RAM upgrades

[Swami]

Antonia gives you memory, some switchable OS's, and an 816 CPU. The 816 and the RAM are great, But I couldn't live without all the features the U1M adds, Especially with Jon's BIOS.

 

Does anyone do installs of the U1MB or the new 4MB upgrades on a Taiwan 800xL or XEGS, or sell 800XLs already upgraded? I don't think my soldering experience is up to it.

[martinez]

As far as U1MB is concerned, you may send mobo to Lotharek and get it back upgraded. He charges additional fee for the job.

[mutterminder]

I'm planning to install the U1MB in my 600xl and in checking my 64K memory upgrade, I found that it does not match any of the common upgrades. I put it in at least 15 years ago, maybe more and I don't remember where I got it. The 64K chips have their markings sanded off. I have wires soldered to the lifted legs of U5-3 and U6-9, but they go to U2-4, and 5. Also U18 pins 8, 9, and 10 are lifted. There are just the two wires. Does anybody know anything about this upgrade?

[mutterminder]

To add to the above, in case it isn't obvious. Because the wires are soldered to the MMU, I'm not sure that this particular memory upgrade is even compatible with the U1MB.

[+tf_hh]

I'm planning to install the U1MB in my 600xl and in checking my 64K memory upgrade, I found that it does not match any of the common upgrades. I put it in at least 15 years ago, maybe more and I don't remember where I got it. The 64K chips have their markings sanded off. I have wires soldered to the lifted legs of U5-3 and U6-9, but they go to U2-4, and 5. Also U18 pins 8, 9, and 10 are lifted. There are just the two wires. Does anybody know anything about this upgrade?

 

Sounds ok. The lifted pin at U6 should be 10, not 9. The both cables connect the missing address lines needed for selecting something over 16K - A14 and A15. You can take these both from the MMU like in your solution, the CPU, the 74LS375 (U15) or some solder joints.

 

U18 (74LS32) is only needed to limit the CAS signal to the lower 16K. When pins 8, 9 and 10 are bended up, there must be a connection between pin 8 and 10 somewhere, maybe from the bottom of the PCB or chip itself.

 

I see no problem to install an U1MB. Remove the both wires connected to the MMU and solder them to an other place, for example:

 

A14 = pin 9 of U15 (74LS375)

A15 = pin 15 of U15 (74LS375)

[mutterminder]

 

Sounds ok. The lifted pin at U6 should be 10, not 9. The both cables connect the missing address lines needed for selecting something over 16K - A14 and A15. You can take these both from the MMU like in your solution, the CPU, the 74LS375 (U15) or some solder joints.

 

U18 (74LS32) is only needed to limit the CAS signal to the lower 16K. When pins 8, 9 and 10 are bended up, there must be a connection between pin 8 and 10 somewhere, maybe from the bottom of the PCB or chip itself.

 

I see no problem to install an U1MB. Remove the both wires connected to the MMU and solder them to an other place, for example:

 

A14 = pin 9 of U15 (74LS375)

A15 = pin 15 of U15 (74LS375)

Thanks for the feedback I was just going through the schematic myself to see if I could figure out what was going on. The situation at U18 concerned me. You are probably right, there may be another jumper somewhere on the board that I don't see, like I said, I installed this upgrade a long time ago, so I don't remember anything about it. I Think I'll follow your suggestion about finding A14 and 15 somewhere else.

[mutterminder]

Sure enough there was a jumper on the bottom of the card between U18-8 and 10. While this does preserve the the CAS going where it needs to go, I decided to just lift pin 9 of U18 and short it to ground on PIN 7. (Oh and it was U6-10 and not 9). Now to to install the U1MB.

[tep392]

So, no current memory upgrades available for an 800 past 64K?

An Axlon type board has been design but you would have to order the parts and build it. I've built a few.

http://atariage.com/forums/topic/256464-designing-an-axlon-compatible-board/?hl=+axlon

[+Stephen]

An Axlon type board has been design but you would have to order the parts and build it. I've built a few.

http://atariage.com/forums/topic/256464-designing-an-axlon-compatible-board/?hl=+axlon

Very cool video BTW.

[tep392]

Very cool video BTW.

Thank you! I really love that 800.

[+Stephen]

Thank you! I really love that 800.

If I get this Bit3 working, my Incognito will be the always hooked up machine in my basement setup.

[hueyjones70]

Does anyone hace pictures of a good Rambo/1200XL upgrade. I have one that I have hesitated to install because I can't really follow the instructions that come with the package.

[BillC]

Does anyone hace pictures of a good Rambo/1200XL upgrade. I have one that I have hesitated to install because I can't really follow the instructions that come with the package.

