Atari "Video Chess" 400/800 Cartridge?

[electronizer]

Okay, I tried a few more things today. First, I followed the instructions in this video to use Jindroush’s cartridge dumping utility to dump both the Video Chess cartridge and my Computer Chess cartridge. I uploaded an atr file with both dumps: Video Chess is called VIDEOCHS.R4, and Computer Chess is called CMPTRCHS.R4. I think these are both 4K dumps, but I’m not exactly sure how to read the graphical display in the cartridge dumping utility. Also, it’s strange that the two 4k banks for Video Chess appear to have exactly the same data (see the cartridge dump utility screenshots below).

 

Video Chess Dump.atr

 

Computer Chess Cartridge Dump Screenshot:

 

 

Video Chess Cartridge Dump Screenshot:

 

 

I’m not sure how to compare these two dumps or even what to look for in terms of differences. Does anyone have any advice/tips?

 

 

Next, I took another picture of the inside of the cart to show the PCB revision. It says "CO12963 REV 2." Thanks @Scooter83 for tipping me off that there might be additional markings on the board!

 

 

 

And, just for fun, I noticed that there is a fingerprint on the inside of the case back:

 

 

Anyone have access to a fingerprint database?

 

 

Is the 5-4 on the EPROM labels a date? If so, I was looking through Atari history around that date (on the "Atari History Timelines by Michael Current" website) and found mention of the 4th West Coast Computer Faire, which was held May 11th-13th, 1979, in San Francisco. The website says the following:

 

Entertainment applications promised: Chess (would ship as: Computer Chess)

 

 

It seems like Atari hadn't yet decided on a final name for their 8-bit chess program, though I wish the website had said the name of the promised application was "Video Chess" instead of just "Chess." Also, I'm wondering if this cartridge was made specifically to show at the Faire.

 

One next step would be to dig through the archives for San Jose and San Francisco newspapers from around that date, but it may be some time before I get a chance to go down to the library and fire up the microfiche reader.

[Mclaneinc]

Lol...Love the big ass fingerprint there, lets fire up the CSI machine

 

As for the files, you could go here

 

https://www.mh-nexus.de/en/

 

Get Hxd and do a compare on the cart dumps and post the differences, now IF this is a proto there might be minimal differences bar possibly a name BUT it could also be a person just editing, I'm starting to not think its that, I have a hunch it IS an early version but with no proof as yet that isn't worth the virtual paper its typed on.

Edited February 20, 2017 by Mclaneinc

[tep392]

I traced the two programs in a debugger, comparing just the beginning of the game init code and they are definitely different revisions of the game. The code is shifted in memory a bit, but there are also differences in the instructions. Not significant, but different. The one on the left is Computer Chess.

 

[electronizer]

Nice @tep392! What debugger is that?

[+DjayBee]

Get Hxd and do a compare on the cart dumps and post the differences, now IF this is a proto there might be minimal differences bar possibly a name BUT it could also be a person just editing, I'm starting to not think its that, I have a hunch it IS an early version but with no proof as yet that isn't worth the virtual paper its typed on.

 

If you can mix Linux/Cygwin with Windows go this way:

 

Convert your binary files on Cygwin/Linux to a hex dump using xxd -g 1 "BINFILE" "HEXDUMP"

 

and then use Winmerge http://winmerge.org/?lang=en to see the differences. I would guess that something similar is also available for MacOS.

 

This way I do my comparisons of different disk dumps.

[Mclaneinc]

 

If you can mix Linux/Cygwin with Windows :

 

 

Won't this cause a paradox in the space-time continuum!

 

[Mclaneinc]

Nice @tep392! What debugger is that?

 

Its the in built debugger in the wonderful emulator, Altirra..

[Mclaneinc]

I traced the two programs in a debugger, comparing just the beginning of the game init code and they are definitely different revisions of the game. The code is shifted in memory a bit, but there are also differences in the instructions. Not significant, but different. The one on the left is Computer Chess.

