Date   
Re: 8 slot RCA Microboard Chassis

gregory simmons
 

David, thank you for sharing that link.  I had been looking for a source of backplanes.

In my case, the chassis I saw was 8 slot... I didn't have an option for a smaller one.  However, I agree with you that I probably won't ever fill up all 8 slots!


On Saturday, August 17, 2019, 11:51:57 AM EDT, David Schultz <david.schultz@...> wrote:


On 8/15/19 10:24 AM, gregory simmons via Groups.Io wrote:
> I recently purchased an 8-slot RCA Microboard Chassis on eBay.  It
> includes the backplane.  It's beautiful, heavy, and solid as a rock.  If
> there's any interest, I'd be glad to disassemble it and post photos of
> its constituent pieces, including the backplane, in case someone wanted
> to use the photos to make a template to create their own microboard
> chassis.  -greg/ab8im  

8 slots is kind of overkill when you can get a 512KB CMOS SRAM. I
decided that 3 was good enough for my needs:

https://oshpark.com/shared_projects/OC8TKQk6


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Re: 8 slot RCA Microboard Chassis

David Schultz
 

On 8/15/19 10:24 AM, gregory simmons via Groups.Io wrote:
I recently purchased an 8-slot RCA Microboard Chassis on eBay.  It
includes the backplane.  It's beautiful, heavy, and solid as a rock.  If
there's any interest, I'd be glad to disassemble it and post photos of
its constituent pieces, including the backplane, in case someone wanted
to use the photos to make a template to create their own microboard
chassis.  -greg/ab8im  
8 slots is kind of overkill when you can get a 512KB CMOS SRAM. I
decided that 3 was good enough for my needs:

https://oshpark.com/shared_projects/OC8TKQk6


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Re: 8 slot RCA Microboard Chassis

bill rowe
 

that's an excellent idea. 


From: cosmacelf@groups.io <cosmacelf@groups.io> on behalf of Lee Hart <leeahart@...>
Sent: August 16, 2019 10:47 PM
To: cosmacelf@groups.io <cosmacelf@groups.io>
Subject: Re: [cosmacelf] 8 slot RCA Microboard Chassis
 
chuck cmdrcosmac wrote:
> ... I found that a card-cage new was WAY over my budget. Card-
> edge connectors aren't much cheaper than the DIN connectors, and
> proto-boards with edge fingers aren't cheap.
>
> An important consideration is ease of debugging. You must be able to
> get instrument probes anywhere on the board under test. This is where
> card cages and backplanes are inconvenient.

Here's a scheme I have used since my very earliest micro (a Mark-8):

Use ribbon cable as your "bus" instead of a motherboard full of
connectors. Crimp a female IDC (Insulation Displacement Connector) onto
the ribbon cable every inch or two.

Put matching right-angle male headers on each of your PC boards.

The cards can all be placed in a card rack to hold them parallel to each
other. Or, you can use long screws and spacers to hold them apart.

For servicing and troubleshooting, the cards can be opened like pages in
a book. The ribbon cable is flexible enough so you can get at both sides
of any card, even while it's connected to the rest of the system.

--
Whether we or our politicians know it or not, Nature is party to all
our deals and decisions, and she has more votes, a longer memory,
and a sterner sense of justice than we do. -- Wendell Berry
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com




--
Bill Rowe
Olduino - an arduino for the first of us
https://olduino.wordpress.com/about-2/about/

Re: 8 slot RCA Microboard Chassis

cmdrcosmac
 

 Lee,
Thank you for your response. I had thought of the ribbon cable concept.
Unless you use the proper tooling to crimp on the connectors, the connections
may not be reliable. Where I used to work we used a lot of IDC/ribbon stuff.
it sometimes caused trouble. I didn't want to buy the tooling. ($$)
 Thinking back, there are suppliers who will make up short runs of this stuff.
Samtec comes to mind. Actually this is probably the cheapest way to do a backplane.
 Space the connectors to fit a card cage if needed, and one on a longer "tail"
for accessibility.
-Chuck

Re: 8 slot RCA Microboard Chassis

Lee Hart
 

chuck cmdrcosmac wrote:
... I found that a card-cage new was WAY over my budget. Card-
edge connectors aren't much cheaper than the DIN connectors, and
proto-boards with edge fingers aren't cheap.

