Author: Ratko V Tomic
Date: 09:08:01 10/03/99
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> Right now I think there are 2 possibilities what causes the programs play > strange with auto232: > 1) DOS program > 2) Nimzo7.32 autoplayer which would let me suspect that the other CB > products produce the same behaviour, Fritz5, Junior5, Nimzo99 and > Hiarcs7.32. But it will take time to find this out. There is also possibility that your serial port (UART) is one of those which occasionally get in a mode where they continuosly generate transmit interrupt (indicating that transmit buffer is redy to transmit). Normally this interrupt is one shot i.e. it kicks in when the transmit buffer on the chip becomes empty so that a COM program can feed another byte. Over years I had run into some chips which keep reissuing this interrupt at the baud rate of the port. If the program uses extended memory via some protected mode DOS extender, the severity of the interrupt overhead increases dramatically over the plain real mode DOS. By setting the baud rate to a very slow one (e.g. 300 baud, that's plenty for sporadic few byte packets in an autoplay) and comparing the Rebel's nps, you could test whether this was the problem. In any case, good or bad serial chip, a positive correlation of baud rate and decrease in nps would indicate excessive or otherwise faulty serial port activity. Another issue is whether Rebel is communicating with the driver supplied, or whether the communication somehow fails (from the start or at some point) and the driver reverts to a brute-force scan of video memory which could slow things down quite a bit. Are there somewhere the specs for programs communicating with the auto232 DOS drivers? (The Gambitsoft free file auto232p.zip has only the specs for windows programs.)
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