Specifications

If both a monochrome video display controller board (with external monochrome
display) and a COMPAQ video display controller board are installed, the
monochrome video display will be active during power on if the display select
jumper (ED) is set on pin 1 to pin 2.
Table 8.4. COMPAQ PORTABLE 286 System Board Jumper Settings
==============================================================================
Jumper
Location Function Pin to Pin 2 Pin 2 to Pin 3
------------------------------------------------------------------------------
ED Display select Monochrome video COMPAQ dual mode
display controller video display
controller, non
COMPAQ extended
graphics controller,
non COMPAQ RGB
controllers (default
setting)
------------------------------------------------------------------------------
ES Speed select Primary or fast Secondary or common
speed (8 MHz) speed (default
setting)
------------------------------------------------------------------------------
EM Future Use Do not change Do not change
(default setting)
------------------------------------------------------------------------------
E1 - E3 System Board Memory 128 Kbytes, 640 Kbytes
or "MS" 256 Kbytes, or
512 Kbytes *
------------------------------------------------------------------------------
* For optional 512 Kbyte configuration, PAL (PN 105045-001) must be
installed in U2 if not already present.
==============================================================================
Chapter 8.5 Compaq Portable 286 Diskette/Tape Controller Board Switch and Jumper Settings
Two different versions of the board may be used in the COMPAQ PORTABLE 286 for
control of the diskette/tape controller. Version 1 contains jumpers J1, J2,
J3, and J4; Version 2 contains Switch SW1 and shunt jumpers J1 and J2, which
replace jumpers J1 through J4. Determine which board is installed by
referencing Figure 8.5-1 and 8.5-2 before changing the settings.