Quick links: PIC-based Model-102 printer emulator
New - Version 2 (Updated 11/18/2008) — Click on each thumbnail to view full-size image.
This hardware emulator converts the printer interface signals that come from the calculator hardware into ASCII characters output over the PIC's serial port (configured by default to drive an external RS-232 level shifter). This interface can be used to drive a serial LCD display, PC running a terminal emulator, etc. The emulator also provides the calculator firmware running on the 4004 with the all-important "heartbeat" sync pulses. Without the proper timing pulses, the calculator won't work at all!
I built the exerciser to test the emulator. This was necessary because my own hardware replica wasn't quite working yet (and then Bill "scooped me" :-). The exerciser runs on a separate PIC connectected to the emulator PIC. It generates all the signals that the calculator would send to the printer, and responds to the index pulses. I extracted the test data by running calculator examples on an instrumented 4004/Busicom simulator written in Java.
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