witchy at binarydinosaurs.co.uk
Thu Dec 22 12:29:30 CST 2016
On 21/12/2016 00:58, "Paul Berger" <phb.hfx at gmail.com> 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.
Out of 4 outputs 2 are fed back into itself as inputs, one goes off to RESET
via a 74LS04N and the 4th disappears into the phone side of things possibly
to an Intel D8741A as well as seemingly being used as a base driver for a
BC548 transistor. Inputs are from a 5V-fed resistor network and Vcc for all
3 CMOS chips comes from a 12V line via a 1kohm resistor.
Tonight I'll make sure all the verdegris'd resistors and caps are ok.
The 8085's arrived yesterday too, thanks!
Binary Dinosaurs creator/curator
Www.binarydinosaurs.co.uk - the UK's biggest private home computer
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