Mystery 8085-related IC identification needed please

Pete Turnbull pete at
Sat Dec 17 09:06:42 CST 2016

On 17/12/2016 14:28, Tony Duell wrote:
> On Sat, Dec 17, 2016 at 2:02 PM, Adrian Graham
> <witchy at> 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 Turnbull

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