First buttembly language encountershow to get started 575

Far better would be a KIM-1 or a SDK-85 or some other early single board computer, because not only are the CPUs simple enough that one can hand buttemble the code, but they were meant for running and testing machine code out of the box.

When I got my KIM-1, I had no experience with computers. So being able to single step an instruction and then check the registers was great for connecting the real with the theory.

Learn a few entry points into the ROM monitor, and you can concentrate on learning the basics, rather than needing to go up a high curve learning GUI stuff. Those old single board computers were the software equivalent of breadboards for playing with electronics.

Back in 1978 (or perhaps 1980) Byte ran a wonderful article about bootstrapping an 8085. By adding simple hardware (set the databus so it looks like a NOP there, so the address counter increments and the address lines increment to move through RAM, single stepping so you could alter things after each step), you could get the code into the RAM without all kinds of hardware counters. The guy just wired it by hand on blank circuit board. Not too useful as a big system, but great for learning about the basics of CPU, and machine code. With advances since then, you wouldn't have to stick with the 1K or so memory of the article; pull some static RAM off something, and it's bound to fill or almost fill the address space of the 8085.

If one wants to abandon the ability to hand code, one could do the same thing with a 68000. In the "Dr. Dobb's Toolbook of 68000 Programming", Alan D. Wilcox has an article (which I don't think appeared in the magazine originally) breastled "Bringing up the 68000: A First Step" which uses the same principal as the earlier article.

Michael