Will overclocking 8085 Microprocessor reduce the number of clock cycles

Question

I'm studying about 8085 microprocessor and found that it works on 3 Mhz and takes for instance 4 clock cycles for opcode fetch, 3 clock cycles for IO/M read or write.

So now, If I somehow overclock 8085 to work at 10 Mhz then will the number of clock cycles get reduced ?
Or the number of cycles will remain same but the effective time for 3 or 4 complete cycles will get reduced ?

Answer 1

Overclocking reduces the length of a cycle. Instructions still take the same number of cycles.

The clock cycle is a heart beat that is used to synchronise actions across a circuit. Different parts act simultaneously, passing data at appropriate moments based on the clock. For example, a four-cycle instruction for a fictional architecture might be performed as:

1. load accumulator with value of register while issuing memory read cycle;
2. add low four bits of fetched value to accumulator;
3. add high four bits of fetched value to accumulator;
4. move value from accumulator back to register.

You can't cut a cycle from that without changing the architecture somewhere — simply providing a faster clock can't make the ALU suddenly work in 8-bit quantities and, even if it did, the register to which its final value goes wouldn't expect to receive a value earlier than the fourth cycle.

Simply changing the clock rate doesn't change the layout or overriding logic of the circuit so it can't change the number of cycles it takes different parts to do things or the relative times at which they expect other parts to have things done.