Description
Powers-Samas machines detected the holes in punched cards mechanically, unlike IBM equipment where holes in punched cards are detected by electrical circuits. Pins that could drop through round holes in punched cards were connected to linkages and their displacement when a hole was present actuated other parts of the machine to produce the desired results. Setting up a machine involved building a suitable network of linkages. According to one user, this:was achieved by locating above the reading block, in contact with the tops of the matrix pins, a removable Y-shaped 'connection box' (equivalent to the Hollerith plug board) which was hard-wired to the job. The box had at the base as many rods as were needed to read the positions within the used data fields, so that, when forced down, appropriate features of the machine - printheads, counters or control links were physically set as a reaction to the moving tops of the connecting box rods. Thus while many connection wires were straight-through, some sensed holes needed to allow multiple actuation, while some multiple code-punching needed to be combined to achieve a single purpose. Designing the system, including setting up the tabulator, was the sales engineers job, while soldering the 'conn-box' forest of cranked rods to meet the design requirement was down to the skill of the Powers Engineer who was thus the doyen of the machine room.email from Robin Hill, Norrk?ping, Sweden, 2005, to the computermuseum.org.ukPowers-Samas used a variety of card sizes and formats, including 21, 36, 40, 45, 65 and 130 column cards. The 40-column card, measuring 4.35 by 2 inches, was the most common.
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Notes
Further reading
* *{{cite book , author= Cemach, Harry P. , title= The Elements of Punched Card Accounting , publisher= Pitman , year= 1951 Defunct manufacturing companies of the United Kingdom International Computers Limited Unit record equipment British companies established in 1915 British companies disestablished in 1959