SCH3112I-NE SMSC [SMSC Corporation], SCH3112I-NE Datasheet - Page 89

• Manufacturer Part Number: SCH3112I-NE
• Description: LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports
• Manufacturer: SMSC [SMSC Corporation]

LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports
Datasheet
SMSC SCH311X
00
01
02
..
7F
7F
64
0.5
1
..
63
63.5
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.
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.
Relative Seek
The command is coded the same as for Seek, except for the MSB of the first byte and the DIR bit.
DIR Head Step Direction Control
RCN Relative Cylinder Number that determines how many tracks to step the head in or out from the
current track number.
The Relative Seek command differs from the Seek command in that it steps the head the absolute
number of tracks specified in the command instead of making a comparison against an internal
2M
128
1
2
..
126
127
1M
DIR
0
1
DATASHEET
ACTION
Step Head Out
Step Head In
256
2
4
..
252
254
73
500K
HLT
426
3.3
6.7
..
420
423
300K
512
4
8
.
504
508
Rev 0.2 (09-28-04)
250K