limitations of sampling itself.

Analog oscilloscopes are desirable for new or unsophisticated users because the results are less likely to be misunderstood. Digital oscilloscopes have many limitations and pitfalls that analog oscilloscopes do not. They require that their results be interpreted carefully. The digitized data from a signal can be further processed mathematically to extract additional information from it or, for example, to reduce the noise in the digitized data. There are many other things that can be done to a digitally sampled signal after it has been captured to further process it.

Dennis Tillman W7PF





--
Dennis Tillman W7PF
TekScopes Moderator

Re: 2465B - Weak Readout Intensity

toby@...
 

On 2020-01-20 8:51 PM, flanneltuba@... wrote:
Thanks Chuck.

That was the sort of conclusion I was dreading. I do have a perfectly good 2465 (no suffix) with what I believe is the same CRT. It pains me though to pull a CRT out of an otherwise healthy scope just to prove that the subject unit has a weak CRT. I suppose it's that or roll the dice and buy a CRT off of EBay. There's a seller from Israel offering 154-0850-01 CRTs for $67, shipping included. "Very Good Working Condition." I'll admit to being a little apprehensive about buying parts from overseas.
Israel has a lot of surplus tech. I'd go for it, it's probably fine.

The real no-go are Chinese ICs that purport to be US brands.

But then you CAN get good US surplus chips via Eastern Europe. So...

--T


One other thought: In the good old CRT television days, (were those the good old days?) one could often perk up a sagging CRT by bumping up the filament voltage on the heater. Sounds like something of a fool's errand for a tek scope of this sort, and more effort than it could possibly be worth, but I would be interested in knowing if anyone's ever given it a try.

Thanks,

- Scott


Re: 2465B - Weak Readout Intensity

John Griessen
 

On 1/20/20 7:51 PM, flanneltuba@... wrote:
There's a seller from Israel offering 154-0850-01 CRTs for $67, shipping included. "Very Good Working Condition." I'll admit to being a little apprehensive about buying parts from overseas.
I would talk to the seller and tell them that you will immediately test it and ask for money back if not working. If they still want to sell to you, don't worry.
Ebay really takes care of buyers more than sellers, so all you have to do is make it plausible with photos and
they return your money.

Re: TDS3000B polarizer film

Tom B
 

Hello,

Thank you for the information.  It occurred to me that all I need to do is buy a large sheet and rotate it until it looks right and then cut to size.

Tom

Re: 2465B - Weak Readout Intensity

flanneltuba@...
 

Thanks Chuck.

That was the sort of conclusion I was dreading. I do have a perfectly good 2465 (no suffix) with what I believe is the same CRT. It pains me though to pull a CRT out of an otherwise healthy scope just to prove that the subject unit has a weak CRT. I suppose it's that or roll the dice and buy a CRT off of EBay. There's a seller from Israel offering 154-0850-01 CRTs for $67, shipping included. "Very Good Working Condition." I'll admit to being a little apprehensive about buying parts from overseas.

One other thought: In the good old CRT television days, (were those the good old days?) one could often perk up a sagging CRT by bumping up the filament voltage on the heater. Sounds like something of a fool's errand for a tek scope of this sort, and more effort than it could possibly be worth, but I would be interested in knowing if anyone's ever given it a try.

Thanks,

- Scott

Re: What Tektronix means to me

Michael A. Terrell
 

I repaired Commodore computers from the PET era, to the 128 at the
component level. MOst failures were bad RAM. Some brands were always bad,
while others were rare. The 4164? chips were in short supply, so they used
whatever they could get. I wrote a decompiler in Commodore basic to look at
the ROM based DOS of their 1581, 3.5" floppy drives that wrote the output
to a blank in the drive. Club members made fun of it, but the commercial
software they had would hang after about 5%.

The Exorcisor based computers were built and sold to the Cable TV industry.
The pair of computers, and one 8" floppy subsystem cost us over $60,000 in
1980. Then they went out of business in 1983.

I still have a couple Intel Multibus computers that I've never fired up.
They came from an auction at the old Orlando Naval Training Center.

I have worked with VME/VXI and PC104 based systems. Microdyne used the
MC68340 for several embedded controllers in their later Analog products.
They used 6803 and some others in early products. I troubleshot the MC68340
boards at the factory, without a logic analyzer. I couldnt even get a JTAG
interface because only engineers were allowed to use that. They insisted
that only the commercial units would work, and the simple one in the
databook would destroy to processor. Not a lot f fun, but it gave me more
skills to repair poorly documented test equipment. :)

On Mon, Jan 20, 2020 at 8:06 PM Harvey White <madyn@...> wrote:

comments interleaved:

On 1/20/2020 7:50 PM, Michael A. Terrell wrote:
Did you ever use the 6510 processor? It was a 6502 with an
onboard I?O port that was made foe the Commodore 64.
By the time the commodore 64 came out, I had either almost stopped my
own designs or I had used Apple ][ clone boards from Japan. I had, in a
way, more software than could had in some versions of the commercial
systems (and in some cases, far less).

I had a console run inverse assembler, that took the 6502's assembler
and ran it backwards to produce the opcode from the mnemonic. The
operating system had a system call table so that the user programs could
be complied with just the table, and the program would still work.
Didn't have to assemble it with a specific version of the OS. It ran
Tiny Forth, and also had (at one time) a tape (paper tape) reader, since
I could get that at work. If I wanted to upgrade the OS, well, still
needed to program Proms.

Story about someone who was building a system. The nomenclature 27xx
where the xx showed the size in K bits was common for the proms.

He said, "well, I could use 2716's, but they're really small and I
really want to use something bigger. I'll wait until I can get some
2732's."

A year later, or so, I asked him how his system was working... He said.
"Well, I was going to use 2732's, but I really like the 2764s, and
they're going to be available in about 3 months....."

