Mike's PCjr Page

I have been trying to get Lemmings to run on the PCjr in Tandy Mode. The PCjr has had the Tandy mod. It runs fine in CGA mode. In Tandy mode It gets as far as the "PC Lemmings loading ---- Please Wait". I hear the the sound circuit click on and then it freezes. Anyone get Lemmings to run on a Tandy modified PCjr?

I tried it as well, and if I remember correctly, I got the same results.

I poked at lemmings a bit today. You can obtain different behavior when running tgalemmi.exe by changing the amount of video memory reserved by jrconfig.sys, and/or booting without jrconfig at all.

The latter results in the closest thing to a running state I can achieve - after the initial "please wait" message, the screen mode changes to 320x200x16 and is filled with garbage. The garbage changes slightly if you hit enter/esc/etc. (keys that do things on the main menu).

With jrconfig.sys reserving 64k of video memory, a different interesting thing happens, which is that after the initial "please wait" message, the screen mode stays in color text, but all sorts of strange/not-entirely-random patterns appear and change - it looks to me like program data is being written over video memory.

All other configurations just result in hangs.

based on this, it seems likely that the program is making some (incorrect, in the context of the Jr) determination about where video memory is, rather than using compatible BIOS calls.

I did decompress and disassemble the tgalemmi executable, but I saw nothing like an obvious reference to [hardcoded start of well-known Tandy 1000 video memory region] that I could tweak, so doing anything about this is firmly beyond my meager skills - giving up on this one.