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Intel 8042 KBC

1984

Intel microcontroller used as the PC/AT keyboard controller, also handling the A20 gate and system reset.

Reference & documentation

External technical references for programming Intel 8042 KBC and for writing emulators.

ResourceTypeNotes
Intel UPI-41AH/42AH Universal Peripheral Interface Datasheet ↗DatasheetOfficial 8042/8742 electrical and timing datasheet
MCS-48 and UPI-41 Assembly Language Reference Manual (Intel) ↗Instruction setOfficial Intel opcode and instruction-set reference
Intel UPI-41AH/42AH Datasheet (pin descriptions) ↗Pinout40-pin package pinout and signal descriptions
I8042 PS/2 Controller - OSDev Wiki ↗ProgrammingController commands, ports, init and driver flow
The Keyboard Controller Interface 0x60/0x64 - basicinputoutput ↗ProgrammingModern deep-dive on 8042 register interface
MCS-48 and UPI-41 Assembly Language Manual (programming) ↗ProgrammingAssembler directives and programming model
Halicery/8042 - IBM keyboard controller ROM dumps ↗ROMsIBM AT/PS2 8042 ROM dumps and disassembly
8042 Commands and Status (Port 64h) - HelpPC ↗ReferenceConcise port 64h command and status-bit table
Halicery/8042 - Commented IBM 8042/8048 ROM disassemblies ↗SourceAnnotated IBM AT and PS/2 8042 firmware disassembly
IBM PC/AT 8042 Internal Operation (pcjs) ↗SourceReverse-engineered 2KB AT 8042 ROM internals
MAME MCS-48/UPI-41 CPU core (mcs48.cpp) ↗SourceCycle-accurate 8042/UPI-41 emulation implementation