Early circa 1970s high power 8-pin ballistic type print head, made in the USA by Wang Laboratories. It is unusual in that it uses solenoids to drive pins directly into the media, thus the ballistic designation. The pins would strike a ribbon which in turn would impart ink onto paper. This design, popularized by Digital Equipment Corporation in 1970, replaced the teletype which was basically a motorized typewriter. It marks an important milestone in computer output technology since dot matrix printing evolved into laser and inkjet printers, which use dots to make up characters.
This is a very early hand-assembled, 8-pin version where piano wires were directly pushed by a solenoid through copper tubing guides and a jewel. High power means that the pins could directly strike a ribbon and impart images through 5-part tractor fed paper. Later non-ballistic versions used leverage to fire the pins accomplishing the same task with much smaller coils. This example was not a field replaceable unit, meaning that each individual component like solenoids, print pins, and the jewel had to be replaced in the field by an engineer. This was at a time when computer technicians were engineers. On top of possessing engineering skills, a certain level of craftsmanship was needed to work on this equipment since every pin in the matrix had to be individually replaced and adjusted upon failure. If a pin jammed in the jewel and snagged a ribbon, it would mean a service call by a skilled engineer, unlike nowadays where a consumable print-head could be installed in a matter of seconds and the old one disposed of in the trash. This unit required monthly preventative maintenance which included removing the black dust cover, cleaning, adjusting or replacing the individual pins and lubricating the felt pad behind the jewel with sewing machine oil.
This print-head is new old stock in the original box and is in fine condition. It measures 4 1/2″ long by 3″ wide by 2 3/4″ high. It weighs a considerable amount for a print-head at 10.4 ounces. A more modern matrix print-head weighs less than an ounce for comparative purposes. The main body was designed and cast by future-thinking engineers so that it could eventually support 9 pins instead of 8. This would allow the next generation of printers to perform the underscore function. A solenoid is not missing, indicated by the jewel which only has 8 holes.
Although its original purpose was not an art form, savvy retro computer collectors consider these to be beautiful sculptures! It would display handsomely in any collection or computer museum.
Terms and abbreviations used in our descriptions.