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Alternate Screen Buffer LC


New member
Hello, I am working with System 7.5.3 and Think C 7.0, with Basilisk Emulator (Mac LC 68020 ).

I am programming a game and need the Alternate Screen Buffer because it flickers now.
In the Inside Macintosh books there are explanations in assambler and on https://www.mactech.com/ there is a Pascal explanation. Unfortunately I don't know these languages, I'm programming in C. Does anyone have a C example of how to use the Alternate Screen Buffer? Thanks for help


Well-known member
Don't quote me here, but I don't think there is an alternate screen buffer in anything other than 68000 Macs.

Do you have a link of that ASM article ? You can embed ASM in C easily.


Well-known member
Yes, using the alternate screen buffer will really restrict the machines your thing will run on and I agree with @demik, I think it's only the monochrome 68000 Macs that have it.

(Also, please remember that Basilisk II is not a hardware-accurate emulator, nor is it intended to be; it loads lots of its own code into the emulated Mac to do stuff, and if you try to bypass the OS on it, you can probably expect it not to behave quite as a real machine would)


Well-known member
Depending on what you want to achieve the 6.0.7-and-later would be to use offscreen GWorld - you draw in them off-screen then copy them over quickly.
Also if you want some things to happen between screen refresh, you can use the Vertical Retrace Manager.