On Tue, 23 Jul 1996, Andrew Warren wrote:

> Make sure that your 17C42 is configured for "EC" (External Clock)
> oscillator mode... The "XT" mode is only guaranteed to work down to
> 1 MHz.
>
> -Andy

Thanks also to John Knechtel for his similar suggestion.

It is indeed the reason for the problem. I'm cheating by using the
unprogrammed 17C42 OTP chip ( much cheaper ) for the design, and this is
initially in XT mode.

Thanks for your help.

Cheers.

J.W.

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        Johnnie Walker
        MSc Digital Systems Engineering
        Heriot-Watt University
        email: ceejbcw@cee.hw.ac.uk
               ceejbw@pp.hw.ac.uk
               ceejbw@torduff.hw.ac.uk
        www: http://www.cee.hw.ac.uk/~ceejbcw
        tel: (0131) 343 2864
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