32bit Windows Serial Port Bug, Results for Windows 2000 & XP

This is a subsidiary page to 32bit Windows Serial Port Bug.

Chris Rowland has kindly run the test program on a Windows 2000 system but his results are a litte suspect as the system had previously been used to run a substitute for the MSCOMM driver (from Sax Comm). This may or may not have mucked with the lower level drivers in Windows. However, Martin Harnois reports the same results for both Windows 2000 and XP indicating that the Sax Comm driver is not implicated and that XP works the same way.

Chris' results were:

Rx buffer size set to 500.
XoffLim set to 50.
Should give 450 character space on all systems.
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CTS signal seen low after 4046 characters sent.
XoffLim set to 100.
Should give 400 character space on all systems.
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CTS signal seen low after 3996 characters sent.
Rx buffer size set to 450.
Should give 350 character space but may leave it at 400 on some systems.
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CTS signal seen low after 3996 characters sent.
Rx buffer size set to 300.
Should give 200 character space but may overrun the buffer on some systems.
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CTS signal seen low after 3996 characters sent.

In other words, it appears that Windows 2000 behaves the same as Windows NT except that the buffer size is fixed at 4096 bytes rather than 1024.