4 ms·
Wasn't int21h a call to MS-DOS functions? (Also understood by Windows) I'm not sure it would work if you stuck this in a boot sector.
by gruturo 7y ago
Wasn't int21h a call to MS-DOS functions? (Also understood by Windows)
I'm not sure it would work if you stuck this in a boot sector.
- a1369209993 7y agoDon't remember (and can't be arsed to check) if it was int21, but IBM PC BIOS does have a call to write text to the (B8000, usually) screen text buffer, complete with scrolling.
- spc476 7y agoI do remember (and don't have to check [1]) but MS-DOS used interrupts 20h through 2Fh (mostly 21h). BIOS used interrupts 10h through 1Fh. 10h was for text and graphics. The "text" screen could be at either B000:0000 (physical address B0000) or B800:0000 (physical address B8000) depending on if it was monochrome or color, so to be pedantic, one had to make a few checks to see what card was installed (if you wanted to bypass the BIOS). [1] Why do I even remember this stuff? I haven't used any of this since the early 90s! Sheesh!
- fmakunbound 7y agoDOS used a bunch in from 20 to 2F, but mostly 21. IIRC, BIOS was 10 and 13.