Not sure what he ever built....



There were several
undocumented opcodes thet were different on different production runs.
Some commercial software would only run on a specific group, so I fad to
keep as many different runs on hand, as possible to get someone's sytem
back up and running.
Nope, ran into a similar problem with generations of the 6502 from
ground zero....


Also: Did any of you work with Motorola's 6800 based
Exorcisor bus? I had to maintain a pair of six NTSC output character
generators built with those boards. Each video output had its own card,
but
each computer only had 32KB of RAM.
I pretty much was in the camp of having to build my own boards, so I did
what I could from essentially bare metal. Never (other than Apple ][
boards) used anyone else's design.


Harvey



On Mon, Jan 20, 2020 at 1:21 PM Harvey White <madyn@...>
wrote:

I (very early on) tried to build a Tektronix calculator out of TTL,
jumps, program flow, and then an FPU.

Got the jumps and program flow working, you could do an indirect jump
through a location in hardware (and yes, this was very early....)

I built an 8 trace scope switch to be able to look at digital traces on
my 513D (I got lucky getting the 513D, P11 phosphor).

Simple enough, sync a counter to the sweep trigger output, take the
counter, run it to a multiplexer and weight the multiplexer output as
'1' in a very crude D/A.

Take the appropriate counter outputs and weight them 2, 4 and 8.

Instant 8 traces on a 1 channel scope, for 5 volt TTL, of course.

Then along came the 6502, for 30 dollars, one each (while the 8080 was
still 100 dollars or so). I looked at my 130 chip wirewrapped design
(still not done), and felt a bit bad.......

I bought two (and literally, drove to the MOS technology factory to pick
them up with the original books). Still have them, I think.

There were some bugs in the microcode, some things not implemented, and
I seem to remember being bitten by that once I got the "newer"
processors.

Naturally, the whole thing was in assembly language. Program the thing
at work (someone tweaked the DG macro assembler), program the UVPROMS,
take it home and single step (hardware) through the program.

Everything was wirewrap then. Just everything.

Harvey


On 1/20/2020 9:39 AM, Chuck Harris wrote:
Many of us early adopters to microprocessors got bit by
the discovery that not all of the 8080's made were truly
compatible.

Everyone knows that Intel developed the 8080, but some might
not remember that the Japanese company NEC, almost immediately
introduced a cheaper, unauthorized, second source to the 8080...
only theirs was partly done from Intel's design, and partly
done on their own.

Some of the subtle differences were in the settings of flags
after some arithmetic operations, and in the numbers of clock
cycles used by some common instructions.

I discovered the flag problem, when I found some code that
should have branched, only it didn't... NEC fixed a mistake in
the Intel microcode.

I discovered the clock cycle problem when I was writing a music
program, that played on a transistor radio... using timing loops.

I meticulously counted cycles, ala the Intel data book, but
several notes were coming out sharp.

It turns out that Intel used 5 cycles for one instruction, and
NEC found a way to do it in 4 cycles...

And, I had stacks of these instructions, inside of loops that
timed the note pitch.

-Chuck Harris

Dave Seiter wrote:
Grin! Things were different back then. In high school we had dial
up line to a HP2000 at the Stanford business school using DECWriters,
and
one could wander through the directories, browsing students projects. It
was usually very responsive, but sometimes it would really bog down, and
we'd have to use one of the in-class micros (PET/APPLEII/TRS80) to work
on
our projects. But they were all more reliable than our PDP8/E; we had
to
use that for Fortran, and it was always breaking down. I think I was
one
of the last people to learn how to use a keypunch machine!
-Dave




Re: What Tektronix means to me

Harvey White
 

comments interleaved:

On 1/20/2020 7:50 PM, Michael A. Terrell wrote:
Did you ever use the 6510 processor? It was a 6502 with an
onboard I?O port that was made foe the Commodore 64.
By the time the commodore 64 came out, I had either almost stopped my own designs or I had used Apple ][ clone boards from Japan.  I had, in a way, more software than could had in some versions of the commercial systems (and in some cases, far less).

I had a console run inverse assembler, that took the 6502's assembler and ran it backwards to produce the opcode from the mnemonic.  The operating system had a system call table so that the user programs could be complied with just the table, and the program would still work.  Didn't have to assemble it with a specific version of the OS.  It ran Tiny Forth, and also had (at one time) a tape (paper tape) reader, since I could get that at work.  If I wanted to upgrade the OS, well, still needed to program Proms.

Story about someone who was building a system.  The nomenclature 27xx where the xx showed the size in K bits was common for the proms.

He said, "well, I could use 2716's, but they're really small and I really want to use something bigger.  I'll wait until I can get some 2732's."

A year later, or so, I asked him how his system was working... He said. "Well, I was going to use 2732's, but I really like the 2764s, and they're going to be available in about 3 months....."

Not sure what he ever built....



There were several
undocumented opcodes thet were different on different production runs.
Some commercial software would only run on a specific group, so I fad to
keep as many different runs on hand, as possible to get someone's sytem
back up and running.
Nope, ran into a similar problem with generations of the 6502 from ground zero....


Also: Did any of you work with Motorola's 6800 based
Exorcisor bus? I had to maintain a pair of six NTSC output character
generators built with those boards. Each video output had its own card, but
each computer only had 32KB of RAM.
I pretty much was in the camp of having to build my own boards, so I did what I could from essentially bare metal.  Never (other than Apple ][ boards) used anyone else's design.


Harvey



On Mon, Jan 20, 2020 at 1:21 PM Harvey White <madyn@...> wrote:

I (very early on) tried to build a Tektronix calculator out of TTL,
jumps, program flow, and then an FPU.

Got the jumps and program flow working, you could do an indirect jump
through a location in hardware (and yes, this was very early....)

