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// Retro Vintage Connectors

Apple SCSI DB25

Apple used a DB25 D-sub connector for external SCSI on Mac Plus, SE, II, and early Power Macs instead of the Centronics 50-pin connector used by PCs, for connecting hard drives, scanners, and CD-ROMs.

// Specifications
Standard
Apple SCSI-1 DB25
Pin Count
25
Speed
5 MB/s SCSI-1
Voltage
5V TERMPWR
Status
Obsolete replaced by FireWire and USB
Use Case
Mac Plus SE II Quadra external SCSI devices
// Pin Reference Table
Pin Name Function Type
1 /REQ Request active low I/O
2 MSG Message I/O
3 I/O Input output direction I/O
4 /RST Reset I/O
5 ACK Acknowledge I/O
6 BSY Busy I/O
7 GND Ground GND
8 DB0 Data bit 0 I/O
9 GND Ground GND
10 DB3 Data bit 3 I/O
11 DB5 Data bit 5 I/O
12 DB6 Data bit 6 I/O
13 DB7 Data bit 7 I/O
14 GND Ground GND
15 C/D Control data I/O
16 GND Ground GND
17 ATN Attention I/O
18 GND Ground GND
19 SEL Select I/O
20 DBP Data bus parity I/O
21 DB1 Data bit 1 I/O
22 DB2 Data bit 2 I/O
23 DB4 Data bit 4 I/O
24 TERMPWR Terminator power 5V PWR
25 GND Ground GND