The single sided boards are alot easier to produce than double sided boards, at least in my opinion.

With double sided boards, I have to expose, develop and etch both sides, AND align both sides up properly.

I almost got my design compatible with a single sided board. I just have to figure out how to reduce the number of chips required without changing the microprocessor or ram.

What I am ultimately achieving out of this is a simple 8052 processor unit with a built-in programmer.

This is how my programmer works.

Code is sent in from the PC to the onboard parallel port. Then in programming mode, when PSEN goes from low to high, it activates a flip flop that freezes the clock, This will send a signal to the PC indicating that data can be accepted. Then the port must send and hold data until the next time PSEN goes high.

The reason why I am waiting it for the rising edge is because I want to make sure the data being fed in is the same during the time PSEN is low.

In simple terms, I am using a parallel port that emulates the EEPROM, and that functions at any address. That way, I can have the 8051 process code, directly from the parallel port if I wanted it to.

Why that? so that I can write data to the EEPROM, and I won't have to rearrange or remove anything.

In the past, I made two circuits. One circuit programs the chip and addresses it with counters. The other circuit is the 8051 SBC with a socket where I insert the chip to use it. The huge drawback is that I had to use 2 circuits, and constantly hook up and remove power. IOW, too much work.

so now I want to make everything into one central system.