>>>>> "G" == George Toft <[EMAIL PROTECTED]> writes:
G> I would invite you to do the math: 115,200 baud with one start bit,
G> one stop bit and eight data bits (total of 10) means the computer
G> has to pump out 11,520 bytes per second to the serial port. I
G> think if a 386 at 25Mhz can handle a hard drive and move 700K bytes
G> per second, it can surely handle less that 12K, especially since
G> the modem has a higher priority interrupt than the hard drive.
If a modem were a hard drive, that would be correct. But it's not.
First, the hardware controlling a hard drive is quite different than
serial hardware. Serial hardware has very samll buffers. If the CPU
doesn't service it in a very short amount of time, characters are
lost. A hard drive often has DMA, and certainly has different
hardware buffering it.
Second, the CPU is doing vastly different things when it runs a PPP
connection vs. reading from a disk. There's a lot to be done in a TCP
stack, which is why with even fast computers, sniffing on an ethernet,
for instance, can drop packets. There's less work to be done on a PPP
link, but there's also a much smaller CPU.
--
Alan Shutko <[EMAIL PROTECTED]> - By consent of the corrupted
You will be run over by a beer truck.
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