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1986-06-29
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111 lines
Application Notes
for
Mercury 1200
(a.k.a. FHR 1200)
Intelligent Modem
and
NUBYE or IMP
by
Roger Warren
(San Diego, CA.)
Introduction
The MERCURY 1200 is a cheapie HAYES clone which is supplied with
minimal documentation. The information supplied here is the results
of some experimentation in the application of the MERCURY, and is
intended to help those who are trying to use this modem with NUBYE
or IMP.
Hardware Notes
1) VERY IMPORTANT!! The nomenclature on the case of some of the
MERCURY modems is INCORRECT, and NOT ALL are supplied with an
errata sheet! From the rear of the device, the connections
and switches ARE (from left to right): POWER, LINE, PHONE, RS-
TTL switch, DCE-DTE switch. The incorrect case markings
transpose the RS-TTL and DCE-DTE switch!
2) SW4- Internal DIP switch:
Position 2 is called HCD and is documented as follows:
In the OFF position (default) Carrier Detect operates
independent of the DTR input. In the ON position Carrier
detect is held off until DTR is presented.
Experimentation has yielded the following information:
With position 2 in the OFF (default) position. DTR has NO
effect on MODEM operation. The modem escape sequence (if
online) followed by the ATH command MUST be used to hang up
the phone! With position 2 in the ON position. DTR can be
used to hang up the phone and hold off answer. However,
with this setting the modem will dial, but will not
originate a carrier under IMP.
The author has made the following mod to his modem:
SW4 position 2 is left open and a separate switch has been
run external to the case and attached in parallel to DIP
switch. I've labelled this ANS/ORIG. In the OPEN (ORIG)
position the modem will ORIGINATE under IMP, but will not
use the DTR signal. In the CLOSED (ANS) position the modem
can be used under NUBYE using the DTR signal to hang up the
phone.
Of course, you can always leave the case off and change the
switch MANUALLY!
REMEMBER to turn modem power OFF when changing any switch
setting!!
IMP installation
To originate under IMP, the switch discussed above should be
OPEN (in the ORIG mode). DTR will have no effect on modem
operation. Under IMP244 , use the NODTR feature to inform IMP.
In previous versions, you'll have to code in your own online
ESCAPE and HANGUP command in the IMP overlay.
NUBYE installation
Use under NUBYE is not so straightforward.
USE the ANS mode (SW4 position 2 CLOSED) if possible!!!
USE the following NUBYE EQUATE settings:
IMODEM equ YES ; intelligent modem
IMAT equ YES ; MODEM uses protocol
ECHO equ NO ; MERCURY does not echo ESC chars,if used
ANCHOR equ YES ; MERCURY ACCEPTS the extended commands,
; but IGNORES them. THE ANCHOR subset is
; sufficient. ALSO, when answering at
; 300 BAUD it returns the resutl code at
; at 300 (as does the ANCHOR)
HS1200 equ YES ;
NODTR equ NO ; use the DTR line to hang up
NOATA equ NO ; MERCURY USES ATA
SHORTB equ xx ; doesn't matter, use NO.
NOTE: If you MUST use NODTR equ YES then you'll have to edit the
NUBYE source code. The combination of EQUATES ANCHOR = YES
and NODTR = YES causes NUBYE to initialize the modem with an
escape character of 128d (80h). While the MERCURY ACCEPTS the
setting, sending three bytes of 80h (preceeded and followed by
a 1 second pause) does not cause an online escape. Change the
code to eliminate the S2=128 initialization command! NUBYE
will use the +++ escape sequence. SET SW4 position 2 to OPEN!
Special NOTE:
Setting ANCHOR=YES and NODTR=YES will currently cause a
combination where the modem (not just the MERCURY) is
programmed as having the escape character as 80h, while NUBYE
issues an ascii +++.