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130XE (64X4) DRAMS?


Larry

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you shouldve got 41256s.. Theyd work just as good. and then when you decide you want more ram, you just add 1 memory adress line, 2 lines to the pia portb outputs, a multiplexer IC and a resistor (basically 50 cents worth of parts), and youve got a scott petersen 320k XE.

I have plenty of 41256's, but I didn't think they could be used -- I only had two extra sockets (64X4 DRAM) not eight. And I've read that 44256's are 20-pin DIPS rather than the 18-pin 4464. Could you explain this a little further?

Thanks,

-Larry

A lot of pins for the 4464 are on the same place as the 44256. It takes a minimum of wires like this.

But sure, the 41256 can also be used. If you want to go that way, it's much easier to use a 30 pin module.

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you shouldve got 41256s.. Theyd work just as good. and then when you decide you want more ram, you just add 1 memory adress line, 2 lines to the pia portb outputs, a multiplexer IC and a resistor (basically 50 cents worth of parts), and youve got a scott petersen 320k XE.

I have plenty of 41256's, but I didn't think they could be used -- I only had two extra sockets (64X4 DRAM) not eight. And I've read that 44256's are 20-pin DIPS rather than the 18-pin 4464. Could you explain this a little further?

Thanks,

-Larry

A lot of pins for the 4464 are on the same place as the 44256. It takes a minimum of wires like this.

But sure, the 41256 can also be used. If you want to go that way, it's much easier to use a 30 pin module.

 

Hi Guus-

 

I'll look at the pinouts of the 44256 and see if I can't figure it out. Most of the upgrades that I have looked at all used the same basic scheme of the stacked 74LS158's, and as I mentioned earlier, the article that I saw from Rich Andrews best explained "why." Please don't do a lot of searching, but if you would run across your article, I'm sure several people (including me) would be interested. In English, I presume?

 

Thanks,

Larry

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Hello Larry

 

IIRC I once downloaded a description of an upgrade using 256kb x 4 chips. Probably for the XEGS, since it's the only Atari 8 bit that only has two RAMchips AND 64kB standard.

 

It should work on any XE with only 2 RAMchips. Problem is, it's probably on my Atari system somewhere (which isn't up yet) and the print out has probably faded so much (if I can find it) that the scanner won't see anything.

 

Greetings

 

Mathy

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Larry, here is a very early request finally filled. Sorry about the wait.

USA 64x4 130XE picture

 

I have two of these and both work fine. They DO contain the extra memory test OS which is the same code to be found in the XEGS even though the XEGS does not have any extended memory. The extra memory shows as four long blocks (green or red) below the usual "field" of green squares everybody else knows about.

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Hello Larry,

 

The article has been found. And I scanned it.

The text is in Dutch, but the schematic is clear anyway.

If you need any explanation, let me know.

Only thing is, how do I get the file to you? I don't know if /how I can upload about 90K.

 

BR/

Guus

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Sorry it took so long!

 

post-6925-1184169882_thumb.jpg

 

Thanks, JR and 1050-

 

I appreciate the the pics! Mine now looks just like your photos, except I installed several sockets for the ram and CO25923 logic chip.

 

I'd like to go to 320K, but I won't until I'm very confident that I have an upgrade that I can fully understand. (Call me cautious, but I just hate frying these little guys!) Everything I've looked at to date is for the 4164/41256 versions (not the 4464).

 

There absolutely was a commercial upgrade for the XEGS to take it from 64K to 128K to 192K by Innovative Concepts. In fact, B&C still has the XEGS 128K upgrade listed in their catalog for $49+. I don't think I want it that badly... This required stacking 2 new 4464's on the existing 2-each drams, and was actually two separate upgrades. I've looked at several upgrades that provide for piggybacking, but as of yet, no 4464 piggybacks. Several folks recall seeing this elusive 4464 upgrade, so it's probably out there, somewhere.

-Larry

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Hello Larry,

 

Fortunatelly, it is very unlikely thay you kill the machine. Specially if you've put the extra Ram on sockets.

 

About the upgrade.

The RAS-pulse is used for refresh. This should be connected to the new Ram, like the data-lines and address-lines.

Also, don't forget the R/W signal.

The CAS-pulse is the final selection. This signal concludes the selectin of the Ram-address.

In other words, the original Ram or the extension is selected by the Cas-pulse.

If this signal is not activated for a particular chip, the data will just stay there. (Refresh is done by the Ras-Pulse only)

The only other thing to take care of for the refresh is the address-counter.

This counter is in the Antic-chip. The oldest Antics have a 7 bit refresh only.

The later models have an 8-bit refresh. (Like in the 130XE)

Using larger Ram-chips will also ihave to nclude that the refresh has enough bits.

In the schematics that I've designed, a 74LS393 was used for a refresh counter. (8 bits max.)

In case a nine bit refresh is needed, another flip-flop is needed to count one more bit. (1MB-Ram)

Also, another channel in a multiplexer is needed.

 

Hopefully, this explains a bit, how the memory works...

