On 01/10/19 18:52, Francesco Messineo wrote: > On Thu, Jan 10, 2019 at 5:33 PM Pasi 'A1bert' Ojala <a1bert@iki.fi> wrote: >> On 10.01.2019 17:22, smf wrote: >>> On 10/01/2019 08:11, André Fachat wrote: >>>> I know this solution, but IIRC this prevents bidirectional operation >>>> without extra direction control. >>> Don't the c128 & 1571 have extra hardware for direction control on the >>> 6526 ? >> http://www.iki.fi/a1bert/Dev/burst (already mentioned earlier, but this >> is the "forever link"): >> >> "The C128 hardware includes a buffer driver between SRQ and the cassette >> read line so that cassette activity or cassette drive presence will not >> disturb the fast serial port. It also has a two-directional buffer that >> connects SRQ and DATA to the CIA1 synchronous serial port. The direction >> is controlled by the MMU chip. These buffers are required to hide the >> fast serial connection is C64 mode." > I can't find this bidirectional buffer in the C128 schematic > (zimmers). Wrong schematic? http://www.zimmers.net/anonftp/pub/cbm/schematics/computers/c128/310378-3-left.gif See CIA1 SP and CNT, U58 and U60. From my article: "Theoretically you should be able to make the modification work with C128 in both modes by first connecting the wires and then cutting/bending up U58 (74LS03) pins 3 and 8, and U60 (7407) pins 6 and 8. This disables the C128 fast serial hardware and the added wires will perform their function in C128 and C64 modes. I have not tested this, so if you try it, I would be very interested in your results." > > Frank >Received on 2019-01-10 21:03:11
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