Macintosh-HW
/
SE-VGA
mirror of https://github.com/techav-homebrew/SE-VGA.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

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

This commit is contained in:
techav 2021-05-21 21:47:29 -05:00
parent 5b1e2ecc72 bfeba8c649
commit b0815fb726
1 changed files with 2 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
README.md
View File

@ -1,7 +1,7 @@
# 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.
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.
@ -19,7 +19,7 @@ The Mac SE primary framebuffer starts at 0x5900 below the top of RAM. Since it's
| 000 | 0x07a700 | 0x072700 | 0x080000 | 0.5MB | `[256kB 256kB][ --- --- ]` |
## 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|
|---|---|---|