6 ms·

At the Vintage Computer Fest last week Bill Mensch mentioned to the audience that no one ever hears about the 65C02 and 65C816’s use in defibrillators and pacem

At the Vintage Computer Fest last week Bill Mensch mentioned to the audience that no one ever hears about the 65C02 and 65C816’s use in defibrillators and pacemakers - life critical applications - unless he tells them! Does anyone know of good write ups or explanations of what makes the 6502 so reliable and what competition it had in being chosen for medical applications?

yitchelle 5y ago
I don't have any documentation but I would imagine that as these chips have been in existence for so long, its behaviour is extremely well understood, including most, if not all, of its weak points. The work around for these weak points should also be well known.
- flohofwoe 5y ago
  The nice thing about the 6502 is that it is completely reverse engineered down to the transistor level, so it's possible to explore what exactly is going on in the chip for each clock cycle even when the original design documents had been lost: http://visual6502.org/JSSim/index.html http://visual6502.org/JSSim/index.html (and shameless plug, my own 'remix' with better performance and more features: https://floooh.github.io/visual6502remix/ https://floooh.github.io/visual6502remix/)
  - danbolt 5y ago
    I wonder if that makes finding replacements easier too, since you can comfortably find (or even make) new ones.
  - ncmncm 5y ago
    Blank black window for the remix. What should I be seeing? [Edit: It's webgl. I don't have webgl in QubesOS :(.]
deleted 5y ago
[deleted]
jacquesm 5y ago
Simpler is an advantage in that world, if you can understand the functioning of your device to the cycle level then you have a much better chance of delivering something that will work reliably.
- dhosek 5y ago
  One of the things that I loved about the Apple ][ was that it was possible for one person to completely understand everything about that computer from the hardware to the software. I've never had that level of complete understanding of any system I've used since.
  - jacquesm 5y ago
    Yes, that was the beauty of the 8 bit era, and many people lost it without even knowing that they lost something very precious. The total control is a very nice feeling.
    - zozbot234 5y ago
      I'm not sure why "simple, understandable system design" would have to be synonimous with 8-bit computing. One of the most appealing things about new open hardware initiatives is how they bring this simplicity and surveyability together in what's otherwise a very modern design and context.
      - wcarey 5y ago
        Are there any good sources of documentation for working with Arm chips? Like, a simple single board (or breadboard) computer?
        ThrowawayR2 5y ago
        It's unclear what you're asking for here? The Raspberry Pi Pico and Raspberry Pi Zero are existing and very well documented ARM based single board computers.
pkaye 5y ago
Though I'd think they would use a microcontroller with a 6502 CPU which integrates ROM/RAM/GPIO/peripherals into one. Here is a microcontroller with a 6502. https://pdf1.alldatasheet.com/datasheet-pdf/view/103795/ETC/ST2202.html https://pdf1.alldatasheet.com/datasheet-pdf/view/103795/ETC/...
wvenable 5y ago
I just read an article recently about how 6502-based chips are used inside of satellite receiver boxes. I wonder if it's just a function of the time. I imagine anything designed new now would use an ARM based microcontroller but likely when many of these systems were originally designed those were much less common and more expensive.
- tzs 5y ago
  I'd expect that there are still a lot of new designs where something like an 8-bit microcontroller such as an AVR makes more sense than using something ARM based.
  - mlyle 5y ago
    It's getting harder and harder to find places where this is true. ARM Cortex M0/M0+ blows AVR out of the water, and is usually cheaper except for the very lowest end AVR parts. Generally will use less power, too. And that's assuming your unit counts are so high that firmware developer time is free. Of course, it's getting impossible to find 5V VCC ARM parts, so that's something that would steer you towards AVR if your system is really a bunch simpler by having a 5V micro.
    - milesvp 5y ago
      This is not strictly true. Many AVR chips can handle more computation than their clockspeed would suggest due to some really nice assembly codes that allow for common DSP calculations. I ported an AVR code base to a cortex M4 last year, and some of the inlined asm didn’t translate. I ended up having to use inlined C instead. So, my 120Mhz M4 chip struggled to do what a 90Mhz AVR did no problem.
      - mlyle 5y ago
        Note that it seems you're talking about AVR32, then, and not an 8-bit AVR like we were talking about. AVR32 was neat, but has lost all commercial relevance.