I built an 8 trace scope switch to be able to look at digital traces on
my 513D (I got lucky getting the 513D, P11 phosphor).

Simple enough, sync a counter to the sweep trigger output, take the
counter, run it to a multiplexer and weight the multiplexer output as
'1' in a very crude D/A.

Take the appropriate counter outputs and weight them 2, 4 and 8.

Instant 8 traces on a 1 channel scope, for 5 volt TTL, of course.

Then along came the 6502, for 30 dollars, one each (while the 8080 was
still 100 dollars or so). I looked at my 130 chip wirewrapped design
(still not done), and felt a bit bad.......

I bought two (and literally, drove to the MOS technology factory to pick
them up with the original books). Still have them, I think.

There were some bugs in the microcode, some things not implemented, and
I seem to remember being bitten by that once I got the "newer" processors.

Naturally, the whole thing was in assembly language. Program the thing
at work (someone tweaked the DG macro assembler), program the UVPROMS,
take it home and single step (hardware) through the program.

Everything was wirewrap then. Just everything.

Harvey


On 1/20/2020 9:39 AM, Chuck Harris wrote:
Many of us early adopters to microprocessors got bit by
the discovery that not all of the 8080's made were truly
compatible.

Everyone knows that Intel developed the 8080, but some might
not remember that the Japanese company NEC, almost immediately
introduced a cheaper, unauthorized, second source to the 8080...
only theirs was partly done from Intel's design, and partly
done on their own.

Some of the subtle differences were in the settings of flags
after some arithmetic operations, and in the numbers of clock
cycles used by some common instructions.

I discovered the flag problem, when I found some code that
should have branched, only it didn't... NEC fixed a mistake in
the Intel microcode.

I discovered the clock cycle problem when I was writing a music
program, that played on a transistor radio... using timing loops.

I meticulously counted cycles, ala the Intel data book, but
several notes were coming out sharp.

It turns out that Intel used 5 cycles for one instruction, and
NEC found a way to do it in 4 cycles...

And, I had stacks of these instructions, inside of loops that
timed the note pitch.

-Chuck Harris

Dave Seiter wrote:
Grin! Things were different back then. In high school we had dial
up line to a HP2000 at the Stanford business school using DECWriters, and
one could wander through the directories, browsing students projects. It
was usually very responsive, but sometimes it would really bog down, and
we'd have to use one of the in-class micros (PET/APPLEII/TRS80) to work on
our projects. But they were all more reliable than our PDP8/E; we had to
use that for Fortran, and it was always breaking down. I think I was one
of the last people to learn how to use a keypunch machine!
-Dave

Re: What Tektronix means to me

Harvey White
 

Hah.  I think you underachieved on your design <grin>.

I have to remember back more time than I care to remember, but the ALU for the jump computer was 74181's, and I think that the FPU CPU was 74181's, but 4 of them.  I had hardware multiply, since I didn't know microcode, nor did I have a memory chip (this was before even 1702's)  I may have had 7489's as memory, and the arithmetic was BCD.  Don't quite remember how I did that, but I did.  The address computation was a separate processor and did some odd things to get the addressing done.  Memory was 2102 1K x 1 static memory (two voltages) which were also part of the video display controller.  It had its own NTSC driver (a separate NTSC sync generator with a dot/bar/crosshatch generator, also had R-Y and B-Y encoders. (IVC Camera schematic, homemade PC boards), and that drove the display.  Since the CPU was sharing the video display memory, you had a bit of an idea what was going on.

Very old design.....

The next scope I got was a Telequipment D75 when Tektronix was closing them out, many years later and when I actually had a bit of money.  It had its own share of problems.......

Harvey

On 1/20/2020 4:35 PM, Chuck Harris wrote:
I wonder how many of us have had to suffer through using
a 513D?

I was given one for Christmas when I was about 14, with
the express understanding that my dad could use it if he
needed it.... He did, and burned out the front end by
probing around in a horizontal section of a TV set.

And thus began my great adventure fixing the all mighty
513D.

I had to scrape away the arc'd over section of micarta on
the vertical input attenuator switch, fill it with epoxy,
replace the burned out precision resistor with selected
carbon composition resistors, and replace a few capacitors
and tubes.

Then I replaced all of the bumble bee capacitors, as they
were all leaky, both physically and electrically. And then,
all of the Sprague 20uf-20uf, 450V FP style capacitors...
and most of the 1 and 2W carbon composition resistors that
fed them... and the screen of the forest of 6AG7 metal tubes...

And, then, one of the 5642 diodes in the HV can popped, making
the beam dim and very large... So, I learned to puddle in
an oil filled assembly...

Fun!

I still have it at my mom's house. I wonder if it still
works?

I too designed a ttl computer, but that was when I learned
that I am truly greedy. I couldn't be satisfied with TTL
speeds, so I had to use STTL. A modest instruction set wasn't
good enough, so I had to give it all 16 possible logical/arithmetic
functions of two inputs... and a full 74S181 ALU. An accumulator
and an address register wasn't enough, so I designed in a 16 word
register file. I couldn't even consider making it byte wide, as
that would take multiple fetches per instruction, so it was at
first 16 bit, and then became 24 bit...

I accumulated parts, spending all of my lunch money... until
Morrow's Microstuff announced its $130 front panel/CPU replacement
board for the S100 IMSAI 8080 computer... and my own design died.

I never had an assembler for the 8080, I assembled everything by
hand directly into located machine language.

I guess I have always been a CISC over RISC guy.

-Chuck Harris

Harvey White wrote:
I (very early on) tried to build a Tektronix calculator out of TTL, jumps, program
flow, and then an FPU.

Got the jumps and program flow working, you could do an indirect jump through a
location in hardware (and yes, this was very early....)