An important consideration is ease of debugging. You must be able to
get instrument probes anywhere on the board under test. This is where
card cages and backplanes are inconvenient.
Here's a scheme I have used since my very earliest micro (a Mark-8):

Use ribbon cable as your "bus" instead of a motherboard full of connectors. Crimp a female IDC (Insulation Displacement Connector) onto the ribbon cable every inch or two.

Put matching right-angle male headers on each of your PC boards.

The cards can all be placed in a card rack to hold them parallel to each other. Or, you can use long screws and spacers to hold them apart.

For servicing and troubleshooting, the cards can be opened like pages in a book. The ribbon cable is flexible enough so you can get at both sides of any card, even while it's connected to the rest of the system.

--
Whether we or our politicians know it or not, Nature is party to all
our deals and decisions, and she has more votes, a longer memory,
and a sterner sense of justice than we do. -- Wendell Berry
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com

Re: 8 slot RCA Microboard Chassis

cmdrcosmac
 

My $0.02 worth...

I did a backplane expander for my SuperElf. It's a piece of perf-board extending
from the the rear of the Elf board. A DIN 50-pin female vertical-mount connector,
 DigiKey H11206-ND  is soldered on the bottom side of the Elf. Its mate, DK H11166-ND,
is mounted on the top of the perf-board. 4 female connectors, D-K A32831-ND are mounted
on the top of the Perf-board an inch apart.
 The Elf and the backplane are mounted on a board, on standoffs such that the Elf plugs
into the backplane. The addon cards have the DK A32297-ND mounted at one edge.
There is no card cage, so the size of the boards is not constrained.
This is all point-to-point wired.
 There may be pictures of this in the "Commander Cosmac" files
section.
 
 When designing this, I found that a card-cage new was WAY over my budget. Card-
edge connectors aren't much cheaper than the DIN connectors, and proto-boards with
edge fingers aren't cheap. This arrangement is cheap and flexible.
 
 An important consideration is ease of debugging. You must be able to get instrument
probes anywhere on the board under test. This is where card cages and backplanes are
inconvenient. With a cage, you need an extender to get the card out where you can get
at it and it's still standing up. With an open backplane you may have to rearrange
the cards so that you can get at the one you are working on.
 
 If I were making another backplane I would have one right-angle card connector on
the side, so a card under test would lay flat and unobstructed.
 As it is, my system has been very reliable.
-- Chuck

RetroShield 1802 released

Erturk Kocalar
 

Hi all,

 

I know it would never feel like the real thing but if there is any use for any purpose or anybody, I released the 1802 version of RetroShield.  If one is familiar with Arduino Mega and have a 1802 chip, it should be easy to bread-board it in one night. Schematics and Arduino code are available here.

 

https://gitlab.com/8bitforce/retroshield1802

 

Currently, it runs a combination of MCSMP, Tiny BASIC and RCA BASIC3 (combinations of two, and even all three). I also got the IDIOT monitor working, but need to do clean-up in SW and get permission from Lee before releasing it publicly.

 

I owe huge thank you to i) Chuck for helping with the MCSMP binary images, documentation and answering questions, ii) Lee for helping w/ hardware details earlier on.  Arduino software prints credit to everybody involved and provides a link to Lee’s website for membership card. Hopefully we get more 1802’s working.

 

I found another monitor, Dave’s monitor, that I got permission to use so that’ll be next in a few weeks. This is the link.

https://sites.google.com/site/walztronix/electronics/1802-projects

 

I want to switch tracks to other processors little bit (2650 and 4004), but for 1802, I got permission to use STG1681 design files so that’ll be something to work on down the road.

 

Thank you for all your help. I already forgot about 8031 and 8085, but I will continue to play with 1802 for awhile 😊

 

Erturk

Sent from Mail for Windows 10

 

Re: 8 slot RCA Microboard Chassis

Herbert Nowell
 

I am very interested.  After I get a classic ELF up something with a backplane to experiment is on my to do list.

