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by weinzierl 141 days ago
Do you have an example? All the 8-bitters I know drew the characters from memory, which was a character ROM per default but could be changed either with a screw driver or by bank switching some RAM in-place.

EDIT: If you mean they were not copied in a frame buffer first, you are right. I should not have written 'blitting'.
7 comments
awkwardleon 141 days ago
Maybe too old to be applicable here, but the TRS-80 Models I and III (and probably more models) had no way to address pixels. You had to use semigraphic characters to emulate larger blocks at sub-character resolutions. https://bumbershootsoft.wordpress.com/2022/01/28/touring-the...
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LoganDark 141 days ago
The character ROM was not read and processed by the CPU. The CPU set some bytes in video RAM, which served as indexes into the character ROM by the video output hardware.

I believe on some systems there were some tricks that allowed some bitmap display by redefining glyphs. One example off the top of my head is The 8-Bit Guy's Planet X2, which can use text mode but with glyphs redefined to use for icons, units, terrain, UI, etc.

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worthless-trash 140 days ago
I believe you are correct, VGA even had character rom, where 'individual pixels' were not drawn by the CPU itself, the software presented an array of indexes into the rom and the vga hardware itself blitted the characters onto the screen.
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adiabatichottub 141 days ago
I recommend reading the TV Typewriter Cookbook.

https://archive.org/details/tvtcb_doc

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nine_k 141 days ago
IBM PC / AT / PS/2 all had a separate text mode, with glyphs defined in character ROM or RAM. Read about CGA, EGA, VGA. So TUIs basically owned the place since mid-1980s when PCs became ubiquitous, until mid-1990s when Windows started to dominate.
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direwolf20 141 days ago
With character RAM you can still only have up to 256 unique 8x8 blocks on screen.
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numpad0 140 days ago
> which was a character ROM per default but could be changed either with a screw driver or by

No. Stop believing everything ChatGPT told you on this topic and DYOR. That's some bad hallucinations.

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RetroTechie 140 days ago
Actually a small flathead screw driver is a useful tool to pull an (EP)ROM from its socket. Been there, done that (80s/early 90s).

Might be fun though to check with ChatGPT on how to use a screw driver in this context. :-)

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Brian_K_White 140 days ago
kaypro & trs-80, just a couple I happen to know myself. There is no way I just happen to know about the only 2.
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