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CPM/Z-80 card for the 1090XL -- Calling anyone with Z-80 experience!


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Waiting with bated breath.  

 

So any idea what's going to happen when you plug it in and power it up?  I assume that it will need a ribbon cable to connect it to an adjacent ram card since there's no ram on board...or is there?  Is there rom on board?  How does this puppy work?

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15 minutes ago, Geister said:

Waiting with bated breath.  

 

So any idea what's going to happen when you plug it in and power it up?  I assume that it will need a ribbon cable to connect it to an adjacent ram card since there's no ram on board...or is there?  Is there rom on board?  How does this puppy work?

 

At first, it will do nothing.   🙂  The card doesn't have RAM or ROM, either.

 

My plan is to first plug the card in with a minimal number of chips installed and make sure the clock timing is correct.  Then I'll install all of the chips except the Z-80 and make sure the decoding and reset toggle work as planned. 

 

Today, the last component of the 64k RAM card is to arrive so I should be able to test the 64k RAM card today.  Assuming the RAM card works, I'll connect both cards together via a ribbon cable at the top.  The RAM would work in Bank Switched mode so that the host can initially load it prior to the Z-80 booting up.  There are two completely unknown chips on the card.  Based on the traces going to one of the chips, it looked like that chip had to be used to control the Z-80 from the host.  So I put a 74LS74 in it's place and configured it to hold the Z-80 in a reset state when the host boots up.  After the host loads the RAM, the host can then tell the Z-80 to boot.

 

It's the job of the host computer to load at least a boot loader into the RAM and to handle all I/O.  I think a next logic step would be to see if the Z-80 can do something.  Having the Z-80 do something simple, like executing an XOR operation seems to be the easiest test to make.  So my plan is to create a little bit of Z-80 code that does nothing but take whatever value the host provides, XOR it, and return it, seems to be a nice simple test to ensure the Z-80 and host can work together.  After that, I'll have to figure out the proper CP/M BIOS changes and figure out how to load CP/M into the RAM.   

 

The 64k RAM card, below, is almost done.  I just need to install the delay line, a 470pF capacitor, and some DRAM and the 64k RAM card is ready for testing.  Assuming it works, I'll install the 40 pin connector.  🙂

 

 

64kRAMcardalmostassembled.thumb.jpg.00a586cb5117fae8c0106ae1e8b502ce.jpg

 

 

 

 

 

 

 

 

 

 

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Sound like a good step by step plan to bring it up.  What changes need to be made to the ram card I bought to make it work with this?  Is it ready as is?

 

Are the ROM and character ROM we have for the Z80 for this particular board or were they from the external Z-80 build?

 

 

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1 minute ago, Geister said:

Sound like a good step by step plan to bring it up.  What changes need to be made to the ram card I bought to make it work with this?  Is it ready as is?

 

Are the ROM and character ROM we have for the Z80 for this particular board or were they from the external Z-80 build?

 

 

Any character ROM would be for a separate board, such as the 80 column card.

 

The 320k RAM card wouldn't work with this setup.  I am using the legacy 64k RAM card design to try to bring this up.  Realistically, this 64k RAM card is at least a $200 card as it's rather expensive and involved to bring up.  In addition, it requires chips that aren't made anymore, such as the DRAM, delay line, and 74LS133.

 

I think of this process as more of a stage to replicate what Atari was doing in 1984.

 

Once this is working, I can envision a next step whereby a Z-80 card would be created with 64k of RAM onboard.  This would make the card more feasible by both dropping the price and using components that are still manufactured today.

 

 

 

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Would this also require the original 80-column card as I expect that the original design had no video out of its own.  Could the current 80 column card be used as a terminal from the Atari side?

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18 minutes ago, Geister said:

Would this also require the original 80-column card as I expect that the original design had no video out of its own.  Could the current 80 column card be used as a terminal from the Atari side?

The HDMI 80 column card would work.  Yes.  All I/O would go through Atari's device handlers. 

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Posted (edited)

I just looked closely at this picture and some answers have been in front of us for years.

 

Looking at the cards, from front to back.

 

1.  Z-80 card with the "waffle pattern" on the front instead of the back.  The traces are on the wrong side.  Compare the traces of this card with the other three cards.

2.  64k RAM card.  However, this card is different from the schematic as shown by the 40 pin DIP in the center.

