Tandy 1000 & PCjr mode VS EGA

[Robin_Gravel]

I'm still wondering why tandy 1000 mode (or PCjr) 320x200x16 colors uses more memory than EGA 320x200

In Robocop, it takes only 512k for both CGA and EGA. Both modes you'll have to fight a boss at the end of each level.
Too bad, you don't see any bosses if you're using PCjr mode or Tandy 1000 mode and it requierts 640k to use this mode.


Robin Gravel

[sonneveld]

Probably because the Tandy/pcjr's video memory was shared with system memory. So anygame that used graphics had to allocate more memory just for the video card to work in.

I don't know much about how the pcjr worked.. but i think the game had to allocate the memory specifically? I remember the loader for AGI was slightly different if it was a Tandy/pcjr computer.

- Nick

[Robin_Gravel]

Probably because the Tandy/pcjr's video memory was shared with system memory

You must be right. But in all sci games I saw, 640k is requiert for PCjr but it's 512k for Tandy mode as other modes like CGA, EGA,...

I think the PCjr's graphic adress is &h1800 while Tandy's graphic adress is &hb800 the same than CGA adress


Robin Gravel