6 ms·

I'm glad to see the 6502 getting so much attention on HN. I like the article title Unwind used here, so I've changed the article's original title to match. (Not

by kens 14y ago

I'm glad to see the 6502 getting so much attention on HN. I like the article title Unwind used here, so I've changed the article's original title to match. (Note to self: try to come up with better titles.) I've seen that story before that the 6502 worked perfectly the first time, but I think there's some mythologizing going on. The ROR instruction was totally broken on the first release of the 6502 and wasn't fixed until months later. [1] The quote above says that the 6502 has 3510 transistors, and this number appears many other places. It turns out that the 6502 has 3510 enhancement transistors and 1018 depletion transistors, for a total of 4528 transistors, according to the visual6502 analysis. And if you're interested in the inner workings of the 6502, you should definitely check out the huge transistor-level schematic at: http://www.downloads.reactivemicro.com/Public/Electronics/CPU/6502%20Schematic.pdf http://www.downloads.reactivemicro.com/Public/Electronics/CP... [1] http://en.wikipedia.org/wiki/6502#Bugs_and_quirks http://en.wikipedia.org/wiki/6502#Bugs_and_quirks and details at http://www.pagetable.com/?p=406 http://www.pagetable.com/?p=406

simcop2387 14y ago
You might also want to check out someone building a computer based off a 6502, very fun to see someone going through the steps to design and build something out of older hardware. http://quinndunki.com/blondihacks/?p=680 http://quinndunki.com/blondihacks/?p=680
- vidarh 14y ago
  Part of the appeal to me of this hardware is that it is so simple that even without much electronics experience you can get away with a lot more trial and error while learning. I did all kinds of crazy things with my C64 and got away with it without breaking stuff, like powering it off batteries (the C64 takes multiple different voltages in, but you can get away with just one - don't remember if it was 5v or 9v - just that some things like the user port and realtime clock won't work) and attaching leds and relays to the user port without a clue what I was doing, replacing the IO chips (CIA) with a different version from my 1541 disk drive when one of the ones in the C64 broke (standard troubleshooting: If the CIA chips were hot right after turning the machine on, they had short-circuited - they were the source of breakage on C64's and Amiga's...), and at a later point with one from my Amiga (they're all pin compatible, but some functionality is different, e.g. the Amiga version has a 32 bit timer instead of the realtime clock nobody used...), or replacing the 6510 in my C64 with a 6502 from a 1541 just to see what would happen (the 6510 has 8 general purpose IO lines, mapped to the tape drive IO and I think bank switching - I believe the machine will still start but...) On my Amiga I at one point made a pause switch by soldering stuff straight onto a pin on the CPU...
joezydeco 14y ago
Have you checked out the documentary that Jason Scott is working on? He ran a Kickstarter to fund the development of three films. One of them is specifically about the 6502: http://www.kickstarter.com/projects/textfiles/the-jason-scott-documentary-three-pack http://www.kickstarter.com/projects/textfiles/the-jason-scot...
vidarh 14y ago
I suspect that the "worked perfectly the first time" basically implies (whether that is accurate or not) "they only had to create one mask before their tests passed", not that it was entirely bug free. Possibly that the mask faithfully replicated the design, but that the revision of the design they first manufactured still had bugs. In any case, the main thing is that a lot of MOS' early success came from saving a tremendous amount of money being able to get to market quickly and cheaply compared to the competition thanks to actually having guys like Mensch and Peddle coupled with superior process (though that did not last all that long).

by kens 14y ago

simcop2387 14y ago

You might also want to check out someone building a computer based off a 6502, very fun to see someone going through the steps to design and build something out of older hardware. http://quinndunki.com/blondihacks/?p=680 http://quinndunki.com/blondihacks/?p=680

vidarh 14y ago
Part of the appeal to me of this hardware is that it is so simple that even without much electronics experience you can get away with a lot more trial and error while learning. I did all kinds of crazy things with my C64 and got away with it without breaking stuff, like powering it off batteries (the C64 takes multiple different voltages in, but you can get away with just one - don't remember if it was 5v or 9v - just that some things like the user port and realtime clock won't work) and attaching leds and relays to the user port without a clue what I was doing, replacing the IO chips (CIA) with a different version from my 1541 disk drive when one of the ones in the C64 broke (standard troubleshooting: If the CIA chips were hot right after turning the machine on, they had short-circuited - they were the source of breakage on C64's and Amiga's...), and at a later point with one from my Amiga (they're all pin compatible, but some functionality is different, e.g. the Amiga version has a 32 bit timer instead of the realtime clock nobody used...), or replacing the 6510 in my C64 with a 6502 from a 1541 just to see what would happen (the 6510 has 8 general purpose IO lines, mapped to the tape drive IO and I think bank switching - I believe the machine will still start but...) On my Amiga I at one point made a pause switch by soldering stuff straight onto a pin on the CPU...

joezydeco 14y ago

Have you checked out the documentary that Jason Scott is working on? He ran a Kickstarter to fund the development of three films. One of them is specifically about the 6502: http://www.kickstarter.com/projects/textfiles/the-jason-scott-documentary-three-pack http://www.kickstarter.com/projects/textfiles/the-jason-scot...

vidarh 14y ago

I suspect that the "worked perfectly the first time" basically implies (whether that is accurate or not) "they only had to create one mask before their tests passed", not that it was entirely bug free. Possibly that the mask faithfully replicated the design, but that the revision of the design they first manufactured still had bugs. In any case, the main thing is that a lot of MOS' early success came from saving a tremendous amount of money being able to get to market quickly and cheaply compared to the competition thanks to actually having guys like Mensch and Peddle coupled with superior process (though that did not last all that long).