MT15 is a (mostly) transistorised CPU.
"Mostly" means, that 74xx chips are used in three places:
74LS164/74LS27 is used to generate the 4_phase_clock,
instruction decoder outputs are buffered with four 74HCT245,
and another four 74HCT245 work as buffer for the 16 Bit
address and data bus.
Everything else (Registers, Flags, ALU, instruction decoder etc.)
was built with BC847/BC857 low_frequency_transistors,
running with a 2.5 Volt supply.
