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Retrotink / Apple-II-VGA

Apple II/II+/IIe VGA card
GNU General Public License v3.0
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Question about this version of VGA #1

Closed TedThompson closed 1 year ago

TedThompson commented 1 year ago

https://github.com/V2RetroComputing/analog/issues/19#issue-1799680730

The issue linked above occurs with a more complex version of this card (https://github.com/hanshuebner/AppleII-VGA) which has a GAL for some device selection logic tricks which I think are required for uploading to and configuring the Raspberry Pi using programs running on the Apple.

Features I won't really use.

I'm wondering if this version exhibits the same funny behavior with HGR2?

I also wonder if, since it doesn't seem this version of the card does anything in the card ROM space, if it can live in Slot 3 of a //e without issue?

dkgrizzly commented 1 year ago

I believe you are having a conflict between the 80 column firmware on the motherboard and the VGA card. I would advise against placing any cards in slot 3 on a IIe which use the ROM address space, as this can cause conflicts. There are specific guidelines in the Apple Tech Notes for the IIe about how to avoid these conflicts, which my card (and many others) does not currently implement.

This version of the card only mirrors memory, and does not respond to reads, so should not have any problems in slot 3. You can also achieve this on my card by removing the PAL.

TedThompson commented 1 year ago

Understood. Thanks.