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Atari 64K Memory Card (Atari 64KMR) for 1090 xl expansion system

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Forgive my ignorance on the topic.  Does the RAM expansion in the 1090 work differently than the stand alone 1064?  I was always under the impression that it would take a stock 600XL to 64kB, but if used on an 800XL, it would disable the internal RAM and you still only had a 64kB system.

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16 hours ago, ClausB said:

Be careful there. The 4264 needs 256 cycle refresh and so won't work correctly with the older ANTIC chips. Also MT branded RAMs have a poor reputation.

Please post the 64K board schematic so that I can confirm this warning.

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Thanks for the schematic. I'm surprised to see two busses, one on P1 and another on P2. What's the second bus for?

 

Either way the 4264 needs 8 bits of refresh address and the older ANTIC supplies only 7. All 600XLs had the newer ANTIC and would be OK, but many 800XLs had the older one, so they could fail.

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11 minutes ago, ClausB said:

Thanks for the schematic. I'm surprised to see two busses, one on P1 and another on P2. What's the second bus for?

 

Either way the 4264 needs 8 bits of refresh address and the older ANTIC supplies only 7. All 600XLs had the newer ANTIC and would be OK, but many 800XLs had the older one, so they could fail.

But is that true for non 1064 mode — 800xls not being able to bank switch?

 

some cards had a header to daisy chain them which is probably the 2nd bus. 

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My warning has nothing to do with bank switching, only with refreshing. The schematic says 4164 RAMs (7 bits refresh), and that's what the board needs.

 

Daisy chaining, eh? Interesting.

Edited by ClausB

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I'm coming late to this party. I can't recall, was the 1090 64KB upgrade card supposed to bring an extra 64KB to the machine, or take the machine up to 64KB? The only reason I ask is that there were only two XL models with a PBI port and one of them already had 64KB.

 

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1 hour ago, bfollowell said:

I'm coming late to this party. I can't recall, was the 1090 64KB upgrade card supposed to bring an extra 64KB to the machine, or take the machine up to 64KB? The only reason I ask is that there were only two XL models with a PBI port and one of them already had 64KB.

 

Yes and yes.  
 

three cards for a 600xl would be 64k stock (1064 mode card) and 128k banked (2 cards in bank mode). 
The 800XL and 1450XLD could only use the 2 banked mode cards. 

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7 hours ago, ClausB said:

Thanks for the schematic. I'm surprised to see two busses, one on P1 and another on P2. What's the second bus for?

 

Either way the 4264 needs 8 bits of refresh address and the older ANTIC supplies only 7. All 600XLs had the newer ANTIC and would be OK, but many 800XLs had the older one, so they could fail.

hi,

the second bus is for a jumper to the z80 card as it does not have it's own ram.

 

Ken

 

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Looks like the board is already designed to handle 256K. Just plug in some 41256 DRAMs instead of 4164s, and plug a 74LS153 into U20 and you're good. (This will also require the newer ANTIC.)

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10 hours ago, ClausB said:

Looks like the board is already designed to handle 256K. Just plug in some 41256 DRAMs instead of 4164s, and plug a 74LS153 into U20 and you're good. (This will also require the newer ANTIC.)

Does this open up the possibility of multiple 256K cards in a single system for up to 1MB of RAM?

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Never mind - I deleted my original post because I realized that people are looking at this from a nostalgic viewpoint, and not necessarily what makes sense in 2021 :)

 

Edited by mytek
Deleted original post
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5 hours ago, x=usr(1536) said:

Does this open up the possibility of multiple 256K cards in a single system for up to 1MB of RAM?

Possible. will need to add extra card select logic tho.

 

James

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Right. As it stands you could have two 256K boards plus one 64K in 1064 mode for a total of 576K.

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Hello Michael

 

13 hours ago, mytek said:

Never mind - I deleted my original post because I realized that people are looking at this from a nostalgic viewpoint, and not necessarily what makes sense in 2021 :)

 

Not everybody looks at this only from a nostalgic point of view.  This topic probably is interesting for those who do AND those who don't.  And if at some point somebody would want to reproduce the hardware (read: The 1090 case and motherboard), quantity matters.

 

Sincerely

 

Mathy

 

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Well, let's face it, there are newer, and likely much better versions of most everything the 1090 did or could have done. They probably do it better too. So, strictly speaking, there's really absolutely no need for the 1090 other than nostalgic reasons. At least none that I can think of. Still, nostalgia is a good enough reason for most, I'd say.

