Re: Todd's ELF-ish gets some more I/O #ELF #Homebrew


Hi again Chuck -

On Sat, May 11, 2019 at 11:58 AM, cmdrcosmac wrote:
>> It's one of the reasons I put battery backup on all of the memory - so I don't have to reload the programs.

Note that a common bug when programming is a runaway stack, wherein the INC STACK and DEC STACK's aren't balanced.
This causes a stack crawl and may overwrite the program. Time to reload. I have an EEPROM to save stuff in.
The Elf and IDIOT's !M load routine is slow enough that the chip's byte write mode works just like RAM. I then
disable write with a jumper and block-move the code into RAM.
That's a great idea - will work that into the sprawl.

>> And it should not be hard to patch UT4 to use the UART.
 Since you have the UART, that's probably the easiest. But keep the Q/EF wiring in place as most 1802 software uses
bit-banged serial I/O.
Good point.  There's no reason for me to remove any of that.

 As for Monitors, most folks appear to be using UT4, IDIOT, Chuck Yakym's MCSMP, or ELF2K. The first 3 have similar
functions. ELF2K supports a disk operating system that can run on CF card "disks". MCSMP loads and saves I8hex files.
IDIOT and UT4 use RCA's !M format. MCSMP will run 9600 Baud at a CPU clock of 1.8 MHz. I use IDIOT, and an assembler that
creates RCA-compatible list files that IDIOT (or UT4) can load. IDIOT is run-time relocatable, and will find RAM to
save the registers. UT4 needs to be assembled with a RAM location coded in. UT4 supports JAM_8000 RUN_U, IDIOT does not.
 I am redesigning my Elf expander to locate IDIOT at F800, an EEPROM at 8000 or C000, and the rest RAM. RUN_U will use
the scheme in Ipso Facto.
Thanks for the monitor comparison.  I need to spend some quality time looking over the options.  I'll probably borrow from everything and cobble something together.

I really want to be able to load the Intel HEX dump fromat from the assembler directly, rather than having to use the UT4 !M interface for that.

 I like the labels on the underside of the chip sockets. How are these done??
I'm using the plastic Wrap-ID's where I could get them.  But they are expensive nowadays, so I won't be buying more.

The paper ones are just done up in Inkscape, and then stuck in place with a piece of two-sided tape - I have a roll of very narrow tape for this.

This is just a by-product of my layouts.  I design a full detail layout in Inkscape, and then also flip it over (reversing all of the text again) so I have both a TOP and a BOTTOM view.

For example, from the VIS build:

Printing an extra copy of the bottom view gives me the labels to cut out.

>>  My design approach has been to use as many of the CDP1800 series as I could source
>> - and I managed to get just about the complete set.

Where did you get the 1863 frequency divider??
Just did a search on eBay and it popped up from someone in China.  He seems to still have some available.  They are used though, but mine worked fine.

Please tell us more about the Logic Analyzer!
Just like you can get very cheap scan converters today, you can get very check logic analyzers.  They are built using a little MCU development board, but with Logic Analyzer FW added.

This one I found on (I'm in the UK) from Hobby Components Ltd for about £16 (~ $20).

The board is basically just and interface card - all of the processing happens on the laptop using the open source package sigrok.

Nothing fancy, but get's the job done and cheaply.


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