NEC Silentwriter 2 Model 90 doesn't print with OS/2 Warp

World         Australia | Europe | North America | Singapore
Europe        Austria | Birmingham | Budapest | France | Italy | London | TeamOS/2 (Germany)
North America Berkeley | Chattanooga | Minnesota | Nova Scotia | Ontario | Pennsylvania | TeamOS/2

Last update: 6th November, 1995

Symptoms

Printer does not print.

Hardware

NEC Silentwriter 2 model 90

Problem

OS/2 is not recognising rising ACK when BUSY line is high.

Procedure

Contact author for details of hardware fix.

Notes

Earlier this week I was trying to get my NEC silentwriter2 model 90 to function. Looking at the signals I found some interesting information about them. The printer was connected to LPT1.

OS/2 was sending out the first charecter of the file repeatedly (it turns out to be a % sign which is a remark in postscript). The signal timing for the printer was as follows: strobe signal pulsed low for 10 uS and busy went high. ack signal fell about 20uS later Busy went low about 5uS after that ack went high 5uS later and then the cycle repeated

This was slightly different from the star NX10 printer that does work with OS/2. The signal timing is as follows: Strobe pulsed low for 10uS and busy went high wait for a few uS Ack pulsed low for 10uS wait for a few uS busy went low

The only difference between the two is that the busy falling edge leads the rizing edge of the ack signal. By only allowing the busy signal to fall after the rizing edge of the ACK signal the problem was corrected and the printer functions. If you are interested in the hardware fix I can send it to you.

It looks to me as if OS2 is waiting for the RIZING edge of the ACK signal to indicate the information is recieved. Since it does not see this before the printer reads "not busy", OS2 assumes the information was not recieved and sends the same charecter again.

Alan J. Bayko