Steve

I’ve finished the design changes for interrupts. It worked out pretty much how I’d outlined earlier, using a GAL to implement the special OP register that has both a load enable and a clear input, since no such 7400-family part…

I made an accounting of all the components needed by my design as it stands today. It totals up to 50 components altogether, with a combined cost of $114.32. Count Part Purpose Price Each Price Total ALU Module 2 74LS181…

Buddy Betts had some interesting thoughts about multitasking on BMOW. That’s so far off in the future that it’s probably useless to speculate about it now, but what the heck. Running several programs at once would require: A timer interrupt…

Here come the GALs: I’ve decided to use GALs in a few places, to make my life easier. GALs (gate array logic) are a simple kind of programmable logic device. Each output pin can be programmed to compute an arbitrary…

Programming update: I wrote a simple microcode assembler, and used it to implement a dozen or so common instructions. Then I wrote a few simple programs using those instructions, to count through a loop a fixed number of times, and…