On Mon, 28 May 2001, William Levak wrote: > On Mon, 28 May 2001, [ISO-8859-1] Marko Mäkelä wrote: > > > I didn't know that the RS-232 interface of the plus/4 user port was > > pin-compatible with the software-emulated interface on the C64 and VIC-20 > > user ports, but it sounds plausible. > > There is one pin different. The Commodore modems have a jumper to disable > this one line. I cannot find the documentation right now. I'll look for > it and give you more information when I find it. Let me clarify this. There is one pin different for the serial interface part of the user port. The parallel interface part has several differences. I havn't found the documentation, but I took apart the modem and it is pin "H" that has the jumper. This is "Carrier Detect In" on the serial cartridge. The signal on that pin on the Plus/4 is incompatible, at least for the modem. As far as I remember, it is necessary to open this jumper on the modem in order to avoid damaging the modem when using it on the Plus/4. Unfortunately, I did not find this out until after I tried the modem on the Plus/4, and I now have a modem without carrier detect. - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail cbm-hackers-request@dot.tml.hut.fi.
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