Jumper Settings - Compaq PORTABLE 286 Maintenance And Service Manual

Chapter 8.8 Compaq Portable and Compaq Plus Asynchronous Communications/Clock Board

Jumper Settings

Jumpers on the COMPAQ Portable and COMPAQ PLUS asynchronous communications/
clock board determine the communications address and the interrupt selection
on the board. Device U13 allows the selection of a 20 mA current loop
operation rather than the standard RS-232-C voltage operation.
DO NOT attempt to install two asynchronous communications/clock boards in one
system. If two boards are installed, incorrect operation will result.
For locations of the COMPAQ Portable and COMPAQ PLUS asynchronous
communications/clock board jumper settings, see Figure 8.8-1.
See Table 8.8 for jumper setting information for the asynchronous
communications/clock board.
Table 8.8. COMPAQ Portable and COMPAQ PLUS Asynchronous Communications/Clock
Board Jumper Settings
==============================================================================
Jumper
Location Function
------------------------------------------------------------------------------
J702 COM1/COM2 select
------------------------------------------------------------------------------
J703 Interrupt select
------------------------------------------------------------------------------
U13 Current or voltage
operation
(shunt module)
Pin 1 to Pin 2
COM2 Address
IRQ3
Pins 5-12, 6-11,
7-10,8-9:
Serial RS-232-C
operation
Pins 1-16, 2-15,
Pin 2 to Pin 3
COM1 Address
(default setting)
IRQ4 (default setting)