Because it seemed like a good idea at the time. The Apple II line of computers had an amazing run, from 1977 to 1993. In that time, hundreds of thousands of pieces of software were written for it, including many tens of thousands of games. Like any platform, however, the number of truly great games within read more
Because Interrupts Are Hard. The Apple II was (well, still is) a computer devoid of interrupts. I think most modern software engineers probably under-appreciate the implications of that. Folks skilled in writing main loops for games or graphics will at least be familiar with the evolution of main loops in games, so let s start there. read more
The cost of procrastination. If you re a regular reader of this blog, one thing you know is that I ve been having chronic problems with the Start button on my 1995 Williams pinball machine, Johnny Mnemonic. If you re new to the blog you may be shocked to know that (a) I own a pinball machine read more
Shuffling bits for fun and profit(?) Last time, we got the F18A physically repaired and running off Veronica s power supply. Things seemed to be working okay, and I could copy bytes into registers, but my VRAM block copier was not yet working. You may also recall that I threatened to buy a ZIF socket read more
One step back, two steps forward. If you ve been following this Put-An-F18A-In-Veronica drama, you know that we had some very light early successes, followed by an emotional rollercoaster of tragic failures and heroic repairs (for certain values of heroic ). It is high on my priority list to never repair that transceiver again, so it read more
THIS IS FINE. After the incredible success of our last bit of work on Veronica s F18A, I was very excited to get started on the software to talk to this thing. My ultimate goal is to have the F18A replace Veronica s original GPU, and that means rewriting the core ROM routines for text, sprites, read more
Do not go gentle into that good night. Just when things were starting to go really well on the Put An F18A In Veronica plan, well, I fried an irreplaceable device. Yes, if you re following along, you know that last time I somehow managed to cook the bus transceiver on the F18A, rendering the read more
Testing the limits of my desire to repair. What s this? Is that my elliptical machine on the operating table again? How can this be? The previous repair seemed quite final. Well, I was doing my daily cheeseburger removal ritual the other day, when the machine suddenly developed a distinct starboard list. If read more
It was the best of times, it was the worst of times. With our recent success in remembering how to do address decoding, it was time to look at the control signals. The V9918A has three basic ones- /CSR, /CSW, and MODE. The first two are active low signals for reading from and writing to read more
Bridging The Gap As you probably know if you re the kind of person who follows this blog, the 6502 CPU (the 1970s chip around which Veronica is based) talks to the outside world entirely via memory mapping. Contrast this with, say, modern microcontrollers which have a set of general purpose input/output pins, and a read more