Access the SRAM on turboR ST

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By Daemos

Paragon (2044)

Daemos's picture

12-12-2014, 18:55

I hope this has not been asked a million times before but here it goes.

How can I with assembly access the SRAM on the turbo-R ST and GT models? Can I write to it as if its memory etc etc.

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By Grauw

Ascended (10699)

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12-12-2014, 19:39

By Daemos

Paragon (2044)

Daemos's picture

13-12-2014, 00:12

Not so difficult I see. Thanks Smile So I need to put slot 3-3 into page 1 and write 128 to $6800 then I have SRAM on adress $4000. Can I then simply read and write to it as if its memory so I can ldir to it and such?

By Grauw

Ascended (10699)

Grauw's picture

13-12-2014, 01:02

Looks like it yes. The “closing value” is probably to page it out after accessing it so that RAM detection routines etc. won’t corrupt the data.

By Daemos

Paragon (2044)

Daemos's picture

13-12-2014, 10:04

I think it is to get the kanji rom back since the RAM is on page 3-0 in my situation switching the subslot should suffice.

By Daemos

Paragon (2044)

Daemos's picture

13-12-2014, 14:33

Wow.... it actually works!! It is indeed THAT easy as it is stated in the documentation. In the future however I will drop the sram and continue research on writing data to a more accessible format which everyone can have. This is purely to test the load and save function of the project.

I have noticed however that neither openmsx or bluemsx seems to handle the sram well. On the real machine it works like a charm but in the emulator the SRAM always returns $FF on all adresses. I have offcourse used the turboR roms and turboR setting in both emulators. Propably the SRAM is some setting in the emulators?

By Manuel

Ascended (19273)

Manuel's picture

13-12-2014, 21:13

It's not some setting in openMSX.

When I start up the GT with firmware enabled, I can access drive D: (which is the SRAM) fine. And copy files to it, etc.

It would be helpful to have runnable code that demonstrates the problem and works on real turboR.

By Daemos

Paragon (2044)

Daemos's picture

14-12-2014, 01:43

Quote:

It would be helpful to have runnable code that demonstrates the problem and works on real turboR.

I will isolate the code I got and see how it turns out. If the difference remains I will send you the isolated code so you can see for yourself.

By Manuel

Ascended (19273)

Manuel's picture

14-12-2014, 13:30

Great, thanks

By Daemos

Paragon (2044)

Daemos's picture

14-12-2014, 19:22

Manuel you have mail.

By Manuel

Ascended (19273)

Manuel's picture

15-12-2014, 18:45

Should be fixed (thanks Wouter!) in the latest development build (6c784ce). Please verify Smile

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