1200xl 64+1 MEG Upgrade

[Ralphy Rocket]

 

Hi Everybody!

 

What should a guy do when his wife leaves town to visit family.....I KNOW!!!! I'll make a 1 Meg memory upgrade for my 1200xl. I know that there is plenty of upgrades out there but just to entertain myself I wanted to do my own.

 

First. STATIC MEMORY Definetly the way to go (Hi Warerat) but im only using what i have handy So Im gona use a 1 meg 30 pin sim (Dynamic Memory)

Second. Compatability. Since its only proof of concept, I'm using a 8 bit latch mapped to 54592 (WHAT!!) More on this later... but I did use BIT 4 at this location to enable banking so hopefully by looking for 54017($D301) in the software and changing it to 54592 should patc the software.

 

So with that said...

 

Using the software from PCBEXPRESS.COM, I made the schematic and pc board layout. Then using the TONER TRANSFER method I made my double sided pc board and utilized used surface mount chips that came off of old motherboards (a heat gun makes easy work of that) I made the board to hijack most of the needed signals from the multiplexers (piggy back) but I still needed 13 wires Oh Well... I wanted a neat job, but I guess thats the best I can do.

 

I'm using the $D5xx line from the '138 on the xl. I can move it to $D1xx, $D6xx or D7xx should I need to. NOW, the reason for thew funny Memory Register address (54592) is that $D500- $D53ff is decoding a 16bit IDE interface, more on that later

 

I need some help with the following: Is there a memory tester program out there where I can tell it the paramerters (window size, Memory register, bank numbers) so I can test this thing??

When the computer turns on...its already in bank mode, it seems ok if nothing changes the Memory Register, software doesnt now the second 16k is off the simm and not the onboard but I want to initialize it. So, where in the OS can I do that and how..(I forgot to mention , programming is hard for me) I did my initial test by...POKE This Poke that.. PLEASE!

 

Anybody intrested in this mod, drop me a line for the schematics, pcb layout etc, and if you can program, help me out with some code....

 

 

Thanks It was a cool weekend

 

Ralph

[ndary]

you may find that the XRAM memory test utlity can be usefull for your project

 

http://www.atari.sk/satantronic/xXRAM.htm

[walter_J64bit]

WOW, is it compatible with 130XE?

[puppetmark]

Anybody intrested in this mod, drop me a line for the schematics, pcb layout etc, and if you can program, help me out with some code....

 

 

Thanks It was a cool weekend

 

Ralph

very cool, can you send me the info, I would live to see the schematics and such. I don't think I can help with the code but I would live to see if the upgrade can be used in other machines.

[Ralphy Rocket]

Hello Again,

 

Well sadly my design DIDNT WORK! ..YET.

 

NDARY: XRAM is GREAT! YOUR software helped alot. It helped me find a broken wire. All I had to do was change $d301 to $d540 (my memory register) on the software. Again Thanks!

 

WALTER_J64BIT: Its not XE compatible because I use a diffrent register for the bank switching, but if you used the PIA PORTB bits insted of my own register, it would be XE CPU Banking compatible (not ANTIC banking compatible). In retrospect, I just should of done an existing design....

 

PUPPETMARK: I took a "Generic 6502" attitude in the design, so it can go on any 6502 machine. I keep saying "My Design" but its all bits and pieces of other schematics. This is a good time to credit and thank Bob Wooley for the MEMORY REFRESH design. Here is the schematic. I tested the SIMM by itself and its stable. I test the main ram, and its stable. but when I try banking, It crashes. I also tried this neat trick while fooling around tring to catch the problem. I loaded DROPZONE into the main memory, Held down RESET while i changed the wire that controls Main/SIMM. then loaded QUASIMODO into the SIMM. Played for a while, then held down reset, moved the wire and PRESTO! DROPZONE! I switched back and forth for about half and hour. Thats why I think the memory is stable, It just fails when it banks. If I get a break this weekend, I'm gonna try gating the bank enable line with o2 or /o2. Thats all I can think of to try and fix the problem. I know I talk like I know what i'm doing, but when it comes to delaying signals or gate propagation...I QUIT.

1MegAtari.bmp