You'd have a hard time trying to source many of the parts in this project today...

The main processor is a Zilog Z8671 Single-Chip BASIC Interpreter.  This is a Z8 processor with an implementation of BASIC in its internal ROM.

Phone line interface is a Cermetek CH1810 Direct Connect Protective Hybrid (DCPH).  This was an FCC-certified telephone interface from back in the day when you had to tell the phone company every piece of equipment that you plugged into your phone line (and its Ringer Equivalence).  Of course, I was connecting to a private PBX so that really wasn't a concern, but this greatly simplified the phone line interfacing.

The Teltone M956 provides DTMF tone decoding, allowing the caller to enter the passcode.  A FIFO (74S225) provides buffering of entered tones, in case the code is so slow that it might miss a digit.

A 76489 sound chip provides audible feedback to the caller - a dial tone when it answers the call, and a gunshot sound when it resets the target machine.

Random logic is implemented by a PAL10L8, which was new and cool at the time.  Memory address space decoding is done with a 74S288 PROM.

The passcode is stored in an EEPROM, which was also new and cool at the time this was built.