LSI 53C875A User Manual

Page 176

Advertising
background image

4-84

Registers

SEL[3:0]

Selection Time-Out

[3:0]

These bits select the SCSI selection/reselection time-out
period. When this timing (plus the 200

µ

s selection abort

time) is exceeded, the STO bit in the

SCSI Interrupt

Status One (SIST1)

register is set. For a more detailed

explanation of interrupts, refer to

Chapter 2, “Functional

Description.”

HTH [3:0]

SEL [3:0]

GEN [3:0]

Minimum Time-out

(80 MHz Clock) With

Scale Factor Bit Cleared

1

1. These values are correct if the CCF bits in the

SCSI Control Three (SCNTL3)

register are set according to the valid combinations in the bit description.

Minimum Time-out

(80 MHz Clock) With

Scale Factor Bit Set

0000

Disabled

Disabled

0001

100

µ

s

1.6 ms

0010

200

µ

s

3.2 ms

0011

400

µ

s

6.4 ms

0100

800

µ

s

12.8 ms

0101

1.6 ms

25.6 ms

0110

3.2 ms

51.2 ms

0111

6.4 ms

102.4 ms

1000

12.8 ms

204.8 ms

1001

25.6 ms

409.6 ms

1010

51.2 ms

819.2 ms

1011

102.4 ms

1.6 s

1100

204.8 ms

3.2 s

1101

409.6 ms

6.4 s

1110

819.2 ms

12.8 s

1111

1.6 + s

25.6 s

Advertising