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FreeDOS on SBC188 (Announce)

posted by GizMo79, 13.09.2020, 22:09

> > 4. If you want, I can give you further instructions on how to debug the
> > failing loader. The files i12debug.com (run with "A:") and ldebug.com
> (copy
> > to the diskette) in this archive can be used to set up my bootable
> > debugger. Then "ifd12org.com A: /F1=TESTPL.COM
> > /B=A:\b12test.bin" can be used to generate a chainloadable boot
> > sector dump with the failing loader. Next, boot the debugger, and try
> > running the BOOT
> > command "boot protocol chain b12test.bin" then
> > "q". If this displays the test payload status dump
> something
> > strange is going on. If it hangs the same way as that loader otherwise
> > does, we can actually debug it. (If you want to do this, tell me and
> I'll
> > get around to it within the week.)
>
> I got around to a very simple test right away. Here's what I did (using
> dosemu2):
>
> $ dd if=/dev/zero of=../diskette.img bs=1 count=$((1440 * 1024))
> $ touch autoexec.bat
> $ dosemu -dumb -quiet -K "$PWD" -I "floppy { threeinch device
> ../diskette.img }" -E "format A:"; dosemu -dumb -quiet -K "$PWD" -I "floppy
> { threeinch device ../diskette.img }" -E "ifd12quc.com A: /F1=TESTPL.COM";
> dosemu -dumb -quiet -K "$PWD" -I "floppy { threeinch device ../diskette.img
> }" -E "copy testpl.com A:"; dosemu -dumb -quiet -K "$PWD" -I "floppy {
> threeinch device ../diskette.img }" -E "copy C:kernel.sys A:"; dosemu -dumb
> -quiet -K "$PWD" -I "floppy { threeinch device ../diskette.img }" -E "copy
> D:\\dosemu\\exitemu.com A:"; dosemu -dumb -quiet -K "$PWD" -I "floppy {
> threeinch device ../diskette.img }" -E "copy C:command.com A:"; dosemu
> -dumb -quiet -K "$PWD" -I "floppy { threeinch device ../diskette.img }" -E
> "copy autoexec.bat A:"
>
> {press Enter each time for the format application's prompts}
>
> $ dosemu -dumb -quiet -K "$PWD" -I "floppy { threeinch device
> ../diskette.img }" -E "ifd12org.com A: /F1=TESTPL.COM /B=A:\b12test.bin";
> dosemu -dumb -quiet -K "$PWD" -I "floppy { threeinch device ../diskette.img
> }" -E "i12debug.com A:"; dosemu -dumb -quiet -K "$PWD" -I "floppy {
> threeinch device ../diskette.img }" -E "copy ldebug.com A:"; dosemu -dumb
> -K "$PWD" -I "floppy { threeinch device ../diskette.img }" -A
>
> How to set up the diskette:
>
> 1. Format it, leave the volume label empty.
>
> 2. Copy testpl.com to the file system. Important: This should be the very
> first file to copy onto it. (Not needed to boot it generally, but important
> to make the cluster numbers the same as those I got.)
>
> 3. Copy other files, such as the debugger, the FreeDOS kernel, FreeCOM
> (FreeDOS command.com), etc.
>
> 4. Create empty autoexec.bat for FreeCOM. (Otherwise it will prompt for
> date and time during startup.)
>
> 5. ifd12org.com A: /F1=TESTPL.COM /B=A:\b12test.bin
>
> 6. i12debug.com A:
>
> 7. Boot it.
>
> Next, to debug the loader in a very basic way, we can tell the debugger to
> step through it until execution leaves the boot loader. I uploaded a
> recording of the debugger I/O for this in
> https://ulukai.org/ecm/test/20200913.txt
>
> First you need to enter boot protocol chain b12test.bin and
> then the following: tp fffff while !( cs != 7C0 && cs != 0 && cs !=
> 1FE0 || ip < 7C00 || ip > 7C00+#512 ) silent
>
> This may not be sufficient to debug the loader but it will probably tell us
> something about how it fails.

where can i find testpl.com?

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