I built an 8 trace scope switch to be able to look at digital traces on my 513D (I
got lucky getting the 513D, P11 phosphor).

Simple enough, sync a counter to the sweep trigger output, take the counter, run it
to a multiplexer and weight the multiplexer output as '1' in a very crude D/A.

Take the appropriate counter outputs and weight them 2, 4 and 8.

Instant 8 traces on a 1 channel scope, for 5 volt TTL, of course.

Then along came the 6502, for 30 dollars, one each (while the 8080 was still 100
dollars or so).  I looked at my 130 chip wirewrapped design (still not done), and
felt a bit bad.......

I bought two (and literally, drove to the MOS technology factory to pick them up with
the original books).  Still have them, I think.

There were some bugs in the microcode, some things not implemented, and I seem to
remember being bitten by that once I got the "newer" processors.

Naturally, the whole thing was in assembly language.  Program the thing at work
(someone tweaked the DG macro assembler), program the UVPROMS, take it home and
single step (hardware) through the program.

Everything was wirewrap then.  Just everything.

Harvey


On 1/20/2020 9:39 AM, Chuck Harris wrote:
Many of us early adopters to microprocessors got bit by
the discovery that not all of the 8080's made were truly
compatible.

Everyone knows that Intel developed the 8080, but some might
not remember that the Japanese company NEC, almost immediately
introduced a cheaper, unauthorized, second source to the 8080...
only theirs was partly done from Intel's design, and partly
done on their own.

Some of the subtle differences were in the settings of flags
after some arithmetic operations, and in the numbers of clock
cycles  used by some common instructions.

I discovered the flag problem, when I found some code that
should have branched, only it didn't... NEC fixed a mistake in
the Intel microcode.

I discovered the clock cycle problem when I was writing a music
program, that played on a transistor radio... using timing loops.

I meticulously counted cycles, ala the Intel data book, but
several notes were coming out sharp.

It turns out that Intel used 5 cycles for one instruction, and
NEC found a way to do it in 4 cycles...

And, I had stacks of these instructions, inside of loops that
timed the note pitch.

-Chuck Harris

Dave Seiter wrote:
  Grin!  Things were different back then.  In high school we had dial up line to a
HP2000 at the Stanford business school using DECWriters, and one could wander
through the directories, browsing students projects. It was usually very
responsive, but sometimes it would really bog down, and we'd have to use one of
the in-class micros (PET/APPLEII/TRS80) to work on our projects.  But they were
all more reliable than our PDP8/E; we had to use that for Fortran, and it was
always breaking down.  I think I was one of the last people to learn how to use a
keypunch machine!
-Dave

Re: What Tektronix means to me

Michael A. Terrell
 

Did you ever use the 6510 processor? It was a 6502 with an
onboard I?O port that was made foe the Commodore 64. There were several
undocumented opcodes thet were different on different production runs.
Some commercial software would only run on a specific group, so I fad to
keep as many different runs on hand, as possible to get someone's sytem
back up and running. Also: Did any of you work with Motorola's 6800 based
Exorcisor bus? I had to maintain a pair of six NTSC output character
generators built with those boards. Each video output had its own card, but
each computer only had 32KB of RAM.

On Mon, Jan 20, 2020 at 1:21 PM Harvey White <madyn@...> wrote:

I (very early on) tried to build a Tektronix calculator out of TTL,
jumps, program flow, and then an FPU.

Got the jumps and program flow working, you could do an indirect jump
through a location in hardware (and yes, this was very early....)

I built an 8 trace scope switch to be able to look at digital traces on
my 513D (I got lucky getting the 513D, P11 phosphor).

Simple enough, sync a counter to the sweep trigger output, take the
counter, run it to a multiplexer and weight the multiplexer output as
'1' in a very crude D/A.

Take the appropriate counter outputs and weight them 2, 4 and 8.

Instant 8 traces on a 1 channel scope, for 5 volt TTL, of course.

Then along came the 6502, for 30 dollars, one each (while the 8080 was
still 100 dollars or so). I looked at my 130 chip wirewrapped design
(still not done), and felt a bit bad.......

I bought two (and literally, drove to the MOS technology factory to pick
them up with the original books). Still have them, I think.

There were some bugs in the microcode, some things not implemented, and
I seem to remember being bitten by that once I got the "newer" processors.

Naturally, the whole thing was in assembly language. Program the thing
at work (someone tweaked the DG macro assembler), program the UVPROMS,
take it home and single step (hardware) through the program.

Everything was wirewrap then. Just everything.

Harvey


On 1/20/2020 9:39 AM, Chuck Harris wrote:
Many of us early adopters to microprocessors got bit by
the discovery that not all of the 8080's made were truly
compatible.

Everyone knows that Intel developed the 8080, but some might
not remember that the Japanese company NEC, almost immediately
introduced a cheaper, unauthorized, second source to the 8080...
only theirs was partly done from Intel's design, and partly
done on their own.

Some of the subtle differences were in the settings of flags
after some arithmetic operations, and in the numbers of clock
cycles used by some common instructions.

I discovered the flag problem, when I found some code that
should have branched, only it didn't... NEC fixed a mistake in
the Intel microcode.

I discovered the clock cycle problem when I was writing a music
program, that played on a transistor radio... using timing loops.

I meticulously counted cycles, ala the Intel data book, but
several notes were coming out sharp.

It turns out that Intel used 5 cycles for one instruction, and
NEC found a way to do it in 4 cycles...

And, I had stacks of these instructions, inside of loops that
timed the note pitch.

