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Cherry B80-08AC

B80-08AC is an unusual Cherry M5 keyboard. It contains both secretarial shift and at least pne M4 corner-illuminated switch. All switches are 10° angled and consequently have white plungers. The space bar, illuminated and secretarial shift keys are straight (–) stem while the remainder are T stem. The top right switch is Style A; the others cannot be conclusively determined from the photos but are a later design that appears to be Style B; that would suggest that the top-right key is a special type. Left shift has a dummy key for a stabiliser, with a black plunger.

The Cherry serial number is 919299 and the customer part number is 495306036-001. Encoding is performed by a National Semiconductor MOS/LSI encoder, part MM5740FDL/N, a variant of the MM5740. A single 1980 chip gives us an estimated year of manufacture as 1980.

There is a speaker attached to the unit.

The photos below were provided by UncleFan.

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Top
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Right side; note the Style A switch
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Top, right side
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Cherry branding on the PCB
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National Semiconductor MM5740FDL/N encoder, made in 1979
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Logic chips (1979 and 1980)
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Logic chips (1976 and 1979)
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M4 switch
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Secretarial shift
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Space bar switch with customary red dot
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Bottom of PCB
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PCB markings, including artwork code/part number 001-1051 REV B
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Plate stamp of customer part number