a2kkv wrote on 2026-10-30, 20:16:

Please send a BIOS dump (astra.exe /B) for more details.

I use this MR BIOS version 1.65 (1994 MR BIOS V1.65 STD_286 Generic (non-Chipset) 286 / 386 /486):

If you insist, I can try "ASTRA /B" from the command line, but mind that the program locks the computer (on "Determining BIOS" message box), when started normally.

New ASTRA 7.24 beta has been released.

ASTRA 7.24 beta download link:
http://www.sysinfolab.com/files/beta/astrabet.zip

New in this beta:

- Added detection of the Pentium FDIV bug
- Improved support for Trident video chips (detects memory type and width, memory and video engine clocks, FIFO state, video ROM access width, etc.)
- Fixed a hang on 286 machines with MR BIOS 1.65

a2kkv wrote on Yesterday, 17:32:

- Fixed a hang on 286 machines with MR BIOS 1.65

I can now confirm. This bug is fixed.

analog_programmer wrote on Yesterday, 20:30:

I can now confirm. This bug is fixed.

Thank you for bug report.

I was able to reproduce the problem in the 86Box emulator.
The system hangs when attempting to execute the following BIOS interrupt:

INT 15h, AX = 5300h — Advanced Power Management (APM) v1.0+ — Installation Check.

Disassembly of MR BIOS 1.65 revealed that its APM interrupt handler uses 80386-specific instructions (PUSHAD and MOVZX) without checking the CPU type beforehand.
Since these instructions are not supported by the Intel 80286, attempting to execute them causes an invalid opcode exception, resulting in a system hang.

a2kkv wrote on Today, 05:47:

Thank you for bug report. […]
Show full quote

Thank you for bug report.

I was able to reproduce the problem in the 86Box emulator.
The system hangs when attempting to execute the following BIOS interrupt:

INT 15h, AX = 5300h — Advanced Power Management (APM) v1.0+ — Installation Check.

Disassembly of MR BIOS 1.65 revealed that its APM interrupt handler uses 80386-specific instructions (PUSHAD and MOVZX) without checking the CPU type beforehand.
Since these instructions are not supported by the Intel 80286, attempting to execute them causes an invalid opcode exception, resulting in a system hang.

Thanks for finding that out.

If the BIOS is targeted towards 286 systems, then why it contains such 386+ CPU specific instructions, or they doesn't mess with the 286 CPU, if it doesn't support APM functions?

analog_programmer wrote on Today, 06:43:

a2kkv wrote on Today, 05:47:

Thank you for bug report. […]
Show full quote

Thank you for bug report.

I was able to reproduce the problem in the 86Box emulator.
The system hangs when attempting to execute the following BIOS interrupt:

INT 15h, AX = 5300h — Advanced Power Management (APM) v1.0+ — Installation Check.

Disassembly of MR BIOS 1.65 revealed that its APM interrupt handler uses 80386-specific instructions (PUSHAD and MOVZX) without checking the CPU type beforehand.
Since these instructions are not supported by the Intel 80286, attempting to execute them causes an invalid opcode exception, resulting in a system hang.

Thanks for finding that out.

If the BIOS is targeted towards 286 systems, then why it contains such 386+ CPU specific instructions, or they doesn't mess with the 286 CPU, if it doesn't support APM functions?

Probably part of some modular code that made it into all their BIOS images.