Memory expansions for the 800XL

[Mugo]

Hello guys,

 

I'm thinking of expanding my 800XL's RAM, and looking around in the internet, i've found the Satantronic 1MB expansion schematics.

But i'm kinda stuck, because seems the schematics are for a FREDDIE equiped 800XL (and mine isn't).

Somewhere else i read there is a version for non FREDDIE machines.

Do someone here have sucessfully instaled this expansion in a non FREDDIE 800XL machine?

Being more specific for the people that may be able to help, i don't know where to find the FA14 and FA15 signals in my 800XL . . .

 

Thanks in advance for any help!

[classics]

FA14 and FA15 are pins 23 and 24 of Freddie.

 

Steve

[Mugo]

FA14 and FA15 are pins 23 and 24 of Freddie.

 

Steve

 

 

Hey Steve,

 

Thank you for your reply.

The problem is, as i've stated in my previous message, my 800XL doesn't have a FREDDIE chip. Or at least i think it doesn't. Couldn't find U6...

I don't know what i should do with these signals in the Satantronic's schematics.

I've read somewhere in the Internet, they demoed this expansion (back then) in some meeting and there were 2 versions, one for Freddie equiped machines, and another for machines with no Freddie chip. But in their website there's only the Freddie version of the schematics...

If someone could provide me with some info on this matter, i'll very much apreciate this.

 

Thanks!

[sup8pdct]

FA14 and FA15 are pins 23 and 24 of Freddie.

 

Steve

 

 

Hey Steve,

 

Thank you for your reply.

The problem is, as i've stated in my previous message, my 800XL doesn't have a FREDDIE chip. Or at least i think it doesn't. Couldn't find U6...

I don't know what i should do with these signals in the Satantronic's schematics.

I've read somewhere in the Internet, they demoed this expansion (back then) in some meeting and there were 2 versions, one for Freddie equiped machines, and another for machines with no Freddie chip. But in their website there's only the Freddie version of the schematics...

If someone could provide me with some info on this matter, i'll very much apreciate this.

 

Thanks!

 

On the 800XL, there are no FAx signals, even if the XL has a freddie chip. On the XL freddie, FA14 and FA15 are A14 and A15.

The FAx signals are unique to the 130XE. They come from a small PAL chip that handles all the bank switching and are modified A14 and A15.

Modified only when extra memory is enabled (either cpu or antic) and which bank is selected.

 

James

Edited May 22, 2008 by sup8pdct

[Mugo]

 

On the 800XL, there are no FAx signals, even if the XL has a freddie chip. On the XL freddie, FA14 and FA15 are A14 and A15.

The FAx signals are unique to the 130XE. They come from a small PAL chip that handles all the bank switching and are modified A14 and A15.

Modified only when extra memory is enabled (either cpu or antic) and which bank is selected.

 

James

 

Thanks James, for your reply.

 

After some deepen researching on the Internet (it's amazing how interesting info can vanish just when you need it, on the Internet), i found out that you're right. But this don't solve my problems, unfortunately.

 

I still don't know what to do with the FAx signals shown on the Satantronic's 1MB memory expansion (installing it on my 800XL, as said before).

 

I've found another 1MB expansion for the A8 computers, developed by Mathy van Nisselroy, but it requires a CO25953 that i don't have and really don't plan in acquire. In his docs, he says that the FAx signals can be found on an A800XL by lifting 2 pins in one of the 2 74LS158 installed in the mobo (they are near the RAM chips). These pins are usually connected in the A14 and A15 lines. But i couldn't understand if the new FAx signals are in the board or in the IC pins.

 

Anyway, i tried to use these "new" FAx signals, but the expansion still don't work. The A8 don't boot, only black screen and sometimes a lot of green garbage on the screen.

 

As i've already fixed a socket for the 30pin SIMM module onboard, and soldered a lot of wires to connect it (dessoldered all the original RAM chips), i decided to try the SIMM alone, as oposed to the original RAM chips. And the A8 works OK.

 

As i wanted any aditional RAM i could get, instead the bare 64KB i had before, i tried the Claus Buchholz 256k upgrade, but using the 30pin SIMM instead individual 256k chips. Connected all the relevant signals from the A8 board to the socket (D lines, A lines, RAS, CAS, WE) and used the A8 line to address the extra 256k RAM.

