[cctalk] Re: RS232 then and now

[Paul Koning via cctalk]

> On Jan 31, 2025, at 1:55 PM, Steve Lewis via cctalk <cctalk@classiccmp.org> 
> wrote:
> 
> re: on UARTS..
> 
> Didn't it basically standardize the process of that task of converting a
> byte to bits and vice versa, in a fashion specified by RS232?

No, RS232 is a way to send binary information between devices, using specified 
voltage levels and interface conventions.  It has nothing to with UARTs.

> And do so at the above-300-baud rates, since that task was too stressful
> for 1MHz processors to pull off on its own (in addition to whatever else it
> was doing, like flashing a cursor on a CRT?)?
> And the buffer just gave grace time for if one of the systems got overly
> busy? (like when scrolling said CRT)?

You can do a UART in software at pretty high speeds if the processor doesn't 
have too much else to do.  Conversely, a 110 baud UART is very painful in 
software on a 4004.

> Might a UART be an early example of an ASIC?

Yes, I would say so.

        paul