bbs or crude facsimile of such

geneb geneb at
Fri May 19 09:01:36 CDT 2017

On Fri, 19 May 2017, John Labovitz via cctalk wrote:

> Another BBS obscurity —
> I ran a BBS in the early 80s called The Bethesda RCP/M. Those of us who 
> couldn’t afford dedicated lines often used a method called ‘ringback.’ 
> This was a clever way to share a regular home phone with a modem.
> The idea was that if you wanted to dial up to the BBS, you’d call my 
> number, but hang up after one ring, then call back. The software (BYE, 
> as someone else here mentioned) would be monitoring the ring-detect line 
> on the modem’s serial port, and watch for ring patterns. If it saw a 
> second ring within ~4 seconds, it would ignore the call, assuming it was 
> a voice call; otherwise, it would send the Hayes code to answer the line 
> (ATA). It’s weird how I still remember all that logic, 35 years later...

I recall seeing the feature in BYE, but this is the first time I've heard 
of someone using it.  Neat! :)

For those that don't know what BYE is, it's basically a fancy I/O 
redirector for CP/M.  It would handle the serial comms and a few other 
things, and redirect I/O from the serial port, to the console.  This meant 
that you could run BBS software that didn't have any serial I/O.  The 
first versions of RBBS were like this - simply compiled BASIC with regular 
INPUT and PRINT statements.

BYE was written in 8080 assembly (I think MBYE was Z-80, but I'm not sure) 
and used an "insert" for the type of computer you were going to use it on. 
The insert contained code for all the machine-specific features that BYE 
needed (serial port control, 25th line support for status bar, etc.).

At some point a version of BYE was created for the IBM PC, but as far as I 
know, there was only a single release of it.


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