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ClausB

Atari 800 Engineering Serial 26

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Does the Basic match with Rev-A ?

 

Could that "4-18" on the stickers be the burn date? April 1979 if the case might mean that it's an earlier build. Although didn't Atari stupidly get hundreds of thousands manufactured early on before being told it was buggy and a fix was on the way?

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If Atari had taken the prototype design into production, a full 800 would have had 4K+16K+16K RAM. Would 36K total RAM have been so bad?

 

I don't think so, as long as they had offered DOS in a right cartridge ROM, so it would not take up any RAM. Then total free RAM for BASIC programs would have been even a little more than it was with the RAM-based DOS. Atari was big on ROM-based software, so it would have been logical for them to put DOS in ROM. Besides, what else was the right cart slot good for?

 

Does anyone know whether they actually ever considered making a DOS cart?

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CB....So is your A800 just an early production model or an Engineering prototype (i.e so that jay, Joe, Doug and Co can check that everything works as it should do)

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It's some of both. The 1978 motherboard and RAM boards, along with the unmarked ROM boards, are laid out according to the prototype memory map posted above (see also posted schematics). Then they were cut-and-jumpered to work with the production map and their EPROMs were written with production code. The CPU board is early production, hand-soldered with no solder mask, and its chips are nice early ceramics, but it is not from the original prototype.

 

What purposes #26 served, I can only guess. As a prototype, it participated possibly in early firmware and software testing. After the production mods, it may have been an internal software development machine, as the sticker underneath hints. After going to PDI, it probably developed their first Atari titles.

 

I have never seen another 800 like it. Has anyone?

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It's some of both. The 1978 motherboard and RAM boards, along with the unmarked ROM boards, are laid out according to the prototype memory map posted above (see also posted schematics). Then they were cut-and-jumpered to work with the production map and their EPROMs were written with production code. The CPU board is early production, hand-soldered with no solder mask, and its chips are nice early ceramics, but it is not from the original prototype.

 

What purposes #26 served, I can only guess. As a prototype, it participated possibly in early firmware and software testing. After the production mods, it may have been an internal software development machine, as the sticker underneath hints. After going to PDI, it probably developed their first Atari titles.

 

I have never seen another 800 like it. Has anyone?

 

 

 

 

 

What, you've seen an actual proto atari 800, any pics....

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OK, I used the word "prototype" too loosely there. It's certainly not a hand-wired breadboard nor was it the first functional 800. But it was the 26th of what was likely the first pre-production run for Engineering use. The RAM boards say 78 REV 1 and the motherboard says 1978 REV 2. Many boards are hand-soldered. Curt said he has only seen one other cart door label like this one. I have not seen detailed pics of Curt's early 800s and 400s, so I don't know how unique #26 really is. The fact that Atari let it go may have saved it. Companies often destroy pre-production units when their job is done.

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Was there any reason why atari went with a replaceable O/S like that...or were they planning different iterations/versions of A8

The 800 has at least two OS revisions, A and B. The OS board allows updates.

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If Atari had taken the prototype design into production, a full 800 would have had 4K+16K+16K RAM. Would 36K total RAM have been so bad?

 

I don't think so, as long as they had offered DOS in a right cartridge ROM, so it would not take up any RAM. Then total free RAM for BASIC programs would have been even a little more than it was with the RAM-based DOS. Atari was big on ROM-based software, so it would have been logical for them to put DOS in ROM. Besides, what else was the right cart slot good for?

 

Does anyone know whether they actually ever considered making a DOS cart?

 

So, would 36K total RAM have been so bad if DOS were in ROM?

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Claus, is 6502 any special, or it is generic not atari branded (without any atari catalouge markings)?

your chips are much older, and they have their names written in front of catalouge number too ;)

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The 6502's label is badly scratched but it says A, which might mean 6502A (not 6502B as in other Ataris). Also, it does not quite work in this 800 (see post 23 above).

 

There might be an interesting story there about the 800's development. The 6502A is supposed to be good to 2 MHz but something about Atari's timing requires a 6502B even though it's just 1.8 MHz.

