Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!oakhill!craig
From: craig@oakhill.UUCP (Craig Shaw)
Newsgroups: sci.electronics
Subject: Re: 6809 greater than 2 Mhz
Keywords: 6809, 68HC11
Message-ID: <3011@sol.oakhill.UUCP>
Date: 23 Feb 90 18:20:14 GMT
References: <1344@talc1.UUCP> <20158@bellcore.bellcore.com>
Reply-To: craig@sol.UUCP (Craig Shaw)
Organization: Motorola Inc., Austin, Texas
Lines: 25
Summary:68HC11's do it

In article <20158@bellcore.bellcore.com> leo@dduck.UUCP (Leo Zvenyatsky) writes:
>
>As far as I know (and I've worked with 6809's for about five years
>now), the fastest 6809 version runs at 8Mhz external quadrature clock
>which translates to 2Mhz internal clock (500 nSec/cycle).  Since the
>fastest instructions take up at least 2 cycles, you wind up with
>maximum 1 instruction/uSec.  This is the fastest in the 68xx family.

  Actually, if you include the 68HC11 family in the category of 68XX,
Motorola makes at least 1 version of the 68HC11 that is guaranteed to
operate to 4 MHz (from -40C to +125C no less). The device I'm familiar
with is the 68HC11F1, and it uses non-multiplexed address and data buses.
It also provides chip-select outputs for external memories, plus many
other nice features.

  If operating temperatures are limited to around 30C or below, the regular
multiplexed-bus HC11's (a long list of part numbers) will definately run
at an E-clock rate of 4 MHz. Of course, Motorola does not spec. faster
operation over a reduced temperature range.

 Unfortunately for the original poster, 68HC11's are not 6809 compatible.
-- 

I'M THE NRA.
Craig D. Shaw - MCU Systems Design (512)891-2245  Motorola Inc., Austin, TX.