That's a machine from IBM's 600 line, cost-effective business machines that did automated arithmetic. The IBM 601 (1931) read and punched punch cards, multiplying fields as set by a plugboard. It was entirely mechanical. The IBM 602 (1946) was similar, and could divide. The IBM 602A ("a 602 that worked" 1948) was in wide use into the early 1970s.
IBM had been working on electronic arithmetic prior to WWII, and the IBM 603 Electronic Multiplier (1946) was IBM's first deployed product with large numbers of tubes. It was built to find out if tube machines could be successfully deployed in a business environment and used commercially without constant tending by skilled technicians.
That was the commercial limitation - the ENIAC and UNIVAC sized machines required large numbers of on-site techs to keep the hardware going. The 603 didn't. All IBM machines at the time were rented by IBM, and rental included on-site servicing by IBM Customer Engineers in white shirts and ties. IBM had to keep the servicing cost down.
IBM was only willing to deploy tubes if the operating and maintenance costs were acceptable.
The 604 was a more commercial version of the 603. The 603 looked like a very large suitcase built of black perforated metal. The 604 looked like IBM's other tabulating machines and had better access to the components. This was the first high-volume product with tubes.
None of these machines had much memory. Just a few registers. There were no good memory devices yet suitable for field deployment. They were all programmed with plugboards.
Everybody involved knew they needed better programmability, and there was an effort at Columbia University in the 1930s to do that. It involved Eckert and Mauchley, who went on to design the ENIAC and the UNIVAC I. But there was no good place to put the program.
The memory problem persisted for years. Williams tubes were unreliable. Acoustic delay lines had temperature stability problems. Rotating drums could work at a commercial price point. The IBM 650 (1953) was IBM's first real business computer, with drum main memory and all-electronic computation. Knuth's first book is dedicated to the IBM 650.
This side of computing gets less attention in histories, which tend to focus on the military machines.
But this was the side that shipped in volume and made real money. It came from the engineers with relays and clutches in Endicott and the accountants at Armonk, who had to develop something IBM Sales could sell to large and medium sized businesses. No need for Turing, von Neumann, etc.
The IBM 1401 (1959) ended the 600 line. At last, all-transistor, all core memory, in a reliable box that could be deployed to customer sites. It's a very strange machine, with variable-length everything, but it works well.
Then, of course came the IBM System/360, which standardized architecture for decades to come.
My favorite part was a footnote: Footnote 2 specifically. I'd always wondered how plugboards worked and the footnote and the linked pdf gave me some sort of idea.
Fantastic deep dive as always, thanks for doing such stellar work!
On that note, any chance we might get a teardown/history of Cray architectures in the future? Specifically the Cray-1 and 2?
To throw a more serious challenge your way: How about a write-up on the original Frank Rosenblatt Perceptron? I know finding an original Mark-1 part would be close to impossible but it blows my mind that they were successfully doing real-time visual classification in 1957 with an electro-mechanical machine (potentiometers and motors) using a 20x20 "video" feed with some learning algorithm that was not based on backprop.
Roughly how many varieties of module were used for a full 604 system?
I suspect quite a few as other "modular" systems in the transistor era like the later IBM Standard Modular System and DEC Flip-Chips ended up with plethora of specialised modules, but I'd be interested if that growth had already begun in the tube era.
I don't have the information for the 604, but the 605 used about 36 different types of tube modules. IBM couldn't resist making different types of modules; the 650 had sixteen types of cathode followers alone.
Philbrick op amp K2-W was an analog circuit with two dual-triode tubes on top of circuitry, with an octal plug at the bottom. I have one with data sheet but have never fired it up.
Univac had similar single-tube modules (but without the handle), as well as multiple-tube modules. See this video: https://www.youtube.com/watch?v=NVbjXHR6WAY
The BRLESC computer used printed-circuit boards that had components and a single tube (parallel to the surface). I have a Burroughs module with 8 tubes.
I haven't seen a tube deployment like that before - where the tube is combined with it's supporting components into one module - and that module plugs into a tube socket.
It's clever. It should reduce time for some repairs.
No questions, but I really enjoyed the article - thank you for sharing. It amazes me how few vacuum tubes these early computers use, compared to the billions and trillions of mosfet transistors used in modern devices.
One way they get away with using relatively few tubes is that most of the Boolean logic is done with semiconductor (germanium) diodes, using tubes to amplify the results.
That's a machine from IBM's 600 line, cost-effective business machines that did automated arithmetic. The IBM 601 (1931) read and punched punch cards, multiplying fields as set by a plugboard. It was entirely mechanical. The IBM 602 (1946) was similar, and could divide. The IBM 602A ("a 602 that worked" 1948) was in wide use into the early 1970s.