 

Everything seems to work OK, but when i run the XRAM util from Satantronic, it reports only 240k of expanded RAM. The table showing the available banks is missing 1 bank - $87 (the program reports 15 banks instead of 16). Also, the program reports an error in the first bank ($83)

 

I can't find out why this is happening. Tried 5 different SIMMs (2 different brands among them), and all them worksthe same way.

 

In the Satantronic's schematics, the CAS signal is processed before being connected to the SIMM module, instead of using the original CAS signal. Maybe this is where my problem is?

 

Or maybe the XRAM utility don't work OK with this expansion?

 

If anyone knows of anything that can help me, i'll be glad.

 

As soon as i solve this problem, i'll try the 512k mod for the Claus expansion. This will be enough memory for my purposes. As long as i can use the 30pin SIMM instead individual chips (that i can't find locally) i'm OK.

 

Thank you all very much,

Marcelo.

 

PS.: Sorry for the long message :-\

[Mathy]

Hallo Mugo

 

I've reread the text you probably are refering too. It says "were". Meaning the board, not the pins. BTW you have two possibilities and only two pins. Why not try first one, then the other option.

 

What I read in you message above, is that you build something and if it doesn't work, try something else. This methode ofcourse does not work. When I install something, stuff usually doesn't work the first time around. Check, double check and triple check everything. Put the thing aside for a couple of hours, days, month even and have a look at it again after a while.

 

BTW there's another thread here that explains your 240kB problem with the 256kB Claus Buchholz upgrade. The Buchholz and (almost?) all other 800XL upgrades all suffer from this. They don't add 256kB (or 64kB, 128kB, 512kB or 1MB) to your system, they replace the memory that was inside by 256kB (or ...). Meaning you don't get a RAMdisk of 256kB but 192kB. The rest (64kB) is used as main memory.

 

That's why I'm using a CO25953 in my upgrade. It adds 1MB. My XEGS doesn't have 1MB, it has 64kB plus 1MB.

 

BTW BigBen's upgrade uses a PAL (or simular IC) instead of the CO25953.

 

Greetings

 

Mathy

[ClausB]

As i wanted any aditional RAM i could get, instead the bare 64KB i had before, i tried the Claus Buchholz 256k upgrade, but using the 30pin SIMM instead individual 256k chips. Connected all the relevant signals from the A8 board to the socket (D lines, A lines, RAS, CAS, WE) and used the A8 line to address the extra 256k RAM.

 

Everything seems to work OK, but when i run the XRAM util from Satantronic, it reports only 240k of expanded RAM. The table showing the available banks is missing 1 bank - $87 (the program reports 15 banks instead of 16). Also, the program reports an error in the first bank ($83)

 

I can't find out why this is happening. Tried 5 different SIMMs (2 different brands among them), and all them worksthe same way.

I think your upgrade is working fine. As Mathy noted, it is not 64K+256K, rather it's 64K+192K. So, the first 4 banks ($83, $87, $8B, $8F) address the same physical RAM as the non-extended system RAM. And since the switched banks all appear in place of the 2nd 16K block of system RAM, the 2nd bank ($87) appears in place of itself. A test program would therefore detect no bank there. So, the first 4 banks should not be used as extended RAM since they are your system's normal 64K. One exception is that the 4th bank is the same as the RAM underneath the OS ROM, so if you don't use the RAM OS switch, you can use the 4th bank.

 

I hope that explanation is clear. In summary, the 12 banks at $Ax, $Cx, and $Ex are your 192K extended RAM, and the 4 banks at $Ex are equivalent to the 130XE extended RAM. Enjoy your reborn XL!

[Mugo]

Hallo Mugo

 

I've reread the text you probably are refering too. It says "were". Meaning the board, not the pins. BTW you have two possibilities and only two pins. Why not try first one, then the other option.

 

What I read in you message above, is that you build something and if it doesn't work, try something else. This methode ofcourse does not work. When I install something, stuff usually doesn't work the first time around. Check, double check and triple check everything. Put the thing aside for a couple of hours, days, month even and have a look at it again after a while.

 

BTW there's another thread here that explains your 240kB problem with the 256kB Claus Buchholz upgrade. The Buchholz and (almost?) all other 800XL upgrades all suffer from this. They don't add 256kB (or 64kB, 128kB, 512kB or 1MB) to your system, they replace the memory that was inside by 256kB (or ...). Meaning you don't get a RAMdisk of 256kB but 192kB. The rest (64kB) is used as main memory.

