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~