🚀 go-pugleaf

In article <814848990snz@tyunnos.demon.co.uk>
           rwj@tyunnos.demon.co.uk "robert jones" writes:

> I am a complete non-expert on this topic so you can judge the authority
> of this post for yourself :-) but I thought that the need for a 16550A
> serial port DID NOT APPLY if you are running in DOS (but maybe not if
> in a DOS box in Windows) since in that case (unlike in a multitasking
> environment) even a slowish processor such as a 286 is allegedly
> fast enough to service the interrupts from the port without delay or
> consequential data loss as it has nothing else to do anyhow.

All I can do is recount my own experience:

Processor:  386SX-25

Using Telix for DOS I was _just_ able to download zipfiles from BBSs at
a little over 1600cps, using Zmodem protocol.  Where modem-link
compression could work, lost characters were quite common with a
14400bps modem  and 19200bps serial port speed.

The DIS software could just about handle nntp, but ftp connections were
unusable, and in both cases there were many hardware over-runs.

I installed a 16550-based serial card and cured the problem.  Oddly
enough, when using Windows, there seemed to be far fewer problems.


Other experiences over the years suggest that some software has much
faster code than other software which does _the same job_.  But running
a TCP/IP stack, and multiple tasks using the stack, will always take up
far more processor time than a single task comms program.

Frankly, I think anyone building computers today that don't use buffered
serial ports is ripping off their customers.


--
David G. Bell -- Farmer, SF Fan, Filker, Furry, and Punslinger..

Never criticise a farmer with your mouth full.