It's probably not so bad. I recently found some code that was 25 years old. It was actually pretty decent, though of course not quite as clean as what I would

It's probably not so bad. I recently found some code that was 25 years old. It was actually pretty decent, though of course not quite as clean as what I would write today. It basically did bit-banging across a COM-port using TxD/RxD + several control lines in order to talk to an external memory card (across a level-converter). It contained two control loops two autoregulate the speed across many different PCs, work nice with Windows, etc. It autodetected first the COM-ports and then whether there was a card reader connected to it, while talking care to work well with serial mice. All this before I knew what control theory was (or even just the name!). Still, it wasn't bad code at all. Your code solved much harder problems so I would assume you were a better programmer then than I was, having only written small toy compilers. I can't imagine the objective quality of your old code to be bad in any reasonable way, even if you know you can do better now.