If anyone wants a project..

[exxos]

http://atari4ever.free.fr/#ram

16MB RAM board for every ST.


Never seen one or heard of it being done.. Though probably a H4 project to use a 16mb simm. It also decodes TOS 206 but might be avoidable doing that part.

From what I can tell it generates MAD10 and fools the GLUE on address ranges. I assume to fool the MMU into thinking its accessing valid ST-ram when its actually accessing higher ranges.

[Icky]

I havent heard of anyone doing this either. Here is the main schematic.

TABPlus.png (97.5 KiB) Viewed 1687 times

[exxos]

Never seen any info of images of it either. Would think the bulk of the logic could go in a GAL.

[frank.lukas]

There was a 16MB (15MB) real ST Ram extension. It works by doing bank switching. Eight 2MB banks are possible ...

-> https://forum.atari-home.de/index.php?topic=13517.0

[rubber_jonnie]

Like I need another project....

[terriblefire]

Like I need another project....

Happy to route anything anyone sets up in eagle. Right now I’m going nuts

[Icky]

You might regret that offer @terriblefire

[PhilC]

H4 Mega ST version @terriblefire ?

I guess the pcb is the easy but in this case, it's the software to make it all work afterwards.

[exxos]

There was a 16MB (15MB) real ST Ram extension. It works by doing bank switching. Eight 2MB banks are possible ...

-> https://forum.atari-home.de/index.php?topic=13517.0

~Interesting that someone else did similar solution then. So TOS may need patching to see the full RAM, but no great surprise. I also wonder how the TAB board also got around this issue as it just seems to mention using TOS206.. I guess lack of information there is the issue.

Though I half recall suska gave 14MB ST RAM, but not sure, think that was TOS206.

[exxos]

Happy to route anything anyone sets up in eagle. Right now I’m going nuts

There is the DRAM board I mentioned a couple weeks ago if you wanted a board to route.. This one would be 68k footprint pretty much PLD and DRAM. As it would be 68k, no use in any DRAM over 16mb as we can only really use 4mb - 14mb range for alt-ram anyway. I did get the xlinix chips, don't think I decided on a RAM yet though. RAM would need to be quick to use up to 60mhz CPU. Such a board would plug right into a H4. The 5v sram ones I designed end up costing towards £100 mark.. Its why I wanted some help with your dram controller stuff to design a cheaper board.