Vintage Calculator Semiconductors

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Casio 103-MR

Make and number:	Hitachi HD3692
Package:	40 pin DIL, 0.6” width, black plastic
Known date codes:	5F42 (June 1975)
Known date of fabrication:	1975
Calculators:	Casio 103-MR, Casio 102-MR
Secondary ICs:	1 x HD3233P 6B43 16 pin DIL, 0.3" width black plastic (February 1976)
Power supply:	6.0V
Display capability:	10 digit + 0
Basic Functions:	Four standard plus CE, C
Constant:	Double hit operator on multiply and divide only
Advanced functions:	Percentages, square root Switch fixed decimal point (6/4/3/2/1/0) Switch for floating, cut or round
Scientific functions:	None
Memory:	Three function memory (MR) (M+) (M-) No indication of storage Memory overflow clears the memory
Overflow states:	Input overflow is suppressed Overflow shows “E” in first digit only Zero divisor shows “E” in first digit only
Overflow recovery:	None
Negative sign:	Immediate left digit shows “-“, nine digit negative numbers only
Bugs:	Negative root gives negative number, tbd
Comments:	Looks to have been designed with financial desktop calculators in mind with the fixed decimals and rounding options. Quite poor logic with no recovery, memory loss on overflow and limitation of nine digit negative numbers (even though my example calculator had an 11-digit display!). As common with early ICs, this one needed lots of extra components to aid it including an extra IC.