 

That's why I'm using a CO25953 in my upgrade. It adds 1MB. My XEGS doesn't have 1MB, it has 64kB plus 1MB.

 

BTW BigBen's upgrade uses a PAL (or simular IC) instead of the CO25953.

 

Greetings

 

Mathy

 

 

Hello Mathy,

 

Thank you so much for your reply.

 

Regarding the FAx signals, i tried both ways, and the expansion didn't work.

 

But there are some other possible problems in my assembly history that could cause this.

 

I've used an HC00 instead of an HCT00. I know the HC00 is slower, but i couldn't find the HCT one. Maybe this would not be enough for tha Atari not boot, but i'm not sure.

 

Also, when i connected everything the first time, i inverted the VCC and GND connections (i know, pretty noob, pretty lame, but these things happens). Some (if not all) of the chips can be toasted since this mistake, but i don't have replacements.

 

The thing is that all i want is to be able to run all the software that requires expanded memory. I don't need huge amounts of memory. I don't even use RAMDisks.

 

I understand the problem with the 240k issue, and now i'm reliefed. Seems that my assembly is OK. Now i'll try the 512k upgrade for Claus interface.

 

Also, one more question, in another thread i've seen someone saiyng that Mr. Metalguy66 has developed a fix for the Claus expansion, that allows Antic access. Do someone know where i can find more info on this subject?

 

A big thanks to everyone that helped me so far :-)

[Mugo]

As i wanted any aditional RAM i could get, instead the bare 64KB i had before, i tried the Claus Buchholz 256k upgrade, but using the 30pin SIMM instead individual 256k chips. Connected all the relevant signals from the A8 board to the socket (D lines, A lines, RAS, CAS, WE) and used the A8 line to address the extra 256k RAM.

 

Everything seems to work OK, but when i run the XRAM util from Satantronic, it reports only 240k of expanded RAM. The table showing the available banks is missing 1 bank - $87 (the program reports 15 banks instead of 16). Also, the program reports an error in the first bank ($83)

 

I can't find out why this is happening. Tried 5 different SIMMs (2 different brands among them), and all them worksthe same way.

I think your upgrade is working fine. As Mathy noted, it is not 64K+256K, rather it's 64K+192K. So, the first 4 banks ($83, $87, $8B, $8F) address the same physical RAM as the non-extended system RAM. And since the switched banks all appear in place of the 2nd 16K block of system RAM, the 2nd bank ($87) appears in place of itself. A test program would therefore detect no bank there. So, the first 4 banks should not be used as extended RAM since they are your system's normal 64K. One exception is that the 4th bank is the same as the RAM underneath the OS ROM, so if you don't use the RAM OS switch, you can use the 4th bank.

 

I hope that explanation is clear. In summary, the 12 banks at $Ax, $Cx, and $Ex are your 192K extended RAM, and the 4 banks at $Ex are equivalent to the 130XE extended RAM. Enjoy your reborn XL!

 

 

Hey Claus,

 

Thank you very much for your reply.

 

It's clear for me now. Thank you guys for this very enlighteen lesson about computer memories :-)

 

I don't have any extensive knowledge about digital electronics (my analogic skills are far better), and this is being very interesting to me.

 

My doubt about the correct working order of the expansion was mainly because in the Atari800WinPlus emulator, the 320k(RAMBO) expansion is rightly detected by the XRAM utility. Seems that the emulator is not really emulating this expansion correctly.

 

Now i only need to get a 74LS139 to expand the RAM a little bit

 

Ah! and need some info on the Antic compatibility matter too . . .

[ClausB]

Thank you very much for your reply.

 

Ah! and need some info on the Antic compatibility matter too . . .

My pleasure. It's good to know that the old mod is still useful. Here's the original article if you are still interested. It also explains the ANTIC difference in refresh address bits.

http://www.atariage.com/forums/index.php?s...t&p=1496872

[Mugo]

Thank you very much for your reply.

 

Ah! and need some info on the Antic compatibility matter too . . .

My pleasure. It's good to know that the old mod is still useful. Here's the original article if you are still interested. It also explains the ANTIC difference in refresh address bits.

http://www.atariage.com/forums/index.php?s...t&p=1496872

 

 

 

Thanks again, Claus!

 

By the way, i tried the 512k upgrade (on top of your 256k upgrade), but it didn't work.

