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Some MODE numbers wrong #277

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jgharston opened this issue Jan 20, 2023 · 2 comments
Open

Some MODE numbers wrong #277

jgharston opened this issue Jan 20, 2023 · 2 comments

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@jgharston
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jgharston commented Jan 20, 2023

Some MODE numbers are wrong
What is MODE 2 should be MODE 1

@bobbimanners
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I wondered about this.

The rationale right now is that MODE 0 is 640 pixels wide and MODE 1 is 320 pixels wide. I think they are the same resolution as the respective modes in the US model Beeb (200 lines rather than 256.) However both of these modes have more colours than their Beeb counterparts - four colours in MODE 0 and 16 in MODE 1.

MODE 2 is pretty awful and is limited to the NTSC-artifact mode of the original Apple II, which has many quirks. I also use a third party lib for this mode at the moment, which limits my ability to implement some of the Beeb plotting functionality. Really MODE 2 is 280x192 monochrome, or 140x192 if you treat it as colour (so not so far off from Beeb MODE 2 in terms of pixels.)

How would you propose we map them to modes?

@bobbimanners
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@jgharston Have you had a chance to play much with MODE 0 and MODE 1? Most stuff is implemented except for triangle filling, the other horizontal filling mode, dotted lines, and lines with last point omitted. VDU5 is implemented. Also VDU19 palette changes are there. I plan to do PLOT 85 triangle filling in the next little while.

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