Two Stop Bits | AKA the one where IBM mentions the unsupported "160 PELs by 100 rows" low-resolu...

viler 13 days ago | parent

AKA the one where IBM mentions the unsupported "160 PELs by 100 rows" low-resolution mode, but gives only a vague hint about actually setting it up... and even that is wrong! ("requires special programming and is set up as the 40 by 25 alphanumeric mode.")

Smooth move, but the real details cropped up in magazines and BBS writeups a couple years later.

ddingus 11 days ago
Like we know it can do it, but we can't actually tell you, because some manager pissed in the feature set and it would annoy them greatly...
Probably not, but it seems like maybe?
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- viler 8 days ago
  I guess the most mundane explanation is that proper 'BIOS support' for this mode would have been too complicated. It's character based, so you'd need to write all-new versions of those BIOS graphics routines for setting pixels and printing text - not to mention the BASIC stuff for lines, ellipses, and flood fills. That could well have exhausted the allotted ROM space, but you'd also have to "snow-proof" those routines, what with the CGA RAM bandwidth issue in 80 column mode... which would've made them even slower than the original versions, if you can imagine that!
  In hindsight of course, the BIOS functions didn't matter when you wanted any sort of performance, regardless of the video mode. But IBM will be IBM.
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  - ddingus 6 days ago
    That tings true. Supporting a mode required full service, and the work inherent in that one would likely overshadow value to many users
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