W83877TF Datasheet, PDF (44/154 Pages) Winbond – I/O chip disk drive adapter

W83877TF
POWER-DOWN (Bit 6):
0 FDC in normal mode
1 FDC in power-down mode
PRECOMP2 PRECOMP1 PRECOMP0 (Bit 4, 3, 2):
These three bits select the value of write precompensation. The following tables show the
precompensation values for the combination of these bits.
PRECOM
210
000
001
010
011
100
101
110
111
PRECOMPENSATION DELAY
250K - 1Mbps
2 Mbps Tape drive
Default Delays
Default Delays
41.67 nS
20.8nS
83.34 nS
41.17nS
125.00 nS
62.5nS
166.67 nS
83.3nS
208.33 nS
104.2nS
250.00 nS
125.00nS
0.00 nS (disabled)
0.00nS (disabled)
DATA RATE
250 KB/S
300 KB/S
500 KB/S
1 MB/S
2 MB/S
DEFAULT PRECOMPENSATION DELAYS
125 nS
125 nS
125 nS
41.67 nS
20.8 nS
DRATE1 DRATE0 (Bit 1, 0):
These two bits select the data rate of the FDC and reduced write current control.
00 500 KB/S (MFM), 250 KB/S (FM), RWC = 1.
01 300 KB/S (MFM), 150 KB/S (FM), RWC = 0.
10 250 KB/S (MFM), 125 KB/S (FM), RWC = 0.
11 1 MB/S (MFM), Illegal (FM), RWC = 1.
The 2MB/S data rate for Tape drive is only supported by setting 01 to DRATE1 and DRATE0 bits, as
well as setting 10 to DRTA1 and DRTA0 bits which are two of the Configuration CR2D. Please refer
to the function of CR2D and the data rate table for individual data rates setting.
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Publication Release Date: March 1998
Version 0.61