Edited by ClausB

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Claus, could you check if it would work with known 6502A (ie from some apple or your kim-1)

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No, it uses 4K select lines where the production cart slots have 8K selects. It could only address 8K of ROM at most.

What is the left cartridge/slot pin-out.

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Thanks for the schematic.

 

It is hard to follow the pin order in your schematic, I will post it bellow to make it clearer.

 

I am trying to compare it with the production version.

If you could label the signals on your pictures of the front and back of the Basic cartridge you have it would be easier to compare.

The production has the pin-outs (pin order of signals) listed/labeled on the port and cartridge PCB A thru S and 1 thru 15.

 

Please check the following to see if I have it correct... especially the chip select with address range ...

Pin-out for BASIC cartridge and Serial#26:

 

Cartridge Slot (present on all machines; Left Cartridge Slot on 800):

 

CARTRIDGE COMPONENT SIDE (toward BACK of system when inserted)

12 11 10 09 08 07 06 05 04 03 02 01

o o o o o o o o o o o o

o o o o o o o o o o o o

N M L K J H F E D C B A

CARTRIDGE FOIL SIDE(toward FRONT of system when inserted)

 

1. A3 CPU Address bus line A. GND

2. A2 CPU Address bus line B. A4 CPU Address bus line

3. A1 CPU Address bus line C. A5 CPU Address bus line

4. A0 CPU Address bus line D. A6 CPU Address bus line

5. D4 CPU Data bus line E. A7 CPU Address bus line

6. D5 CPU Data bus line F. A8 CPU Address bus line

7. D2 CPU Data bus line H. A9 CPU Address bus line

8. D1 CPU Data bus line J. SC' Chip Select--

9. D0 CPU Data bus line K. D3 CPU Data bus line

10. D6 CPU Data bus line L. D7 CPU Data bus line

11. SB' Chip Select--$B000 - $CFFF M. A11 CPU Address bus line

12. +5V N. A10 CPU Address bus line

 

 

Right Cartridge Slot (800 only):

 

CARTRIDGE COMPONENT SIDE (toward BACK of system when inserted)

12 11 10 09 08 07 06 05 04 03 02 01

o o o o o o o o o o o o

o o o o o o o o o o o o

N M L K J H F E D C B A

CARTRIDGE FOIL SIDE(toward FRONT of system when inserted)

 

1. A3 CPU Address bus line A. GND

2. A2 CPU Address bus line B. A4 CPU Address bus line

3. A1 CPU Address bus line C. A5 CPU Address bus line

4. A0 CPU Address bus line D. A6 CPU Address bus line

5. D4 CPU Data bus line E. A7 CPU Address bus line

6. D5 CPU Data bus line F. A8 CPU Address bus line

7. D2 CPU Data bus line H. A9 CPU Address bus line

8. D1 CPU Data bus line J. SA' Chip Select--

9. D0 CPU Data bus line K. D3 CPU Data bus line

10. D6 CPU Data bus line L. D7 CPU Data bus line

11. S9' Chip Select--$9000 - $AFFF M. A11 CPU Address bus line

12. +5V N. A10 CPU Address bus line

 

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

See pin-out for production 800 bellow,

Cartridge Slot (present on all machines; Left Cartridge Slot on 800):

 

CARTRIDGE COMPONENT SIDE (toward BACK or BOTTOM of system when inserted)

15 14 13 12 11 10 09 08 07 06 05 04 03 02 01

o o o o o o o o o o o o o o o

o o o o o o o o o o o o o o o

S R P N M L K J H F E D C B A

CARTRIDGE FOIL SIDE(toward FRONT or TOP of system when inserted)

 

