Mark Data Products Early versions of these games had trouble running on Dragons (which are almost TRS-80-compatible). After switching a timing routine from looking at how long it took to scan the keyboard to using IRQs, the games ran fine. The problem caused the graphic animations to run too fast. Shenanigans Type: Bitmap graphics Written 1983 by Bob Whithers and Stephen O'Dea. Runs on: TRS-80 Color Sea Search Type: Bitmap graphics Written 1983 by Bob Whithers and Stephen O'Dea. Runs on: TRS-80 Color Calixto Island Type: Text only/TO/BG (animations) Written 1983 (the TO version might be earlier) by Ron Krebs [text version], Bob Whithers [graphic version] and Stephen O'Dea [graphic version]. Runs on: TRS-80 Color [Text only/Bitmap graphics; The 16K version was text only, the 32K version had animated color graphics.] Notes: The text-only version was written by Ron Krebs of Mark Data. It preceeded all the graphic versions. The graphic version was a straight remake of the text version. Black Sanctum Type: Text only/Bitmap graphics Written 1983 (the TO version might be earlier) by Ron Krebs [text version], Bob Whithers [graphic version] and Stephen O'Dea [graphic version]. Runs on: TRS-80 Color [Text only/Bitmap graphics; The 16K version was text only, the 32K version had animated color graphics.] Notes: The text-only version was written by Ron Krebs of Mark Data. It preceeded all the graphic versions. The graphic version was a straight remake of the text version. Trekboer Type: Bitmap graphics Written 1984 by Bob Whithers and Stephen O'Dea. Runs on: TRS-80 Color The Vortex Factor Type: Bitmap graphics Written 1985 by Bob Whithers and Stephen O'Dea. Runs on: TRS-80 Color Comments: It involved a time machine.

Adventureland was created by Hans Persson and is now maintained by Stefan Meier.

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