Make a retro scientific calculator with LED display and mechanical keypad.

[EdS2]

Aha - looks like quite a few manufacturers used that chip (Edit: but these are programmable, which is confusing me):

Quote:Used in: ASTOR: 2, ATABA: AT687, AURORA: TB607, CANON: F300, CITIES: 8700, CITIZEN: SRP145, CITIZEN: SRP40, DYNA-TONE: G3/8700, IBICO: 098, INTERTRONIC: SC88P, KNIGHT: K31A, MBO: 610PR (version-1), MBO: 820PR, PIRACOMP: PR40, PIRACOMP: PR80, PRIVILEG: LC650PR, RADIO SHACK: EC4021, RADIO SHACK: EC4036, WHIRLPOOL: CW201

Also apparently Levis and Shangji.

Edit: is it the 42-key SHARP EL-506P we need? I see there was a 506A and 506H too, with different number of keys.

If so, there's a list of 20 clones here.

Edit: this is confusing!

Quote:With the replicas of the chip used in EL-506P, the first „clones” was built in similar housing as used in EL-506H, at various factories in Hong Kong, Taiwan and China. Later, with similar appearance and same model number, a simple programmable calculators based on a genuine Sharp chip — which was made for Sanyo — completed.