[cctalk] Re: RS232 then and now

[Paul Koning via cctalk]

> On Feb 1, 2025, at 5:57 PM, Chuck Guzis via cctalk <cctalk@classiccmp.org> 
> wrote:
> 
> On 2/1/25 13:31, Frank Leonhardt via cctalk wrote:
> 
>> I started with minilogs which were +/- 10V logic.
>> 
>> Anyone remember those?
> 
> I remember HTL (15V) being basically a high-voltage version of DTL.
> 
> --Chuck

Similarly, early CMOS logic IC, both the original Philips 4000 series and the 
74HC series, support a surprisingly wide range of supply voltages.  3-15 volts 
for the 4000 series (according to my Radio Shack reference that is), 2 to 6 
volts for 74HC.  The speed drops off dramatically with lower voltages, though, 
as I found out when using a 74HC bus driver in a 3.3 volt logic design.

        paul