Everything you SHOULD know about your Computer but don't!

I miss when computers used to come with manuals. And those manuals had schematics.

"When we use a modern computer, we're standing on the shoulders of giants so tall that the details are obscured by clouds." That's just poetic, man.

I'd love to see you walk through everything that happens from the moment of powerup, through someone typing PRINT "HELLO WORLD" on the keyboard, and finally hitting return and the output shows. It would be quite a journey!

I started a new project and went from c# to embedded c and c++. I went from thinking I understood computers to spending hours relearning what I thought I understood. I fell from the shoulders of giants but gained a giant respect for them climbing back up.

It's nice when you have the schematic for something, but even nicer when you fully understand it and know exactly what each part does and why that's useful.

As a 14-year-old, I cut my coding teeth handwriting machine code and punching it into a ZX81 (and then a TS 1000 after I fried the ZX81 when clumsily trying to upgrade its SRAM to 4K :P). Your video reminded me of those old days when you could actually fully understand both the hardware and software of a machine. Zoom forward to 2022 and I have no idea how or what, let alone why, my Windows machine is doing what it is doing :S

This is where I learned to code, ended up having 3 of them. A 2001, a uncommon Purple screen 4032, and a SuperPET 9000. I still have all three tucked away.

This is so valuable. I also grew up in that era and slightly before. By the time I was teaching programming at university, students were already getting abstract information without any base history. It was a little painful to watch. I still teach, and I’m now having to make videos on steps to programming that I never thought would be necessary. Students come to my courses with nearly no understanding of what a computer is or does, even if they are reasonably good at using one. The horrors of tech support are hilarious reading, but also a tale of shame. If you get a chance to read Reddit’s tech support tales, highly recommended.

I bought a second hand Pet in about 1988 off the company I worked for at the time. The only experience I had at the time was with cheap home computers such as the ZX81 and Oric 1, plus a week long 6502 assembly course when I was 13 in 1984. With no instructions, and of course no Internet it was a great learning experience. I actually managed to program a rudimentary BASIC horse racing game where you could bet on the outcome of each race, each horse was just the number 1-6 moving along a track made of the minus symbol and a random number generator to decide if each horse moved based on their odds. If I remember correctly the entire screen was redrawn at every passthrough of the code. Years later I managed to get a job in IT support but knowing how to code certainly helped my career, especially in the early days of DOS and UNIX support. Still dabble in C based languages to this day. Videos like this remind me of those days and how exciting computers were before they became a tool just for work, and help reignite the passion :)

Commodore's way of editing was so underappreciated, but so innovative.

A series on the C64 (assuming there is to much for a single episode) would be amazing. Interesting stuff as always look forward to seeing more in the future.

The book "Microprocessor interfacing techniques" by Rodnay Zaks is a great introduction to this kind of stuff, first published in the late 70s, it's a brilliant read

Literally the first computer I ever used and I’ve always had a soft spot for it. I rebuilt one recently on my channel (barely more than a 100 subs) but I got it like a museum piece. I have made the point many times that old 8 bit machines were totally different in that even as a teenager I could understand assembly language, understand the hardware and understand the OS. I wrote an expansion ROM for the CPC range that added 150 new commands whilst still at school and a disc copier better than literally any on the market for the BBC micro. Videos like this really take me back!

The reason the PET didn't have user defined characters is that the character ROM isn't in the 6502's address space, it is hard-wired into the video circuitry. You can't read the character ROM on a PET from a program even if you wanted to. The video circuitry in the PET essentially operates asynchronously on its own, with the CPU grabbing access to the video RAM when it wants it - do this at the wrong moment and you'd see "snow" on the screen where the wrong data gets shifted out to the electron beam! That is why BASIC usually waited for the vertical retrace interval before writing to the video memory. Later PETs, the 16K and 32K pets (2016, 2032, 3016, 3032 etc) did use dynamic ram. These are often referred to as the "Dynamic PETs" by forums.

It used to be more fun when we still could at least pretend to understand the whole stack from digital circuits to all levels of software. Becoming a software or system person was possible and even beneficial to start from digital circuits, hardware and moving upwards.

Dave, thank you so much! Your story telling skills are pretty much godlike, metaphorically speaking of course. But yeah, the way you present the information in your stories is so much fun to watch and absorb. Big hug!

If the PET could use characters from RAM, it would have to access main memory for a byte around once every microsecond, starving the CPU like the ZX81 suffered. The C64 alternated accesses of main memory between the CPU and VIC, but that would have taken a lot of discrete logic chips to implement (which is why the VIC does so much in the '64), and probably faster ram chips, Ram chip access times from the 70's has alas faded from my memory..

Dave is the man!! Really enjoy these trips down memory lane. I was a TRS-80 Mod-1 guy and loved Z-80 assembler.

I love that you took as an example the journey of a character from the keyboard to the screen. This is one of my favorite examples to show the complexity of computers as the character has to traverse many layers of hardware and software. Yet it looks obviously trivial to everyone.

Dave this such a great walk back through history.. my own experiences reflect those early day's where you were close to the system, or writing an input routine to grab the keystrokes and then move onto the next task and be back in time to pickup the next keystroke. Thank you for putting a wide smile on my face.