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A Publication Featuring The Information Services Technology of Maine State Government
|Volume IV, Issue 6||June 2001|
By Phil McSweeney, IBM Systems Services Representative (SSR)
This idea for this article started with a message left on my home answering machine. The caller inquired if I was the person who worked for IBM, and, if so, to return his call if I knew of a system that had a card reader still attached. A card reader??? Afraid not! I contacted coworkers in Massachusetts, and they suggested the cards be sent to Florida where they have experience reading punched cards. That call brought back memories of the way data processing worked 35-40 years ago - although use of the punched card goes back to the late 1800s when Hollerith's punch card tabulating equipment was first used in the 1890 U.S. Census.
During the early 1960s, at Maine State government, and in businesses, most data was transferred from input sheets to punched cards (80 columns of data). Most businesses had a room of keypunch and verifier machines. The keypunch operators would input the data to cards, and the verifier operators would verify the data was correct. (Do you remember the old data processing saying "Garbage In Garbage Out"?) Machines that sensed the holes with wire brushes read the cards. These brushes made contact with a contact roll, and through an assortment of circuit breakers and relays, could then decipher the holes and the character each hole represented.
Drowning in punch cards at the Bureau of Accounts and Control, circa 1974.
There was an assortment of machines, each with its specific function, in these special equipment rooms. The sorter would sort columns to put cards in order. The collator merged two stacks of cards. An interpreter would interpret the data and print it on the card in fields so humans could read it. But the whole system came back to a piece of card stock subject to handling, humidity, and usage. A damaged card meant it had to be recreated.
Most customers I worked with had a system that consisted of a central processing unit (CPU) with 8k of memory, a card reader/punch and a printer and a tape drive or two. The punched card input could contain the program that would tell the system what to do with the data, or could be the data itself. Cards were kept in trays or drawers stored in file cabinets throughout the building. Imagine the problems generated if a tray was dropped! In this event, we had to start over with sorting, etc. The cards would be read and data handled according to its program - going to print or tape. Most systems at that time were strictly batch type jobs; there were no online systems.
As time went on, the systems and the applications grew. Systems had consoles attached into which data or commands were entered, and system operation monitored. The keypunch and punch cards gave way to directly attached data entry stations, and the punch cards were slowly phased out. The early tape drives performance was measured in bits per inch - 100, 200, 556 and 800. The cartridge drive, introduced in 1984, had 38,000 bits per inch! Magnetic core memory grew as did the speed of access. Monolithic memory and metal oxide semiconductors eventually replaced magnetic core memory. The 8k memory grew to megabit chips.
Over time, systems had disk drives attached. The early disk drives operated via hydraulic access controlled by electronics. Access to data time was measured in fractions of seconds. Today, new "servo" drives access data in milliseconds.
Early printing equipment used gears with letters on the outside edges. These gears were moved by a rack depending on the data to be printed. Later, printers used a chain of attached segments, which spun in a cartridge to make impressions on paper. The chain gave way to a train cartridge, which used individual type slugs on a track to print. Opposite the train were hammers that would impact the character when it was at the print position at the time needed.
A print train type printer used in the Central Computer Services Operations machine room (now Bureau of Information Services Production Services data facility) in 1974. Rick Irish says this photo is of lottery tickets being printed.
The impact printers kept getting faster in both the speed of the chain/train as well as the speed of the paper passing through the machine. Early printers moved paper by hydraulics and later by servomotors. All this changed with the introduction of laser non-impact printers in 1975. Speed went from 3,600 lines per minute on the fastest impact printers, to 20,000 lines per minute with the laser printers.
Stand back and think about the computer systems we routinely use today, and remember the little piece of card stock that was the center point of data processing four decades ago.
Phil McSweeney has been the IBM Systems Services Representative (SSR) assigned to the State of Maine account for the past twenty-two years. He has seen much technology evolve over time!