How Acorn Computers Became Arm | Matt Godbolt

so by this time I graduated on from the BBC master so like I think I was 17 so it's like last or penultimate year of of uh high school that I got an Archimedes which was made by Acorn who were the same company that made the BBC micro it was a natural progression from that but they had decided to jump this 8 bit era all the way to 32-bit and forget this 16bit era so like all my contempor so I hung on to the be three years past its best before day right it was way overdue everyone else was already on their Ataris and their Amigas and learning about blitter chips and things that were really cool and interesting but I was like no I can do this on my 8 bit machine it's fine and then eventually when I gave in I thought well I'm going to go with Acorn still and by this point Acorn had designed their own 32-bit microprocessor and this microprocessor uh was inspired heavily by the 6502 that they' cut their teeth on the team had knew all about it they went out to Western Digital or whoever was the designer at the time of the 6502 and said can you tell us about how you make a chip and it turns out it's like three people in by this point three people in like a bungalow in Texas going like sure this is how we made it what you this is so it's possible for like Mortal humans like small number of them to design a chip and they're like yeah of course it is I I I think you know the original 6502 Bill mentioned all that kind of stuff was you know bided men again unfortunately as is the way in our industry at the moment although we're trying to change that right um with Shar is on a big acetate sheet drawing out the 6502 but it was you know the the the later versions of it were done similarly and so anyway the folks from Acorn came away and said well we can do this too how hard can it be nobody told them how hard it was to make a chip so they you know they were like we can do this and they designed this really beautiful 32-bit machine and they' learned from the 6502 where it's like this almost nice separation of addressing modes and flag setting and all this thing and they thought well if I I've got 32-bit fix size op codes I can fit them in nice places and so it's really kind of a nicely designed system and that they called it the acor risk machine because it was very much a load store architecture with 15 registers or 16 if you include the program counter and of course we all know I'm doing the whole long reveal for you here as you're smiling of me knowing what I'm talking about here as more almost all of your listeners but this was the arm chip the very first arm chip and so the very first 32-bit machine I ever got my hands on was an arm and just like the acor before it uh sorry the BBC before it straight into assembly because it was the same basic you could open squiggly braces and start typing uh uh 652 arm assembly and it was you know it was beautiful it was so uh simplistic uh it was super fast for the the clock speed I think mine was like an 8 MHz or 12 MHz and you know and so and the multiple load and store instructions that it had which was a lovely lovely way of like reading and writing multiple registers from like ascending or descending memory location which was perfect perfect for pushing and popping going in and out of functions but also was amazing CU you could point it at the screen and Blitz Sprites as fast as you could so although it didn't have Sprite Hardware to write games you could do pretty well with these with clever use of these multiple load and store instructions you know read from here put the over here um and so I had learned arm assembly and I'd thrown everything out the wall and so I was writing everything still in arm assembly so I got to University that's where we were but before we started this I discovered the internet and the internet was amazing and uh one of the first things I did was write an Internet relay chat client for my acon because they were still Niche even in the UK you know nobody had them right um and so if you wanted to join in IRC you either went to the the lab and you used ilc like the command line client in Unix or if you had as a client on your your your local machine and you had like a Serial cable to connect to the network then you could you know actually uh do it from gooey I decided to write my own and because I only knew assembly I wrote the whole thing in arm assembly and it's I don't know how many thousands and thousands of lines it's on GitHub if you want to go and laugh at it all but it was we'll Link in the show notes for sure with people want to torture themselves but it was a fascinating experience of of learning so while I was supposedly doing my Physics degree I was writing this IRC client um the ISC client ended up because all ISC clients at the time had like scripting languages built in them so you could like do Auto greeters and things like that I ended up writing a scripting language in it which looks remarkably like BBC basic except it was object orientated and then I was doing managed memory and so I invented this way of cleaning up the memory after you'd finished with it without having to free it manually which I later discovered is Mark sweep garbage collection and oh right and at some point along this PO path it should have dawned on me that I could should ask my roommates who were like doing a actual computer science degree what the heck it was I was really building um but towards the end of this it became obvious that it was absurd to be writing large guy applications in pure assembly and so begrudgingly and and because I wanted to have my programs run on um the computers at the University lab I learned C

Channel: Microarch Club

Views: 681

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Id: VBMBH1uPacM

Length: 5min 18sec (318 seconds)

Published: Tue Apr 16 2024