RE: Checking Speeds

["Albertson, Chris" <CAlbertson@primeadvantage.com>]

> -----Original Message-----
> From: Tom Droege [mailto:tdroege@veriomail.com]
> 

A while back I did the tests below, only in compiled 
"C".  I think even on a slow computer the current
code runs as fast as the ISA bus will allow.  There
is some settling time required for the latches to
set so the motherboard wait states the CPU some
number of cycles each time the ISA bus is read.  I
use a machine instruction that reads a block of data
from a port into a memory buffer, so I don't need
the inner loop.  The software reads a 16K block with
just one machine instriction now, so the speed is
completely controlled by the number of wait states
the CPU inserts.  On some M/Bs this is adjustable in
the BIOS setup.  For maximum speed remove _all_ ISA
cards except Tom's RAM buffer card then go into the
BIOS and hot rod the setting as far as you can.  Don't
worry Tom's card is faster then the bus.

In summary, it's the speed of the ISA bus, not CPU
speed that determins the readout speed of the RAM card.

On my system (a P100) it takes about 8 secods to read
out the RAM card.

> Noio:
> FOR i = 0 to 2042
> FOR j = 0 to 2036
> NEXT j
> NEXT i
> 
> Withio:
> FOR i = 0 to 2042
> FOR j = 0 to 2036
> a = INP(&H301)
> b = INP(&H301)
> c = INP(&H301)
> d = INP(&H301)
> NEXT j
> NEXT i
> >