W83627HF/ F/ HG/ G
CRF4 (Default 0x00)
FDD0 Selection:
BIT
DESCRIPTION
7
6
Reserved.
Precomp. Disable.
1: Disable FDC Precompensation.
0: Enable FDC Precompensation.
Reserved.
5
4 - 3
DRTS1, DRTS0: Data Rate Table select (Refer to TABLE A).
00: Select Regular drives and 2.88 format
01: 3-mode drive
10: 2 Meg Tape
11: Reserved
2
Reserved.
1 - 0
DTYPE0, DTYPE1: Drive Type select (Refer to TABLE B).
CRF5 (Default 0x00)
FDD1 Selection: Same as FDD0 of CRF4.
TABLE A
DRIVE RATE TABLE
DATA RATE
SELECTED DATA RATE
SELDEN
SELECT
DRTS1
DRTS0
DRATE1
DRATE0
MFM
1Meg
500K
300K
250K
1Meg
500K
500K
250K
1Meg
500K
2Meg
250K
FM
---
1
0
0
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
0
1
0
1
1
0
0
1
1
0
0
1
1
0
0
0
0
250K
150K
125K
---
0
1
1
0
250K
250K
125K
---
250K
---
125K
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