Hi Jonathan,
JDBP>  I suspect that it's as simple as unbuffered UARTs. Remember that OS/2 
is
JDBP>  a multitasking operating system, where a program does not have 
exclusive
JDBP>  use of the CPU at all times.  The problem that you have encountered 
s,
JDBP>  essentially, that LapLink is receiving a corrupted data stream over a
JDBP>  serial device.
Unless you set COM_DIRECT_ACCESS in the setting notebook the DOS session
will emulate 16450s to the program. Tested on my system with 16550
present using COM.SYS, with default COM_DIRECT_ACCESS off LapLink 4.0a
reports a 16450 and fails self test, if I set COM_DIRECT_ACCESS on it
reports a 16550A and tests OK.
When I was with Richard recently we tried to use LapLink on one of his
machines with SIO installed with no success, so I suspect SIO may
provide some problems if installed. Just a minute...
I've just swapped to SIO, and indeed LapLink can't determine the UART
type and fails self test with it installed.
JDBP>  This is easily explained if you happen to have a 16450, or other
JDBP>  unbuffered UART, for your serial hardware.  On DOS, LapLink just sits 
in
JDBP>  a dedicated loop waiting for characters.  However, OS/2 is 
multitasking,
JDBP>  and it is possible for a second character to be received by the UART
JDBP>  before its predecessor has been read from the 1-character UART receive
JDBP>  buffer, because OS/2 may be doing something else at the time that the
JDBP>  character receive interrupt occurs.  This results in character loss, 
and
JDBP>  protocol errors in programs such as LapLink.
My experience of using LapLink is that it requires the serial interrupt
and uses it, so I don't believe this criticism is valid and in my
experience is not a problem.
JDBP>  A buffered UART, such as a 16550, has an 8-character receive buffer, 
o
JDBP>  RX buffer overruns like the above are much less likely on multitasking
JDBP>  operating systems.
Agreed.
JDBP>  The solution if this is the case ?  Fix your hardware.
Should not be needed. I've run LapLink under OS/2 using 16450 UARTS
sucessfully in the past.
George
 * SLMR 2.1a * Desk: A very large wastebasket with drawers.
--- Maximus/2 3.01
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