Remove HCT buffers for the CPU

[apoloval]

For curiosity, I checked the [Z80 datasheet][1] to verify if it is actually affected by the CMOS voltage levels and we really need to use buffers of the HCT-family to operate.

This is what I've found:

As it accepts VIH of 2.2V, the inputs can be driven from TTL circuits. So voltage level adapters are not really needed.

We have to verify the designs of 100 and 200 series and check whether these HCT components can be removed.