Making com ports work on DELL: for info 
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 Making com ports work on DELL: for info

I posted a request for assistance on this newsgroup a while ago, received a
few suggestions (thanks) but none of them as it turns out, on the ball. The
question was why assembler code accessing UARTs using direct access I/O,
which runs correctly on several other machines, consistently failed to work
on Dell machines. I now have the answer, here it is in case anyone else
incurs the same problem and would like assistance:

The Dell opsys sets bit 10H, the Modem Loopback bit, in the modem control
register, 03FB for COM1:. In order to make things work as normal, clear
this
bit as part of the UART setup. It appears to get set back on as soon as the
program relinquishes control back to the exec.


remove ecks and kyoo to email



Tue, 31 May 2005 02:25:39 GMT  
 
 [ 1 post ] 

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