PDP 11/24 - A Step Backwards

[Jay Jaeger]

On 4/2/2022 5:49 AM, Noel Chiappa via cctalk wrote:
>      > does [disabling the MCLK counter via DCLO, asserted by the two
>      > E126 monostable chain from ACLO] happen just on power-down, or on
>      > power-up too? I'd need to understand how that two monostable chain
>      > works in both cases, which I currently don't. (I only understand
>      > monostables when pulses trigger them, not edges, which is a big part of
>      > why I don't completely understand it.)
> 
> So this was bugging me, so I hauled out my TI TTL databook and looked up the
> LS123.
> 

And, if that 'LS123 wasn't made by TI, it could be considered suspect 
until it has been checked out with a 'scope.  I remember, from somewhere 
back in the day, that not all '123s were created equal, and that TI's 
were demonstrably better than the others in terms of stability and 
trustworthiness.  I also recall *vaguely* one experience where replacing 
a '123 made by someone else with a TI one fixed the issue.

JRJ