"Panic: Bus Error." with new MIST and Atari ST emulation

[hanshuebner]

Hi,

I've just received a new MIST from Lotharek and am trying to follow the instructions on https://github.com/mist-devel/mist-board/wiki/GettingStarted to get the Atari ST emulation running. When I start the box, I see this message:

Panic: Bus error.
misc = 2314, address = 00e02314, opcode = 2314, sr = 2314, pc = 00e06e82
Dregs: 0000ff00 000003e8 00000000 00000000  0000ffff 00000000 00000000 00000000
Aregs: 00000000 00000522 00004a4c 00000000  01000000 00000200 00e00b38 00000ede
 usp = 00000000

It seems that the m68k is running, but somehow crashes. I've tried both the files linked from GitHub as well as the files present in the Subversion repository. I've tried a few of the other bitstreams (colecovision, spectrum, Amstrad), and they all seem to work to some degree. Does anyone know whether this is a hardware or software issue?

Thanks!
Hans

[renaudhelias]

Hi Till,

By the way,

Here a HOWTO about adding/merging CRC16 into MiST-board core firmware :)

For Amstrad dsk access robustess I make my own firmware (but it is not a official one, just running for CoreAmstrad, and failling perhaps in "firmware update" OSD task), Till you can try to merge it, inserting it firstly with a general "boolean switch" to activate/desactivate this functionnality, adding slowly and friendly this purpose to your main firmware core.

CRC16 is activated adding some post-instruction in mmc.c MMC_Init()
http://github.com/mist-devel/mist-binaries/blob/master/cores/amstrad/amstrad_150729_r003.10.crc16.firmware.zip

In mmc.c, do look after "Calculate CRC16 CCITT", it defines two main functions about computing a CRC16 for sdcard SPI protocol :
http://github.com/mist-devel/mist-binaries/blob/master/cores/amstrad/amstrad_150729_r003.10.crc16.firmware.zip

In the other hand, in sd_card.v, do look after "CRC16_WRITE" you should turn into 1 value (instead of 0) in others project than CoreAmstrad to activate compute of CRC16 in verilog way (in Amstrad the CRC16 is computed further : in my own bootloader component)
http://github.com/renaudhelias/CoreAmstrad/blob/master/BuildYourOwnZ80Computer/sd_card.v

I know that my firmware fork does run fine with Amstrad sdcard read/write, but not with MIST core (as sd_card.v is not merged with my own one)
I didn't succeed in compiling and running last official firmware, so I let you make the stuff Till if you want (first step merging with a switch boolean, second step trying it)

Regards,

Renaud (CoreAmstrad)

[hanshuebner]

Following Till's advice, I tried using TOS 2.06 from http://www.atariworld.org/tos-rom/ and with that, the ST core booted fine.

[harbaum]

I still need to integrate Renauds changes. But before i need to make sure these changes don't break any of the other cores which also use the SD card.