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From: seeker@indirect.com (Stan Eker)
Subject: Re: MC68HC24 Port Replacement Unit
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Date: Thu, 18 May 1995 05:35:39 GMT
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Rich 924 (rich924@aol.com) maundered:
: Has anyone used the MC68HC24 Port Replacement Unit on a MC68HC11 board? It
: is supposed to let you use all the ports even in expanded mode.

Works fine.  There's a few caveats you have to watch out for, but it's MUCH
simpler to deal with on an 'HC11 than, say, a 6821, and it's sturdier.  I've
blown a pile of 6821s, never yet blown the 'HC24.

You can (generally) write your program in expanded mode WITH the 'HC24 and
then directly migrate to single-chip mode, making debug sans-ICE easier.

The 'HC27 is the equivalent part for the 68HC11Dx and 68HC11Fx chips, but
you don't get the full function of all the pins back.  There's a couple of
the Dx pins that won't work normally, no matter what you do.  That's
normally in the single-chip sense.  I think it's the ones usurped by AS and
R/W, but don't quote me on that.

