The following is the text of an IBM press technical fact sheet dated July 20, 1955.

650 Technical data sheet

Important additional devices, including magnetic tape input-output, high-speed magnetic core storage, and printer input-output, for the IBM 650 Magnetic Drum Data Processing Machine increase the power and versatility of the 650 system and will open many new areas for its application. The 650 will now be available either with a tape system and printer output or with its regular card input and output to effect further advances in office automation.

Magnetic Tape System

The IBM 727 Magnetic Tape Unit, coupled with the 653 High-Speed Storage Unit, will provide rapid-fire data entry and exit for the 650. The tapes used with the 650 are compatible with the IBM 700-series electronic data processing machines.

The information on tape for input or output with the 650 is recorded as a fixed record length of 100 characters subdivided into 10 words of 10 digits, each with its own sign. If alphabetic characters are used, there can be up to five characters to a word, with a maximum of nine words per record. The average storage capacity for a tape reel is approximately 23,000 records, each with 100 characters plus 10 signs.

Other operational characteristics of the 650 tape system are the same as those of the 702 and 705 systems. Interchangeable for either reading or writing, the 727 tape unit operates at the rate of 15,000 characters a second. The density of recording is 200 characters per inch, permitting permanent files of data to be compressed onto a 10 ½ inch diameter reel holding 2,400 feet of the oxide-coated plastic tape. The tapes rewind at an average speed of 500 inches a second.

Records to be placed on tape should be prearranged in the desired sequence for processing. If tapes are prepared on an IBM 704 for use on a 650, they must be in the 702 code.

The 652 Tape Control Unit for the 650 tape system will handle up to four tape units in any combination of input and output. Only one 652 may be specified for each 650.

The ability to handle alphabetic and special character information is incorporated in the tape system, permitting the use of all alphabetic characters and the special characters available with the IBM 407 Accounting Machine in a tape record. Alphabetic data from tape cannot be directed to any other type output unit unless that unit has an alphabetic device.

Besides providing automatic tape input and output for 650 customers, the 650 magnetic tape system will provide many other advantages. With the high-speed storage unit, it will provide greater capacity and input-output speeds. In addition, the use of tapes will increase the scope of stored program techniques by offering greater flexibility in programming, input, and output, and will substantially reduce the space requirements for record files.

High-Speed Magnetic Core Storage

The IBM 653 High-Speed Storage Unit is an integral part of the 650 magnetic tape system, but can also be used independently to effect an increase in 650 operating speed. The 653 has a dual purpose in the 650 system -- providing temporary storage for either input data from the tape or output data to the tape, or serving as 60 words of high-speed direct access storage for the 650 when information is not being transferred between the 653 and tape. Not only does the 653 provide increased storage capacity, it also permits greater programming flexibility.

It has a capacity of 660 positions divided into 60 words, each with 10 digits and a sign, and may contain either instructions or data, The new unit will handle tape records in variable lengths, from a minimum of one word to a maximum of 60 words. A single instruction can block transfer one to 10 words or one to 50 words of 653 storage either to or from the 650 magnetic drum, or each word can be addressed individually. Magnetic cores -- tiny, doughnut-shaped objects that can "remember" information indefinitely, and recall it in a few millionths of a second -- make up the internal storage of the 653.

Printer input-output

The IBM 407 Accounting Machine can now be adapted for direct coupling to the 650 as an output printer. In addition, the 407 will be able to introduce information into the 650 system.

Heretofore, the 407 has been used with the 650 but it has been necessary to remove punched cards from the 650 and transfer them by hand to the input of the 407. The direct cable connection of these two machines eliminates this and other time-consuming steps.

The 407 may be used with or without the 650's regular punched card input-output unit. If both are attached to the 650, complete flexibility is provided between the two. When cards are read by the regular card read, the information is processed through the 650 and can be printed by the 407. The 650 output goes to the 407 control panel where it may be rearranged as desired by control panel wiring. The 407 can also read data, pass it to the 650 for calculation, and print it or store the results, or do both. This provides a collating type operation between the feeds of the 407 and the regular card read.

The maximum speed of the 407 is 150 cards a minute, but when attached to the 650 as input, output, or both, its speed depends upon the complexity of the operation performed. Many functions normally associated with the standard 407 Accounting Machine, such as comparison, program control, print control, and summary punching, can be performed when the machine is attached to the 650. When disconnected from the 650, the 407 may be used as an independent accounting machine.

The 650 thus becomes a more flexible "electronic assistant" than ever. The input and output facilities of the 407 as well as those now used with the 650 will be available to the 650's magnetic drum "memory" and computing unit. With a summary punch connected to the 407 - - one usually is - - the improved 650 system will have two punched card inputs, two punched card outputs, and a printer output, all operating under the direction of the 650 stored program. All five of the new 650's input and output facilities may be used during a processing operation, opening many new data processing possibilities.

Another new feature will allow the 650 to use - - in addition to letters and numbers - - special codings such as the dollar sign, ampersand, and pound symbol. The 407 already can use these codings and print the characters.