Motorola MC14081B

[allison]

On 12/20/2016 07:58 PM, Paul Berger wrote:
> On 2016-12-20 8:50 PM, Adrian Graham wrote:
>> Evening folks,
>>
>> (it's evening here)
>>
>> Typically for troubleshooting around $FESTIVAL I find a more-than-likely
>> dead MC14081B (CMOS quad dual-input AND gates) just as UK postage
>> ends for
>> the next few days so getting a replacement won't happen until next week.
>>
>> Question is, aside from having to make up an adapter board to change the
>> pins around and making sure Vcc is +5V is there any reason I can't use
>> something like a 74LS08 for testing? One of the outputs is RESET for an
>> 8085A so nothing too demanding.
> If one of the other outputs is driving a CMOS device the output may
> not go high enough to satisfy it, however I would expect the reset
> input on the 8085A to be TTL compatible.
The 8085 reset input is not TTL, its schmidt trigger, and the level is
at the upper level for TTL.
If you use a 1K pullup then TTL, or open collector parts can be used as
well as CMOS.
The 8085 was designed to have simple reset for cost sensitive aps where
the circuit was usually
22K pullup and 1uf to ground.

If you using anything a 74HCxx would easily satisfy the drive and loading.

>
>>
>> (I might have a CD4081B somewhere too, which is pin compatible
>> according to
>> the datasheet)
> Same component Motorola prefixed their 4000 series CMOS numbers with a
> 1 to be different.
Critical as Moto had ECL and MECL parts with 4xxx numbers along with
parts for communications
and peripherals (Phase detector, VCOs, Counters).

Motorola was always MC prefix where RCA was CD4xxx That helped keep the
whos what straight.

I know this as I did a lot of PLL work using the moto parts mixed with
RCA CD parts for power savings.
Also the 8085 in many aps.

Allison

>>
>> Cheers,
>>
> Paul.
>
>