[tyingq]

I didn't do the math, but not many. Here's the 74XX ICs from the BOM list with short descriptions of what they are:

  74HC74  Dual D Flip-Flop
  74HC161 4-bit binary counter
  74HC541 Octal Buffer 
  74HC574 Octal 3−State Noninverting D Flip−Flop
  74HC14  Hex Schmitt−Trigger Inverter
  74HC08  Quad 2-input AND gate
  74HC02  Quad 2-input NAND gate
  74HC273 Octal D-type flip-flop with reset
  74HC138 3-to-8 line decoder/demultiplexer
  74HC139 Dual 2-to-4 line decoder

Though it's not straightforward to map microcode lookup through an EPROM into "gates".