Everex EV-170B card with 16550A's
Mark W. Snitily
mark at zok.UUCP
Mon Aug 21 16:16:25 AEST 1989
The following is a somewhat long note about a nice three port serial I/O
card and a question about RS-232 pin orderings.
With the recent info on how to fix uucico throughput with 16550A's, I went
shopping for a new serial I/O card that would allow me to replace *all* of
the 16450 UART chips with 16550A chips. (Typically serial I/O cards have
one 16450 (or equivalent) soldered in place and have one socket for an
additional UART for COM2.)
What I came across was the Everex EV-170B card. Nice. Typical inexpensive
I/O card; has parallel port, game port, but has *three* serial ports. Each
serial port's UART is socketed and each serial port allows the selection of
independent interrupt vectors and I/O addresses. In other words, this
card *is not* like the typical DOS configuration of forcing COM1/COM2 to
share the same interrupt vectors with COM3/COM4.
So, if you have an unused interrupt vector (either 5 or 9) then you can
configure Unix (386/ix 2.0.1 in my case) to have *three* serial lines.
And, if you're using a device driver that supports the 16550A, *all* three
lines can enjoy the super throughput that the 16550A provides.
So far, all nice and grand -- now for the real reason why I'm writing this.
To make what could be a *real* long story short, IMHO the pins on the card
that connect to the RS-232C cables are really ordered *weird*.
RS-232C J Connector Pins on Card
--------------------- ------------------------
9-pin 25-pin Signal Normal Everex EV-170B
1 8 DCD 1 (8) 1 (8)
2 3 RX 2 (3) 3 (2)
3 2 TX 3 (2) 5 (7)
4 20 DTR 4 (20) 7 (4)
5 7 GND 5 (7) 9 (22)
6 6 DSR 6 (6) 2 (3)
7 4 RST 7 (4) 4 (20)
8 5 CTS 8 (5) 6 (6)
9 22 RI 9 (22) 8 (5)
For example, on the card the J connector pin number 5 normally connects
to pin number 5 on the 9-pin RS-232, (or pin number 7 on the 25-pin
RS-232). But on the EV-170B, the J connector pin number 5 needs to
connect to pin number 9 on the 9-pin RS-232, (or pin number 22 on the
25-pin RS-232).
[The above mapping was obtained only after: exchanging the card once
thinking it was defective -- no difference; calling Everex tech support --
it was configured correctly according to them; buying a RS-232 breakout
box -- that's something I've avoided for over a decade; and finally
tracing the lines on the PC card -- it now works!]
If anyone from Everex is reading this, may I suggest that you please
add the pin's signals to your manual. There's no hint that buying a
standard cable (from someone other than Everex) won't work.
Has anyone ever seen the pin ordering that's on this card? Is it
*weird*, or is it yet another standard used by some vendors?
-- Mark W. Snitily
894 Brookgrove Lane
Cupertino, CA 05014
(408) 252-0456 (voice with answering machine)
...!{amdcad,ardent,athertn,claris,daisy,limbo,mips,sgi,voder}!zok!mark
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