DOS Game Compatibility Notes

Various notes I've taken on possible compatibility issues when running DOS games and programs. This is likely to grow as I continue to experiment.

Bear in mind that excepting the official IBM models in the very early days (i.e. the 1980s), PCs have not had the same level of standardization as consoles or early microcomputers, and different combinations of hardware may show greater or lesser compatibility with some software. The tests here applied to my computers, but you may find that your particular rig performs differently.

EGA overscan border colors

On EGA displays, it was possible to set the overscan border (outside of the main drawable area) to one of the 16 colors, similarly to comparable features in many 8-bit microcomputers of the 1980s. Some later display adapters did not maintain support for this, and it is also not currently emulated in DOSBox, although it was not widely used and rarely for critical information. The following games are known to have used it:

  • Crystal Caves (red border if there are crystals left, turns green when all are collected)
  • Catacomb 3D (cyan border normally, flashes purple when taking damage)
  • Catacomb Abyss (black border normally, flashes red when taking damage and yellow if a treasure is destroyed)
  • Catacomb 3D Adventures trilogy (border flashes to indicate damage and item destruction, Apocalypse uses a white flash as a secret hint)
  • Commander Keen Episode 1 (cyan border, brown flash when a Vorticon is killed)
  • Commander Keen Episode 2 (cyan border, brown flash when a Tantalus Ray is destroyed)
  • Commander Keen Episode 3 (cyan border, brown flash when part of the final boss is damaged)
  • Hovertank (black border normally, red flash when taking damage and blue flash during end of level tank repair)
  • Secret Agent (red border, no flashes?)

AMD compatibility issues

While AMD's clone processors theoretically had all the same features as Intel chips, there are some instances where the differences between them may be to blame for compatibility issues when running games natively. The following games could be made to run natively on an Intel chip (Pentium III) but had issues on an AMD-based system (K6-2):

  • Demon Stalkers (locks up at title screen)
  • Iron Blood (game silently terminates when attempting to run)
  • Bio Menace (very strange behavior; works under true DOS 6.22 kernel but when run under Windows 9x, even using DOS prompt only, will lock up during play - on Pentium both were fine. FreeDOS also appears to be okay.)

Assumes CD is drive D:

These programs appear to make a hardcoded assumption that your CD-ROM drive is located at D: and may fail if this is not the case, at least in some CD releases.

  • 101 Games Rec Room
  • Daemonsgate
  • Fade to Black
  • Star Crusader

Clock speed issues

Runtime error 200 (Turbo Pascal)

If you see the message "Runtime error 200 at XXXX:XXXX" (the hex address will vary), this is a sign that the program in question is subject to a bug acquired from the once-popular Turbo Pascal compiler. This subset of issues can be rectified with speed throttling, but thankfully there is also a universal patch to correct this bug and allow such programs to be run at a computer's full speed.

Here is the TPPATCH program that can fix programs that have this issue. The messages produced by this patching program are in German; if it says "Die Datei wird jetzt gepatcht... fertig" ("The data will now be patched... done") then this indicates that the patching was successful.

Note that not every error 200 is immediately fixable with this patch. This may be due to things like EXE compression (LZEXE etc.) or the like.

Error 200, fixable with TPPATCH:

  • D! frontend for Doom
  • Halloween Harry / Alien Carnage (although at least one problematic version exists, investigate)
  • Jazz Jackrabbit