Assembling Acorn Atom’s on the kitchen table that had a glorious 2K of RAM (expandable to 12K, though now I own one with 32K due to a 3rd party expansion board)
Publishing small 1/8th page ads in glorious black & white to sell assembled Acorn ATOMs.
Getting my program listings published in Popular Computing Weekly, Computer & Video Games (before it became crap, when it still had “The Bugs” cartoon, and Adventure Corner), The ATOM, Acorn User, and many other magazines of the day.
Screwing the RAM pack on to the back of the ZX81 to stop it from wobbling.
Writing a chess program in 1K.
Fighting with the assembler to save 200 bytes to get it down to less than 32KB so we could ship with only one ROM in the arcade machine.