HUT
SRT
2M
64
4
..
56
60
1M
128
8
..
112
120
500K 300K 250K
2M
4
3.75
..
0.5
0.25
1M
8
7.5
..
1
0.5
500K 300K 250K
0
1
..
E
F
256
16
..
426
26.7
..
512
32
..
16
15
..
26.7
25
..
32
30
..
224
240
373
400
448
480
2
1
3.33
1.67
4
2
HLT
2M
64
0.5
1
1M
128
1
2
..
500K
256
2
4
..
300K
426
3.3
6.7
..
250K
512
4
8
.
00
01
02
..
..
7F
7F
63
63.5
126
127
252
254
420
423
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 signaled by the FDRQ pin. Non-DMA
mode uses the RQM bit and the FINT pin to signal
data transfers.
EIS - Enable Implied Seek. When set to "1", the
FDC will perform Seek operation before
executing a read or write command. Defaults to
no implied seek.
a
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".
Configure
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.
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:
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.
EIS - No Implied Seeks
EFIFO - FIFO Disabled
POLL - Polling Enabled
FIFOTHR - FIFO Threshold Set to 1 Byte
PRETRK - Pre-Compensation Set to Track 0
PRETRK
-
Pre-Compensation Start Track
Number. Programmable from track 0 to 255.
Defaults to track 0. A "00" selects track 0; "FF"
selects track 255.
Version
The Version command checks to see if the
controller is an enhanced type or the older type
(765A). A value of 90 H is returned as the result
byte.
11
SMSC [ SMSC CORPORATION ]
