🚀 go-pugleaf

In article <1aehh5INNa0r@stephen.cs.ubc.ca> sritchie@cs.ubc.ca (Stuart Ritchie) writes:

>What is the future of serial ports?  Most general purpose processors
>can't keep up with the high interrupt rate.  Will a serial port
>replacement eventually evolve... perhaps something like a serial
>port version of SCSI?  What is the bandwidth of Apple Desktop Bus?

Serial ports don't have to interrupt on every character.  If there
were a moderately intelligent serial controller, plus DMA support for
the I/O transfers, then things could be quite zippy, thank you.

Doing transfers on the SCSI bus, while cheaper than fielding thousands
of interrupts per second, are not free either.  Consider that with the
current products, you'll likely make a context switch into user code
for the process that actually drives the SCSI device.  A well designed
serial interface, with proper kernel support, ought to be able to do
better.

The real shame is that the NeXT 68030 boards in the original cubes had
hardware support for DMA channels for the serial interfaces, though
the software apparently didn't us it.  Those DMA channels were dropped
in the 68040 products..

louie