TG43 signal and the Nec 765

Hi Guys, I'm using a relatively modern 1/2 height 8" drive for my PC interface, which does not seem to care about TG43 - I left it unconnected, and it appears to be writing images just fine. It would however seem to be a good idea to support it for older drives and drives that need it... Question: According to the NEC 765 datasheets, pin 38 is LC/DIR, it indicates "Low Current" (TG43) during writes to inner tracks, and "direction" during STEP operations. It would seem that you might be able to simply stuff this signal into both pins 34 (Direction) and 2 (TG43) of the 8" interface, since the drive should not care about DIRECTION when STEP is not active, and it should not care about TG43 when WRITE is not active, and the two operations are mutually exclusive. However none of the information and cable diagrams I've seen indicate such a connection, suggesting that this might not work. Q: Can you simply drive both signals from the one source, or do TG43 and STEP need to be externally demultiplexed? As an alternative, I think I will also provide an option to generate TG43 via a parallel port output. Q: Should TG43 be asserted any time the drive is positioned to a cylinder >43, or should it be asserted only during WRITE operations when at a cylinder >43? Regards, Dave -- dave04a (at) Dave Dunfield dunfield (dot) Firmware development services & tools: www.dunfield.com com Collector of vintage computing equipment: http://www.parse.com/~ddunfield/museum/index.html