If anyone wants a project..

General discussions or ideas about hardware.
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exxos
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If anyone wants a project..

Post by exxos » Wed Apr 08, 2020 4:42 pm

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.
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Re: If anyone wants a project..

Post by Icky » Wed Apr 08, 2020 6:07 pm

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

TABPlus.png
TABPlus.png (97.5 KiB) Viewed 1687 times

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Re: If anyone wants a project..

Post by exxos » Wed Apr 08, 2020 6:21 pm

Never seen any info of images of it either. Would think the bulk of the logic could go in a GAL.
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Re: If anyone wants a project..

Post by frank.lukas » Wed Apr 08, 2020 6:27 pm

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

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Re: If anyone wants a project..

Post by rubber_jonnie » Wed Apr 08, 2020 8:00 pm

Like I need another project....
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
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Re: If anyone wants a project..

Post by terriblefire » Wed Apr 08, 2020 8:14 pm

rubber_jonnie wrote:
Wed Apr 08, 2020 8:00 pm
Like I need another project....
Happy to route anything anyone sets up in eagle. Right now I’m going nuts
———
I get cranky when asked to repeat myself.

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Re: If anyone wants a project..

Post by Icky » Wed Apr 08, 2020 8:47 pm

You might regret that offer @terriblefire :)

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Re: If anyone wants a project..

Post by PhilC » Wed Apr 08, 2020 8:55 pm

H4 Mega ST version @terriblefire ? :lol:

I guess the pcb is the easy but in this case, it's the software to make it all work afterwards.
If it ain't broke, test it to Destruction.

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Re: If anyone wants a project..

Post by exxos » Thu Apr 09, 2020 12:02 am

frank.lukas wrote:
Wed Apr 08, 2020 6:27 pm
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.
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Re: If anyone wants a project..

Post by exxos » Thu Apr 09, 2020 12:27 am

terriblefire wrote:
Wed Apr 08, 2020 8:14 pm
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.
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