Author: Harald Faber
Date: 22:33:59 10/03/99
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On October 03, 1999 at 12:08:01, Ratko V Tomic wrote: >> 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. Can you give me a hint how to do this? >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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