COMPAQ DeskPro 386 Machines

All the CGA and EGA configurations use the Rev F COMPAQ DeskPro 386 ROM, dated September 4, 1986. It is currently the oldest available DeskPro 386 ROM. The VGA did not exist until 1987, so it makes sense to use the CGA and EGA with the older ROM.

All the VGA configurations use the Rev J.4 COMPAQ DeskPro 386 ROM, dated January 28, 1988.

All these machine configurations also include an unformatted “Type 5” 47Mb Hard Disk. To create a single 47Mb partition, you must use COMPAQ MS-DOS 3.31 or newer; older versions of DOS could create partitions only up to 32Mb, and all partitions had to reside within the first 32Mb of disk space.

In addition, all the Visualizer configurations are running the “uncompiled” version of PCx86, so that BackTrack information is available to the PCjs Debugger. As a result, those machines run much slower. To reduce DEBUG or BACKTRACK overhead, you can add debug=false or backtrack=false to an uncompiled machine’s URL; for example, this DeskPro 386 with Visualizer will run much faster than the link provided below.

Since DEBUG support is automatically enabled in uncompiled code, you get automatic instruction history buffering (up to 100,000 instructions), which can then be dumped with the PCjs Debugger’s “dh” command. Instruction history is supported in the compiled version as well, but only up to 1,000 instructions and only if one or more breakpoints are set.