yitchelle 5y ago

I don't have any documentation but I would imagine that as these chips have been in existence for so long, its behaviour is extremely well understood, including most, if not all, of its weak points. The work around for these weak points should also be well known.

flohofwoe 5y ago
The nice thing about the 6502 is that it is completely reverse engineered down to the transistor level, so it's possible to explore what exactly is going on in the chip for each clock cycle even when the original design documents had been lost: http://visual6502.org/JSSim/index.html http://visual6502.org/JSSim/index.html (and shameless plug, my own 'remix' with better performance and more features: https://floooh.github.io/visual6502remix/ https://floooh.github.io/visual6502remix/)
- danbolt 5y ago
  I wonder if that makes finding replacements easier too, since you can comfortably find (or even make) new ones.
- ncmncm 5y ago
  Blank black window for the remix. What should I be seeing? [Edit: It's webgl. I don't have webgl in QubesOS :(.]

deleted 5y ago

[deleted]

jacquesm 5y ago

Simpler is an advantage in that world, if you can understand the functioning of your device to the cycle level then you have a much better chance of delivering something that will work reliably.

dhosek 5y ago
One of the things that I loved about the Apple ][ was that it was possible for one person to completely understand everything about that computer from the hardware to the software. I've never had that level of complete understanding of any system I've used since.
- jacquesm 5y ago
  Yes, that was the beauty of the 8 bit era, and many people lost it without even knowing that they lost something very precious. The total control is a very nice feeling.
  - zozbot234 5y ago
    I'm not sure why "simple, understandable system design" would have to be synonimous with 8-bit computing. One of the most appealing things about new open hardware initiatives is how they bring this simplicity and surveyability together in what's otherwise a very modern design and context.
    - wcarey 5y ago
      Are there any good sources of documentation for working with Arm chips? Like, a simple single board (or breadboard) computer?
      - ThrowawayR2 5y ago
        It's unclear what you're asking for here? The Raspberry Pi Pico and Raspberry Pi Zero are existing and very well documented ARM based single board computers.

pkaye 5y ago

Though I'd think they would use a microcontroller with a 6502 CPU which integrates ROM/RAM/GPIO/peripherals into one. Here is a microcontroller with a 6502. https://pdf1.alldatasheet.com/datasheet-pdf/view/103795/ETC/ST2202.html https://pdf1.alldatasheet.com/datasheet-pdf/view/103795/ETC/...

wvenable 5y ago

I just read an article recently about how 6502-based chips are used inside of satellite receiver boxes. I wonder if it's just a function of the time. I imagine anything designed new now would use an ARM based microcontroller but likely when many of these systems were originally designed those were much less common and more expensive.

tzs 5y ago
I'd expect that there are still a lot of new designs where something like an 8-bit microcontroller such as an AVR makes more sense than using something ARM based.
- mlyle 5y ago
  It's getting harder and harder to find places where this is true. ARM Cortex M0/M0+ blows AVR out of the water, and is usually cheaper except for the very lowest end AVR parts. Generally will use less power, too. And that's assuming your unit counts are so high that firmware developer time is free. Of course, it's getting impossible to find 5V VCC ARM parts, so that's something that would steer you towards AVR if your system is really a bunch simpler by having a 5V micro.
  - milesvp 5y ago
    This is not strictly true. Many AVR chips can handle more computation than their clockspeed would suggest due to some really nice assembly codes that allow for common DSP calculations. I ported an AVR code base to a cortex M4 last year, and some of the inlined asm didn’t translate. I ended up having to use inlined C instead. So, my 120Mhz M4 chip struggled to do what a 90Mhz AVR did no problem.
    - mlyle 5y ago
      Note that it seems you're talking about AVR32, then, and not an 8-bit AVR like we were talking about. AVR32 was neat, but has lost all commercial relevance.