LSI LSI53C1000, Technical Manual

Page: 190 / 384

4-80 Registers
HTHSF Handshake to Handshake Timer Scale Factor 4
Setting this bit causes this timer to shift by a factor of 16.
Refer to the
SCSI Timer Zero (STIME0) register
description for details.
GEN[3:0] General Purpose Timer Period [3:0]
These bits select the period of the general purpose timer.
The time measured is the time between enabling and
disabling of the timer. When this timing is exceeded, the
GEN bit in the
SCSI Interrupt Status One (SIST1) register
is set. Refer to the table under SCSI Timer Zero
(STIME0) , bits [3:0], for the available time-out periods.
Note: To reset a timer before it expires and obtain repeatable
delays, the time value must be written to zero first, and then
written back to the desired value. This is also required
when changing from one time value to another.
Register: 0x4A
Response ID Zero (RESPID0)
Read/Write
RESPID0 Response ID Zero [7:0]
RESPID0 and Response ID One (RESPID1) contain the
selection or reselection IDs. These two 8-bit registers
contain the SCSI ID that the chip responds to on the
SCSI bus. Each bit represents one possible ID; the most
significant bit of
Response ID One (RESPID1) represents
ID 15, and the least significant bit of RESPID0 represents
ID 0. The
SCSI Chip ID (SCID) register still contains the
1011 128 ms 2 s
1100 256 ms 4.1 s
1101 512 ms 8.2 s
1110 1.024 s 16.4 s
1111 2.048 s 32.8 s
HTH[3:0], SEL[3:0], GEN[3:0]
Minimum Time-out
HTHSF = 0,
GENSF = 0
HTHSF = 1,
GENSF = 1
7 0
RESPID0
x x x x x x x x