Well I also attempted building a punched card reader (interfaced to the same PIO) as the university I studied at had a mainframe with punchcards and I had written some Pascal code there which I would have loved to transfer to the Speccy.
Unfortunately I never got it to work reliably - probably the DC brush motor I used for transporting the cards produced just too incoherent movement, or perhaps the photo diodes caught too much ambient 50Hz noise from flourescent lights. Anyway I gave up, re-typed my most important Pascal programs and compensated my frustration by extending Hisoft Pascal, which just displayed numeric error codes on the ZX Spectrum, with actual on-screen text messages. Ha!