 

BR/

Guus

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Hello Guus

 

As far as I know, all RAMchips of 1Mb or higher (this includes 256k x 4bit RAMchips like the 44256) all have auto-refresh ability. You just AND CAS and REF and use the new signal as CAS for the 1Mb or larger RAMchips. No need of extra counters.

 

Greetings

 

Mathy

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Hello Guus

 

As far as I know, all RAMchips of 1Mb or higher (this includes 256k x 4bit RAMchips like the 44256) all have auto-refresh ability. You just AND CAS and REF and use the new signal as CAS for the 1Mb or larger RAMchips. No need of extra counters.

 

BTW IIRC you can't just piggy-bag a 44256 over a 4464. Apart from the fact that the latter chips has more pins, you'll also have to take into account that not all pins on both chips will line up.

 

Greetings

 

Mathy

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Hi,

 

I've developed a ram upgrade, to put 256K chips in the second bank of 2 sockets..its a plug in daughter board with only three wires to solder. Can't just drop in chips, the pinouts are different.

 

But, I don't have this type of xe to test the prototype on.

 

 

Rick D.

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Hi,

 

I've developed a ram upgrade, to put 256K chips in the second bank of 2 sockets..its a plug in daughter board with only three wires to solder. Can't just drop in chips, the pinouts are different.

 

But, I don't have this type of xe to test the prototype on.

 

 

Rick D.

 

I might have a 130XE with 4 chips. I will check. It would be really cool if your upgrade could be adapted to the XEGM wich has 2 4464 chips in it.

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Creating an XEGS version is something to look into, but I don't know if it has the ram circuitry the XE already has since it has 128K. It may be there but being used by other rom functions.

 

An XEGS is something I do have now. A memory upgrade is not something in my current list of hardware projects. I'd need to know if there is interest to add it. A daughter board could be made, maybe the existing drams could be moved, with 256K added. Don't know.

 

 

Rick D.

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Creating an XEGS version is something to look into, but I don't know if it has the ram circuitry the XE already has since it has 128K. It may be there but being used by other rom functions.

 

An XEGS is something I do have now. A memory upgrade is not something in my current list of hardware projects. I'd need to know if there is interest to add it. A daughter board could be made, maybe the existing drams could be moved, with 256K added. Don't know.

 

 

Rick D.

 

Thanks for considering it. It looks like the XEGM is almost the same as a 65XE. I think just the mmu is different. Perhaps sometime we can start a thread here and see what the interest would be.

 

I got busy last week with a project but I will check and let you know tomorrow if I have a 4 chip 130XE.

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Creating an XEGS version is something to look into, but I don't know if it has the ram circuitry the XE already has since it has 128K. It may be there but being used by other rom functions.

 

An XEGS is something I do have now. A memory upgrade is not something in my current list of hardware projects. I'd need to know if there is interest to add it. A daughter board could be made, maybe the existing drams could be moved, with 256K added. Don't know.

 

 

Rick D.

 

Thanks for considering it. It looks like the XEGM is almost the same as a 65XE. I think just the mmu is different. Perhaps sometime we can start a thread here and see what the interest would be.

 

I got busy last week with a project but I will check and let you know tomorrow if I have a 4 chip 130XE.

 

 

Looks like all 4 of my 130XEs are 16 chips. Well, I guess it gives me something else to search for and add to the collection!

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Creating an XEGS version is something to look into, but I don't know if it has the ram circuitry the XE already has since it has 128K. It may be there but being used by other rom functions.

 

An XEGS is something I do have now. A memory upgrade is not something in my current list of hardware projects. I'd need to know if there is interest to add it. A daughter board could be made, maybe the existing drams could be moved, with 256K added. Don't know.

 

 

Rick D.

 

Thanks for considering it. It looks like the XEGM is almost the same as a 65XE. I think just the mmu is different. Perhaps sometime we can start a thread here and see what the interest would be.

 

I got busy last week with a project but I will check and let you know tomorrow if I have a 4 chip 130XE.

 

 

Looks like all 4 of my 130XEs are 16 chips. Well, I guess it gives me something else to search for and add to the collection!

Can somone point me in the right direction? I have a 65 xe, board says 65xe rev c. What do I need or get a kit to put it to 320k or higher?

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Creating an XEGS version is something to look into, but I don't know if it has the ram circuitry the XE already has since it has 128K. It may be there but being used by other rom functions.

 

An XEGS is something I do have now. A memory upgrade is not something in my current list of hardware projects. I'd need to know if there is interest to add it. A daughter board could be made, maybe the existing drams could be moved, with 256K added. Don't know.

 

 

Rick D.

 

Thanks for considering it. It looks like the XEGM is almost the same as a 65XE. I think just the mmu is different. Perhaps sometime we can start a thread here and see what the interest would be.

 

I got busy last week with a project but I will check and let you know tomorrow if I have a 4 chip 130XE.

 

 

Looks like all 4 of my 130XEs are 16 chips. Well, I guess it gives me something else to search for and add to the collection!

Can somone point me in the right direction? I have a 65 xe, board says 65xe rev c. What do I need or get a kit to put it to 320k or higher?

