6 ms·
I was told by Leonard Tramiel (who was my manager at Atari for a while) that the world record for a production 6502 was 25Mhz. This was demonstrated one Friday
by kabdib 7y ago
I was told by Leonard Tramiel (who was my manager at Atari for a while) that the world record for a production 6502 was 25Mhz. This was demonstrated one Friday evening, some time after the beer fridge had been opened in one of the labs.
I don't know if they applied any kind of external cooling, or what the benchmark was. Probably it was "keep cranking up the clock until pins stop wiggling or smoke comes out." Not very scientific, but quite entertaining.
- paulmd 7y ago"until pins stop wiggling"?
- xentripetal 7y agoMaybe the pins got so hot they melted into the board?
- justwalt 7y agoI think it should be “start wiggling” as that makes more sense.
- brokenmachine 7y agoWiggling pins is what a computer does when it is working.
- mmastrac 7y agoWiggling a pin - ie: toggling it. Basically means "activity on the pins" https://www.cypress.com/blog/technical/more-pdl-examples-wiggling-pins https://www.cypress.com/blog/technical/more-pdl-examples-wig...
- variaga 7y agoThe pins don't physically wiggle. "pins wiggling" is a common metaphor for "the voltage level on a pin is changing". As a signal driver is toggled at increasing frequencies ('cranking up the clock'), the signal amplitude (voltage difference between the 'high' and 'low' period) starts to drop. At a high enough frequency, the signal will be indistinguishable from noise and 'stops wiggling'.
- duskwuff 7y ago> At a high enough frequency, the signal will be indistinguishable from noise and 'stops wiggling'. It's not that the signal will be indistinguishable from noise, but that the CPU will stop working correctly, so its outputs will stop toggling (or will toggle in unexpected ways).
- kabdib 7y agoI was actually thinking about catastrophic failure, as in something on the chip burning out and making the clock stop. My guess is that they were probably cooling it with beer (or at least cold beer bottle bottoms) to get that last critical Mhz, before drinking the beer.
- numpad0 7y agoI had an impression that they might be talking what a digital I/O pin looks on oscilloscope. Scopes lock at first rising edge after last horizontal scan, so display starts at H, then drops to L after how long CPU held that pin high. That creates ￣￣l＿ lines on the screen superimposed to one another, X position “wiggling” ￣lll＿ depending on how many consecutive H bits just happened to be sent. When the CPU halts, the pin would flatline at H or L and you’ll know.
- metaphor 7y agoEuphemism for when you don't see output pins transition state on a measuring instrument, e.g. oscope.
- tyingq 7y agoThere's an FPGA 65C02 core running at ~73Mhz. https://github.com/MorrisMA/MAM65C02-Processor-Core https://github.com/MorrisMA/MAM65C02-Processor-Core
- duskwuff 7y ago18 MHz, actually -- the FPGA clock speed is 73 MHz, but it executes the equivalent of one 6502 clock cycle in four of its clocks. That being said, this was implemented on a budget-line FPGA from 2006 (XC3S50A - a small Xilinx Spartan-3A). A modern performance-line FPGA would probably hit a couple hundred MHz easily.
- baybal2 7y agoIt's still surprising how little relatively to the level of perceived performance have IPC count improved since seventies.
- nikanj 7y agoThe perceived performance for an average desktop has been pretty stagnant since, I don't know, at least the mid-nineties.
- spullara 7y agoSoftare expands to fill the CPU available.
- woadwarrior01 7y agoAKA Wirth’s Law[1]: “Software is getting slower more rapidly than hardware is becoming faster.” [1]: https://en.m.wikipedia.org/wiki/Wirth%27s_law https://en.m.wikipedia.org/wiki/Wirth%27s_law
- FeepingCreature 7y ago
- bemmu 7y agoFrom the Commodore book, about the early 80s: "We actually made a couple of really hot processors for a chess tournament for somebody. He literally water-cooled it, and he ran it at something like eight megahertz. It was just ridiculous how fast he ran it." Earlier it was explained that some processors coming off the production line could run faster than others, and they could test for it to pick the best ones for such purposes. They didn't end up increasing the clock speed for released computers, as other components could not keep up.
- QuadrupleA 7y agoCan anyone with an electronics background explain why it's so hard to clock a 6502 higher than a handful of MHz, when modern chips can do 1000x that? Is it just larger transistor scale leading to excess capacitance / slower switching?
- raverbashing 7y agoOne reason is that: transistor size and switching speed. Though the technology of the 6502 probably could go 50MHz? 100MHz? Not sure. Would it be equivalent to 74HC TTL line? Again not sure But the main (basic) reason is that the internal logic blocks don't worry too much about processing and arrival times beyond the speed at which they need to operate. What's simultaneous at 1MHz might be not so simultaneous at 10MHz or 100MHz Another (advanced) reason why overclocking it might be hard is EM interference inside and outside the chip.
- MagerValp 7y agoThe 6502 has very limited pipelining, and every CPU cycle is tied to a memory access with no support for wait states or stalls. At 1 MHz it can work with really slow memory (roughly 500 ns), but at 10 MHz it needs ~60 ns, and at 20 MHz something like ~20ns. The architecture simply wasn't designed for anything above single digit clock speeds.
- JoachimS 7y agoOne of my old companies (InformASic) developed a VPN solution for serial communication. The product LinkShield (later renamed and spun off to form CrypTango) was implemented as a small ASIC. The main CPU was a 6502 clone with memory protection. We clocked it at 33 MHz, but usually ran them at 25 MHz in the products. That 6502 clone was cycle correc, that is the number of cycles required for an instruction was the same as for the original MOS 6502. Nowdays you can quite easily to a 6502 implementation in a FPGA running at 100 MHz. Esp if you allow the design to use more cycles for some instructions. Sadly the product never took off and the companies folded. I have some chips somewhere. Googling at least revealed a picture of the product: https://www.google.com/imgres?imgurl=https%3A%2F%2Ffarm3.staticflickr.com%2F2745%2F4321331473_d8a845b40d_b.jpg&imgrefurl=https%3A%2F%2Fwww.flickr.com%2Fphotos%2F47119537%40N04%2F&tbnid=n5SmONjPFFT0NM&vet=12ahUKEwjfz6DnwOfoAhUTEZoKHdj6AeUQMygEegQIARAp..i&docid=xgjqyCAUxVzIiM&w=1024&h=768&itg=1&q=InformAsic%20Cryptango&ved=2ahUKEwjfz6DnwOfoAhUTEZoKHdj6AeUQMygEegQIARAp https://www.google.com/imgres?imgurl=https%3A%2F%2Ffarm3.sta...
- Cthulhu_ 7y agoI love reading the stories about overclocking attempts (actually that scene doesn't seem to be much of a thing anymore?), people bolting pipes on top of CPU's and filling them with liquid nitrogen, nearly supercooling the CPU's and breaking speed records.