1. S4' Chip Select--$8000 to $9FFF A. RD4 ROM present--$8000 to $9FFF

2. A3 CPU Address bus line B. GND Ground

3. A2 CPU Address bus line C. A4 CPU Address bus line

4. A1 CPU Address bus line D. A5 CPU Address bus line

5. A0 CPU Address bus line E. A6 CPU Address bus line

6. D4 CPU Data bus line F. A7 CPU Address bus line

7. D5 CPU Data bus line H. A8 CPU Address bus line

8. D2 CPU Data bus line J. A9 CPU Address bus line

9. D1 CPU Data bus line K. A12 CPU Address bus line

10. D0 CPU Data bus line L. D3 CPU Data bus line

11. D6 CPU Data bus line M. D7 CPU Data bus line

12. S5' Chip Select--$A000 to $BFFF N. A11 CPU Address bus line

13. +5V P. A10 CPU Address bus line

14. RD5 ROM present--$A000 to $BFFF R. R/W' CPU read/write

15. CCTL' Cartridge control select S. B02,Phi2 CPU Phase 2 clock

 

Right Cartridge Slot (800 only):

 

CARTRIDGE COMPONENT SIDE (toward BACK of system when inserted)

15 14 13 12 11 10 09 08 07 06 05 04 03 02 01

o o o o o o o o o o o o o o o

o o o o o o o o o o o o o o o

S R P N M L K J H F E D C B A

CARTRIDGE FOIL SIDE(toward FRONT of system when inserted)

1. R/W' CPU read/write late A. B02,Phi2 CPU Phase 2 clock

2. A3 CPU Address bus line B. GND Ground

3. A2 CPU Address bus line C. A4 CPU Address bus line

4. A1 CPU Address bus line D. A5 CPU Address bus line

5. A0 CPU Address bus line E. A6 CPU Address bus line

6. D4 CPU Data bus line F. A7 CPU Address bus line

7. D5 CPU Data bus line H. A8 CPU Address bus line

8. D2 CPU Data bus line J. A9 CPU Address bus line

9. D1 CPU Data bus line K. A12 CPU Address bus line

10. D0 CPU Data bus line L. D3 CPU Data bus line

11. D6 CPU Data bus line M. D7 CPU Data bus line

12. S4' Chip Select--$8000 to $9FFF N. A11 CPU Address bus line

13. +5V P. A10 CPU Address bus line

14. RD4 ROM present--$8000 to $9FFF R. R/W' Read/write

15. CCTL' Cartridge control select S. B02, Phi2 CPU Phase 2 clock

 

Thanks to FAQS.ORG for the above, I slightly modified it for troubleshooting.

http://www.faqs.org/faqs/atari-8-bit/faq/section-17.html

Edited by Defender II

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Oh well, if there are any errors in my previous post, it won't let me correct them now. :P

It looks like your BASIC cartridge should work in a production 800 if you align the left most pad with the third slot pins from the left, is that correct?

I think that was what Rybags was referring to as downward compatible in post #38.

Edited by Defender II

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You and Rybags are right that the 24-pin cart pinout is a subset of the production pinout, except for the 4 KB select lines at 11 and J. The production cart has an 8 KB select (S5) on 12 and A12 on K.

 

So, what would happen if I aligned 26's BASIC cart in a production 800 as you say? For addresses between $A000 and $AFFF, S5 and A12 would both be low, so both 4 KB EPROMs would be selected at the same time, so their outputs would collide and give the CPU junk data. So it won't work.

 

There are a couple other threads around here, one about a 24-pin Dorsett Educational cart and one about a pre-production 400, if that interests you.

http://atariage.com/forums/topic/270445-candy-prototype

http://atariage.com/forums/topic/203281-atari-400800-smaller-cartridge-slots

 

Edited by ClausB
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Thanks for the updates. I'd really love to check it out; it is such a great missing link.

Please let me know if you ever decide to part with it and the BASIC cartridge.

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The original 800 Operators Manual also confirms the memory map in this thread's first post - except for the 48K part. "... experienced computer operators" indeed - experienced with a soldering iron!

 

https://archive.org/details/Atari800OperatorsManualFirstVersion1979

 

attachicon.gif4k800.jpg

 

*N*I*C*E* 800, the "Boss" !

 

Mhmmm... that black face-plate / color around the front joystick ports.... looks BAD-ASS !

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