Floppy Drive Interface
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Floppy Drive Interface (from ZX-Team schematics)

The floppy drive interface was a PCB I designed after having built the PCB for the floppy drive interface as provided by the ZX-Team, it was kindly sent to me by mail by Kai Fischer. In itself, the PCB is great quality, and it works perfectly, nothing wrong with it at all. However I did decide to make the PCB layout for a few reasons:

- proving the schematic for later use in combined projects

- making a more component/board space and placement efficient design.

- including the full backplane connector on the PCB rather than only a partial soldering into the PCB while other pins needed to be manually wired in

Some of these reasons are not absolutely necessary or urgent, but they are a nice bonus to doing this project anyway. The project is a single sided PCB which is easily built at home by someone with sufficient skills, basic electronics knowledge of parts and soldering, patience and accuracy.

Project's prototype status is completed.

Please note a few things before requesting the design:

- pin connections of this expansion match the ZX-Team backplane connection scheme, however this backplane is not perse necessary if the floppy drive interface is the only interface you want to use. In that case you can also solder the two boards together with wiring or pin strips in some fashion rather than building a backplane.

- the ZX-Team buffer/poke board is necessary in order to operate this expansion (PCB Designs available for this board, also designed by me) on any ZX81.

- the buffer/poke board can be connected directly to the euro-ZX81 and ZX97 Lite because of pin-compatibility, however it needs some pinout conversion to be plugged into the Micro-ZX81 or ZX81 Issue 4. The idea for these latter two ZX81 designs is to include some combined expansion boards in a similar design level at a later stage, however, they can be connected if the builder converts the signals to the proper pins in some way. This is not a terribly difficult job at all. The reason for a different pinout of the expansion busses is simply based on PCB-space efficiency which was necessary for the type of project.

- operating the Floppy dos requires a few steps: poke 8,1 activates the floppy drive dos into the ZX81 memory map, while rand usr 16384 will call the DOS program into operation. Poke 8,0 switches the floppy dos out of the ZX81 memory map again.