SCSI Interface Signals

Pin No

Pin Name

I/O

Description

33

ACK

I/O

Acknowledge, active low

6

ATN

I/O

Attention, active low

4

BSY

I/O

Busy, active low

30

C/D

I/O

Control/Data, active low

32

I/O

I/O

Input/Output, active low

29

MSG

I/O

Message, active low

34

REQ

I/O

Request, active low

2

RST

I/O

Reset, active low

37~41,

43, 44, 1

DB0–DB7

I/O

SCSI Data Bus, active low

35

DBP

I/O

SCSI Parity Bit, active low

5

SEL

I/O

Select, active low

VSS

3, 12, 31, 36, 42

VDD

23

Registers

Address 0

Current SCSI data register(READ ONLY)

DB7

DB6

DB5

DB4

DB3

DB2

DB1

DB0

The SCSI bus parity is checked at the beginning of the read cycle.

Output data register(WRITE ONLY)

DB7

DB6

DB5

DB4

DB3

DB2

DB1

DB0

HT6576A

3

14th July ’97