From: brtmac@maverick.ksu.ksu.edu (Brett McCoy) Subject: Re: 486SXs as Unix Iron? Date: 2 Nov 1992 20:27:58 GMT
In <Bx3r3F.FoL@max.physics.sunysb.edu> dmcquaid@csws19.ic.sunysb.edu (Devin McQuaid) writes:
>(like your video card and disk controllers) As I understand it the
>local bus is alot faster since both the ISA and EISA buses run at a
>really low speed (under 10Mhz I think).
Okay, I have a 40mhz 386dx (amd cpu) and it has a jumper for running
the ISA bus at either 10mhz or 13mhz. I have it set to run at 13mhz
and haven't had any problems yet, and I can see a difference while
running X (under 386BSD) with the bus at 10mhz and 13mhz (30% increase
in performance, I would think). Scrolling in an xterm is faster and
smoother. So, how does one calculate the max throughput on an ISA
bus? I know it's not as simple as 2*13 megabytes/sec. Is it half of
this, 1/3rd, 1/4th? How much overhead is there in setting up each
transfer, and how many bytes are transferred per request? How much
different is EISA and VL? Is the only difference in the width of the
data path and the clock speed, or are there other differences in the
protocol used to talk to the bus? I've heard that EISA supposedly has
a burst mode which ISA doesn't. Is this true?
++Brett;