17 Dec
2016
17 Dec
'16
7:06 a.m.
On 17/12/2016 14:28, Tony Duell wrote:
On Sat, Dec 17, 2016 at 2:02 PM, Adrian Graham
<witchy at binarydinosaurs.co.uk> wrote:
> Thanks all, the pinouts are matching the LS9x
counters so I just need to
> trace more lines to hopefully narrow it down. Pins 6 and 7 are definitely
> inputs so you're right Tony, the reset must come from elsewhere. One of the
> outputs is confusing though since it appears to come FROM 5V via a resistor,
What value resistor?
It is possible that whatever it is driving needs a swing to +5V,
rather than just
a TTL high level. Adding a pull-up resistor is a way to kludge this.
The CLOCK line on a Z80 is usually arranged like this, with a 330R (or
thereabouts) pullup.
--
Pete
Pete Turnbull