🚀 go-pugleaf

In Article<33294B2B.38E4@nospam.net.au>, <deanh@nospam.net.au> wrote:

> 
> Chris Dennis wrote:
> 
> > My laptop (an Olivetti Echos 42) has an 8250 UART behind its serial 
> > socket,
> > and the man at my local ISP recommended getting a modem with a 16550A UART
> > to overcome the limitations of the 8250.
> 
> The 16550A would replace the 8250.

Very very few laptops use an actual 8250 chip.  Most often the 8250 is 
integrated into a chip with a lot of other functions too.  So, generally it is 
not feasible to replace the "8250"

>  
> > Does this make sense?  Surely the data still has to go through the serial
> > port and therefore through the 8250.  Or do I understand less about PC
> > hardware than I thought?
> 
> Yes, therefore you have to replace the 8250 with the 16550A. The main
> difference between the two is that the 16550A has (in most cases) a 1 or
> 2k buffer. So, if the processor is busy when a packet is received, the
> packet can be buffered and does not need to be resent.

True 16550A chips have two 16 byte FIFOs, one for transmit and one for 
recieve.  With this small 16 byte buffer, you'd hardly be able to squeeze a 
whole packet in there while the processor was off doing something else. 



> 
> > The alternative is to use a modem in the PCMCIA slot which would avoid the
> > serial port altogether.  Is that option worth the extra cost of a PCMCIA
> > modem?
> 

This is a probably a reasonable solution.


J.Galvin