RAM Upgrade Options

[+bob1200xl]

You just asked if there were any...

 

Which machine did you have in mind? I made my own for the 1200XL and 130XE, but I know there were others. PB4 selects CPU (if HALT is not asserted) and PB5 selects ANTIC (if HALT is asserted). Those old designs used 256K dynamic memory - modern designs should use static RAM.

 

Like this:

 

 

 

 

 

 

 

This SRAM has a battery that keeps the data safely through power cycles. Don't know if I would bother with that again - flash memory seems like a better idea. All the logic is in the MMU GAL on the motherboard, except for the one gate for phase02. This configuration could be set up to operate in any desired mode. (this one does not do true banking)

 

ABBUC had a configurable memory upgrade like this in their hardware contest last year. Check their website.

 

Bob

 

 

can we be directed to the true banking upgrades?

[_The Doctor__]

absolutely wonderful if you speak German or can make sense of pseudo translations from google or yahoo.

 

I was looking towards getting the older upgrades updated with the logic you described on XE's, and upgrading untouched XE's ones with the newer mod like the one you have shown us i the above post.

 

The battery keeps a ramdisk alive then I presume.

 

Flashram for dram should be interesting... bubble memory reborn!

[+bob1200xl]

Yes, the battery keeps the data in the extra RAM. Works well... I have a MyDOS disk that is configured with a 512K ramdisk as drive D1:. I boot from the floppy and the ramdisk comes up automagically. Not quite as good as a CF card but not bad. Ramdisks aren't that much faster than a CF card, however. Throw out the battery and load/save to CF or Flash when you boot/shutdown. You could put the OS into Flash, also - boot with the configuration application and jump into whatever you select.

 

So, you want a 130XE with a 512K upgrade using separate ANTIC and CPU banking? Or, do you want it programmable for any banking scheme?

 

How much detail do you need? Can you build this if I design it?

 

Bob

 

 

 

absolutely wonderful if you speak German or can make sense of pseudo translations from google or yahoo.

 

I was looking towards getting the older upgrades updated with the logic you described on XE's, and upgrading untouched XE's ones with the newer mod like the one you have shown us i the above post.

 

The battery keeps a ramdisk alive then I presume.

 

Flashram for dram should be interesting... bubble memory reborn!

[_The Doctor__]

If the upgrade has true antic and cpu banking following the 130XE banking method my hope is it won't need a particular banking scheme to be selected, or at least only need a much reduced set of switch positions to act like a certain upgrade. I can see why 512k would help since it covers two sets of banks in and of itself.

I can solder and desolder. I have installed memory upgrades on XE's, ST's, MegaST's. Rebuilt a power supply or two. Clearpic mod etc. Typical home hobby. I also stuffed boards and wave soldered back when people actually did those tasks. So it is my hope building it should not be a problem. The last XE I did only used 9 chips, a couple of sockets, resistors and a switch so I can understand why it is limited with the either antic/cpu follow or antic main when in extended mode. My hopes are 512k true antic and true cpu access, and still have basic and selftest. I have only seen two that kinda look like they might do it, something mathy was up to and what you were talking about in a discussion here at AtariAge. Sort of our own English speaking version of ABBUC here!

 

I follow an old school mod method.

 

1. a parts list.

2. a step by step prep.

3. a step by step installation. so as it is done i check it off and can resume where I left off if interrupted (important since I am older now and have many interruptions)(can you say kids&wife?)

 

 

 

 

Yes, the battery keeps the data in the extra RAM. Works well... I have a MyDOS disk that is configured with a 512K ramdisk as drive D1:. I boot from the floppy and the ramdisk comes up automagically. Not quite as good as a CF card but not bad. Ramdisks aren't that much faster than a CF card, however. Throw out the battery and load/save to CF or Flash when you boot/shutdown. You could put the OS into Flash, also - boot with the configuration application and jump into whatever you select.

 

So, you want a 130XE with a 512K upgrade using separate ANTIC and CPU banking? Or, do you want it programmable for any banking scheme?

 

How much detail do you need? Can you build this if I design it?

 

Bob

 

 

 

absolutely wonderful if you speak German or can make sense of pseudo translations from google or yahoo.

 

I was looking towards getting the older upgrades updated with the logic you described on XE's, and upgrading untouched XE's ones with the newer mod like the one you have shown us i the above post.

 

The battery keeps a ramdisk alive then I presume.

 

Flashram for dram should be interesting... bubble memory reborn!

 

Edited February 19, 2009 by _The Doctor__

[+bob1200xl]

Selftest isn't a problem but BASIC is, if you want 512K and true banking. Even with BASIC crippled, some software may only see 128K of banked memory. (or 256K...) Keeping internal BASIC will give you, at best, a 320K XE. There are so many extended memory configurations - that's why some kind of selector would be useful.

 

So, if I tell you to solder a wire to pin 4 of U17, you won't end up with solder bridges to pins 5 and 3 on U9?

 

Bob

 

Mathy has some kind of tricked-out banking scheme. How does it work?

 

 

If the upgrade has true antic and cpu banking following the 130XE banking method my hope is it won't need a particular banking scheme to be selected, or at least only need a much reduced set of switch positions to act like a certain upgrade. I can see why 512k would help since it covers two sets of banks in and of itself.

