Ahhh, I love the smell of solder flux in the morning ...
The PIC Programmer:
PICs are versatile little microcontrollers. You can find out all about them at theMicroChip Web site. The first thing you need is a means to program them. Luckily the manufacturers supply an IDE free on their site which I found to be excellent. You also need a way to get the programs you have written into the chip. There are zillions of programmer circuits on the Web. The one that I plumped for was designed by Michael Covington. It comes with software and I have had no trouble with it at all.
The Periodic Error Compensator:
My LX10 telescope didn't track siderial motion very accurately. Unfortunately this limited me to CCD exposures of about 10-15 seconds. This is inadequate for most deep sky objects. It is also a nightmare trying to focus.
The compensator is a simple recording device that stores the drive corrections I make over an 8 minute sample (the period of the worm gear in the 'scope) and then plays back the corrections repeatedly.
It contains two 16F84 PIC microcontrollers. The first decodes the membrane keypad (not ideal for working in the dark) and the second manages an 8k static RAM chip which holds the samples. Cascaded ripple counters generate the address lines for the RAM. The data comes from the first PIC or from an optional external source souch as an autoguider. The telescope is controlled by four relays.
Using PICs reduces the amount of logic chips required and makes the whole thing more versatile and flexible.