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Copyright 1991 David Jurgens |
INT 1E - Disk Initialization Parameter Table Vector
- not an interrupt, but a far pointer to the diskette base table
- this table contains initialization parameters for the disk
controller used during formatting, reading, and writing to a disk
Disk Initialization Parameter Table Vector Definition:
Offset Description
00 │7│6│5│4│3│2│1│0│ Disk Controller Mode byte 1
│ │ │ │ └─┴─┴─┴──── head step rate in milliseconds (0-F)
└─┴─┴─┴─────────── head unload time in milliseconds (0-F)
01 │7│6│5│4│3│2│1│0│ Disk Controller Mode byte 2
│ │ │ │ │ │ │ └──── DMA flag (0 = use DMA)
└─┴─┴─┴─┴─┴─┴───── (head load time/2)-1 in milliseconds
02 clock ticks until motor off
03 FM or MFM Mode: Log2 (Bytes per Sector/128)
FM=Frequency Modulation used on single-density disks
MFM=Modified Frequency Modulation used on double-sided disks
04 last sector on track
05 gap length in bytes:
Bytes Per Sectors Write Format
MFM Sector Per Track Gap Gap
1 256 18 0Ah 0Ch
1 256 16 20h 32h
2 512 8 2Ah 50h
2 512 9 1Bh 6Ch
3 1024 4 80h F0h
4 2048 2 C8h FFh
5 4096 1 C8h FFh
06 disk data length
80h for 128 bytes/sector
FFh otherwise
07 gap length when formatting
08 data pattern used during formatting
09 floppy head bounce delay (in milliseconds)
0A floppy motor start delay (in 0.125 second intervals)
0B floppy motor stop delay (in 0.25 second intervals)
- see INT 13,18
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| Esc or Alt-X to exit |
int 1e |
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