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1. Xenenic (xenenic@bitbang.social)'s status on Monday, 18-Sep-2023 17:41:51 JST Xenenic

   Ok #retrocomputing and #vintagecomputing I need some assistance modifying the 386SX #BIOS for my "Magnavox Professional Metalis SX-20" as adding a drive overlay causes a checksum failure.

   The BIOS is hard locked to NONE/40/60/80MB HDD options and modifying what appears to be the drive table via MODBIN has failed me thus far.

   Any recommendations for disabling the checksum?

   I'm looking at the dump via "objdump -D -b binary -mi386 -Maddr16,data16 mvox.bin".

   • Xenenic (xenenic@bitbang.social)'s status on Monday, 18-Sep-2023 17:41:49 JST Xenenic

     in reply to

     • Hak Foo

     @hakfoo I'm actually messing with the BIOS atm and was thinking of trying to use XT-IDE if I can get the JMPs figured out as another possible solution to the hard coded disk geometry. BIOS screenshot of the 16MHz board for reference.

   • Hak Foo (hakfoo@mstdn.party)'s status on Monday, 18-Sep-2023 17:41:51 JST Hak Foo

     in reply to

     @xenenic Is there any way to install an option ROM and use the XT-IDE Universal BIOS? Or even set it as "no hard disc", boot from floppy, and use something like https://github.com/rvalles/optromloader to load it?

     I have a 386SX Magnavox desktop, and its BIOS will let you enter a geometry up to 8Gb(!) but the onboard BIOS did not know what to do with a SD-IDE adapter with a large card in it. XUB solved it, although the original BIOS reports an IDE error before booting.

     Machismo repeated this.