Calculator CPU information: MDP1220C

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Motorola? MDP1220C Calculator IC

ID:	MPD1220C	Used in:	Toshiba BC-1287
Type:	Calculator IC, 12+1 digit, switched constant, %, add-on (discount), square root, overflow recovery, sum of individual products/quotients, (switched) sum of individual totals and differences, mark-up/down, four function memory, switched floating/fixed modes, rounding modes.
Maker:	Motorola?
Typical date range:	Early 1980s
Package:	36 pin DIL (aka USA DIP) black plastic
Date coding system:	TBD
Notes:	Designed for desktop financial calculators, drives VFD direct

		Pin-outs and near example circuitry is shown for your information. Please note - this is a back view. Pins D1-D13: display grid drivers SA-SG and SDP: display segments and keyboard matrix K0-K4: keyboard matrix MIIL, MIL: memory indicators CH, AC, CG: look like on-board oscillator ER, MIIS: unknown Voltages are given for this example respective to GND VDD -9V VCC -29V
		Notes: Lacks input overflow suppression but has overflow recovery Interesting that the segment controls rather than the grid controls are used for part of the keyboard matrix. This creates the need for 17 diodes in the matrix. Second on-board memory is not used in the above circuit.