EMUTos + AltRAM

[dad664npc]

Whilst developing PiStorm for Atari, I have noticed a couple of problems with EMUTos and AltRAM
1. if emulating a 68000 CPU, EMUTos does not recognise AltRAM (defined at 0x01000000)
2. I can assign a maximum of 32MB to AltRAM (68020, 30 and 40). Anything more, results in EMUTos reporting the AltRAM size = AltRAM + available system RAM - which then causes a Bus Error and EMUTos to abort loading.
eg. AltRAM defined as 64MB and Atari has 4MB of RAM, EMUTos reports AltRAM = 68MB

Does anyone know if these are known limitations?

[DaveC]

1. if emulating a 68000 CPU, EMUTos does not recognise AltRAM (defined at 0x01000000)

68000 is 24bit address bus so is limited to 16Mb address space.

[chronicthehedgehog]

Does your EmuTOS build have the correct MMU flags? Have you tried a custom build?

custom build

Just a long shot idea - I'm no expert on the matter

[dad664npc]

I can never successfully build on that website - can you?
/home/www/usr/bin/../lib64/gcc/m68k-atari-mint/4.6.4/cc1: error while loading shared libraries: libmpfr.so.4: cannot open shared object file: No such file or directory

[stephen_usher]

Looks like someone didn't set their LD_LIBRARY_PATH.

[Steve]

maybe invoke @czietz the expert on EmuTOS

[alexh]

1. if emulating a 68000 CPU, EMUTos does not recognise AltRAM (defined at 0x01000000)

68000 is 24bit address bus so is limited to 16Mb address space.

That was a physical hardware limitation of the 68000 chip. I don't think emulated 68000 need to have that limitation. But you'd need to check the coding of the emulator.

[chronicthehedgehog]

I can never successfully build on that website - can you?
/home/www/usr/bin/../lib64/gcc/m68k-atari-mint/4.6.4/cc1: error while loading shared libraries: libmpfr.so.4: cannot open shared object file: No such file or directory

never tried

Just did - same error

[chronicthehedgehog]

I can never successfully build on that website - can you?
/home/www/usr/bin/../lib64/gcc/m68k-atari-mint/4.6.4/cc1: error while loading shared libraries: libmpfr.so.4: cannot open shared object file: No such file or directory

Maybe you can copy and paste the 'make' command (i.e. the comp. flags) to your own local build

[czietz]

As far as the TT-RAM question is concerned, I can confirm (personally from my TT) that EmuTOS runs fine with 256 MiB TT-RAM. Therefore, I like to rule out any general issue with EmuTOS. This must be a problem specific to the PiStorm; which I have no experience with.

For the "fake" 68000 with TT-RAM, you should check whether IS_BUS32 (32 bit bus) is set to 1, otherwise EmuTOS will not try to detect TT-RAM: https://github.com/emutos/emutos/blob/a ... C14-L36C31

Regarding the custom build website: This is generously provided by @thorsten.otto; he would have to look into the error message.

Feel free to continue the discussion on the EmuTOS-devel mailing list in case you have more technical questions: https://sourceforge.net/p/emutos/mailman/emutos-devel/.