Re: Klunky IIGS - no docs - where do I start?

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

In article <4cqqa2$a0p@yama.mcc.ac.uk>,
Duncan Entwisle <duncane@jumper.mcc.ac.uk> wrote:
> David Empson (dempson@atlantis.actrix.gen.nz) wrote:
> 
> : No - you set the video scan frequency by using the
> : Control-Option-Reset menu.  Items 2 and 3 on this menu are used to set
> : the scan rate to 50 Hz or 60 Hz.  They also cause all other Control
> : Panel settings to be restored to their defaults.
> 
> Isn't this the standard reset? In which case this doesn't produce a menu 
> for me :-(

There are four reset methods:

Control-Reset          "soft" reset - might work with 8-bit software
                       (taking you to a reset handler), but never under
                       16-bit software.  If the reset vector isn't set
                       up, this will cause a reboot (like Ctrl-Apple-Reset).

Control-Apple-Reset    Force reboot.

Control-Option-Reset   Bring up the menu offering control panel, restore
                       defaulls (x2) or restart.

Control-Apple-Option-Reset   Start the self-test.

In the last three cases, let go of the RESET or CONTROL key first, and
make sure you hold down the Apple/Option modifier keys until you hear
the beep.

(In a ROM 3 IIgs, it is possible to use the "sticky keys" feature to
do a modified reset - press SHIFT five times to enable sticky keys,
then press, one at a time, Control, Apple and Reset.)  :-)

> : If you want to replace this chip yourself, I strongly suggest you do 
> : it by cutting off the pins of the old chip (next to the plastic part
> : of the chip), then soldering a new chip (or socket) onto the pins.  Do
> : not attempt to desolder the pins from the motherboard, as it is a
> : four-layer board, and you could damage it quite easily.
> 
> Phew - thanks for that - with luck I may be able to do a board swap with 
> a ROM0 IIGS, and swap the ROMs over (I presume this is all that needs to 
> be done - the ROMS are socketed)

You should also swap the VGC (Video Graphics Controller, a socketed
PLCC chip under the power supply), if the one in the ROM 0 is
344S0046-0 and the one in the ROM 1 has a different suffix.  The
original VGC has a fault which causes pink fringing effects in
monochrome double hi-res mode, and also affects 80-column text mode in
some machines.

This is only a cosmetic problem, so you can get away with just
swapping the ROM in the meantime.

To swap the VGC, you will need a PLCC extraction tool.  If you haven't
removed a PLCC chip before, I suggest you find someone else who has.
I managed to bend pins and scratch the chip the first time I did this
(not with a VGC, thank goodness!).
-- 
David Empson
dempson@actrix.gen.nz
Snail mail: P.O. Box 27-103, Wellington, New Zealand