IBM had been working on electronic arithmetic prior to WWII, and the IBM 603 Electronic Multiplier (1946) was IBM's first deployed product with large numbers of tubes. It was built to find out if tube machines could be successfully deployed in a business environment and used commercially without constant tending by skilled technicians. That was the commercial limitation - the ENIAC and UNIVAC sized machines required large numbers of on-site techs to keep the hardware going. The 603 didn't. All IBM machines at the time were rented by IBM, and rental included on-site servicing by IBM Customer Engineers in white shirts and ties. IBM had to keep the servicing cost down. IBM was only willing to deploy tubes if the operating and maintenance costs were acceptable.
The 604 was a more commercial version of the 603. The 603 looked like a very large suitcase built of black perforated metal. The 604 looked like IBM's other tabulating machines and had better access to the components. This was the first high-volume product with tubes.
None of these machines had much memory. Just a few registers. There were no good memory devices yet suitable for field deployment. They were all programmed with plugboards. Everybody involved knew they needed better programmability, and there was an effort at Columbia University in the 1930s to do that. It involved Eckert and Mauchley, who went on to design the ENIAC and the UNIVAC I. But there was no good place to put the program.
The memory problem persisted for years. Williams tubes were unreliable. Acoustic delay lines had temperature stability problems. Rotating drums could work at a commercial price point. The IBM 650 (1953) was IBM's first real business computer, with drum main memory and all-electronic computation. Knuth's first book is dedicated to the IBM 650.
This side of computing gets less attention in histories, which tend to focus on the military machines. But this was the side that shipped in volume and made real money. It came from the engineers with relays and clutches in Endicott and the accountants at Armonk, who had to develop something IBM Sales could sell to large and medium sized businesses. No need for Turing, von Neumann, etc.
The IBM 1401 (1959) ended the 600 line. At last, all-transistor, all core memory, in a reliable box that could be deployed to customer sites. It's a very strange machine, with variable-length everything, but it works well. Then, of course came the IBM System/360, which standardized architecture for decades to come.
Nice summary! For anyone interested in these systems, the book "IBM's Early Computers" provides a detailed history.
They were all programmed with plugboards.
Arguably, that is the ROM.
Arguably more like soft wired CPU logic, since the contents of the plugboards were not uniformly addressable words.
My favorite part was a footnote: Footnote 2 specifically. I'd always wondered how plugboards worked and the footnote and the linked pdf gave me some sort of idea.
Author here for your vacuum tube questions...
No vacuum tube questions.
Fantastic deep dive as always, thanks for doing such stellar work!
On that note, any chance we might get a teardown/history of Cray architectures in the future? Specifically the Cray-1 and 2?
To throw a more serious challenge your way: How about a write-up on the original Frank Rosenblatt Perceptron? I know finding an original Mark-1 part would be close to impossible but it blows my mind that they were successfully doing real-time visual classification in 1957 with an electro-mechanical machine (potentiometers and motors) using a 20x20 "video" feed with some learning algorithm that was not based on backprop.
Roughly how many varieties of module were used for a full 604 system?
I suspect quite a few as other "modular" systems in the transistor era like the later IBM Standard Modular System and DEC Flip-Chips ended up with plethora of specialised modules, but I'd be interested if that growth had already begun in the tube era.
I don't have the information for the 604, but the 605 used about 36 different types of tube modules. IBM couldn't resist making different types of modules; the 650 had sixteen types of cathode followers alone.
Have you ever run into that method (discrete module+components) in non-IBM configurations? What abut non-computing configs? I've never seen it before.
Philbrick op amp K2-W was an analog circuit with two dual-triode tubes on top of circuitry, with an octal plug at the bottom. I have one with data sheet but have never fired it up.
Univac had similar single-tube modules (but without the handle), as well as multiple-tube modules. See this video: https://www.youtube.com/watch?v=NVbjXHR6WAY The BRLESC computer used printed-circuit boards that had components and a single tube (parallel to the surface). I have a Burroughs module with 8 tubes.
I powered up the module independently, powering a light bulb, so it's a non-computing configuration. (I'm not sure if that's what you're asking.)
I haven't seen a tube deployment like that before - where the tube is combined with it's supporting components into one module - and that module plugs into a tube socket.
It's clever. It should reduce time for some repairs.
> 1948 was an interesting time for computing.
Not a commonly seen statement :-)
No questions, but I really enjoyed the article - thank you for sharing. It amazes me how few vacuum tubes these early computers use, compared to the billions and trillions of mosfet transistors used in modern devices.
The Gamma 3, which competed with the 604, only had about 400 tubes as far as I remember: https://en.wikipedia.org/wiki/Bull_Gamma_3
Both the 604 and the G3 were bit serial to save components.
One way they get away with using relatively few tubes is that most of the Boolean logic is done with semiconductor (germanium) diodes, using tubes to amplify the results.
The 604 isn't really a "computer", but more like an ALU hardwired to some I/O.