40 MHz RCA COSMAC
- IEEE mentions in a brief abstract text a 40 MHz RCA processor back in 1978 (see http://tinyurl.com/oeosk2g):"Silicon-on-sapphire (SOS) technology has been applied to the RCA COSMAC microprocessor to obtain a high-speed single-chip CPU. The chip has 4827 transistors and measures 5.3 mm square. The low device count is obtained through use of bit-serial arithmetic logic, a byte-serial incrementer, and a 5-transistor static storage cell. The low parasitic capacitance of the SOS structure permits a 40-MHz clock rate at 14 V."Was such a chip ever massproduced and sold, and if so under what name/number?Jorg
- Well I was fortunate enough to just be amazed and happy that I didn't fry my 1802 chips back in the day (late 70's) because I tended to fry most of the other chips I had as well as the FETs I was trying to use in amplifier circuits. Darn FET's… They were expensive and sensitive. I never managed to handle them without frying them; same with some of the early Op Amps. 741's were bulletproof but the RCA 3130's were pretty useless as soon as I got my clumsy, static charged hands on them.I think the 1802D was on the slower end of 1802's at 2.5MHz. The 1802ACE was 3.5MHz and then the 1802BCE was the fast one at 5MHz. I have a pair of BCE chips so I think I may build a little speed demon ELF with one. I'll bet someone here like Lee has info about over clocking 1802 chips although I think the value with them is going in the opposite direction and slowing the clock speed way down so that it can be run off a small battery or two.I too have a bunch of chips from back in the day (circa 1979) including the radio shack 74150 that somehow survived my many hex keypad experiments. I have no idea how it survived but I pulled it out of retirement a few weeks ago and sure enough it's still going strong. I'll have to take inventory one of these days and catalogue all of my vintage electronic components.Andrew
On 2013-05-28, at 2:50 AM, Mark Graybill <saundby@...> wrote:
I was using 1802Ds. I did the experiments in late '77 to early '78 as I recall. I felt flush from a new job on top of my paper route and 7-Eleven income, so I bought a bunch of chips in fall '77. Then I fried a bunch during school breaks.
I still have and use ICs from that buying spree, but unfortunately not 1802s, my current stock of those is much newer. And I have no interest in overclocking any more. ;)
Here I have a drawer full of 8755s and no programmer that will handle them now. I should have bought one then, but back then I built up ad-hoc programming circuits on a bread board. Anyone know a current hobby-cost programmer that'll do it? Nowadays, the more time it takes to complete a project, the higher the chances something will shoulder it aside before completion.
Mark, W8BITOn May 27, 2013 11:22 PM, "Andrew Wasson" <awasson@...> wrote:
Mark, were you using the 1802ACE or the 1802BCE.As I understand it the ACE would run at 3.2MHz at 5 volts but the BCE would run at 5MHz. I'm not sure how high you can run the voltage with them but you would certainly do better with a BCE in your over clocking projects.Andrew
On 2013-05-27, at 10:03 PM, Mark Graybill <saundby@...> wrote:
Then we just need to scour the surplus yards for ICBM warhead buses (sans warheads, hopefully), and take our handy Civil Defense radiation counter with us. :DI used to push ceramic 1802s pretty hard to see what I could do with them (did myself out of a _lot_ of chips that way, experimenting and continuing to think that I _almost_ had it last time when the chip went dead.) I remember running them up to 15 or 18V and at least momentarily getting speeds around 10-14MHz.I monkeyed around with Vcc, Vdd, and clock in various ways trying to find the "magic" combination. Then one day I realized how much I'd spent on all the chips I'd fried in those late-night marathons trying to create a speed demon...If I'd had more of a clue at the time, I might have been able to get one stable at about 10MHz, but I knew nothing about, for example, heat sinking DIP ICs (I got the idea with cans--transistors and op amps--but anything else, I had a blind spot.)Still, it was educational. If for no reason other than when I learned something later I was able to look back and say, "I wish I'd known that before I fried all those 1802s!"On May 27, 2013, at 2:54 PM, Lee Hart wrote:
On 5/27/2013 3:52 PM, Kent Andersen wrote:
> Thanks for the information Lee, do you happen to know what pieces of
> equipment were built with the SOS 1802?
Sorry; I have no idea. I don't know if RCA ever found *any* customers
for the SOS 1802. But since it was fast, low power, naturally radiation
resistant, and expensive, I would guess it would have been in some
military or NASA equipment.
If you want to build a ship, don't drum up people to collect wood
and don't assign them tasks and work. Rather, teach them to long
for the endless immensity of the sea. -- Antoine de Saint-Exupery
Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.htm