Strange TOS 1.04 Issue
Posted: Mon May 07, 2018 4:08 pm
I have been trying to upgrade my 520ST from TOS 1.02 to 1.04. It had six NEC D27256D EPROMs in it containing the old TOS and were working fine. I erased said EPROMs in a real EPROM eraser (none of this leaving them in the sun business) and then programmed them with a QG-4X programmer which I've used many times before. Of course, I did a blank check before, double write, and verify after.
I got the image from http://www.avtandil.narod.ru/tose.html, "TOS 1.04 - Rainbow TOS" as the American 192K image. That image works fine in Steem. I split it into 3 64K chunks using WinHex, then split those chunks into even/odd pairs, giving 6 files in total - L0, L1, L2, H0, H1, H2. Burned those to the EPROMs, read them back and verified. All is good.
I stuck those ROMs into the system - no booting. On composite, I see green and purple junk all over the screen. No bombs. No reboots. Nothing.
So then I tried using ROMSPLIT on an emulated ST inside Steem to re-split the ROMs. Those produced identical content to the files I produced with WinHex. Further, when loading into the files produced with ROMSPLIT the programmer and then re-verifying the content of the ROMs I burned, the results are identical.
Testing the ST with Atari Diagnostic Cart 4.4 (containing similar EPROMs burned with the same programmer and working fine) shows TOS 1.4 USA NTSC. OS ROM checksum test fails with CRC error on L2/H2 and CS error on H0/L0. The machine otherwise passes all tests.
So... the ROMS seem to have bad data and indeed, don't run. However, they're identical to the images online, which work in Steem, and produced by splitting both with WinHex and ROMSPLIT. EPROMs are burned and tested good, and these exact chips were working in this machine with an earlier TOS version. But the machine doesn't even get as far as bombing when they're installed, even though the Diagnostic cart runs fine.
Any ideas? I'm lost.
I got the image from http://www.avtandil.narod.ru/tose.html, "TOS 1.04 - Rainbow TOS" as the American 192K image. That image works fine in Steem. I split it into 3 64K chunks using WinHex, then split those chunks into even/odd pairs, giving 6 files in total - L0, L1, L2, H0, H1, H2. Burned those to the EPROMs, read them back and verified. All is good.
I stuck those ROMs into the system - no booting. On composite, I see green and purple junk all over the screen. No bombs. No reboots. Nothing.
So then I tried using ROMSPLIT on an emulated ST inside Steem to re-split the ROMs. Those produced identical content to the files I produced with WinHex. Further, when loading into the files produced with ROMSPLIT the programmer and then re-verifying the content of the ROMs I burned, the results are identical.
Testing the ST with Atari Diagnostic Cart 4.4 (containing similar EPROMs burned with the same programmer and working fine) shows TOS 1.4 USA NTSC. OS ROM checksum test fails with CRC error on L2/H2 and CS error on H0/L0. The machine otherwise passes all tests.
So... the ROMS seem to have bad data and indeed, don't run. However, they're identical to the images online, which work in Steem, and produced by splitting both with WinHex and ROMSPLIT. EPROMs are burned and tested good, and these exact chips were working in this machine with an earlier TOS version. But the machine doesn't even get as far as bombing when they're installed, even though the Diagnostic cart runs fine.
Any ideas? I'm lost.