MZ-80B project (Floppy Disk I/O Card cloning!)

[psmart]

SFD800 - 1.png (438.63 KiB) Viewed 11229 times

115.5mm x 95mm x (edge connector facing towards you, 34mm x 57mm x 24mm).

You can still buy all the ICs, the 74HCT are an ideal replacement, the WD-1773 can be found on ebay, ie. https://www.ebay.co.uk/itm/362668881645 ... SwnDRcXYEn - be wary of IC's from China, I've had my share of remanufactured duds (or more to the point, completely different IC's rebranded with the code your expecting!!). The PAL can be found here, https://www.ebay.co.uk/itm/383594580439 ... SwSTFe6lWG. It shouldnt be too difficult to work out the PAL fuse map as the inputs and outputs are known, just need to connect up a parallel port to the inputs and step through noting the outputs to recreate the boolean equations, you could probably even guess them as it is simple decoding.

One thing to note on the design is the missing Schottky drivers. I say this as I have had issues with the SFD800 and a Lotharek HxC Floppy Emulator due to a long (~1m) ribbon cable, a shorter cable gave me no issues. Without the schottky drivers you may find similar issues with signal reflection and degradation (but you may be able to compensate inside the FPGA as it makes it a lot more flexible).

ps) The Chimay is needed, it lubricates the electrons

[arnuphis]

Going to build one of these as soon as I can. Built A Mockingboard and Ram Express for my Apple II so this will be cake.

[psmart]

Yep, should be as it is quite simple, especially compared to the Sharp disk interfaces. The Sharp devices use a lesser WD Floppy Disk controller and therefore need the data separators and filters etc. Hopefully the boards will arrive next week.

[dat-alex]

good morning . This was exactly the same board tha inspired me of a more simpe 80B FD Controller card (as you can see in previous posts) -going one step further trying to implement digital logic in CPLD for a simpler board. (still in progress).

The only thing to try is if it working with 80b but I cannot see why not as the registers mapping , status register e.t.c are the same.

One thing to note on the design is the missing Schottky drivers. I say this as I have had issues with the SFD800 and a Lotharek HxC Floppy Emulator due to a long (~1m) ribbon cable, a shorter cable gave me no issues. Without the schottky drivers you may find similar issues with signal reflection and degradation (but you may be able to compensate inside the FPGA as it makes it a lot more flexible).

You are right my friend.I left Schotttky in order to test & minimize components hopping to use short cable. (we will test & see)

Good luck with the project and I think we are in a good direction.