Zapojení 40 Pin SCSI pro 2,5" HDD
2.5-Inch Drive SCSI Connector (40-Pin Header)

Pins 1, 2, 39, and 40 are +5V. Pins 3, 4, 37, and 38 are ground returns for the +5V supply. Pins 5, 7, 9, 11, 13, 15, 19, 21, 23, 27, 31, and 35 are signal grounds. Pin 17 is used as a connector key and should not be present.

Pin 6: *Data 0
Pin 8: *Data 1
Pin 10: *Data 2
Pin 12: *Data 3
Pin 14: *Data 4
Pin 16: *Data 5
Pin 18: *Data 6
Pin 20: *Data 7
Pin 22: *Parity
Pin 24: Terminator Power
Pin 25: *ATN
Pin 26: *BSY
Pin 28: *ACK
Pin 29: *RST
Pin 30: *MSG
Pin 32: *SEL
Pin 33: *I/O
Pin 34: *C/D
Pin 36: *REQ

Ostatní atypické SCSI konektory

External SCSI Connector (DB25 Future Domain-Type Female Pseudo-SCSI)
(Note: This is a rare alternate standard for the DB25 connector. It was only used on the Future Domain TMC-830/845 and TMC-850/860/885, and is included here in case you end up with a cable meant for these boards.)

Pin 1: Ground
Pin 2: *Data 1
Pin 3: *Data 3
Pin 4: *Data 5
Pin 5: *Data 7
Pin 6: Ground
Pin 7: *SEL
Pin 8: Ground
Pin 9: Terminator Power
Pin 10: *RST
Pin 11: *C/D
Pin 12: *I/O
Pin 13: Ground
Pin 14: *Data 0
Pin 15: *Data 2
Pin 16: *Data 4
Pin 17: *Data 6
Pin 18: *Parity
Pin 19: Ground
Pin 20: *ATN
Pin 21: *MSG
Pin 22: *ACK
Pin 23: *BSY
Pin 24: *REQ
Pin 25: Ground

External SCSI Connector (DB25 Macintosh-Type Female Pseudo-SCSI)
(Note: This is by far the most common style of DB25 SCSI connector. Most [probably all] Amiga SCSI interfaces with DB25 connectors--like the A2091--use this pin-out.)

Pin 1: *REQ
Pin 2: *MSG
Pin 3: *I/O
Pin 4: *RST
Pin 5: *ACK
Pin 6: *BSY
Pin 7: Ground
Pin 8: *Data 0
Pin 9: Ground
Pin 10: *Data 3
Pin 11: *Data 5
Pin 12: *Data 6
Pin 13: *Data 7
Pin 14: Ground
Pin 15: *C/D
Pin 16: Ground
Pin 17: *ATN
Pin 18: Ground
Pin 19: *SEL
Pin 20: *Parity
Pin 21: *Data 1
Pin 22: *Data 2
Pin 23: *Data 4
Pin 24: Ground
Pin 25: Terminator Power

SCSI* - Differential
SCSI* (Small Computer System Interface) is an intelligent device interface that allows up to 8 devices (usually 7 plus the host system) to be connected together. Unlike other older interfaces, requests on a SCSI* bus are just that, requests. For example, rather than the low-level device commands like the familiar STEP+ and STEP- of ST412, SCSI* accesses data using the higher level SEEK to a location (LBA or logical block address on drives).

Differential SCSI* (Small Computer System Interface) varies from standard SCSI* at the bus level in that it is capable of operating up to a 25 meter cable, and the electrical specifications are quite different. Input voltages vary from a low of -7VDC to a high of +12VDC. These high voltage changes are measured from the positive (+ or POS) portion of a signal, in relation to the negative (- or NEG) signal of the same name.

These devices ARE NOT* BUS COMPATIBLE with SCSI* standard devices. They are hovever command compatible. Attempting to share the SCSI* bus with a non-differential device will quite possibly damage the single-ended SCSI* device. The electrical specification follows the EIA RS-485-1983 standard. Pin designations are as follows:

Pin number Signal Description
1 GND* Shield ground
2 GND* Ground
3 +DB0 Pos data bit 0
4 -DB0 Neg data bit 0
5 +DB1 Pos data bit 1
6 -DB1 Neg data bit 1
7 +DB2 Pos data bit 2
8 -DB2 Neg data bit 2
9 +DB3 Pos data bit 3
10 -DB3 Neg data bit 3
11 +DB4 Pos data bit 4
12 -DB4 Neg data bit 4
13 +DB5 Pos data bit 5
14 -DB5 Neg data bit 5
15 +DB6 Pos data bit 6
16 -DB6 Neg data bit 6
17 +DB7 Pos data bit 7
18 -DB7 Neg data bit 7
19 +DBP Pos parity bit
20 -DBP Neg parity bit
21 DIFFSEN Not used
22 GND* Ground
23 GND* Ground
24 GND* Ground
25 TERMPWR Ground
26 TERMPWR Termination pwr
27 GND* Ground
28 GND* Ground
29 +ATN Pos attention
30 -ATN Neg attention
31 GND* Ground
32 GND* Ground
33 +BSY Pos busy
34 -BSY Neg busy
35 +ACK Pos acknowledge
36 -ACK Neg acknowledge
37 +RST Pos reset
38 -RST Neg reset
39 +MSG Pos message
40 -MSG Neg message
41 +SEL Pos select
42 -SEL Neg select
43 +C/D Pos command/data
44 -C/D Neg command/data
45 +REQ Pos request
46 -REQ Neg request
47 +I/O Pos input/output
48 -I/O Neg input/output
49 GND* Ground
50 GND* Ground