** Requires 512KB
IMPORTANT: The files in this repository are under a variety of licenses.
IMPORTANT: No warranty given, no liability accepted if you chose to use this
IMPORTANT: WARNING: Here be bugs aplenty. Don't change or reference other disks...
Want to just run it and not build it? See rdy2run directory
Hardware and firmware:
Set up for building on win32, can build on other platforms Just need an assembler.
Buildable MSDOS source obtained from pcjs
https://www.pcjs.org/blog/2018/11/21/
Derived from MS repo
https://github.com/microsoft/MS-DOS
You will need dosbox-x
Win32 nasm is included. Use a nasm for your platform.
build loader with nasm: nasm loader.asm -fbin
copy loader.asm to autoboot.bin
Edit skelio.asm to your tastes, primarily to set max memory size -
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bios size in paragraphs is used to calculate location of msdos.sys
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A paragraph is 16 bytes.
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Since loader loads logical sectors, this is the position of msdos in memory
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The fat12 format used is 8 sectors/cluster.
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msdos will be 512*8 bytes after start of bios
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If your bios becomes larger than 4kb, this will be 512*16
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You may need to alter the loader to load more sectors **
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Bios size - this allows moving msdos.sys to just after the bios to save some bytes of memory. I am currently wasting space
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Bios segment - this is where the loader places the bios, my loader uses 00C0
If you change the boot block definition, you will need to alter seltrack to account for a different sectors per track The value is hard coded in the function
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Run dosbox-x with the build-msdos.cfg
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Run dosbox-x with the build-image.cfg
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This is not automatic. Input is needed. Watch for errors*
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There is a prompt asking for a segment. Enter 00C0 (your bios segment)
copy autoboot.bin and ds00n00.dsk & ds01n00.dsk to v20mbc Follow directions in rdy2run
mount the disk image in dosbox-x: imgmount f ds1n00.dsk -t hdd -fs fat
You can now copy files to the image. Close dosbox-x and recopy to SD.