Macintosh-HW/SE-VGA
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Merge branch 'main' of https://github.com/techav-homebrew/SE-VGA into main

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techav 2021-05-21 21:47:29 -05:00
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# SE-VGA # SE-VGA
Simple CPLD project to mirror the Mac SE video over VGA. No scaling is performed -- the Mac 512x342 video is displayed letterboxed (black borders) in a 640x480 frame. Simple CPLD project to mirror the Mac SE video over VGA. No scaling is performed -- the Mac 512x342 video is displayed letterboxed (black borders) in a 640x480 frame.
Circuit uses a single AFT1508AS-100AU CPLD, 32kx8 15ns SRAM, and a 25.175MHz can oscillator, along with some passives. Circuit uses a single AFT1508AS-100AU CPLD, a pair of 256kbit (32kx8) 15ns SRAM, and a 25.175MHz can oscillator, along with some passives.
Plugs into SE PDS slot and snoops writes to the frame buffer memory locations. Writes are cached and copied to VRAM. Plugs into SE PDS slot and snoops writes to the frame buffer memory locations. Writes are cached and copied to VRAM.
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| 000 | 0x07a700 | 0x072700 | 0x080000 | 0.5MB | `[256kB 256kB][ --- --- ]` | | 000 | 0x07a700 | 0x072700 | 0x080000 | 0.5MB | `[256kB 256kB][ --- --- ]` |
## CPLD Pin Assignments ## CPLD Pin Assignments
Logic uses nearly all available resources in the 128-macrocell CPLD. Attempting to order the I/O pins in a manner more favorable for board layout would just waste precious few remaining resources. Fitter pinout stands. Logic uses nearly all available resources in the 128-macrocell CPLD.
|signal|Direction|Pin| |signal|Direction|Pin|
|---|---|---| |---|---|---|