Date   : Tue, 28 May 1991 14:59:42 GMT
From   : tdatirv!pa1@uunet.uu.net (Pat Alvarado)
Subject: Re: Osborne 1, Questions Answered

In article <1991May23.042256.12302@actrix.gen.nz> ewen@actrix.gen.nz (Ewen
McNeill) writes:
>The verdict on the serial port and modem port appear to be that they are
>the same control lines inside the machine.  The RS232 port apparently is
>only TTL levels, so some line driver/receivr chips would be needed.
>Speed choices are 300 and 1200, although there is apparently a link
>inside which can make this 600 or 2400 (from IMP overlay).
>

The Osborne 1 uses the standard 1488 and 1489 chips to the external port
of the RS232 interface, and uses +/- 12VDC to drive the signals. The speed
of the RS232 port can be software selectable between two speeds. There is
a way to strap the clock chip to allow up to 4800/9600 bps operation.
This information is from my Osborne 1 Technical Reference Manual,
which indicates on the schematic how to strap the clock chip.
-- 
  |||   Pat Alvarado                | 
   v    Teradata Corporation        | tdat!pa1@suntzu.sun.com
 /\ /\  100 N. Sepulveda Blvd.      | uunet!edsews!hacgate!tdat!pa1
/// \\\ El Segundo, Calif. 90245    | pa1@tdat.teradata.com


End of INFO-CPM Digest V91 Issue #97
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