-Chuck Harris

Dave Seiter wrote:
Grin! Things were different back then. In high school we had dial
up line to a HP2000 at the Stanford business school using DECWriters, and
one could wander through the directories, browsing students projects. It
was usually very responsive, but sometimes it would really bog down, and
we'd have to use one of the in-class micros (PET/APPLEII/TRS80) to work on
our projects. But they were all more reliable than our PDP8/E; we had to
use that for Fortran, and it was always breaking down. I think I was one
of the last people to learn how to use a keypunch machine!
-Dave



Re: Paypal Transaction IDs

Jeff Davis
 

Vince,

Thanks SO MUCH for the clarification. I really appreciate it. I'll go back to sleep now... 😊

Jeff N0DY

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Vince Vielhaber
Sent: Monday, January 20, 2020 3:58 PM
To: TekScopes@groups.io
Subject: [TekScopes] Paypal Transaction IDs


I did some digging this morning and found out what the deal is with the transaction ids.

The transaction id that you get will NOT be the same as the one Dennis got (as we all recently found out/are finding out).

The transaction id that you get is for the debit to your account.

The transaction id that Dennis gets is the one for the credit to his account.

They're actually two transactions so they each have a different id. Why they don't have some kind of reference that will be the same for both parties is beyond me.

Vince.
--
K8ZW https://nam05.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.metalworkingfun.com&amp;data=02%7C01%7C%7C9019fdf62efd4ee2f15a08d79e049b93%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637151614930622231&amp;sdata=bf0qXP8J5e2%2FWqtyoD5CFVW4TI%2FM9qfmsrgB9sLxMHY%3D&amp;reserved=0 https://nam05.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.hamradio.fun&amp;data=02%7C01%7C%7C9019fdf62efd4ee2f15a08d79e049b93%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637151614930622231&amp;sdata=UMRdhtCFd%2FZSgPxdyKX0ShSZNSWbNZH9wnLu9FS2rGI%3D&amp;reserved=0

Paypal Transaction IDs

Vince Vielhaber
 

I did some digging this morning and found out what the deal is with the transaction ids.

The transaction id that you get will NOT be the same as the one Dennis got (as we all recently found out/are finding out).

The transaction id that you get is for the debit to your account.

The transaction id that Dennis gets is the one for the credit to his account.

They're actually two transactions so they each have a different id. Why they don't have some kind of reference that will be the same for both parties is beyond me.

Vince.
--
K8ZW http://www.metalworkingfun.com http://www.hamradio.fun

Re: 2465B - Weak Readout Intensity

Chuck Harris
 

I would say that you need a new CRT. I have replaced several
in my customer's scopes that behaved the same way.

-Chuck Harris

flanneltuba@... wrote:

Hi Folks -

I have a 2465B that I have been laboring over for a couple weeks, and have made great progress on from its initial condition, which was pretty sad—flickering speckles where the display readout should be and no visible traces. I bought it as a project, so was expecting some work, but I'm stumped on one last problem. After recapping the power supply, replacing the leaky electrolytics on the A5 board, replacing two resistors in the DAC voltage divider circuit, replacing a 74HCT00 on A5 that seemed twitchy when hit with freeze spray, programming a new Dallas NVRAM from the intact image of the original, which was thankfully still valid, and then finally running through the CAL 08 CRT adjustments, I am left with a basically working scope but one with a very dim Readout.

The main sweep trace(s) intensity is also a bit on the low side, though not nearly as dim. Increasing the intensity control beyond about half way simply causes the trace to stray out of focus rather than bringing the intensity all the way up to what would be considered "bright".

I have tried swapping U950 with one from a working 2465 with no change. I have crawled meticulously over the DAC circuit and double and triple checked all discrete parts and PCB traces, so I'm feeling fairly confident that this circuit is working, at least inasmuch as I can tell from my level of expertise, which is certainly well below anything resembling an expert, but certainly in the realm of capable and knowledgable. I have also gone through the A9 CRT power supply and DC restorer, for any obvious signs of problems or vastly incorrect voltages and found none to speak of, though I did not have the means to check the -1900v on the cathode, since I don't have a HV probe/meter.

I'm, hoping my windy description might ring familiar with one of you here, or that you might have some suggestions of where next I might next check.

Thanks in advance for any thoughts and advice.

- Scott



2465B - Weak Readout Intensity

flanneltuba@...
 

Hi Folks -

I have a 2465B that I have been laboring over for a couple weeks, and have made great progress on from its initial condition, which was pretty sad—flickering speckles where the display readout should be and no visible traces. I bought it as a project, so was expecting some work, but I'm stumped on one last problem. After recapping the power supply, replacing the leaky electrolytics on the A5 board, replacing two resistors in the DAC voltage divider circuit, replacing a 74HCT00 on A5 that seemed twitchy when hit with freeze spray, programming a new Dallas NVRAM from the intact image of the original, which was thankfully still valid, and then finally running through the CAL 08 CRT adjustments, I am left with a basically working scope but one with a very dim Readout.

The main sweep trace(s) intensity is also a bit on the low side, though not nearly as dim. Increasing the intensity control beyond about half way simply causes the trace to stray out of focus rather than bringing the intensity all the way up to what would be considered "bright".

I have tried swapping U950 with one from a working 2465 with no change. I have crawled meticulously over the DAC circuit and double and triple checked all discrete parts and PCB traces, so I'm feeling fairly confident that this circuit is working, at least inasmuch as I can tell from my level of expertise, which is certainly well below anything resembling an expert, but certainly in the realm of capable and knowledgable. I have also gone through the A9 CRT power supply and DC restorer, for any obvious signs of problems or vastly incorrect voltages and found none to speak of, though I did not have the means to check the -1900v on the cathode, since I don't have a HV probe/meter.

I'm, hoping my windy description might ring familiar with one of you here, or that you might have some suggestions of where next I might next check.

Thanks in advance for any thoughts and advice.

- Scott

Re: Your generosity is STUNNING!

Masvingo
 

I also agree with Mr Muir.

