Compaq Deskpro 386 LPT select line raised permanently during initialization? \ VOGONS

Compaq Deskpro 386 LPT select line raised permanently during initialization?

Topic actions

Post a reply

First post, by superfury

Posted on 2020-05-01, 11:15

superfury Offline

Rank l33t++

Rank: l33t++
Posts: 5472
Joined: 2014-03-08, 11:25
Location: Netherlands

I notice that once the Compaq Deskpro 386 starts booting the OS, it calls the initialize function of interrupt 17h(the Printer BIOS interrupt vector) function 00h to initialize the parallel port. But when it's running, it sets the parallel port's SELECT and INIT line high by setting bits 2 and 3 permanently high? Thus peripherals like the Disney Sound Source(DSS) will turn on at boot, never to be turned off?

Anyone knows about this problem? Or is it an emulation problem and it doesn't happen on real HW?

Author of the UniPCemu emulator.
UniPCemu Git repository
UniPCemu for Android, Windows, PSP, Vita and Switch on itch.io

Reply 1 of 1, by digger

Posted on 2020-08-07, 16:23

digger Offline

Rank Oldbie

Rank: Oldbie
Posts: 1128
Joined: 2010-02-12, 18:15
Location: Amsterdam, the Netherlands

The Programmer's Guide to the Disney Sound Source mentions a workaround that has to be applied due to differing parallel port behaviour in Tandy computers that "require a special adapter". Perhaps the same workaround would be required for such Compaq machines as well?

Go to top of page Go to top of page

Back to PC Emulation

Main menu

Common searches