Back in school (I studied electronics), our embedded programming course was done on 8085 machines with a hexadecimal keypad where you could enter data into memory a byte at a time. The assignments were done on pen and paper, we got a printout of the instruction set, a blank piece of paper and a description of what the program was supposed to do. We'd write the assembler code on paper, translate it by hand to hexadecimal using the instruction set reference and then load the resulting binary code by hand. You could pause execution with a button and the address and data buses were available on pins, so you could hook up a scope or logic analyzer to see what was happening under the hood.

Most everybody hated that class, but man did I love it. It was hands-down the most fun class in my studies. Would've been better with a 6502 though.

EDIT: Oh look, I found the machine. Apparently it was a HP 5036A Microprocessor Lab (learning computer): http://www.azur-electronics.com/Pages/hp_5036a_microprocesso...

I can't see how it would have been better with a 6502. The 8080 family had multiple clock cycles per instruction cycle, thus if you are hooking up a scope and watching, there is more going on to see, and if you grok what's happens at each clock transition, you will have learned more about timing and the internal propagation of signals through stages of logic gates. It's somewhat similar to CISC vs RISC, both may be elegant designs, but understanding more complexity is a greater intellectual puzzle and the 8085 had more microcode.

In high school, I used a similar setup from Heathkit with a 6800 processor.

http://www.vintage-computer.com/heathkit3400.shtml

Acorn System 1 for the Win

http://imgur.com/a/f7zZR

http://forum.6502.org/viewtopic.php?f=12&t=3286&hilit=acorn+...

(No I haven't built the replica yet - darn work/life balance)

Raspberry Pi is ARM, not AVR. And it's not really comparable to an Arduino since it runs a full OS.

Oops! I stand corrected. But no, the Raspberry Pi does not necessarily run a full OS. It can, and it certainly makes sense to do that, but it's very possible to run a standalone boot-loaded program on a Raspberry, just as OSes like FemtoOS will run on AVR architecture.

Yes, the combo of read/data and poke was the preferred way to combine Basic and assembly on the C64 also. Technical magazines like The Transactor consisted of program listings that were nothing but these statements and lots of numbers. I believe 169 is LDA, if memory serves...

Pi is ARM of course, but +1 for AVR. 6809 was nice too.

I loved 6809. It's the design of th instruction set that I loved, its simple consistency. That and the fact that it had a SEX (sign extend) function, and two stacks.

>On the other hand, a similar experience can be had on some modern CPUs as well.

There's absolutely no reason you couldn't constrain yourself to a subset of the instructions available on x86 and have a fairly equivalent experience as coding for a 6502.

Yes simple unless you had to add two numbers greater than 255 :)

16-bit arithmetic was not a problem, you just checked the carry flag.