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.