C70:info-cpm (06/03/82)
>From W8SDZ@Mit-Mc Thu Jun 3 13:37:24 1982
The following is forwarded from my RCPM system:
A FIX (AND SOME COMMENTS) FOR BYE V7.9
AS IT APPEARS IN CP-MIG XACCESS
1. Baud Rate Divisors
Every recent version of BYE that I've noticed on various RCPM'S and
here in CP-MIG has included equates for the WD8250 UART. When I
got my copy, it didn't work, so I did a bit of detective work, and
the main thing I found was that the equates for the baud rate divisors
are all wrong. I looked them up in the back of the H89 operations manual,
changed them to the correct values, and got a working BYE program.
The correct values appear below:
;******************BAUD RATE DIVISORS*********************
;
BR300LS EQU 080H ;300 BAUD
BR300MS EQU 001H
BR450LS EQU 000H ;450 BAUD
BR450MS EQU 001H
BR600LS EQU 0C0H ;600 BAUD
BR600MS EQU 000H
BR120LS EQU 060H ;1200 BAUD
BR120MS EQU 000H
Note: While these values are correct from the book, and I am sure
of the 300 baud setting from testing, values above 450 haven't been
tested as I don't have a modem that will go that fast.
In addition, there is a problem with 450 baud that I haven't been able
to locate: some characters (maybe 1 in 100 or so) are garbled. I am sure
it's not the modem as I can normally operate at 450 baud with no problem.
If anybody else has the same problem and figures out what's wrong, I
would appreciate hearing about it.
By the way, for anybody who hasn't tried it, most modems (I have used
the UDS 103, Hayes Smartmodem, and Radio Shack Modem II) which are not
supposed to operate above 300 baud work just fine at 450. You have to
be able to set your UART to this baud rate, however, which is not pos-
sible for some, but which is easy with the 8250.
2. Carrier Detection
The value given below for P2CTS (Clear to Send) is actually the mask
for RLSD (Received Line Signal Detect), but this normally doesn't matter
if your modem supplies this signal.
If you don't have an auto answer modem, however, BYE can be made to
work manually (you have to turn on the modem) by changing this value
to 10H, which is the actual mask for CTS, or alternately, commenting
out the areas in BYE where carrier checks are made. I used the first
method for a while with a UDS 103 modem (manual answer), which doesn't
supply the RLSD signal.
;****************MODEM STATUS MASKS***********************
;
P2DSR EQU 20H ;DATA SET READY
P2CTS EQU 080H ;CARRIER DETECT
P2RDET EQU 040H ;RING DETECT
3. Hayes Smartmodem
It seems to me that a lot of the conditional equates for the Hayes
Smartmodem in the version here are a bit superfluous. I have used
the BYE program with 2 H89's and an H8 (8250 UARTS), all with
Smartmodems. The conditionals were set for WD8250 and NORING
(on a BYE version without Smartmodem equates), and it worked fine.
I haven't tested this version, and it may work fine too, but there
is an implication that special port assignments and modem status
masks, etc., are required for the Smartmodem. As far as the UART
is concerned, the Smartmodem is just another external modem, and
the way BYE handles the modem in the HANGUP routine (turn DTR/RTS
off and back on) is sufficient for the Smartmodem. Make sure, though
that the modem is set not to echo characters and result codes to
the local console. If a result code is sent when the modem answers,
the BYE program will determine the baud rate from that and start
sending the HOW MANY NULLS? question immediately, making it impos-
sible to set the baud rate to match the incoming call.
Good luck!
-- Skip Gilbrech 71445,534