Tried with an 74LS139 chip, because i didn't have the 74S139, but i don't think this is the problem.

The Atari don't boot, unless i connect the CAS line direct to the SIMM. And if i do this, the XRAM util reports 256k of expanded RAM, and reports errors in all banks during the tests.

In this upgrade, among other connections, you should connect the pins 2, 13 and 8 of the LS139 together, and later in the instructions it says to connect the PIA pin 17 to the pin 2 of the LS139. I don't really see the point in connecting the PB7 signal to the GND!

Here is the upgrade link, so everyone knows exactly what i'm refering to:

 

http://atrey.karlin.mff.cuni.cz/~pavel/atari/800xl512K.html

 

If these instructions are correct, and someone had tested this before, please let me know.

Also, if there are other options for memory upgrades that are easy to implement (i can't program PALs or GALs), i would be glad to know about them too.

 

Once again, i'm truly amazed by all the support given in this forum. You guys are the best! Thank you all!

[ClausB]

In this upgrade, among other connections, you should connect the pins 2, 13 and 8 of the LS139 together, and later in the instructions it says to connect the PIA pin 17 to the pin 2 of the LS139. I don't really see the point in connecting the PB7 signal to the GND!

I'm not familiar with this upgrade, but in reading it, I noticed that pin 15 of the '139 is not connected anywhere. Pin 15 is a required input for a 74LS139, so maybe he meant to connect one of the double connections to pin 2 to pin 15 instead. Good luck.

[carmel_andrews]

I just read the orig. post, I guess the 'freddie modded' 800xl's refer to the 'unreleased' XL-F systems

 

Is it possible to moddy a 'non' freddie xl to working with a freddie (or does that also mean replacing the xl o/s, self test, PIA etc for the xe ones)

 

Does the freddie replace the 7LS series chips (in regards to bank switching)

Edited May 24, 2008 by carmel_andrews

[ClausB]

In this upgrade, among other connections, you should connect the pins 2, 13 and 8 of the LS139 together, and later in the instructions it says to connect the PIA pin 17 to the pin 2 of the LS139. I don't really see the point in connecting the PB7 signal to the GND!

I'm not familiar with this upgrade, but in reading it, I noticed that pin 15 of the '139 is not connected anywhere. Pin 15 is a required input for a 74LS139, so maybe he meant to connect one of the double connections to pin 2 to pin 15 instead. Good luck.

After studying the connections, I think that pin 17 of U23 should go to pin 15 of the '139. Give that a try.

[Mugo]

After studying the connections, I think that pin 17 of U23 should go to pin 15 of the '139. Give that a try.

 

 

Did it already, and the Atari still don't boot :-(

I reversed the mods and got back to the 256k again. At least this way i can have some good times with the machine for now.

I don't know if the LS139 chip i used is bad (it's from my used parts pile) or there's some other problem with this mod.

I'll try to get an S139, new from the store, so i can check it again.

 

Anyway, thank you very much for your help so far. I'll let you know when i test it again this week.

 

In the mean time, if someone have any other suggestions about how i can raise the memory a little bit (320k is my goal, so i can run the demos that demand so much memory), i'm all ears! :-)

Edited May 24, 2008 by Mugo

[kenfused]

After studying the connections, I think that pin 17 of U23 should go to pin 15 of the '139. Give that a try.

 

 

Did it already, and the Atari still don't boot :-(

I reversed the mods and got back to the 256k again. At least this way i can have some good times with the machine for now.

I don't know if the LS139 chip i used is bad (it's from my used parts pile) or there's some other problem with this mod.

I'll try to get an S139, new from the store, so i can check it again.

 

Anyway, thank you very much for your help so far. I'll let you know when i test it again this week.

 

In the mean time, if someone have any other suggestions about how i can raise the memory a little bit (320k is my goal, so i can run the demos that demand so much memory), i'm all ears! :-)

Years ago I tried really hard to go from 256K to 512K and never had any luck. I noticed assembling it that a connection or two in the instructions seemed wrong (similar to what you noticed). I tried to rework the logic myself but never got anything working stable at the time.

[Mugo]

Years ago I tried really hard to go from 256K to 512K and never had any luck. I noticed assembling it that a connection or two in the instructions seemed wrong (similar to what you noticed). I tried to rework the logic myself but never got anything working stable at the time.

 

 

Good (in fact it's bad...) to know that you hadn't success with the upgrade too. Seems that i'm not the only one.

