I purchased an Acorn Atom in 1980 (the prebuilt one - a friend opted for the self-assembly and regretted it) and I still remember the thrill of setting it up and turning it on for the first time. It feels like I didn't sleep for a week but I suppose I must have.
When you entered a line of their BASIC, it would check the line for errors. At one point, I kept getting error XX (I don't recall the actual number) and couldn't see the error in my code. Eventually figured out it meant I was out of RAM. There was only 2K and I think the 6502 took some and the screen too so there was only about 500 bytes left over. What a joy it was after I saved up for the 6K upgrade.
And then there was the local computer club presentation that ruined any chance of a public speaking career.... :)
O man, good times.
I remember soldering RAM chips "piggyback" style, then upgrading to 64K of RAM, and adding 8 special-purpose ROMs (from utilities to a spreadsheet program). I even installed a color video board— all of this inside the Acorn Atom itself (which was a keyboard-style computer, similar to the C64).
The Atom also brought together a community of hardware and software enthusiasts through Atom Computer Clubs. These clubs were doing amazing things, including the development of Z80 co-processors and even running CP/M. While Acorn moved on from the Atom to the BBC Microcomputer, the clubs kept the Atom alive well beyond its prime.
It’s fascinating to look back and realize that the same team behind the Atom went on to create the ARM processor, which, interestingly, shares a striking similarity in its instruction set with the 6502.
Sophie Wilson (the designer of the original ARM instruction set) said this when asked which CPU architecture she admired:
Sophie Wilson, chief architect of ARM and more recently of the Broadcom FirePath
October, 2001
Primarily the 6502. I learned about pipelines from it (by comparison with the 6800) and its designers were clear believers in the KISS principle. Plus the syntax of its assembler and general accessibility of it from the machine code perspective. I can still write in hex for it - things like A9 (LDA #) are tattoed on the inside of my skull. The assembly language syntax (but obviously not the mnemonics or the way you write code) and general feel of things are inspirations for ARM's assembly language and also for FirePath's. I'd hesitate to say that the actual design of the 6502 inspired anything in particular - both ARM and FirePath come from that mysterious ideas pool which we can't really define (its hard to believe that ARM was designed just from using the 6502, 16032 and reading the original Berkeley RISC I paper - ARM seems to have not much in common with any of them!). And clearly the 6502's follow-up, the 65816, wasn't "clean" any more, so whichever of Mensch and Moore contributed what to the 6502, Mensch by himself was a bit at sea.
Biggest object lesson was, however, National Semiconductor's 32016 (aka 16032): this showed how to completely make a mess of things. The 32016 first exposed the value of memory bandwidth to Steve Furber and I, showed how making things over-complex led to exceedingly long implementation times with loads of bugs in the implementation, and showed that however hard you tried to approach what compiler writers claimed they wanted, you couldn't satisfy them (no, I never did use a VAX). And an 8MHz 32016 was completely trounced in performance terms by a 4MHz 6502...
That first reply (in the quora link) is a bit too dismissive
A lot of the instruction names are the same, but the apparent similarity becomes less once your start using them. Using the same names was probably very convenient given that Acorn's previous computers used the 6502, and it would have helped the programmers who need to transition.
But the machine was quite different to program, and the Arm made more innovations than just being a 6502 with more registers. Every instruction being potentially conditional, and every instruction being able to make use of the barrel shifter, were both quite radical at the time and contributed a lot to the density of code in those machines (although they are inconvenient to out-of-order microarchitectures, so have been dropped from V8)
I bought an Atom second-hand, it was my first 'own' computer. My father first had a TRS-80 model III and then an IBM clone XT. So the Atom was definitely less capable, but it was my own. I read all the accompanying manuals front to back and I read the computer magazines that came with it and this is how I learned English. I was 9 years old at that point. It came with schematics and of course I opened the case. I could not get the thing to load or save data on my dad's tape recorder. And it was only so much fun trying to type in a program from a listing which I could not save, especially taking into account my limited typing skills at the time and the fact that I had to do this while the Atom was attached to the TV in the living room. Still, it was a worth wile and forming experience and surely worth my pocket money.
Later on in life, end of 90s, I was re-wiring the building of my students union, with a friend. Many amps main board, 380 volts, 40 circuits or so, kind of big install. We had to create plans and supply them to get approval from the city or the utility company or the architect or such. For this we used the Archimedes of some guy that helped us. At this point the Archimedes definitely was dead as a platform, Windows 98 was just out. But it was still possible to use it to create drawings and schematics and quite capable.
I purchased an Acorn Atom from a guy, who assembled one himself. He also helped me upgrade to 12K RAM. Later I got a couple of joysticks, a dot matrix printer and a colour/color card.
It was great, but I soon got hold of a second hand BBC B a couple of years later, and then I was sold.
I eventually got an Archimedes 440 that I used for many years.
When you entered a line of their BASIC, it would check the line for errors. At one point, I kept getting error XX (I don't recall the actual number) and couldn't see the error in my code. Eventually figured out it meant I was out of RAM. There was only 2K and I think the 6502 took some and the screen too so there was only about 500 bytes left over. What a joy it was after I saved up for the 6K upgrade.
And then there was the local computer club presentation that ruined any chance of a public speaking career.... :)