3.  Z-80 card.  Look at the left side by the voltage regulator and compare it to board number 1.  This board has the traces on the correct side.  It's too bad we don't have close-up pictures of both sides of this card, too.

4.  64k RAM card.  This card also shows a 40 pin DIP as well.

 

So, this pictures shows two things:

A.  There was another 64k RAM card and it probably was the card described in the manual as the card we have the schematic for won't function as per the manual.

B.  A Z-80 card was made with the traces on the correct side.

 

 

 

 

1090_slide_image1.thumb.jpg.eb4f61a4e056145830059123114885fc.jpg

Edited by reifsnyderb
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https://atarimuseum.ctrl-alt-rees.com/computers/8bits/xl/xlperipherals/1090/Z80%20Board/z80_board_front.pnghttps://atarimuseum.ctrl-alt-rees.com/computers/8bits/xl/xlperipherals/1090/Z80%20Board/z80_board_back.png

z80

https://atarimuseum.ctrl-alt-rees.com/computers/8bits/xl/xlperipherals/1090/80%20column%20board/80CVC_front.png

https://atarimuseum.ctrl-alt-rees.com/computers/8bits/xl/xlperipherals/1090/80%20column%20board/80CVC_back.png

80 col video

https://atarimuseum.ctrl-alt-rees.com/computers/8bits/xl/xlperipherals/1090/64K%20Board/64k_memory_card-front.png

https://atarimuseum.ctrl-alt-rees.com/computers/8bits/xl/xlperipherals/1090/64K%20Board/64k_memory_card-back.png

memory card

https://atarimuseum.ctrl-alt-rees.com/computers/8bits/xl/xlperipherals/1090/Parallel-Serial%20Board/front.png

https://atarimuseum.ctrl-alt-rees.com/computers/8bits/xl/xlperipherals/1090/Parallel-Serial%20Board/back.png

serial parallel card

 

what else does a growing boy need? Time clock and house controller card, parallel drive card, hard drive card, prototyping card, amy card, sound card, among other things

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Posted (edited)
37 minutes ago, _The Doctor__ said:

 

what else does a growing boy need? Time clock and house controller card, parallel drive card, hard drive card, prototyping card, amy card, sound card, among other things

 

Serial/Parallel card is a lot lower of a priority.....

 

serialparallelcardinprogress.thumb.jpg.8742b42752f51b943b631b9b33600145.jpg

 

:-D

 

 

 

 

 

Edited by reifsnyderb
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192k just like my 800XL and 130XE are when not in 320K mode. so 3 ram card working at once, but a 600XL would still want 64K on it's pcb, as the 1064 plus the two other cards will fall short of the 800xl and cards. It's still great you can upgrade without tearing the 600XL apart but I still like maxing it out.

 

Serial Parallel card with updates as already suggested, BBS folks would still want two serial one parallel ethernet and wifi to get started, with a 1-4 meg ram disk and rtc.

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9 hours ago, reifsnyderb said:

If Freddie chips were available in 1984, possibly.  Without the cards, in hand, or closeup pictures we'll never know.

Freddie was “available” in 1983, every 1400/1450 used them which were all made in the latter half of the year. Some of the very early ones were ceramic.  

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8 hours ago, _The Doctor__ said:

192k just like my 800XL and 130XE are when not in 320K mode. so 3 ram card working at once, but a 600XL would still want 64K on it's pcb, as the 1064 plus the two other cards will fall short of the 800xl and cards. It's still great you can upgrade without tearing the 600XL apart but I still like maxing it out.

 

Serial Parallel card with updates as already suggested, BBS folks would still want two serial one parallel ethernet and wifi to get started, with a 1-4 meg ram disk and rtc.

I still need to find a micro controller for the USB side of things.

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On 3/13/2024 at 10:38 PM, ClausB said:

Could they be Freddie chips?

 

Or maybe PIA chips for banking?

I just saw a schematic where Freddie is used.  Freddie requires a crystal.  Zooming in on the picture shows a crystal right next to the big chip.  I'd say there is now a high probability that the memory cards in the picture have the Freddie chip.

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1 hour ago, _The Doctor__ said:

1090xlexpansion.jpgimage.thumb.jpeg.124807c073bbe1f7f87f3d0dfe7dccd3.jpeg

nice boxes, now if I can just dig up the photos of those cards, because they were online at one time as well.

 

Sorry for going off-topic, but what is that pastel-button unit to the right of the 1090 in the first pic?

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