Rewrote 8086 bootblock trackloader

Last Updated or created 2023-10-05

Loading a 320×200 image from 14 cilinders. There is no msdos on the floppy!

9 sectors, 14 cilinders, 1 head * sector size (512 bytes) = 64512 bytes

Mode 13h (320×200 265 colors)

Cuting the raw part from a BMP (see previous post)

root@battlestation:/mnt/# ls -la MAD.bmp
-rw-rw-r-- 1 fash fash 65078 Sep 14 15:57 MAD.bmp

I need 64000 bytes (320x200)
65078-64000 = 1078

root@battlestation:/mnt/# dd if=MAD.bmp of=mad.raw skip=1078 bs=1
64000+0 records in
64000+0 records out
64000 bytes (64 kB, 62 KiB) copied, 0.441618 s, 145 kB/s

I use debug to write to the sectors

debug mad.raw
-w100 0 9 7f
(write from address 100 drive=0 startsector=9 (cylinder 1) and 7f sectors long

Wrote a little sector viewer to debug/view data written.

  • r – read sector again
  • s – next sector (shift previous)
  • c – next cylinder (shift previous)
  • h – toggle head 0 – 1
  • p – load palette from current 2 sectors
  • l – clear screen
  • 1 – goto graphic mode
  • 2 – goto text mode and show sector,head and cylinder info
  • q – quit
  • -/+ tweak palette offset ( was needed for debugging

I will post the code after some code cleaning and adding some comments

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