 

this is what you need to do ( these instructions are for the65 and 130XE):

 

http://atrey.karlin.mff.cuni.cz/~pavel/atari/130xe320K.html

Edited by puppetmark
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Can somone point me in the right direction? I have a 65 xe, board says 65xe rev c. What do I need or get a kit to put it to 320k or higher?

 

Is your 65XE a 2-DRAM or 8-DRAM version? If it is 8-DRAM, then the Peterson 320K upgrade is fine. If it is 2-DRAM model using 64X4 chips, then no, it won't work (without some very serious changes).

-Larry

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Creating an XEGS version is something to look into, but I don't know if it has the ram circuitry the XE already has since it has 128K. It may be there but being used by other rom functions.

 

An XEGS is something I do have now. A memory upgrade is not something in my current list of hardware projects. I'd need to know if there is interest to add it. A daughter board could be made, maybe the existing drams could be moved, with 256K added. Don't know.

 

 

Rick D.

 

Thanks for considering it. It looks like the XEGM is almost the same as a 65XE. I think just the mmu is different. Perhaps sometime we can start a thread here and see what the interest would be.

 

I got busy last week with a project but I will check and let you know tomorrow if I have a 4 chip 130XE.

 

 

Looks like all 4 of my 130XEs are 16 chips. Well, I guess it gives me something else to search for and add to the collection!

Can somone point me in the right direction? I have a 65 xe, board says 65xe rev c. What do I need or get a kit to put it to 320k or higher?

 

this is what you need to do ( these instructions are for the65 and 130XE):

 

http://atrey.karlin.mff.cuni.cz/~pavel/atari/130xe320K.html

 

 

 

Actually, that link is for the 65XE (8 DRAM) only. It means the upgrade is 130XE compatable. The actual 130XE to 320K upgrade is MUCH simpler. But the 65XE upgrade is the one I will look into for use in the XEGS. It should also work in the 2 Dram 65XE.

 

 

Note that the 130XE upgrade replaces ram in the 2nd row, all of which is banked ram. The 65XE upgrades have to bank the extra ram into a address window within the same ram, so its more complex. Its more like upgrading an 800XL.

 

Rick D.

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Creating an XEGS version is something to look into, but I don't know if it has the ram circuitry the XE already has since it has 128K. It may be there but being used by other rom functions.

 

An XEGS is something I do have now. A memory upgrade is not something in my current list of hardware projects. I'd need to know if there is interest to add it. A daughter board could be made, maybe the existing drams could be moved, with 256K added. Don't know.

 

 

Rick D.

 

Thanks for considering it. It looks like the XEGM is almost the same as a 65XE. I think just the mmu is different. Perhaps sometime we can start a thread here and see what the interest would be.

 

I got busy last week with a project but I will check and let you know tomorrow if I have a 4 chip 130XE.

 

 

Looks like all 4 of my 130XEs are 16 chips. Well, I guess it gives me something else to search for and add to the collection!

Can somone point me in the right direction? I have a 65 xe, board says 65xe rev c. What do I need or get a kit to put it to 320k or higher?

 

this is what you need to do ( these instructions are for the65 and 130XE):

 

http://atrey.karlin.mff.cuni.cz/~pavel/atari/130xe320K.html

 

 

 

Actually, that link is for the 65XE (8 DRAM) only. It means the upgrade is 130XE compatable. The actual 130XE to 320K upgrade is MUCH simpler. But the 65XE upgrade is the one I will look into for use in the XEGS. It should also work in the 2 Dram 65XE.

 

 

Note that the 130XE upgrade replaces ram in the 2nd row, all of which is banked ram. The 65XE upgrades have to bank the extra ram into a address window within the same ram, so its more complex. Its more like upgrading an 800XL.

 

Rick D.

 

You are absolutly correct. My mistake. If You need any help or testing done on a XEGS upgrade, let me know. I think its a great machine. There is lots of room on the inside for upgrades. Actually, I am in the beginning stages of designing a wireless keyboard mod for it.

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Hello Rick

 

The 65XE upgrades have to bank the extra ram into a address window within the same ram, so its more complex. Its more like upgrading an 800XL.

 

Sorry, but that's not true.

 

You can upgrade 65XE's (and 800XE's, XEGS's, 800XL's and 600XL's) with memory upgrades that work just like the ones for the 130XE. My XEGS has 64kB plus 1MB for instance. All you need is to copy what's done on the 130XE. Meaning either using the CO25953 or something that mimics it's funktion.

 

Greetings

 

Mathy

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You are absolutly correct. My mistake. If You need any help or testing done on a XEGS upgrade, let me know. I think its a great machine. There is lots of room on the inside for upgrades. Actually, I am in the beginning stages of designing a wireless keyboard mod for it.

 

Not really a mistake. The title of the article is misleading and should have been changed a decade ago.

 

The version being posted on my site will have a better title.

 

I need to finish other things first. The current 4 bit Dram 130XE upgrade has peculiarities I am running out of ideas on. Though they spark old memory bits.

 

Rick.

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