Hi Al,
Thanks for the suggestion. Yes, I should have said that the cable has been checked and another cable tested with the same results.
In addition to the three wires that carry the transmit data, the receive data and the data signal ground, the 25 pin connector that plugs into the IP-1 is also wired with some shorting wires (pins 5,6 and 21 are connected together). I think this tell the Fuji what type of computer is connected to the IP-1 because the wiring for the 25 pin connector for the MCS30 computer is different as is the F4G PC (we have neither of those, just the connector wiring diagrams).
I think that the RS232 input buffer might have failed and the IP-1 is not able to figure our what computer system is connected to it, hence the OS ERROR (Operating System Error?), but I'm not sure. There are no Fuji techs in New Zealand to my knowledge and the ones in Australia do not handle this old a machine.
I tried cutting the connection between pins 5 and 6 on the 25 pin connector and left the shorting wire between pin 6 and 21 and the IP-1 boots normally but under this situation the MCS16/F does not communicate sucessfully with the IP-1 and the MCS16/F reports a communications error. I don't really know what I'm doing but will try anything that seems safe.
Unless anyone else can offer a suggestion as a last resort I'm going to try to replace the RS232 signal buffer chip. This means unsoldering the MC145406 16 pin dip chip from the multilayer VME CPU board.
Regards,
Bert
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