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FDC37C666GT View Datasheet(PDF) - SMSC -> Microchip

Part Name
Description
MFG CO.
'FDC37C666GT' PDF : 152 Pages View PDF
the time between when the Head Load signal
goes high and the read/write operation starts.
The values change with the data rate speed
selection and are documented in Table 31. The
values are the same for MFM and FM.
Table 31 - Drive Control Delays (ms)
HUT
SRT
1M 500K 300K 250K 1M 500K 300K 250K
0 128
256
426
512
8.0
1
8
16
26.7
32
7.5
..
..
..
..
..
..
E 112
224
373
448
1.0
F 120
240
400
480
0.5
16
26.7
32
15
25
30
..
..
..
2
3.33
4
1
1.67
2
1M
00
128
01
1
02
2
..
..
7F
126
7F
127
HLT
500K
256
2
4
..
252
254
300K
426
3.3
6.7
..
420
423
250K
512
4
8
.
504
508
The choice of DMA or non-DMA operations is
made by the ND bit. When this bit is "1", the
non-DMA mode is selected, and when ND is "0",
the DMA mode is selected. In DMA mode, data
transfers are signalled by the FDRQ pin. Non-
DMA mode uses the RQM bit and the FINT pin
to signal data transfers.
Configure
The Configure command is issued to select the
special features of the FDC. A Configure
command need not be issued if the default
values of the FDC meet the system
requirements.
Configure Default Values:
EIS - No Implied Seeks
EFIFO - FIFO Disabled
POLL - Polling Enabled
FIFOTHR - FIFO Threshold Set to 1 Byte
PRETRK - Pre-Compensation Set to Track 0
EIS - Enable Implied Seek. When set to "1", the
FDC will perform a Seek operation before
executing a read or write command. Defaults to
no implied seek.
EFIFO - A "1" disables the FIFO (default). This
means data transfers are asked for on a byte-
by-byte basis. Defaults to "1", FIFO disabled.
The threshold defaults to "1".
POLL - Disable polling of the drives. Defaults to
"0", polling enabled. When enabled, a single
interrupt is generated after a reset. No polling is
performed while the drive head is loaded and
the head unload delay has not expired.
FIFOTHR - The FIFO threshold in the execution
phase of read or write commands. This is
programmable from 1 to 16 bytes. Defaults to
one byte. A "00" selects one byte; "0F" selects
16 bytes.
71
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