Front panel
Encyclopedia : F : FR : FRO : Front panel
A front panel was used on early electronic computers to display and allow the alteration of the state of the machine's internal registers and memory. The front panel usually consisted of arrays of indicator lamps, toggle switches, and push buttons mounted on a sheet metal face plate. In early machines, an oscilloscope might also be used.
A operator would stand at the front panel to bootstrap the computer, to debug running programs and find hardware faults. Typically, the operator would read from a scrap of paper containing a short series of bootstrap instructions that would be hand-entered using the toggle switches. First, the operator would set the "address" switch, and enter the address in binary using the switches. Then the operator would set the "value" switch, and then enter the value intended for that address. After punching in a dozen or so of these instructions (Most computers had a "deposit next" button, which would deposit subsequent values in subsequent addresses, relieving the operator of needing to toggle in addresses), the operator would then press the "run" switch, which would execute the program. Often, the bootstrap would turn on the punched tape reader, which would load a somewhat longer program complicated enough to load the operating system from disk.
For fun, bored programmers would create program to display animated light shows on the LED lights. Front panels in the late 60s and early 70s were quite brightly colored. When bootstrap ROMs enabled computers to start themselves without operator intervention in the late 1970s and early 1980s, most computers were built without a front switch panel. High powered calculators such as the HP 9830 based on ROM were among the first computers to do away with front panels, or operators.
Operating systems made for computers with blinkenlights would frequently have an idle task blink lights in some recognizable fashion.
Huge banks of "blinkenlights" and "blowenfuzen" were featured on TV and movies as the popular image of the "computer" during the 1950s to 1970s.
From Wikipedia, the Free Encyclopedia. Original article here. Support Wikipedia by contributing or donating.
All text is available under the terms of the GNU Free Documentation License See Wikipedia Copyrights for details.