Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!mips!ptimtc!nntp-server.caltech.edu!toddpw
From: toddpw@nntp-server.caltech.edu (Todd P. Whitesel)
Newsgroups: comp.sys.apple2
Subject: Re: Choosing a language (ML vs HLL)
Message-ID: <1991May2.102811.25676@nntp-server.caltech.edu>
Date: 2 May 91 10:28:11 GMT
References: <usc!cs.utexas.edu!asuvax!hrc!gtephx!campbellb@UCSD.EDU> <9105010011.AA10540@apple.com> <14106@ucrmath.ucr.edu>
Organization: California Institute of Technology, Pasadena
Lines: 24

rhyde@ucrmath.ucr.edu (randy hyde) writes:

> You think segment- ation on a PC is bad, try segmentation on the 816!

I have. I prefer the 65816's handling of segmentation far more than the
x86 segmentation. The 65816 at least has absolute long, for direct 16Mbyte
addressing at any time. On an 8086 you have to mess with the segment
registers to access anything other than the four 64K segments and they
are DAMN SLOW when you have real time interrupt response to worry about, or
data objects that are larger than 64k.

Last year we built a digitizer/playback unit that required servicing a CODEC
every 128 microseconds. With all the segment registers to bop around (assuming
a real interrupt handler that does not restore certain registers) I couldn't
get it to work using interrupts (80188 @ 8 mhz). I tried to use the DMA section
to do the actual sound I/O, but couldn't get them to kick in -- I eventually
gave up and wrote the thing to be a completely polled system so I could get
it finished before my extension ran out. The same project with a 65816 would
have been a hell of a lot easier to do -- I could have used NMI for the CODEC
and IRQ for the serial chip and keypad polling with plenty of CPU left over
for the rest of it.

Todd Whitesel
toddpw @ tybalt.caltech.edu