I thought I'd do a picture heavy thread showing how I fitted the high density floppy mod as supplied by the esteemed forum user 'ralcool'
it's a tidy piece of kit and the instructions he supplies can even be followed by an electronics thickie like me supplied in my kit were:
1x board with header pins
1x TOS ROM chipped patched to allow 3ms step rate
8x header pin ends
1x useful instructions containing photos
ralcool suggested that I use a 6 chip TOS FM for the mod, so thats what I grabbed from my pile of Ataris.
Lets begin:
First up, open the Atari and remove all the shielding. Then locate the floppy chip and cut the right pin:
Then solder a wire to the pin, this is where the 8/16 clk signal is:
The mod needs 5v - this is taken from pin 40 of the video shifter:
Next up is the 16mhz signal from pin 39 of the video shifter:
DS1 signal is taken from pin 19 of the soundchip:
lastly for the motherboard, a GND is needed, pin 20 of the video shifter can be used (not a good pic)
you also need a HD detect signal and a HDD0 signal, both from the floppy, this sony drive couln't supply a stable HD detect annoyingly:
so this compaq/nec unit was used instead:
as is the case with most modern drives, it didn't have a drive select jumper, but did have a little solder pad thet i bridged:
finally, solder all the 'ends' to the wires and attach to the board:
now is a good time to check it all works, using the AUTO folder prog supplied:
if all is well, install the patched ROM:
the result should be the handy ability to boot using HD disks
the mod handles all the switching too, so you can carry on using the DD disks and HD disks at the same time, no need for switches or reboots.
huge thanks to ralcool for making this kit and giving me help fitting it, despite an 11 hour time difference
hope you all enjoyed this thread, I had fun installing the kit and it'll make life a bit easier
note to the more experienced electrickery types, yes, I did shorten all the wires once I knew it all worked, it's a lot tidier now and secured with the magic glue gun 
