Bull Series 300

The Series 300 was a set of new  punched cards equipment introduced by Compagnie des Machines Bull around 1960 (FCS in 1961). The goal was to upgrade the Series 150 while keeping an unchanged philosophy. It was expected also that the optional addition of magnetic tape, while maintaing the organization of the punched cards workshops, would allow a graceful transition to the computer centric philosophy that was considered too costly (more in terms of programmers talents even that in hardware).

The speed of electromechanical devices was doubled (from Series 150) at 300 cards per minute and 300 lpm for printers. The 300 cpm card punch represented a world record that has not been exceeded later. Mechanically, those devices have also been used in Gamma 60 (and Gamma 30) and sold as OEM to several competitors. Their derivatives have been manufactured in Belfort plant until the mid 1970s.

In fact, from the system point of view, the goal of Series 300 was to integrate and to automate the operation of a card punched workshop of 2 to 6 unit record (card reader, card punch or printer) devices,  surrounded by calculators or electronic calculators (with optional magnetic drum). To that card-oriented system, the series 300  added an optional tape-subsystem the Multiselector.

Series 300 was using a mix of little relay electromechanical technology and electronics (in Gamma 300, Multiselector, Central memory and magnetic storage devices). Programming was through connection boards.

Remark: an attempt has been made to translate concepts from a a marketing pamphlet written in 1960 French language into a more modern English while staying close from the concepts of that time. Revisions can be expected.

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The program-Unit is a control unit for the unit-record (card) version of Series 300.

The "Unité-Programme" (program-unit) was responsible for interconnecting the unit record units and the "Mémoire centrale de transit" (central memory). It also included connection boards, registers buffers and comparators and performed the control of the devices. A workshop could include two interconnected program-units.
A program-unit could have up to 5 ports (a central memory took 2 ports and program-unit interconnection 1 port), the rest being used for unit-record devices.

A configuration with a card reader-(punch) and a printer around one program-unit covered the function of a tabulator (and its associated card-punch).

Electric Calculator

The basic tabulator functions could be improved through the addition of an electric calculator. operating at 300 cycles/minute. It performed arithmetic operations (add, subtract, multiply, divide) on several operands defined among 48 to 120 decimal positions. Add and Subtract were performed in one cycle. Cumulated results were also able to be cheched during the computing cycle.

Card reader-punch

The device includes two hoppers (main and secondary) and two stackers. It allowed the collation cards from the two sources in the main stacker. A one-cycle interval was available for computation between the read and the punch station of the main track. The majority of card operation could be done at the maximum rate of 300 cards per minute.


Operating at 300 lpm, it was based on a drum printer of 120 positions with 60 characters (upper case alphabetics, numerals and 24 special). The number of hammers was 80 or 120 applied to up to two paper feeding mechanisms (operating synchronously or asynchronously).

Mémoire centrale de Transit (MCT)
MCT is literally Central Memory for Data Exchange but is actually the Buffered Control Unit for the "electronic Series 300"

More than a memory controller, this Memory unit was the core of the electronic version of Series 300TI. It allowed the interconnection of the electromechanical devices (through the program-unit) and the electronic components (drum, computer and tape multiselector). The program-unit could access 12 words (containing 12 digits or 6 characters each) for  input in MCT and 16 words as output from MCT. That interconnection used two ports on the program-unit.

To connect to the electronic devices, the MCT used a buffer memory of 64 words of 12 digits.

MCT included its own programs (a connection board) to synchronize the electronic computer Gamma 300, the Multiselector and the unit-record program unit.

Electronic Computer Gamma 300

The Gamma 300 is the successor of the Gamma 3. It has its own program (cabled in a connection board or in registers from the drum). It performed an add on 12 digits in approximately 1 millisecond and a multiply or dovide in 6 ms. The Gamma 300 operates on 7 registers of 12 digits.

Magnetic Drum 300

The drum has a capacity of 14648 words of 12 digits accessible by word or by a set of consecutive words. It is buffered through MCT, so the Gamma 300 did not need to be synchronized with the drum.


The multiselector is a third type of control unit that extended the Series 300 to operate on magnetic tape . The maximum number of tape drives was 8.

The multiselector allowed the autonomous operation of tape-based applications or a joint operation of tapes with unit-records..

Its functions were:
--recording data from card to tape
-- reading and writing data from  tape
-- sorting data records on tapes
-- collating data from tape to tape
-- copying files
-- selection of records



The series 300 was in no respect a commercial success. The tape version (Multiselector) was very expensive and suffered from technical problems. In fact, at the time of its introduction, stored programs and programming languages were becoming the industry rule and the majority of large punched card shops were ordering classic computers (1401 and following soon, Bull introduced Gamma 30. For customers determined to stay on traditional punched cards, Bull had to reduce the price of the Series 150 and decreased the incentive to switch to Series 300.


Revision :19 févr. 2002