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Additional Pictures 

 

Close-up view of the TMC0272 single-chip calculator circuit used with the Spelling B (1st Gen).
PMOS Technology, 40-pin DIP 4-bit Microcontroller, 2,048*9 Bits Instruction ROM, 144*4 Bits Data RAM.

Die Photo of the TMC0272 courtesy of Sean Riddle.

Die Photo (after acid) of the TMC0272 courtesy of Sean Riddle.

Close-up view of the TMC0274 single-chip calculator circuit used with the Spelling B (2nd Gen).
PMOS Technology, 40-pin DIP 4-bit Microcontroller, 2,048*9 Bits Instruction ROM, 144*4 Bits Data RAM.

Die Photo of the TMC0274 courtesy of Sean Riddle.

Die Photo (after acid) of the TMC0274 courtesy of Sean Riddle.


If you have additions to the above article please email: joerg@datamath.org.

Joerg Woerner, April 30, 2021. No reprints without written permission.