 

capture.jpg

 

Nice work Tep392, so this seems to confirm its a lot more than a simple copied and possibly hex edited cart, its possibly work in progress code?

 

That suggests in tentative steps that it just might be a proto...But more work from you clever guys..

[Tempest]

I'm guessing it's a very late WIP and they did a minor bug fix or code cleanup before the final release. Still, very cool.

[tep392]

I looked at the code a bit more. One change I noticed is that the font for the graphics and the display list are copied to RAM at $800 on the release version. The "video chess" version runs the font strait out of ROM. Not sure why that change was made. I couldn't find an instance were the fonts were modified during game play. I found some other area's where the code looked substantially different but I didn't try to figure out what it was doing.

[Scooter83]

Info on the board wasn't the ssy number as expected nor was it like my pacman eprom cart either. Which was most likely a home made thing. Might have been a fair or CES show thing.

 

Still very cool item and I love seeing things like this turn up

[Tempest]

Once we figure out the differences I'll post about it on my site.

 

@Scooter83 - I still need to do that Checkbook cart of yours, even though we really can't do much with it. A prototype is a prototype.

[Kr0tki]

Also, its strange that the two 4k banks for Video Chess appear to have exactly the same data (see the cartridge dump utility screenshots below).

It happens when some address lines are left unconnected. Both Computer Chess and Video Chess are 4KB cartridges. In the case of Video Chess, the cartridge port's A12 line is unconnected, so when reading from the ROM area, one bit of the address is ignored. This causes the contents of the 4K ROM to appear twice in the computer's address space.

 

The ROM dumps in your archive are 16KB in size. this is unnecessary. I've trimmed the ROMs to 4K and attached here for convenience.

Chess-roms.zip

 

I looked at the code a bit more. One change I noticed is that the font for the graphics and the display list are copied to RAM at $800 on the release version. The "video chess" version runs the font strait out of ROM. Not sure why that change was made. I couldn't find an instance were the fonts were modified during game play. I found some other area's where the code looked substantially different but I didn't try to figure out what it was doing.

I have disassembled both cartridges: Chess-disasm.zip Compare the two included source files to find the differences.

 

The font in Computer Chess is copied to RAM because they have ran out of space in the ROM. In Video Chess the font is 144 bytes long; in Computer Chess they shortened it to 112 bytes. It is copied from $B000 to $0810 and the missing parts are then restored algorithmically (see the differences after the LB1B9 label).

 

The only real change is in the area between LBC81 and LBC96 labels. All I know is that this code is reached quite frequently during the computer's move computation.

Edited February 23, 2017 by Kr0tki

[Tempest]

The only real change is in the area between LBC81 and LBC96 labels. All I know is that this code is reached quite frequently during the computer's move computation.

 

Maybe they beefed up the AI? That or maybe they sped it up?

[tep392]

 

Maybe they beefed up the AI? That or maybe they sped it up?

I was thinking the same thing, so I did some tests to compare how long the computer takes to move and they are both nearly the same. Today I spent a little time disassembling each version and identified all the differences. There are not that many. The font being loaded to RAM is one notable difference. The last change was to some code that I haven't figured out the purpose of yet. I'm guessing it's a bug fix. The code runs when the computer is thinking about it's move.

 

Here are the files if anyone want's to have a look.

 

edit: read Kr0tki's post after I posted this. Now I understand the reason for font being loaded to RAM. cool.

CMPTRCH.ASM

VIDEOCHS.ASM

[Mclaneinc]

So would the consensus be that this is coded being worked on and improved thus validating its very very likely to be a proto?

 

I just love hearing about new discoveries in my age old hobby...

[Atari8bitCarts]

For what it is worth, my vote is 50/50.

I'm not a prototype expert by any means but all that I have seen dating back to 1979 were on white/grey boards.

And the label seems odd as we have all discussed. Non-Atari created in their lab.