I take it that there is no way we can pay Groups.io in advance for the next few years?

Finally, I'm afraid I can't see my contribution in the list either, $15 on 1Jan reference 94829316CG900473J

All the best and thanks for all your hard work.

James

Re: What Tektronix means to me

Abc Xyz
 

A Special Thanks to:
Harvey White and Michael Lynch for generously taking me under their Wing!
Also, an Honorable Mention to Nicolas Sullivan & Ron Simmons.
THANK YOU :)
JR

On Mon, Jan 20, 2020, 2:16 PM Abc Xyz <yawrdanza@...> wrote:

Chuck,

I wonder every time I read a Post on this Thread whether you fellas have
any idea how Blessed you are to have all that Talent & Intellect !?

JR

On Mon, Jan 20, 2020, 1:36 PM Chuck Harris <cfharris@...> wrote:

I wonder how many of us have had to suffer through using
a 513D?

I was given one for Christmas when I was about 14, with
the express understanding that my dad could use it if he
needed it.... He did, and burned out the front end by
probing around in a horizontal section of a TV set.

And thus began my great adventure fixing the all mighty
513D.

I had to scrape away the arc'd over section of micarta on
the vertical input attenuator switch, fill it with epoxy,
replace the burned out precision resistor with selected
carbon composition resistors, and replace a few capacitors
and tubes.

Then I replaced all of the bumble bee capacitors, as they
were all leaky, both physically and electrically. And then,
all of the Sprague 20uf-20uf, 450V FP style capacitors...
and most of the 1 and 2W carbon composition resistors that
fed them... and the screen of the forest of 6AG7 metal tubes...

And, then, one of the 5642 diodes in the HV can popped, making
the beam dim and very large... So, I learned to puddle in
an oil filled assembly...

Fun!

I still have it at my mom's house. I wonder if it still
works?

I too designed a ttl computer, but that was when I learned
that I am truly greedy. I couldn't be satisfied with TTL
speeds, so I had to use STTL. A modest instruction set wasn't
good enough, so I had to give it all 16 possible logical/arithmetic
functions of two inputs... and a full 74S181 ALU. An accumulator
and an address register wasn't enough, so I designed in a 16 word
register file. I couldn't even consider making it byte wide, as
that would take multiple fetches per instruction, so it was at
first 16 bit, and then became 24 bit...

I accumulated parts, spending all of my lunch money... until
Morrow's Microstuff announced its $130 front panel/CPU replacement
board for the S100 IMSAI 8080 computer... and my own design died.

I never had an assembler for the 8080, I assembled everything by
hand directly into located machine language.

I guess I have always been a CISC over RISC guy.

-Chuck Harris

Harvey White wrote:
I (very early on) tried to build a Tektronix calculator out of TTL,
jumps, program
flow, and then an FPU.

Got the jumps and program flow working, you could do an indirect jump
through a
location in hardware (and yes, this was very early....)

I built an 8 trace scope switch to be able to look at digital traces on
my 513D (I
got lucky getting the 513D, P11 phosphor).

Simple enough, sync a counter to the sweep trigger output, take the
counter, run it
to a multiplexer and weight the multiplexer output as '1' in a very
crude D/A.

Take the appropriate counter outputs and weight them 2, 4 and 8.

Instant 8 traces on a 1 channel scope, for 5 volt TTL, of course.

Then along came the 6502, for 30 dollars, one each (while the 8080 was
still 100
dollars or so). I looked at my 130 chip wirewrapped design (still not
done), and
felt a bit bad.......

I bought two (and literally, drove to the MOS technology factory to
pick them up with
the original books). Still have them, I think.

There were some bugs in the microcode, some things not implemented, and
I seem to
remember being bitten by that once I got the "newer" processors.

Naturally, the whole thing was in assembly language. Program the thing
at work
(someone tweaked the DG macro assembler), program the UVPROMS, take it
home and
single step (hardware) through the program.

Everything was wirewrap then. Just everything.

Harvey


On 1/20/2020 9:39 AM, Chuck Harris wrote:
Many of us early adopters to microprocessors got bit by
the discovery that not all of the 8080's made were truly
compatible.

Everyone knows that Intel developed the 8080, but some might
not remember that the Japanese company NEC, almost immediately
introduced a cheaper, unauthorized, second source to the 8080...
only theirs was partly done from Intel's design, and partly
done on their own.

Some of the subtle differences were in the settings of flags
after some arithmetic operations, and in the numbers of clock
cycles used by some common instructions.

I discovered the flag problem, when I found some code that
should have branched, only it didn't... NEC fixed a mistake in
the Intel microcode.

I discovered the clock cycle problem when I was writing a music
program, that played on a transistor radio... using timing loops.

I meticulously counted cycles, ala the Intel data book, but
several notes were coming out sharp.

It turns out that Intel used 5 cycles for one instruction, and
NEC found a way to do it in 4 cycles...

And, I had stacks of these instructions, inside of loops that
timed the note pitch.

-Chuck Harris

Dave Seiter wrote:
Grin! Things were different back then. In high school we had dial
up line to a
HP2000 at the Stanford business school using DECWriters, and one
could wander
through the directories, browsing students projects. It was usually
very
responsive, but sometimes it would really bog down, and we'd have to
use one of
the in-class micros (PET/APPLEII/TRS80) to work on our projects. But
they were
all more reliable than our PDP8/E; we had to use that for Fortran,
and it was
always breaking down. I think I was one of the last people to learn
how to use a
keypunch machine!
-Dave





Re: Your generosity is STUNNING!

Jeff Davis
 

Similarly to Larry W6FUB, I also provided details in a private message to Dennis. And I'm also in California. And I also didn't see my contribution on the list. Maybe Paypal changed the transaction ID, I don't know. I just know that I didn't see mine on the list.

