What was the first 64-bit processor?

Model and year, if you know. Speaking about any and all platforms. I’m trying to settle a bar bet with someone who claims that 64-bit computing existed in the 1970’s.

Bonus points for first 32-bit and 16-bit processor as well as any other meaningful multiples that you know.

From http://www.baselinemag.com/print_article2/0,2533,a=61441,00.asp

The first 64-bit processor appeared in 1991 according to this site.

“In 1991, MIPS Technologies introduced its 100-MHz R4000 64-bit RISC processor, followed by Digital Equipment’s 150-MHz DEC chip 21064 Alpha AXP 64-bit architecture in 1992.”

Ahhhhh… the Alpha. You can still run Windows NT 4.0 on the Alpha, and even some early betas of “Windows NT 5.0” (later called Windows 2000) on it too - if you can find them. I miss Digital - my first “real” IT job was there.

The 70’s seems too soon, but I’ve a vague memory of an article in Science, circa 85 or 86, about a group that created a processor with 64 bit registers for string manipulation. They speculated on how long it’d take them to get it up to 1024 bits.

I still have a 233Mhz 21066A with Linux installed somewhere in a closet :slight_smile:

I have a Digital “Personal Workstation” 433AU with a 433Mhz Alpha running VMS 7.x (forget the minor version) in my computer hutch. If you’re gonna buy the obscure, yet cool, hardware, you owe it to yourself to get an OpenVMS hobbyist license and put an obscure, yet very cool, operating system on it. :smiley: One of these days, I’m gonna upgrade my VAX to a more recent version of VMS and make a cluster…

Depends a bit on what you mean by “64 bit” processor. Digical Vax computers like the 11/780 had instruction codes for working on bytes (8 bit), words (16 bits), double words (32 bits), quad words (64 bits) and octowords (128 bits). Since the largest data type they can manipulate is 128 bits, you could call them a 128 bit computer. However, the CPU registers were 32 bits, and if you look at data paths and such I’d be more inclined to call it a 32 bit computer.

Also, while the first 64 bit processor chip may have come out in 1991, you also have to keep in mind that a computer can be built out of multiple chips and doesn’t necessarily have to be based around a single processing chip. Many computers in the 70’s had “processor boards” not “processor chips.” There used to be “bit slice” processor chips that could be strung together to make as big of a processor as you wanted. The AMD 2901 from the 70’s was a very popular 4 bit slice. If you want a 64 bit processor, you just put 16 of these chips together. I bet if you searched hard enough you could find a few dozen computers with at least 64 bits using a bunch of AMD 2901’s strung together.

You lose your bet, NattoGuy. The Cray I supercomputer had a 64-bit word, and it came out in the mid-70’s. I actually worked on one of those, so I can vouch for it firsthand.

As an odd little side note, I also did some programming on a CDC 6600 in the 70’s, and it used a 60-bit word, if I recall correctly.

Just had a chance to do a little googling.

The PDP-11/34 and PDP-11/44 (both from the 70’s) had an optional 64 bit processing board available, which had 16 AMD 2901’s on it.

It looks like the IBM system 360 in the mid 1960’s had various cpu versions available. The m65 version apparently had a 64 bit ALU.

So, not only did you lose your bet, but 64 bit computing was available in the 1960’s as well.

This is an interesting site: http://www.sasktelwebsite.net/jbayko/cpu.html (Great Microprocessors of the Past and Present)

computerhistory.org has in interesting timeline of computers: http://www.computerhistory.org/timeline/

The CDC 6600 mentioned by InvisibleWombat also dates to the mid 1960’s.

You can’t count ALU size or optional hardware. 360s had instructions to process large chunks of memory after all, and IBM1620s were decimal machines which processed a chunk until you got to a stop bit.

From looking at Siewiorek, Bell and Newell. (My copy of Bell and Newell got swiped :frowning: )

The paper on the CDC6600 was from 1964, and I think Thornton’s book was from around then also. But I think the first 64 bit machine was the Illiac IV. The paper on that was from 1972, and I think it has already been shipped from Urbana at the time. It had 64 bit fixed point instructions. I didn’t notice anything earlier.

My vote is for the Commodore 64 back in the 80’s. :slight_smile:


Oh, good point. Just because I used it in the 70s doesn’t mean it was new at the time. Was my recollection right that it had 60-bit (not 64-bit) words? I seem to recall a 6-bit character set, so you could exactly fit ten characters in one word.

Yep, it had 60 bit words. Here’s a nice page about the CDC 6600:

Here’s another page with a lot of info: