Home Page Forums MAME MAME 8bit Apples - Apple I, II, /// and the 16 bit GS

I was looking at some pictures of parallel cards and saw some nice hires pictures of the front and back of the LP Mightypress, and I thought, hmmm maybe I could figure out the schematic from tracing the wires. (Oh boy, was I wrong!)

Flipping the back view to match the front view and labeling stuff and looking up datasheets is pretty time consuming. What's really hard is that you can't see through the chips on the board and know exactly where those traces are going.




I was able to figure out quite a bit, but there were a lot of questions still and missing info.

At one point I decided to look at the rom more closely and looked for strings that may be interesting. There's a string that said that it was PPI which must mean Practical Peripherals. There's a manual for the PPI GraphiCard with schematic and it looks just like the LP Mightypress. However the scanned schematic is missing about an inch in the middle of two pages but it does show 95% and answers how the banking is done.

I love it when manuals include technical information like this.





I got it to mostly work, but for some reason the rotated graphic dumps don't come out properly.

It seems to have some a6 fiddling for $c1c1 compatibility with the apple pic, and a 4k banked rom for $c800-c8ff. The bank gets switched to the upper part by reading c083,x and gets switched back to the lower part by if (((a9 && a10) && a8)) m_rombank=0;.

One interesting feature is if you hit CTRL+I V it will give you a little test and tell you what printer you've got selected in the DIP switches. If it isn't working right, it will say BAD (in flashing) instead of GOOD. When I first saw it say GOOD I was quite happy!