Re: 6702 chip

From: Rhialto <>
Date: Wed, 11 Jul 2012 18:15:28 +0200
Message-ID: <>
On Wed 11 Jul 2012 at 05:20:17 +0000, William Levak wrote:
> I don't see how the chip is initialized.  We know the shift
> registers start with 214 in them.  Also the output register.  Since

I was thinking that the output register, being 8 toggle flip-flops,
could simply be wired to use the not-Q outputs for the bits that start
out as 1.

As for the shift registers, that would probably work differently; there
are D-flipflops with reset circuits (and presumably everything in the
6702 is wired to the reset line), so I spuppose some of the bits in them
could be wired to reset to 1 instead of 0.

There is something special about the number 214 though, since it also
occurs (ok, as 214 + 1) in the 6809 machine code routine.

___ Olaf 'Rhialto' Seibert  -- There's no point being grown-up if you 
\X/ rhialto/at/    -- can't be childish sometimes. -The 4th Doctor

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Received on 2012-07-11 17:00:26

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