Re: floptical and noisetracker questions

[dempson@swell.actrix.gen.nz (David Empson)]

In article <1993Oct6.215418.10622@msuvx2> ustai@msuvx2.memst.edu writes:
> Hiya,
> 	What is Prodos error 0045?  I get that when I tried to run
> NoiseTracker from my floptical disk.

"Volume Not Found".

Does NoiseTracker have any configuration options involving
directories?  If so, they may have been set to point to a different disk.

Does the floptical drive work properly with other ProDOS-8 programs?

> 	Anyways, just got my (2nd hand, but it works! ;-)) Transwarp GS today.  
> How come if Appletalk/Irq is on, Noisetracker says my GS is at 2.4Mhz, but if
> Appletalk/Irq is off, it's 6.0Mhz.  Any ideas?

It is a design feature.  The so-called "AppleTalk IRQ" feature causes
the Transwarp to slow down to standard speed whenever an interrupt
occurs, to allow the System 5 and earlier AppleTalk code to work
properly (it was speed-dependent at 2.8 MHz).  The "slow" burst lasts
for a short time (5 milliseconds?) after each interrupt.

NoiseTracker will have set the Ensoniq DOC to generate frequent
interrupts, and each of these is causing the TransWarp to slow down.
In fact, it looks like the interrupts are happening fast enough that
the TransWarp is never speeding up again!

If you are using System 6.0 or later (or aren't using AppleTalk), then
you don't need the "AppleTalk IRQ" feature, so turn it off.  The
AppleTalk code was changed in System 6.0 so that it was
speed-dependent at 1 MHz.  The TransWarp automatically stops
accelerating if it detects this.

> 	What kind of programs/utilites are capable of checking the
> speed of the GS??  Thanx for any help.  Ciao.

The number reported by NoiseTracker is the effective speed of the
computer, presumably in relation to a 1 MHz IIgs.  It is done by
counting the number of instructions which can be executed in a certain
fixed time period, using one of the regular interrupts provided by the
IIgs - 220 ms, 1 second or the VBL signal.  The latter may be running
at 50 Hz or 60 Hz, and I hope NoiseTracker is checking which if it is
using this to measure the speed.

There are various "benchmark" programs which can be timed to measure
the relative speed of the computer.  In the past, I have used simple
operations like a long FOR/NEXT loop in Applesoft to provide a rough
idea of speed differences.

The exact clock speed usually doesn't mean much - it is the
theoretical maximum speed at which the computer could run in an ideal
(and improbable) situation.  In practise, the computer will be
accessing I/O locations, which causes it to slow down to 1 MHz for
that cycle (and possibly later cycles, depending on what was
accessed).

The effective speed will be lower than the rated clock speed, and will
vary a lot depending on what the computer is doing.
-- 
David Empson                                                               
dempson@swell.actrix.gen.nz                                                
Snail mail: P.O. Box 27-103, Wellington, New Zealand