[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [N8VEM-S100:5541] SCC and Z80/8086 monitor

Hi Rich --

>> For the serial configuration, P60 and P62, I followed the jumpers for a
>> 3-wire configuration. Following the same convention of 1…8
>> (left-to-right), 0-1-0-1-1-0-0-1 (1=jumper, 0=none). The cable to the PC
>> is configured as NULL, with Rx<->Tx and CTS<->RTS (5-wires total,
>> including GND). The instructions on S100computers directly jumpers CTS and
>> RTS at the connector, leaving only three wires to the host device.

Interesting! [Forgive me, but I often find serial connections one of the most vexing problems with setting up a system. I never know the right thing to do! So, maybe what follows is all wrong?]

The way I see the P60 P62 header is: (hope this comes out OK)

                P60                            P62
| 2 (DCD) 4 (Tx) 6 (Gnd) 8 (RTS) | 2 (Rx) 4 (DCD) 6 (Gnd) 8 (RTS) |
|               cable            |            chip                |
|                                |                                |
|                chip            |           cable                |
| 1 (DTR) 3 (Tx) 5 (Gnd) 7 (CTS) | 1 (Rx) 4 (DTR) 5 (DSR) 8 (CTS) |

So, with your jumper settings, you are hooking Tx straight through and the same with Rx (which is fine if Tx and Rx are crossed with your NULL cable). Same goes for CTS and RTS? But, if it is just a 5-wire cable, there is nothing coming to DTR and DCD for the 85c30? And, I don't see that you've got Gnd. Shouldn't there be a jumper at position 3 (using that same position notation) to provide for common Gnd? So, does DTR/DCD matter to the SCC? I don't know.