 

I lean towards project cart, very well by an Atari employee, but if the code difference were so close it doesn't explain to me why the board configuration, including kr0tki's analysis.

 

It looks like someone was trying to make Chess a better version, more games, etc. intentions?

[electronizer]

It happens when some address lines are left unconnected. Both Computer Chess and Video Chess are 4KB cartridges. In the case of Video Chess, the cartridge port's A12 line is unconnected, so when reading from the ROM area, one bit of the address is ignored. This causes the contents of the 4K ROM to appear twice in the computer's address space.

 

The ROM dumps in your archive are 16KB in size. this is unnecessary. I've trimmed the ROMs to 4K and attached here for convenience.

Chess-roms.zip

 

I have disassembled both cartridges: Chess-disasm.zip Compare the two included source files to find the differences.

 

The font in Computer Chess is copied to RAM because they have ran out of space in the ROM. In Video Chess the font is 144 bytes long; in Computer Chess they shortened it to 112 bytes. It is copied from $B000 to $0810 and the missing parts are then restored algorithmically (see the differences after the LB1B9 label).

 

The only real change is in the area between LBC81 and LBC96 labels. All I know is that this code is reached quite frequently during the computer's move computation.

 

 

This is fascinating. Makes total sense about leaving A12 unconnected. What did they do with A12 in the production cartridge?

 

The cartridge dump program I used always creates a 16K file, so thanks for trimming it. Did you need to add a header to the ROM to make it emulator compatible? I'm new to binary file manipulation so I'm curious to learn how it's done/what tools you used.

 

Amazing to think that they would go to the trouble of shortening the font and then using an algorithm to restore the missing parts just to save 32 bytes. Really puts into perspective the challenge of writing a program with the 4K ROM limitation.

 

How much space is left in the Video Chess cartridge? I'm guessing it doesn't completely fill 4K. If not, I wonder if the "10 Computer Games" text is there because they planned to add an additional two skill levels before the official release, then realized it wouldn't be possible in the space they had.

Edited February 24, 2017 by electronizer

[electronizer]

For what it is worth, my vote is 50/50.

I'm not a prototype expert by any means but all that I have seen dating back to 1979 were on white/grey boards.

And the label seems odd as we have all discussed. Non-Atari created in their lab.

 

I lean towards project cart, very well by an Atari employee, but if the code difference were so close it doesn't explain to me why the board configuration, including kr0tki's analysis.

 

It looks like someone was trying to make Chess a better version, more games, etc. intentions?

 

I'm still hoping that this cartridge was made for marketing purposes, possibly to be demonstrated at the 1979 West Coast Computer Faire, and that there will be some mention of this in documentation from the time. This is supposedly the first time that Atari demonstrated the home computer line in public, so it's quite possible they hadn't settled on the final label style/colors. Maybe Atari wanted a label that looked close to the real thing but had to print it using a different method because they weren't ready to print production labels.

 

Are there any pictures of Atari prototype cartridge PCBs? I'd be interested to see what they look like.

 

Also, does anyone have a copy of the proceedings of the 4th West Coast Computer Faire? I'd love to know if there is anything in there about Atari's display. Here's the reference entry from the DigiBarn Computer Museum:

 

The Best of the Computer Faires Volume IV: Conference Proceedings of the

Fourth West Coast Computer Faire, May 11-13, 1979 in San Francisco, Jim C.

Warren, Jr., Editor, ISBN: 0-930418-03-X

[tep392]

 

I'm still hoping that this cartridge was made for marketing purposes, possibly to be demonstrated at the 1979 West Coast Computer Faire, and that there will be some mention of this in documentation from the time. This is supposedly the first time that Atari demonstrated the home computer line in public, so it's quite possible they hadn't settled on the final label style/colors. Maybe Atari wanted a label that looked close to the real thing but had to print it using a different method because they weren't ready to print production labels.

 

Are there any pictures of Atari prototype cartridge PCBs? I'd be interested to see what they look like.

