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...