VT-6 kit (was Re: Making vintage computers)

On Thu, May 28, 2009 at 9:46 AM, Bob Armstrong <bob at jfcl.com> wrote: One problem is that the video circuit for compact Macs is bizarre. The display circuit was optimized for square pixels at 72 dpi on the tube. Here's the stats of the Mac video circuit I was able to dredge up... Resolution........................................512 x 342 Horizontal scan rate..........................22.3KHZ, (4?s on, 40?s off) Vertical scan rate .............................60HZ (180?s on, 16.4ms off) Of course it could be hacked to accept something else, and the VT-6 display routine can be hacked, but I'm not qualified to estimate if there's enough overlap between what is needed to display 80x24 text and what the Macintosh video circuit can provide, but there's some excellent discussion and detailed schematics here: http://68kmla.net/files/classicmac2.pdf As for the keyboard, the original Mac keyboard (128K and 512K) lacks arrow keys, a control key, function keys and a keypad. The Mac Plus keyboard is less spartan, but still would present a challenge for an EDT user. I don't know anything about Mac keyboard protocols or signaling method, but with the modular-jack keyboards (pre-ADB), it's probably similar enough to what everyone else did (power, ground, either data+clock or bi-directional data over the 4 wires) that it shouldn't be too hard to reverse-engineer. If you could find an old 9" mono VGA monitor, that might be easy to physically adapt to an old Mac case, but I don't remember those being too common, even back when they were making them (since they were really only popular with hardcore DOS users). It'd be a cute hack, though. -ethan