W83977G Winbond Electronics Corp America, W83977G Datasheet - Page 42

• Manufacturer Part Number: W83977G
• Description: W83877TF plus KBC, CIR, RTC, Pb-free
• Manufacturer: Winbond Electronics Corp America

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 2 MB/S data rate for Tape drive is only supported by setting 01 to DRATE1 and DRATE0 bits, as
well as setting 10 to DRT1 and DRT0 bits which are two of the Configure Register CRF4 or CRF5 bits
in logic device 0. Please refer to the function description of CRF4 or CRF5 and data rate table for
individual data rates setting.
5.2.7
The Data Register consists of four status registers in a stack with only one register presented to the
data bus at a time. This register stores data, commands, and parameters and provides diskette-drive
status information. Data bytes are passed through the data register to program or obtain results after
a command. In the W83977F/ AF, this register defaults to FIFO disabled mode after reset. The FIFO
can change its value and enable its operation through the CONFIGURE command.
W83977F-A/ W83977G-A/ W83977AF-A/ W83977AG-A
DATA RATE
PRECOMP
2
250 KB/S
300 KB/S
500 KB/S
0
0
0
0
1
1
1
1
FIFO Register (R/W base address + 5)
1 MB/S
2 MB/S
1
0
0
1
1
0
0
1
1
0
0
1
0
1
0
1
0
1
0.00 nS (disabled)
Default Delays
250K - 1 Mbps
125.00 nS
166.67 nS
208.33 nS
250.00 nS
41.67 nS
83.34 nS
DEFAULT PRECOMPENSATION DELAYS
-34
PRECOMPENSATION DELAY
41.67nS
20.8 nS
125 nS
125 nS
125 nS
2 Mbps Tape drive
0.00 nS (disabled)
Default Delays
125.00 nS
104.2 nS
41.17 nS
20.8 nS
83.3 nS
62.5nS