 

Also, does anyone have a copy of the proceedings of the 4th West Coast Computer Faire? I'd love to know if there is anything in there about Atari's display. Here's the reference entry from the DigiBarn Computer Museum:

 

The Best of the Computer Faires Volume IV: Conference Proceedings of the

Fourth West Coast Computer Faire, May 11-13, 1979 in San Francisco, Jim C.

Warren, Jr., Editor, ISBN: 0-930418-03-X

Another approach to take is to track down an Atari employee that was involved in that event. Maybe even try to locate the programmer of the game. Kevin Savetz is an Atariage member and podcaster who has interviewed many Atari employees and programmers. You might try contacting him to see if he knows anything or has any contacts that might help your investigation.

http://atariage.com/forums/topic/236768-the-atari-interview-discussion-thread/page-1?hl=+interview%20+discussion%20+thread

edit:

https://chessprogramming.wikispaces.com/Computer+Chess

[Kr0tki]

So would the consensus be that this is coded being worked on and improved thus validating its very very likely to be a proto?

Although we would have to determine the exact function of the added code to be sure, the nature of the differences suggests that Computer Chess ROM is a later revision of the Video Chess ROM. That doesn't say anything about the authenticity of the physical cartridge or it's label, though.

 

This is fascinating. Makes total sense about leaving A12 unconnected. What did they do with A12 in the production cartridge?

A cartridge can disable either 8 or 16 KB of system RAM. So when a cartridge contains only 4KB (or 2 KB, or anything less than full 8 KB) ROM, what happens with the rest of the memory depends on the physical connections on the cartridge PCB. I guess that your Computer Chess has the A12 line connected to the ROM chip's Chip Enable/Chip Select pin, in a way that disables the ROM chip when reading from the $A000-$AFFF area. So when you read from that area, you get "nothing", ie. the value of $FF.

 

On some other Atari computers, the XEs in particular which lack a few pull-up resistors on the memory bus for cost-cutting reasons, reading the unmapped memory area will result in random bytes instead of $FF.

 

The cartridge dump program I used always creates a 16K file, so thanks for trimming it. Did you need to add a header to the ROM to make it emulator compatible? I'm new to binary file manipulation so I'm curious to learn how it's done/what tools you used.

I just used a hex editor (in my case Okteta) and edited out the first 12 KB.

 

How much space is left in the Video Chess cartridge? I'm guessing it doesn't completely fill 4K.

As far as I remember there's only one unused byte, in both versions, a single NOP instruction in an unreachable location. Edited February 24, 2017 by Kr0tki

[Scooter83]

Makes me want to dump my life cart for changes. Label ull never know unless that book mentioned had pics of the video chess game

[Tempest]

Makes me want to dump my life cart for changes. Label ull never know unless that book mentioned had pics of the video chess game

I forgot about that. I need to review that one too.

[Scooter83]

My gut says it's nothing special but after this who knows. I got a ton to have dumped. A few on here reached out 1 was gonna let me borrow a sio to sd to dump roms. But I'd be interested in knowing more about the black box used in this case and how I can get 1 or have 1 made.

[electronizer]

I sent a message to Kevin Savetz (I love the Antic podcast, BTW). Fingers crossed that he might be able to help!

 

AFAIK, the Black Box only allows you to view the contents of memory onscreen; there's no way to dump memory to a file. Earlier in this thread I linked to a video showing how to use Jindroush's cartridge dumper program; that's how I was able to dump the Video Chess and Computer Chess ROMs. I had to use the 1999 version of the program, which I got off of archive.org, and for some reason it wouldn't work with my SIO2SD. There was write activity when I pressed start to dump the ROM, and the amount of free space on the disk image was reduced after the dump, but I couldn't see the file. The file is saved as "ROM16." (no extension), so I wonder if SIO2SD has an issue with filenames that don't have an extension. Anyway, I hooked up a real 1050 and after dumping the cartridge, I was able to see the ROM16 file just fine.