Texas Instruments 3000 - Manual (Page 139)

Diagnostics
Loopback Connections
The serial and parallel communication tests in the Diagnostics Program offer optional
loopback tests that expect loopback correctors to be placed on the output ports of the
computer. The loopback connector pin assignments are fisted in the following tables.
Loopback Connector Pin Assignments
Serial Loopback Connections
DB89 Pin Signal
1-7-8 CD-RTS-CTS
2-3 TX-RX
4-6 DTR-DSR
Parallel Loopback Connections
DB25 Pin Signal
15-2 DO-ERR
13-1 STRB-SLCT
16-10 INIT-ACK
17-11 SLCTIN-BUSY
14-12 AUTOFEED-PE
Diagnostics D- 11