When I wad in college, we had something similar in lab. This was around early 2000s, and we had Motorola 68K minicomputers with around 512k RAM, IIRC. They were

When I wad in college, we had something similar in lab. This was around early 2000s, and we had Motorola 68K minicomputers with around 512k RAM, IIRC. They were hand built, with wirewrapped connections between the various DIPs. To debug supervisor mode assembler, we had a clock toggle switch that could switch from normal running at 1 Mhz, I think, to a single clock cycle push button. We had a 2 character hex display that showed the 16-bit raw data on the databus. Spent so much time staring at those 16-bit hex values, I was able decode most of the instructions from memory (spent a LOT of time with the 68K ASM programmer manual - still have it on my shell). Couldn't even see the register state. Had to keep track of that in your mind or on paper. I think we had some dipswitches to toggle memory values, as well. Helped save time for trivial changes because downloading a decently sized ASM program could take 15-20 mins over a 1200 baud serial connection. Got in the habit of inserting NOPs in the code so we'd have room to insert a handful of instruxtions here and there. When I say decently sized, I mean around a couple 10ks bytes of machine code. We were working on a supervisor program to load user code, execute it in user mode and debug user code. Some other misc stuff, like commands to act like a calculator, sort arbitrary men locations, etc. It was a really fun class. Still can't believe how much we got done in 1 semester. Lots of late hours, sleeping on lab stools. Beer and sandwiches in lab while we worked. Made some new friends, strengthened bonds with others, lost a few friends that weren't pulling their weight. The lot of us later made an MP3 player around an Atmel AVR chip (forget the model) and a dedicated decoder chip with some wire wrapping and soldering and a crap ton of wiring. For expediency, we streamed the data over a serial port from a PC. Also a fun project. Discovered a lot of engineering stuff we'd been taught, but didn't really understand the relevance, was extremely important (like travelling wave theory and the importance of terminating a bus properly). It was a lot of fun building things in a constrained environment. Can't say I don't miss the college years, when you couldn't just "throw more hardware at it".