I can solder and desolder. I have installed memory upgrades on XE's, ST's, MegaST's. Rebuilt a power supply or two. Clearpic mod etc. Typical home hobby. I also stuffed boards and wave soldered back when people actually did those tasks. So it is my hope building it should not be a problem. The last XE I did only used 9 chips, a couple of sockets, resistors and a switch so I can understand why it is limited with the either antic/cpu follow or antic main when in extended mode. My hopes are 512k true antic and true cpu access, and still have basic and selftest. I have only seen two that kinda look like they might do it, something mathy was up to and what you were talking about in a discussion here at AtariAge. Sort of our own English speaking version of ABBUC here!

 

I follow an old school mod method.

 

1. a parts list.

2. a step by step prep.

3. a step by step installation. so as it is done i check it off and can resume where I left off if interrupted (important since I am older now and have many interruptions)(can you say kids&wife?)

[_The Doctor__]

What you mean by do not to use the whole roll of solder on that connection?

 

No, I won't make icicles, dull cold joints, or globs of bridged pins/pads either.

 

Maybe we can start by adding true banking on my 320XE for now with the switch to change the bank scheme.

 

and once that is accomplished...

we have to go back to mathy's site and look at this again...

 

http://www.holyoak.com/atari/memsch1.txt

http://www.holyoak.com/atari/schalt~1.jpg

 

he states there are a few bugs to work out with the memory upgrade at that stage and it rely's on sims. A second flavor would be nice to have a version work with standard 256k and 512k drams. Would this require and independent refresh circuit of some kind.

[MEtalGuy66]

No offense to anyone, least of all Mathy, but his upgrade is not the most advanced/elegant by a longshot.. Especially where "true separate ANTIC/CPU banking" is concerned..

 

If you guys really want a good "starting point" to go from, as far as what is/has been available/popular in recent years, you should really take a look at Hias's universal single-custom-GAL based memory upgrade.. It is absolutely the slickest I've seen.. Gives true 130xe compatability to ANY XL/XE and auto-senses just about everything as far as supporting "big ram" and reclaiming portB bits to support system features when needed..

 

Also, there is an upgrade which has (may not currently) been in production as a set of small professional PCBs that will also install in any XL/XE with 512k of SRAM on board, provisions for simply attatching a battery (to make it all NVRAM) and mode-switched support for true 130xe, rambo/petersen, compyshop, etc.. This upgrade was sold by Wolfram/MegaHZ of ABBUC and designed by Berndt..

 

All of these guys have done ALOT of advanced devlopment in the way of "universal" extended ram schemes in recent years, and none of it has been "trivial" to say the least..

 

Mathy's upgrade is a nice little project from the standpoint of what he actually set out to do, but it's nowhere near as advanced or functionally complete from the standpoint of what you guys are talking about..

 

I'll see if I can dig up the links for Hias's GAL based upgrade.. I really think this is pretty close to what you guys are looking for..

[HiassofT]

If you guys really want a good "starting point" to go from, as far as what is/has been available/popular in recent years, you should really take a look at Hias's universal single-custom-GAL based memory upgrade.. It is absolutely the slickest I've seen..

Thanks!

 

I'll see if I can dig up the links for Hias's GAL based upgrade.. I really think this is pretty close to what you guys are looking for..

No need to search any longer, I just uploaded the preliminary docs to my website (as usual, in temporary space):

http://www.horus.com/~hias/tmp/sram12-090220.zip

 

The text description is somewhat unfinished, I started drawing a schematic and also describing how to add battery backup and piggybacking the RAM on top of Basic ROM instead of OS ROM. The battery backup was tested by a friend (and it works, just be sure you use a RAM that operates down to ~2.6-3V), but I haven't tested piggybacking on top of Basic ROM yet.

 

So, there might still be bugs in the schematic, and the text description don't mention battery backup and Basic ROM yet. But the text description is correct and several other people used it to successfully build a memory upgrade.

 

If you find bugs or if something is unclear please drop me a line. Eventually, some day I might finish the docs :-)

 

so long,

 

Hias

[+bob1200xl]

Yes - that's the way to do it.

 

Looks nice!

 

Bob

 

 

 

If you guys really want a good "starting point" to go from, as far as what is/has been available/popular in recent years, you should really take a look at Hias's universal single-custom-GAL based memory upgrade.. It is absolutely the slickest I've seen..

Thanks!

 

I'll see if I can dig up the links for Hias's GAL based upgrade.. I really think this is pretty close to what you guys are looking for..

No need to search any longer, I just uploaded the preliminary docs to my website (as usual, in temporary space):

http://www.horus.com/~hias/tmp/sram12-090220.zip

 

The text description is somewhat unfinished, I started drawing a schematic and also describing how to add battery backup and piggybacking the RAM on top of Basic ROM instead of OS ROM. The battery backup was tested by a friend (and it works, just be sure you use a RAM that operates down to ~2.6-3V), but I haven't tested piggybacking on top of Basic ROM yet.

 

So, there might still be bugs in the schematic, and the text description don't mention battery backup and Basic ROM yet. But the text description is correct and several other people used it to successfully build a memory upgrade.

 

If you find bugs or if something is unclear please drop me a line. Eventually, some day I might finish the docs :-)

 

so long,

 

Hias

[Roydea6]

So, if I tell you to solder a wire to pin 4 of U17, you won't end up with solder bridges to pins 5 and 3 on U9?

 

Bob

 

Someone has been peeking over my shoulder, but I can usually repair any goofs that I do myself. Eyesight isn't good anymore, and the hand's are not as steady.

[hueyjones70]

Does the Peterson upgrade work on a 65XE that has 64K and only one column of RAM chips.