Re: Questions:

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

In article <Pine.A32.3.93.960427103243.31032A-100000@freenet4.afn.org>,
Don Pattee Jr  <afn40469@afn.org> wrote:
> I have several questions for you tech types out there.
> I have been looking through my hardware reference manual and could not
> figure out:
> 	How to use the annuciators available via teh GS`s internal joystick
> 	DIP connector.
> 	I have things attached to the different inputs of that connector,
> 	and the program I wrote can control the outputs and inputs, but
> 	for some reason The outputs just won`t activate my relays...

As Don mentioned, this is because the annunciators can only drive one
TTL load.  You will have to insert an appropraite type of transistor to
close a relay.  (Darlington?  Not my area, so I'm not sure.) 

> Questions 2:
> 	The Video overlay Card likes to work in slot 3, etc. Is there some 
> 	way that I can use a program to direct Standard Error out, etc, to
> the 	overlay card? (Meaning, have one thing on one monitor, and another
> thing on the standard gs monitor port)

Under normal circumstances, the VOC mirrors all operations on the
IIgs's video soft-switches and memory buffers.

There is a facility provided by the Video Overlay Card toolset which
allows the VOC to be de-coupled from the IIgs video display and driven
separately ("Graphics Generator Apple II Bus Control").  This is
mentioned in the Programmer's Reference to System 6, and is probably
covered further in the VOC developer notes.

As far as I can tell, once you have done this it is not possible to
change what is being displayed by the VOC.

What you can do, though, is to display two different video modes using
this technique.  The VOC is initially enabled, and the software sets
up the initial screen to be displayed on the VOC's monitor (this is
also displayed on the IIgs).

The VOC is then disconnected, and the IIgs video display contents or
mode can be adjusted as required.  If the VOC is then enabled again,
you can write to different memory areas to display data on both screens.

The changes made to the VOC screen will also affect the IIgs's video
memory, but should not be visible unless you switch modes again.  This
method cannot be used with conflicting modes (e.g. Hi-res or Double
Hi-res with Super Hi-res), and if the same mode is used, a different
page must be selected (e.g. 80-column text pages 1 and 2).

The VOC also has an "auxiliary RAM page", which provides a second
video buffer.  The chapter in PRforSys6 describes this for the Super
Hi-res display, and I suspect this is all it is used for - it just
selects whether the main or auxiliary area from $2000 to $9FFF is used
for the SHR display.  I can't see how you could actually use this,
because the memory manager uses $E06000 and up for its master pointer
records.

> Question 3:
> 	Does the SecondSight card need to reside in Slot 3?

Yes and no.  It needs the "M2B0" signal (Mega II bank 0 select), which
is only provided to slot 3 on the original IIgs motherboard (ROM 01).
The VOC also needs this signal.

It is possible to run a wire from the appropriate pin on slot 3 to
another slot, which would allow you to use the VOC or Second Sight in
any slot except 7 (slot 7 has another signal going to the same pin).

With the 1MB IIgs (ROM 3), the M2B0 signal is provided to slots 1
through 6, so you should be able to put the VOC and Second Sight in
any of those slots.

> Question 4:
> 	There are 3 connectors on the Video Overlay card. The two at the
> back	of the card are used for the RGB and RCA connectors. I do not
> 	know what the connector on the front does. Anybody know?

Nope.

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