NCR Class 445 Sterling Computronic


The Sterling Compu-Tronic


One of the most sophisticated  accounting machines of the National range was released to the selling force in  Great Britain on June 1, 1960.

The Sterling Compu-Tronic was an entirely new account­ing machine. It had all the features of the Class 31, and it used transistorized circuits to perform multiplications in £.s.d. It was the first accounting machine ever to be capable of such calculation at electronic speeds.

The electronic equipment is housed in a cabinet on the left of the operating console.


What did it do?

Multiplication in sterling had always been a major headache in accounting work. It utilises a dispro­portionate amount of time and staff and can give rise to many errors. For example, a typical invoicing routine goes like this:

(a) The customer's order is evaluated, a calculating machine being use for this purpose. (The calculating machine operation is performed twice in order to check the accuracy of the work.)

(b) Discounts, purchase tax, etc., are calculated. Again the calculation must be done a second time, preferably by a different clerk, to check on accuracy.

(c) The invoice set is then typed.

(d) The typed invoice is checked for correct copying.

The Sterling Compu-Tronic, by its electronic calcu­lation feature, could complete all these separate steps in one operations sequence. Since all the multiplications and additions are performed by machine, the possibility of error is eliminated and checking is reduced to a minimum.

The operating console, though basically similar to the Class 31, had a number of additional keys with which the operation of the electronic multiplication unit could be controlled manually.

Of particular interest is the row of keys on the extreme right of the keyboard. Beneath these keys were situated fifteen small printed circuit boards, which were known as 'Factormats.' These enabled the Sterling Compu-Tronic to carry out calculations entirely automatically. For example, if ten per cent discount is

allowed on the total of an invoice, the machine can automatically select one of these Factormats which will then instruct the electronic unit to calculate the required percentage.

Besides this use for discount percentages, the Factor-mats could be used for Purchase Tax rates, bonus per­centages on payrolls, interest rates on savings accounts and many other similar jobs.

Often, the percentage or rate to be used may be variable. One customer may receive ten per cent discount, and the next five per cent. It is for this reason that the row of keys is provided, so that when a variable rate is required, the operator can select the appropriate key instead of the machine making the selection automatically. Although there are fifteen Factormats (which, by the way, can be changed very easily by the operator to suit the various different jobs the machine may be handling) only nine of them can be selected by key. The other six are for automatic selection only.

Like the Class 31, the Sterling Compu-Tronic had a 26 inch wide platen, which could be split into two parts so that two sets of documents could be prepared side-by-side. A programme bar controlled the movement of this carriage, the use of the ten registers and many other functions.

The Compu-Tronic was a 'wired machine' and could, therefore, be linked to a punched paper tape recorder, or to a card punch.

This new addition to the range heralded a new generation of accounting machines. It combined mechanical and electronic principles to offer customers a compact, economical accounting unit which could perform, at high speed, tasks which would otherwise demand several separate clerks using several separate types of machine.



Computronic Gallery.