 

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The majority of expansions/enhancements for the 8bit are internal.  Not many (in comparison) use the expansion bus.  I think it would be fun to have an expansion box that used some cool things.  It certainly would be neat to have a PBI floppy or devices that act like that.  [And yes the community that would use and purchase such things would be even smaller than the internal mod community.]

 

Strictly speaking there is no need for anything we do with our 8bits..... it's a hobby.

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50 minutes ago, bfollowell said:

So, strictly speaking, there's really absolutely no need for the 1090 other than nostalgic reasons. At least none that I can think of.

 

1090 is unique and desirable for the following.
1. All upgrades exist externally.
2. All upgrades are plug and play.
3. All upgrades exist in one box.
 

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2 minutes ago, MrFish said:

 

1090 is unique and desirable for the following.
1. All upgrades exist externally.
2. All upgrades are plug and play.
3. All upgrades exist in one box.
 

new upgrades can be made and plugged in, not just what we see from back then either... How about a parallel bus Fujinet or SIDE solution leaving the cartridge port open? Or maybe a PBI ROM SIM that let's you update in real time like back in the day... PC to the RAM/SIM Bank... instant Atari bliss... Coprocessing? or maybe External sound and video... again leaving the cartridge port open so the carts can use the extensions.... or how about a PBI super CART Just because we can?

The parallel bus is just plain better for wifi/lan/etc solutions... Dragon cart proves that for online gaming

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17 hours ago, mytek said:

Never mind - I deleted my original post because I realized that people are looking at this from a nostalgic viewpoint, and not necessarily what makes sense in 2021 :)

 

3 hours ago, Mathy said:

Not everybody looks at this only from a nostalgic point of view.  This topic probably is interesting for those who do AND those who don't.  And if at some point somebody would want to reproduce the hardware (read: The 1090 case and motherboard), quantity matters.

 

Without being a mind reader, I'm going to guess that Michael was initially planning to post about the impracticality of loading up a 1090 with a meg of RAM (4 x 256 KB cards).

 

Edited by MrFish

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15 minutes ago, MrFish said:

1. All upgrades exist externally.

 

One potentially beneficially aspect of this is that all upgrades can be moved to any one of your machines, simply by plugging the 1090 into the machine's PBI/ECI port. Compare this to people who own 3 or 4 machines and have internal upgrades installed in each one of them.

 

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5 minutes ago, MrFish said:

Without being a mind reader, I'm going to guess that Michael was initially planning to post about the impracticality of loading up a 1090 with a meg of RAM (4 x 256 KB cards).

Yep you guessed correctly ;-)

 

But I had a change of heart, not wanting to dictate how I thought it would be better used. So now that the cat is out of the bag, I was going to suggest using a U1MB instead, which kills at least 3 or more birds with one stone, and leaves the 1090 slots free to do other things. Such as video enhancement, ethernet, fast serial or better yet buffered USB. Just seemed like such a waste to pack it full of memory expansion boards and have no room for anything else. Just because Atari was going to create a 64K card BITD, doesn't mean that makes sense to still do so now days, other than for pure nostalgia and trying to exactly mimic what they were doing back then.

 

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1 hour ago, kheller2 said:

Strictly speaking there is no need for anything we do with our 8bits..... it's a hobby.

 

 

25 minutes ago, MrFish said:

1090 is unique and desirable for the following.
1. All upgrades exist externally.
2. All upgrades are plug and play.
3. All upgrades exist in one box.
 

 

16 minutes ago, _The Doctor__ said:

new upgrades can be made and plugged in, not just what we see from back then either... How about a parallel bus Fujinet or SIDE solution leaving the cartridge port open? Or maybe a PBI ROM SIM that let's you update in real time like back in the day... PC to the RAM/SIM Bank... instant Atari bliss... Coprocessing? or maybe External sound and video... again leaving the cartridge port open so the carts can use the extensions.... or how about a PBI super CART Just because we can?

The parallel bus is just plain better for wifi/lan/etc solutions... Dragon cart proves that for online gaming

 

All very good points.

 

I don't know that I'll ever build one or not, but I'm definitely interested in seeing where this project goes, especially if it goes off the rails and expands out beyond the original, officially planned for cards.

 

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