X-ray wrote:
@ PaSha
But what I don't understand is if we have these PCBs why can't I just plug in any old PC drive? And if I took the PCB out, would I then have a machine that behaves exactly like an A4000D...would the floppy header be the same?
Yes, you can plug in any old PC drive, and this drive will operate as a 880 kB DD Amiga floppy. It will not, however, read 1760 kB HD Amiga disks, because it doesn't slow down to half speed like a 'real' Amiga HD floppy drive (Chinon FB-357A/FZ-357A, that's what the 'A' is there for).
The reason for Escom using this hack, was to save time and money. It would simply take too much time and money to have someone produce special/custom Amiga FD's (like C= did)compared to hacking standard PC-drives to fit.
Since the A4KT was designed by good old C=, the floppy header is a proper Amiga one. Remove the small adapter PCB, and you have one 100% normal Amiga floppy header (that behaves exactly like in a A4000D), on which you can stick any Amiga FD, in fact, two of them, provided you make the cable correctly (swap pin 4 with 6('In use 1' and In use 0' and pin 10 with 12('select 0' and 'select '), jumper both drives as DS0, ie don't touch the jumpers) for DF1:, and set J250 to the right position.
OFF: No second internal floppy or second floppy (DF1:) is High Density 1.76MB
ON: Second internal floppy (DF1:) is Double Density (880K)
Most A4000Ds were shipped with a floppy cable that had pins 3&5 swapped instead of pins 4&6. And since 3&5 are both GND, it didn't really make a difference...
http://wonkity.com/~wblock/a4000hard/inflpins.htmlFrom
http://wonkity.com/~wblock/a4000hard/flcbprob.htmlMany (perhaps most) A4000s were shipped with improperly-wired floppy cables. These cables had wires 3-5 twisted, instead of wires 4-6. These cables will work fine for a single drive, but will not properly connect a second drive. To use two drives that are both jumpered as DS0, the floppy cable should have both wires 4-6 and 10-12 twisted. A cable with only wires 4-6 twisted will require the drives to be jumpered as DS0 and DS1.
-Paul
Edit:
The differences between Amiga and PC FDs:
Pins 2 & 34 are swapped, 'Ready' and 'Diskchange'
The 'Diskchange' signal is not used on PCs, and the 'Ready' signal is used differently. Just try reading from an empty FD on PC... The drive will start spinning and making noises, before Windows realizes it's probably empty.
Whereas on the Amiga, the diskchange signal informs WB of the inserted disk and it pops up on WB. Try accessing an empty drive, and WB already knows it's empty.
(The above might not be 100% accurate, but this is the basic idea)
