[time-nuts] Lucent KS-24361, HP/Symmetricom Z3809A, Z3810A, Z3811A, Z3812A GPSDO system

Brooke Clarke brooke at pacific.net
Tue Nov 4 14:58:13 EST 2014

Hi Hal:

Yes for level shifting.  Most micro controllers have the UART built-in so that's all that's needed.
I haven't got my boxes so don't know what chips are in them.
Mail_Attachment --
Have Fun,

Brooke Clarke
Hal Murray wrote:
> brooke at pacific.net said:
>> UARTs are not mandatory, a simple transistor level shifting circuit is all
>> that's needed for TTL/RS-232 levels.
> I think you are confusing UARTs with level shifters.
> In the old days, transistors were expensive enough that a 68000 class CPU was
> all that could fit on a chip.  All memory and peripherals were off chip.
> While not quite mandatory, most of the time it made sense to use a UART chip.
>   If you had a FPGA, you could put a simple UART in there.  (But back then,
> FPGAs weren't very big either.)  If the CPU was idle, you could bit-bang
> things.

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