I'm not concerned with getting a Paypal refund.
I'm not concerned with what Dennis and Michael choose to do with the donation.

I AM CONCERNED that the donation has reached the right hands, since it did not appear on the list that Dennis took the time and I'm sure a great deal of effort to provide.

Dennis, is there any way to allay those concerns? I believe there are a number of us who share them. If we could understand why the transactions aren't matching, speaking only for myself I'd rest a lot easier knowing that the funds did indeed find their way into the right hands. Then, I'll shut up and go back to sleep!

Thanks,
Jeff N0DY

________________________________
From: TekScopes@groups.io <TekScopes@groups.io> on behalf of Larry McDavid <lmcdavid@...>
Sent: Monday, January 20, 2020 11:42 AM
To: TekScopes@groups.io <TekScopes@groups.io>
Subject: Re: [TekScopes] Your generosity is STUNNING!

I don't want to beat this issue to death, but the comment below is very
interesting. I could not find my PayPal transaction number in the list
either and I wrote Dennis privately to explain that. But, mine was *not*
an international transaction; I live in California. My donated amount is
a common amount so I could not identify it by the amount.

So, I wonder if PayPal changes *all* the transaction numbers. Did anyone
actually find his transaction number in the list Dennis published?

It is gratifying that so many did donate and I fully support the
reimbursement; it is money well deserved.

Larry W6FUB

On 1/20/2020 9:45 AM, Raymond Domp Frank wrote:
Dennis,
My transaction could well be
9SK43*******0851N $22.57 TO BE REFUNDED
That's the only transaction in your list for the amount that I transferred.
Siggi may be right in assuming that Paypal references change between sender and receiver (nice!) for international transactions....
--
Best wishes,

Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)

Re: What Tektronix means to me

Mlynch001
 

I am in awe of minds that are assembled in this group. The fact that you folks are accessible to all of us is remarkable.

--
Michael Lynch
Dardanelle, AR

Re: What Tektronix means to me

Abc Xyz
 

Chuck,

I wonder every time I read a Post on this Thread whether you fellas have
any idea how Blessed you are to have all that Talent & Intellect !?

JR

On Mon, Jan 20, 2020, 1:36 PM Chuck Harris <cfharris@...> wrote:

I wonder how many of us have had to suffer through using
a 513D?

I was given one for Christmas when I was about 14, with
the express understanding that my dad could use it if he
needed it.... He did, and burned out the front end by
probing around in a horizontal section of a TV set.

And thus began my great adventure fixing the all mighty
513D.

I had to scrape away the arc'd over section of micarta on
the vertical input attenuator switch, fill it with epoxy,
replace the burned out precision resistor with selected
carbon composition resistors, and replace a few capacitors
and tubes.

Then I replaced all of the bumble bee capacitors, as they
were all leaky, both physically and electrically. And then,
all of the Sprague 20uf-20uf, 450V FP style capacitors...
and most of the 1 and 2W carbon composition resistors that
fed them... and the screen of the forest of 6AG7 metal tubes...

And, then, one of the 5642 diodes in the HV can popped, making
the beam dim and very large... So, I learned to puddle in
an oil filled assembly...

Fun!

I still have it at my mom's house. I wonder if it still
works?

I too designed a ttl computer, but that was when I learned
that I am truly greedy. I couldn't be satisfied with TTL
speeds, so I had to use STTL. A modest instruction set wasn't
good enough, so I had to give it all 16 possible logical/arithmetic
functions of two inputs... and a full 74S181 ALU. An accumulator
and an address register wasn't enough, so I designed in a 16 word
register file. I couldn't even consider making it byte wide, as
that would take multiple fetches per instruction, so it was at
first 16 bit, and then became 24 bit...

I accumulated parts, spending all of my lunch money... until
Morrow's Microstuff announced its $130 front panel/CPU replacement
board for the S100 IMSAI 8080 computer... and my own design died.

I never had an assembler for the 8080, I assembled everything by
hand directly into located machine language.

I guess I have always been a CISC over RISC guy.

-Chuck Harris

Harvey White wrote:
I (very early on) tried to build a Tektronix calculator out of TTL,
jumps, program
flow, and then an FPU.

Got the jumps and program flow working, you could do an indirect jump
through a
location in hardware (and yes, this was very early....)

I built an 8 trace scope switch to be able to look at digital traces on
my 513D (I
got lucky getting the 513D, P11 phosphor).

Simple enough, sync a counter to the sweep trigger output, take the
counter, run it
to a multiplexer and weight the multiplexer output as '1' in a very
crude D/A.

Take the appropriate counter outputs and weight them 2, 4 and 8.

Instant 8 traces on a 1 channel scope, for 5 volt TTL, of course.

Then along came the 6502, for 30 dollars, one each (while the 8080 was
still 100
dollars or so). I looked at my 130 chip wirewrapped design (still not
done), and
felt a bit bad.......

I bought two (and literally, drove to the MOS technology factory to pick
them up with
the original books). Still have them, I think.

There were some bugs in the microcode, some things not implemented, and
I seem to
remember being bitten by that once I got the "newer" processors.

Naturally, the whole thing was in assembly language. Program the thing
at work
(someone tweaked the DG macro assembler), program the UVPROMS, take it
home and
single step (hardware) through the program.

Everything was wirewrap then. Just everything.

Harvey


On 1/20/2020 9:39 AM, Chuck Harris wrote:
Many of us early adopters to microprocessors got bit by
the discovery that not all of the 8080's made were truly
compatible.

Everyone knows that Intel developed the 8080, but some might
not remember that the Japanese company NEC, almost immediately
introduced a cheaper, unauthorized, second source to the 8080...
only theirs was partly done from Intel's design, and partly
done on their own.

Some of the subtle differences were in the settings of flags
after some arithmetic operations, and in the numbers of clock
cycles used by some common instructions.

