The IBM Tree and Tube computers

Bob Bradlee caveguy at
Sun Feb 4 11:21:55 CST 2007

Sorry somehow the opening paragraph to this got lost at sea :-(

Well you get the idea, of where I was going even with the rough intro......


On Sun, 04 Feb 2007 12:11:19 -0500, Bob Bradlee wrote:

>The 701(1952) -> 702 (1953) -> 705-1 (1954) -> 705-II(1957) and ending with the transistorized  1401
>and 701 (1952) -> SAGE, NORC, 704(1954) -> 709(1957) and ending with the transistorized 7090
>and 701 (1952) -> 650(1953) and ending with the transistorized 7070(1958)
>with the 305-RAMAC(1956) appearing by magic during the time between the 650(1953) and second 
>generation 705 (1957). I think the computer in question was a tube computer produced in the gap 
>between the first 705(1954) and the later release in 1957 a period in time where Core memory 
>development was in full swing.

>We were deep in the cold war at the time and a lot of mis-direction was being employed, I have always 
>thought there was a tube based system that evolved between the 650 and the transistorized 7070.

>It would not shock me in the least if this missing TUBE system was not refered to as a 7070 by its 
>users, as one of those little cold war mis-directions Cuz-Ike's boys were so fond of, long before the 
>"Real" 7070 was released in its transistorized form.

>The 305 RAMAC in 1956 and along with the 705 and 709 in 1957 the 305 is considered to be the last 
>tube computers produced.

>So when On Sat, 3 Feb 2007 21:09:10 -0600, Jim Isbell, W5JAI wrote:

>>You see the 7070 that I worked on was purchased by the US government for a
>>very Top Secret installation so it may have been in use before the public
>>had access to it.  Which, by the way, may also be why it was NOT solid
>>state, it was an early model ??  

>And questions started to roll around in my head so I looked back....
>On Fri, 2 Feb 2007 15:41:07 -0600, Jim Isbell, W5JAI wrote:

>>No, it was a 7070, "IBM seven oh seventy", and it used hundreds if not
>>thousands of 12au7s or 12ax7s don't remember which it was.  And it was
>>definitely NOT solid state.  The first solid state addition to it was a
>>memory matrix unit that used germanium or silicon junctions in a plane of
>>12x12 giving 144 bits of permanent memory sitting behind a plastic window so
>>we could look at it and marvel at the wonders of science ( I dont think it
>>was really permanent memory as I seem to remember it required a voltage
>>input to keep it from fading) .  It was a frame about 12 inches square and
>>looked like a course window screen with small dots of junction at every
>>intersection of the wires. 

>Until we can better identify this mystery system I will call it an 707x  and assume it is the
>missing IBM model 707 from sometime between the 705(1954) and the 709(1957) most likely about the 
>time of the 305(1956).

>On Fri, 2 Feb 2007 15:41:07 -0600, Jim Isbell, W5JAI wrote:
>>This was in 1959 and 1960

>My first question is:
>Was 1959/1960 when it was installed or when you worked on it ?

>My second question is: Were the tubes in 10 pin "Fingers" like the 650 or in 8 tube plugins like the 705 

>And my last questions relate to who, what and where, these questions can be answered of list, if you 
>do not wish to shout it out here in an open forum :-) I understand that much if not most of what we 
>could not talk about in the 60's is public knowledge but that does not keep one from thinking twice even 

>Got to run ...

>Bob Bradlee


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