Date   : Mon, 08 Jun 1981000:31:00-MDT
From   : Keith B. Petersen <W8SDZ@MIT-MC>
Subject: Using DC Hayes modem at 450 baud

I picked up the following message from a remote CP/M system
recently:

According to the supplied literature of the D.C.Hayes
MicroModem-100, it cannot be operated above 300 baud.
The limiting factor is not the Uart or it clock
frequency but the Microcoupler itself (according to
its designer). Not accepting that their design was
such that its upper limit was no higher than 300
I decided to experiment. If you replace the diodes
that determine the 12-bit divider for the clock
frequency to a decimal 17 - 00010001 - (I used a
16-pin socket and a removeable header), you can
squeeze out 450 Baud. I couldn't get 600 baud, but
the upper limit probably varies from unit to unit.
If you wish you had a PMMI, give this a try. Anything
is better than 300.

                                Bob Loesch
                                Bel Air, Md.
                                (301) 879-7135