Date   : Wed, 21 Mar 1984 04:16:28-MST
From   : Keith Petersen <KPETERSEN@SIMTEL20.ARPA>
Subject: MDM727/728/729 fix for PMMI ringback

SUBJECT :  MDM727 - MDM729  MOD FOR PMMI USERS FOR RINGBACK NUMBERS

FROM    :  IRV HOFF W6FFC

DATE    :  18 MAR 84


       This mod affects just PMMI modems that are using MDM727 and
       later, including MDM728 or MDM729.  Change one byte:

             097F  from 75  to  69       (then SAVE 73 sectors)

       The ringback circuit should then work normally.  When I fixed
       MDM727 to allow redialing the new (0-9) numbers and changed some
       some labels, this one was overlooked, sorry.   If changing the
       source code, make the following change:
;.....
;
;
; Hang up, redial and listen for dial tone
;
RINGBK1: CALL   HANGUP          ;hang up the phone
         MVI    B,RBWAIT        ;wait 5 seconds before redialing..
         CALL   TIMER           ;..for line to clear, etc.
         CALL   DIALBGN         ;disconnect, reconnect, wait for tone
         JNC    DIAL12          ;go redial number
         JMP    DIALAGN         ;no dial tone heard
;.....
;
-    -    -    -    -    -    -    -    -    -    -    -    -    -    -

(next to last line was:    JNC   DIAL13    which was incorrect)