Posted Thu Jun 23, 2011 10:18 PM
top left photo: probably to program a 27128 as an 8k (2764) chip, as the prices of 2764's and 27128's were very close, so many would just buy the 27128's and use half or make a selectable switch between two choices (i.e. BASIC Rev A and Rev C)
top right photo: i would guess to clone a 8k or 16k cart, plug a cart in the top, and it would save the data from it to floppy, even to another EPROM in the ZIF socket
bottom left photo: this is the most interesting, as the small chip (TL497ACN), shows this isnt just an EPROM reader, but a writer too, what that chip does is take the 5v's from the A8, and multiplies it to ~30V (turns low voltage high current, into high voltage low current, as programming EPROMs require either 12V, 21V, or 25V to program, with the latter two being common in 2716 and 2732 devices). the other chip is an Intel 8255, this is somewhat similar to the 6520 already in your atari or a 6522 (and 'upgraded' 6520), but was originally designed for the Intel 8086 series of chips (yeah the line of CPU's that comes right up to the PC on your desk!), and it is the second part that shows this is a EPROM writer in addition to reader... this is the chip the controls the timing of the pulses that program the EPROMs, it is probly uncommon a 8255 is used on a 65xx based system as a 6522 would be capable of doing the job also, but the designer probably was familiar with the intel products, so chose it, as the cost differences were probably nominal...
bottom right photo: thats an Atari 800 main board on the left, and all the relevent points on the cart have been covered :')
also in the bottom left pic, the board on the bottom looks like an analog board for the 810 disk drive (goes on top of the floppy mech), and down on the bottom left of the same pic, thats a CPU board for the Atari 800, goes in the last slot of the 800...
sloopy.