8 slot RCA Microboard Chassis

gregory simmons
 

I recently purchased an 8-slot RCA Microboard Chassis on eBay.  It includes the backplane.  It's beautiful, heavy, and solid as a rock.  If there's any interest, I'd be glad to disassemble it and post photos of its constituent pieces, including the backplane, in case someone wanted to use the photos to make a template to create their own microboard chassis.  -greg/ab8im  

Re: Still produced (was Re: Intersil approval)

David Schultz
 

On 8/14/19 11:05 AM, Herbert Nowell wrote:
I was under the impression the Renesas had ceased production.  Is that
incorrect?  I hope it is as I just learned about the ELF lat year and am
building my first.  It is the most interesting thing I have found in the
retro world, pulling just head of the Jupiter ACE (which I so dearly
wanted BITD...the ELF was a bit before my time).
It still has a web page. But if you click through to "ordering" you find
that the price for thousand unit quantities is $146 each. Not a mass
production price.

https://www.renesas.com/us/en/products/space-harsh-environment/harsh-environment/microprocessors-peripherals/device/CDP1802A.html#overviewInfo


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Re: Still produced (was Re: Intersil approval)

Lee Hart
 

Intersil was acquired by Renesas in 2017

I was under the impression the Renesas had ceased production. Is that
incorrect?
My understanding is that the 1802 is still produced, but in "batch" mode. That is, they have the masks and wafers, but they are not yet packaged. They wait until they have an "order", then finish the parts and package and test them to suit the customer's order. Most modern uses for the 1802 are for legacy military and aerospace; so they are likely to go in expensive packages and get lots of special testing.

But there are still lots of 1802's from previous batches available in the market. Places like ebay, octopart, etc. will reveal dozens of sources.

--
Whether we or our politicians know it or not, Nature is party to all
our deals and decisions, and she has more votes, a longer memory,
and a sterner sense of justice than we do. -- Wendell Berry
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com

Still produced (was Re: Intersil approval)

Herbert Nowell
 

Raymond Sills: an 1802 chip, which Intersil makes and offers for sale.
and as Dave pointed out:

Intersil was acquired by Renesas in 2017
I was under the impression the Renesas had ceased production.  Is that incorrect?  I hope it is as I just learned about the ELF lat year and am building my first.  It is the most interesting thing I have found in the retro world, pulling just head of the Jupiter ACE (which I so dearly wanted BITD...the ELF was a bit before my time).

Re: Question on CDP18S651 Manual - Floppy Disk Controller

David Schultz
 

On 8/13/19 10:09 AM, Jeff Truck wrote:
David Schultz:


Here's how I see the LK4 and LK5 links on the FDC board.   Do they check
out?   I'm assuming based on the rest of the schematic that GPEN-P is an
active HIGH signal which is set when the particular board, in this case
the FDC, will listen for subsequent 6x data bytes.  If this is correct
then we have a good TABLE II to paste in the document.
Looks reasonable.

One thing to note.  I looked up the tech sheet on U24 - CD4585BE.   Now,
either the schematic is wrong or they've updated the 4585 chip since
this circuit was designed, and this is my reasoning.   The schematic
shows pins 4,5 and 6 to be tied HIGH.   These are the cascading inputs. 
 Now when I look at the truth table for 4585, it shows this:
If you look at the schematic in the CD4585 data sheet you will see that
the A=B output does not depend on either the A<B or A>B inputs. So those
cascading inputs only need to be tied either high or low in accordance
with standard CMOS practice. If you were using one of the other outputs,
things would be different.

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Re: Intersil approval

cellarcat
 

Hi, Dave! I am a lawyer myself so I do understand the legal mindset!  The golden rule for us is that the devil is in the details.  I will see what I can find out.

On Aug 10, 2019, at 11:45 PM, Dave Ruske wrote:

The contact names I had for Intersil are in the FAQ if you get to the RCA copyright section before dozing off, but my last contact with them was years ago and those contacts may no longer be correct. The email addresses are almost certainly outdated, since a quick Google search shows Intersil was acquired by Renesas in 2017:
https://www.renesas.com/eu/en/about/press-center/news/2017/news20170225a.html

I don't have any special insight. Tracking down those contacts was mainly a matter of emailing a general-purpose address found on Intersil's website and asking who in the legal department might be contacted about old copyrights. From past dealings with some corporate lawyers, I've found it is helpful to be brief but specific about what you'd like (lawyers are understandably wary of granting overly broad requests). Patience and respect are usually all that's needed to navigate any corporate hierarchy... or maybe I've just been lucky. :)