You don't say what instructions came with it, a PDF of the original ICD manual is available from Atarimania. 1200XL installation instructions start on page 9.

http://www.atarimania.com/documents/rambo_manual.pdf

[+slx]

I'm planning to install the U1MB in my 600xl and in checking my 64K memory upgrade, I found that it does not match any of the common upgrades. I put it in at least 15 years ago, maybe more and I don't remember where I got it. The 64K chips have their markings sanded off. I have wires soldered to the lifted legs of U5-3 and U6-9, but they go to U2-4, and 5. Also U18 pins 8, 9, and 10 are lifted. There are just the two wires. Does anybody know anything about this upgrade?

One advantage of Antonia is that it doesn‘t need more than 16K in a 600XL to work (as it entirely bypasses system RAM). That‘s the reason I put it in my 600XL. It has several (8?) OS/BASIC slots as well but switching requires a utility and can‘t be done with a hotkey at boot. You also can‘t just toggle the power for a hard reset as Antonia will keep the RAM for some time. It‘s super-easy to install, however and an easy way to experiment with a 65C816 if you‘re so inclined. The 65C816 will not work with some programs however and runs at normal speed.

 

 

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[hueyjones70]

I have just finished installing a Rambo 256K upgrade on my 1200XL and there is a problem somewhere. When I turn on the computer with a basic cartridge, I get a loud beep and then a blank blue screen. If I press a key I get the sound of a keypress but nothing appears on the screen. After a minute or so, (I haven't timed it to see if it is the same every time) I get the sound that the computer makes when booting something, and a BOOT ERROR message. Then the ready prompt appears and everything seems to be normal. I have tested all the keys and have run a short basic program while NORMAL. I assume that I must have a jumper wrong or something. Any trouble shooting tips. I will post a picture of my install in the near future.

[+Stephen]

I have just finished installing a Rambo 256K upgrade on my 1200XL and there is a problem somewhere. When I turn on the computer with a basic cartridge, I get a loud beep and then a blank blue screen. If I press a key I get the sound of a keypress but nothing appears on the screen. After a minute or so, (I haven't timed it to see if it is the same every time) I get the sound that the computer makes when booting something, and a BOOT ERROR message. Then the ready prompt appears and everything seems to be normal. I have tested all the keys and have run a short basic program while NORMAL. I assume that I must have a jumper wrong or something. Any trouble shooting tips. I will post a picture of my install in the near future.

Sounds like the Start key is being held down. This makes the machine want to boot a cassette.

[hueyjones70]

Quadrunner, you may have been correct. I gave the keyboard a small flex and the problem seems to have cleared up. It booted correctly 10 straight times.

 

Another question, I recently saw a post by someone who had written a BASIC program that tested extended memory but with my limited memory I can't remember where I saw it and search hasn't yielded the proper results. ANYONE have a better memory?

[hueyjones70]

​I just finished installing the the Rambo 256 upgrade to my 1200XL. I am posting pictures so anyone that does this in the future can possible use the visual aid. I had to modify the shield in two places for the Rambo. The shield was touching the Rambo card and rather that solder the ribbon cable to the pins on the PIA chip, I cut 5 connectors off of a chip socket and soldered the ribbon cable to the socket. Now if I decide for some reason to uninstall the Rambo, I won't have to desolder the ribbon cable from the PIA.

[hueyjones70]

I have recently bought one of the old wizztronics upgrade boards, (pre Best Electronics) it has a 7-wire ribbon cable whereas the Best version needs only 6 wires, does anyone know where I could find instructions for the OLD wizztronics installation?

[NISMOPC]

I have recently bought one of the old wizztronics upgrade boards, (pre Best Electronics) it has a 7-wire ribbon cable whereas the Best version needs only 6 wires, does anyone know where I could find instructions for the OLD wizztronics installation?

 

https://mafiadoc.com/the-130xe-compatible-800xl-256k-upgrade-bits-of-the-past_5a247af31723ddeec8c4112b.html

[hueyjones70]

What kind of is the nomenclature of the RAM chips that I need to purchase in order to do a wiztronics or Rambo upgrade. (what numbers would be written on the top of the chip) I know the installed chips have a number that ends in 64. I would like to buy them separately from the upgrade boards because I believe they would be much cheaper.

[ClausB]

41256. See: http://atariage.com/forums/topic/122470-ram-upgrade-applications/page-2?do=findComment&comment=1481893

[relo999]

Been a while since I checked up on this post, gave it small update. If anyone has more up to date information please feel free to share so I can edit it.