IBM 705 Console & Components

The museum has a control console from a IBM 705 computer. I believe this to be very rare item since the 705 was first shipped in late 1954 and was withdrawn in early 1960. That's a long time ago and there can't have been many shipped during that short period (but I haven't found credible numbers for the total shipped). Also, the 705 was quite expensive: about $590,000 in 1954 dollars.

(Note that on our console the original IBM 705 banner has been replaced with a customer's banner ("Confederation Life"). Since computers were so rare in the 1950's they were usually proudly displayed in a "glass house" by their users, often with the user's name on them.)

The IBM 705 architecture was heavily optimized for business applications such as billing, payroll, accounts receivable, and inventory control, as opposed to computationally intensive applications. In early computers, hardware was so expensive and limited in capability that the each computer was specifically designed for certain types of applications, with a common differentiator being character handling vs. arithmetic computation. In the 1950's IBM introduced several 700-series computer starting with the pioneering IBM 701. The IBM 702, IBM 705 were optimized for business applications, while the IBM 704 and IBM 709 were optimized for engineering and scientific applications. Shown on the left is a pre-System/360 "family tree" drawing from IBM of its early computers which illustrates the various model and their introduction dates. This application optimization continued through later transistorized descendants of these 1950-era computers (such as the IBM 7080 which was the follow-on to the 705) until the introduction in 1964 of the IBM System/360 family, which had a "general purpose" architecture. Even after that, low-end IBM computers such as the IBM 1130, System/3, System/32, and System/38 were optimized for specific applications. And, process-control applications were addressed by the specialized IBM 1800, IBM System/7, and IBM Series/1 families.

The IBM 705 used vacuum tubes (about 1,700 of them) for its logic and used magnetic core memory for storage. Its instruction-set architecture was heavily optimized for business applications. Of special note is the fact that memory was organized into 7-bit "characters" and the two accumulators (corresponding to current processor registers) each contained 256 characters. The memory size was either 20,000 or 40,000 characters. A load from memory into the accumulator took about 17 microseconds. The main input and output was magnetic tape (5M characters per reel), but a card reader and punch as well as a printer could be directly attached.

In addition to the control console, we also have some electronic components and original documentaion (some probably rare) for the IBM 705. We have several of the pluggable processor logic elements as shown on both sides along with an ad for the IBM 701 showing the same type of pluggable unit. Also shown is our stack of more than 25 original IBM documents about the 705 including the introductory volume of the Customer Engineer (CE) internal documentation. This document describes the details of the logic elements and memory components.

New arrivals 12/2012

One of the most important peripheral I/O devices in a IBM 705 system was the IBM 767 Data Synchronizer. Figure 14 show a picture of the 767 from the IBM 705 Reference manual. The Data Synchronizer was the forerunner of what later became IBM's System/360 "Data Channels". It attached up to 10 IBM 729 tape Drives and allowed overlapping reads and writes across these devices to and from the main memory of the IBM 705. In today's terms it was a "multiplexed buffered DMA (Direct Memory Access) controller".

The museum contains a IBM 767 control panel, as shown in Figures 15, 16, and 17. Note that the front panel has a large bus connector on it.

Figures 18 through 21 show two other control panels that I am sure come from pre-System/360 IBM equipment, but I have not been able to identify them yet.