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“… (by Ants Bull)
The graphics take the same amount of space whether it is 160×200 or 320×200. Each pixel in the 320×200 graphics modes used in the AGI PC games simply is drawn 2 pixels wide. The AGI engine doesn’t store graphics as bitmaps, but drawing instructions – such as draw a red line from (0,0) to (100,100) then a circle etc. So I don’t think size was a problem. …”
So that’s indeed what I thought. Thanks for the confirmation!
“… And since the screen is drawn once when it is loaded, speed wouldn’t have really been affected much either no matter what mode. …”
Well, the speed was affected by the re-drawing of the sprites (characters, castle flags, etc.). The more and bigger the sprites, the slower the gameplay, at least on low-end machines such as the PCjr which is the slowest PC compatible in existence. Having a half-resolution would have freed bus bandwidth for the CPU (let me know if you’re interested in more details about this), and required to move half the data for sprites.
“… Maybe it is just that the 320×200 mode is far more common (e.g. supported on CGA PC, Tandy and PC Jr). …”
It’s true that the CGA BIOS does not support the 160×200 resolution. So maybe porting to CGA was considered right from the beginning of the development of the PCjr version?
“… Also of note to people interested in this is that it was possible to hack standard CGA colour card/RGB monitor setups (the four colour cyan, magenta etc setup) to display 8 or 16 colours at 160×200. If Sierra had known about this back in the day, there could’ve been a driver to get 16 colour AGI games running on CGA! This is probably most interesting to those who had to struggle through the AGI games with CGA (like me!). …”
Well, I’m glad to say Sierra *did* know about this back in the day! 😉
BTW, it does not work on RGB monitors, but on composite monitors.
Or maybe you’re talking about the 160×100 16-color “graphics” mode (which is a hacked text mode)?