I discovered the flag problem, when I found some code that
should have branched, only it didn't... NEC fixed a mistake in
the Intel microcode.

I discovered the clock cycle problem when I was writing a music
program, that played on a transistor radio... using timing loops.

I meticulously counted cycles, ala the Intel data book, but
several notes were coming out sharp.

It turns out that Intel used 5 cycles for one instruction, and
NEC found a way to do it in 4 cycles...

And, I had stacks of these instructions, inside of loops that
timed the note pitch.

-Chuck Harris

Dave Seiter wrote:
Grin! Things were different back then. In high school we had dial
up line to a
HP2000 at the Stanford business school using DECWriters, and one could
wander
through the directories, browsing students projects. It was usually
very
responsive, but sometimes it would really bog down, and we'd have to
use one of
the in-class micros (PET/APPLEII/TRS80) to work on our projects. But
they were
all more reliable than our PDP8/E; we had to use that for Fortran, and
it was
always breaking down. I think I was one of the last people to learn
how to use a
keypunch machine!
-Dave





Re: What Tektronix means to me

Chuck Harris
 

I wonder how many of us have had to suffer through using
a 513D?

I was given one for Christmas when I was about 14, with
the express understanding that my dad could use it if he
needed it.... He did, and burned out the front end by
probing around in a horizontal section of a TV set.

And thus began my great adventure fixing the all mighty
513D.

I had to scrape away the arc'd over section of micarta on
the vertical input attenuator switch, fill it with epoxy,
replace the burned out precision resistor with selected
carbon composition resistors, and replace a few capacitors
and tubes.

Then I replaced all of the bumble bee capacitors, as they
were all leaky, both physically and electrically. And then,
all of the Sprague 20uf-20uf, 450V FP style capacitors...
and most of the 1 and 2W carbon composition resistors that
fed them... and the screen of the forest of 6AG7 metal tubes...

And, then, one of the 5642 diodes in the HV can popped, making
the beam dim and very large... So, I learned to puddle in
an oil filled assembly...

Fun!

I still have it at my mom's house. I wonder if it still
works?

I too designed a ttl computer, but that was when I learned
that I am truly greedy. I couldn't be satisfied with TTL
speeds, so I had to use STTL. A modest instruction set wasn't
good enough, so I had to give it all 16 possible logical/arithmetic
functions of two inputs... and a full 74S181 ALU. An accumulator
and an address register wasn't enough, so I designed in a 16 word
register file. I couldn't even consider making it byte wide, as
that would take multiple fetches per instruction, so it was at
first 16 bit, and then became 24 bit...

I accumulated parts, spending all of my lunch money... until
Morrow's Microstuff announced its $130 front panel/CPU replacement
board for the S100 IMSAI 8080 computer... and my own design died.

I never had an assembler for the 8080, I assembled everything by
hand directly into located machine language.

I guess I have always been a CISC over RISC guy.

-Chuck Harris

Harvey White wrote:

I (very early on) tried to build a Tektronix calculator out of TTL, jumps, program
flow, and then an FPU.

Got the jumps and program flow working, you could do an indirect jump through a
location in hardware (and yes, this was very early....)

I built an 8 trace scope switch to be able to look at digital traces on my 513D (I
got lucky getting the 513D, P11 phosphor).

Simple enough, sync a counter to the sweep trigger output, take the counter, run it
to a multiplexer and weight the multiplexer output as '1' in a very crude D/A.

Take the appropriate counter outputs and weight them 2, 4 and 8.

Instant 8 traces on a 1 channel scope, for 5 volt TTL, of course.

Then along came the 6502, for 30 dollars, one each (while the 8080 was still 100
dollars or so).  I looked at my 130 chip wirewrapped design (still not done), and
felt a bit bad.......

I bought two (and literally, drove to the MOS technology factory to pick them up with
the original books).  Still have them, I think.

There were some bugs in the microcode, some things not implemented, and I seem to
remember being bitten by that once I got the "newer" processors.

Naturally, the whole thing was in assembly language.  Program the thing at work
(someone tweaked the DG macro assembler), program the UVPROMS, take it home and
single step (hardware) through the program.

Everything was wirewrap then.  Just everything.

Harvey


On 1/20/2020 9:39 AM, Chuck Harris wrote:
Many of us early adopters to microprocessors got bit by
the discovery that not all of the 8080's made were truly
compatible.

Everyone knows that Intel developed the 8080, but some might
not remember that the Japanese company NEC, almost immediately
introduced a cheaper, unauthorized, second source to the 8080...
only theirs was partly done from Intel's design, and partly
done on their own.

Some of the subtle differences were in the settings of flags
after some arithmetic operations, and in the numbers of clock
cycles  used by some common instructions.

I discovered the flag problem, when I found some code that
should have branched, only it didn't... NEC fixed a mistake in
the Intel microcode.

I discovered the clock cycle problem when I was writing a music
program, that played on a transistor radio... using timing loops.

I meticulously counted cycles, ala the Intel data book, but
several notes were coming out sharp.

It turns out that Intel used 5 cycles for one instruction, and
NEC found a way to do it in 4 cycles...

And, I had stacks of these instructions, inside of loops that
timed the note pitch.

-Chuck Harris

Dave Seiter wrote:
  Grin!  Things were different back then.  In high school we had dial up line to a
HP2000 at the Stanford business school using DECWriters, and one could wander
through the directories, browsing students projects. It was usually very
responsive, but sometimes it would really bog down, and we'd have to use one of
the in-class micros (PET/APPLEII/TRS80) to work on our projects.  But they were
all more reliable than our PDP8/E; we had to use that for Fortran, and it was
always breaking down.  I think I was one of the last people to learn how to use a
keypunch machine!
-Dave