Dave

Re: Question on CDP18S651 Manual - Floppy Disk Controller

Jeff Truck
 

David Schultz:

Here's how I see the LK4 and LK5 links on the FDC board.   Do they check out?   I'm assuming based on the rest of the schematic that GPEN-P is an active HIGH signal which is set when the particular board, in this case the FDC, will listen for subsequent 6x data bytes.  If this is correct then we have a good TABLE II to paste in the document.

image.png

One thing to note.  I looked up the tech sheet on U24 - CD4585BE.   Now, either the schematic is wrong or they've updated the 4585 chip since this circuit was designed, and this is my reasoning.   The schematic shows pins 4,5 and 6 to be tied HIGH.   These are the cascading inputs.   Now when I look at the truth table for 4585, it shows this:

image.png

U24 only connects output pin 3 (A=B) to feed (based on the LK4 selection to pick either 1:4 or 1:15 addressing) the GPEN-P signal.  According to the truth table, the only time A=B will be set high is when the cascading inputs need to have A<B LOW and A=B HIGH.  But this isn't the case with the schematic showing them both tied HIGH.  Very confusing.   If you have this FDC board, is there anyway you could confirm that pins 4,5 and 6 are tied HIGH?

Thanks for the help!

Jeff
 
 

Re: Question on CDP18S651 Manual - Floppy Disk Controller

Jeff Truck
 

Thanks David - That helps a lot!

Jeff

Re: Question on CDP18S651 Manual - Floppy Disk Controller

David Schultz
 

On 8/12/19 3:53 PM, Jeffrey Truck wrote:
Regarding the above mentioned publication.  Can someone shed some light
on how the links referenced on the bottom of page 5 are to be read?   I
believe this is Table II.  The copy posted doesn’t seem to indicate what
pins are actually being referenced.  I’m trying to study RCA’s two level
IO selection system and knowing this would help.  
That table confused the hell out of me as well and I understand the two
level I/O system. It would help a lot if the columns were labeled!

Look at the schematic on page 23 and U32 and U24 in particular. This is
a four bit latch (CD4076) and a 4 bit comparator (CD45058).

The link to the left (unlabeled unfortunately but it is LK5) of U32
determines the input to the latch. If you want to use one of the 1-of-4
addresss, connect to your choice of DB0 to DB3. On the link to the right
(LK4) pull B0 (pin 11) high and leaves the other links open. (pulled down)

If on the other hand you want to use one of the decoded (1 of 15)
addresses then connect pin 14 of U32 to DB4 using the link on the left.
Then set the particular address you want (present on DB4-7) on the link
to the right.

MicroDOS assumes you are using one of the 1-of-4 addresses. This is the
only circuit I have seen that can deal with both the 1-of-4 addresses or
the 1-of-15 group.

Translating that to the table...

The left most column shows the group address. X1 means group 1 and the
high nybble doesn't matter. Which isn't true. Those bits must be zero or
you select one of those groups as well.

1X means the first group in the 1-of-15 set. The low order bits are
again not really "don't care" as they must be zero to keep from
selecting one of those I/O groups.



The CDP18S604B documentation (in the files area) has a good description
of the two level I/O system on page 6. Probably described other places
as well.



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Re: COSMAC Software Development Package (CSDP)

David Schultz
 

On 8/10/19 1:51 PM, bill rowe wrote:
Wow.   I don’t think I had ever heard of csdp or seen that syntax. It
reminds me of something though...
Probably the source for UT71. Listing included in the MicroDOS manual
and of course can be found in the files area here as ut71.sr.

ASM8 works just fine under MicroDOS in simulation.

A detailed description of the level II syntax is of course in the
MicroDOS manual: MPM-241


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Question on CDP18S651 Manual - Floppy Disk Controller

Jeff Truck
 

Regarding the above mentioned publication.  Can someone shed some light on how the links referenced on the bottom of page 5 are to be read?   I believe this is Table II.  The copy posted doesn’t seem to indicate what pins are actually being referenced.  I’m trying to study RCA’s two level IO selection system and knowing this would help.  

Thanks!

Jeff

Re: Quest Super Elf recreation boards... #SuperElf

Dave Johnson
 

Would be great if we could place a group order for parts.