Tried alternative wirings myself too, but the computer doesn't boot anyway.

I've been away from my A800XL for a long time, and recently got back "the virus" to use it again. Did the MyIDE DIY, started to assemble some images to use with it, and noticed i would need some more memory to run all the software i want to run.

I'm taking knowledge of a lot of things about the A8 machines only now. In my childhood i've won this same A800XL from an uncle, that lived in the USA for some years. But here in Brazil this computer was unknown at that time, so i couldn't put my hands on software, hardware, information, etc.

Anyway, i've been reading a lot of posts here, and some people report they have 512k of RAM in their A800XL. Some even say they had the QMeg from Claus and further upgraded them to 512k. So there's a way. I just need to find out what is this way.

Hope someone will yet shed some light in this issue.

 

Thanks again!

[Almost Rice]

I never got my 512k to work with 512k. It only showed 256k

[Mugo]

I never got my 512k to work with 512k. It only showed 256k

 

 

If i understand correctly, you have the Claus 256k expansion (or the RamboXL), and upgraded it to 512k?

Your computer boots up normally?

I couldn't even get my A800XL to boot with the "upgrade" installed...

[Almost Rice]

If i understand correctly, you have the Claus 256k expansion (or the RamboXL), and upgraded it to 512k?

Your computer boots up normally?

I couldn't even get my A800XL to boot with the "upgrade" installed...

 

Mine was a Newell 256k with a Rambo compatibility switch.

Edited May 26, 2008 by Almost Rice

[ClausB]

I couldn't even get my A800XL to boot with the "upgrade" installed...

I read your posts again and it's not clear how many SIMMs you wired in and what size they are. (256K? 1M?) One 30-pin SIMM has only one 8-bit bank of DRAM, and the Schmidt upgrade is meant for two banks of 256K. So, even if your SIMM is bigger than 256K, if you have only one SIMM, the Schmidt circuit won't work. Where would you attach the second -CAS?

 

There are other upgrades for more than 256K that can use a single SIMM, such as Mathy's. Some can even use SRAM. Just search these forums and find many links.

[Mugo]

I couldn't even get my A800XL to boot with the "upgrade" installed...

I read your posts again and it's not clear how many SIMMs you wired in and what size they are. (256K? 1M?) One 30-pin SIMM has only one 8-bit bank of DRAM, and the Schmidt upgrade is meant for two banks of 256K. So, even if your SIMM is bigger than 256K, if you have only one SIMM, the Schmidt circuit won't work. Where would you attach the second -CAS?

 

There are other upgrades for more than 256K that can use a single SIMM, such as Mathy's. Some can even use SRAM. Just search these forums and find many links.

 

 

Hey Claus,

 

Well, then this is my problem.

I'm really a goofy . . .

After i read this last message from you, i decided to look at the 41256 datasheet, and noticed that the pin 15 mentioned on the Schmidt circuit is a CAS line, and not an A9 (or whatever address line) as i supposed before.

Well, there's my problem. It was purely my fault.

Yes, i have only one 30pin SIMM, and it's 1MB. I've connected the line that was supposed to be in the pin 15 on the new set of RAM chips, to the A9 line in the SIMM. This would never gonna work . . .

Well, i'll see what i'll do. Maybe be it's not worth to put another 1MB SIMM for the extra 256k. Although i have 5 of these modules, and a spare socket . . .

 

Once again Claus, thank you really so much for your help for all this time. It was really important.

Best regards.

[Allas]

What's this?

 

[Mugo]

FINALY!!!!!! It Works!!!!

 

Well, after a long struggle, i've finally succeed in upgrade my A800XL memory to 512k!

I couldn't make the original 256k->512k upgrade instructions work, even after the precious advice from you guys (a big thanks to Mr. Claus!) in this topic.

But i've found similar instructions that put it to rest!

It's right here in AtariAge forums. Link below:

 

http://www.atariage.com/forums/index.php?s...2&hl=256k+-

 

I hadn't much time to put it to some real tests, but some demos that was supposed to require 320k worked OK.

I'll try numen as soon as i get some time.

I decided to reply to my post, so anyone looking for it these days can have some advice.

 

Thanks guys!

[ClausB]

FINALY!!!!!! It Works!!!!

That link would not work for me. What was the name of the thread?

 

So, do you now have 2 banks of 256K or 1 bank of 512K? How many SIMMs?