Subject: Re: Driver Software for
From: dempson@actrix.gen.nz (David Empson)
Date: Tue, Nov 24, 1998 6Ç8(H
Message-id: <1dj0yx0.1qjghji10dr8caN@dempson.actrix.gen.nz>

Jeff Brielmaier <Jeff.Brielmaier@juge.com> wrote:

> j >Can I change the speed of the Transwarp IIe with a Basic/Assembly program?
> j >
> j >I would like to speed it up AND slow it down via software, *without
> j >shutting down or resetting the computer*.
> j >
> j >Can speed up and slow down be controlled with the TITAN with software?
> 
> Accellerator     I/O Addr   Fast     Slow      Disable
> ___--------------------------------------------------
> Transwarp //e    $C074      $00      $01        $03
> Accellerator //e $C086      $05      $01        $0A
> Apple IIgs       $C036      Bit8=On  Bit8=Off   n/a

Bits are normally numbered starting at zero, so the last line should be
referring to "bit 7", not "bit 8".

It is also important to note that there are a few problems playing with
the speed bit in the IIgs:

1. Make sure you don't change any other bits in this register.  They
control essential system functions.

2. The Control Panel speed setting gets used to set the system speed
when certain operations are performed, such as entering the Desk
Accessory menu (Ctrl-Apple-Esc).  In general, you should save $C036,
modify the speed as desired for the required operation, then restore the
speed to its previous setting.

In addition, firmware, OS and toolbox routines can temporarily change
the speed setting to a required value, but mostly restore it to its
previous value.  Examples: line input temporarily goes to fast mode,
WAIT routine and paddle read always run in slow mode.

-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand