PDF datasheet for the Atmel AT89C1051, the smallest member of the 20-pin 8051-compatible family, offering 1 KB of flash, 64 bytes of RAM and an analog comparator. The document typically covers pin functions, limited peripheral set, power-down modes, electrical ratings and the parallel programming steps. Repair technicians use it on simple timers and controllers to check supply, crystal and reset. Writing requires a device programmer, and the firmware must be backed up or obtained separately because lock bits may prevent readout.
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