Questions and Answers
Copyright (c) 1992 Apple Users' Group, Sydney
Republished from Applecations, a publication of the Apple Users' Group, Sydney, Australia.
Source: Internet
Q: What does the Transwarp GS option "AppleTalk/IRQ" do?
A: This option slows the Transwarp GS down to Control Panel speed (2.5 or 1 MHz) whenever interrupts are disabled. This has the advantage of making timing sensitive code work as advertised. Anyone writing timing sensitive code should know that they have to disable interrupts.
Q: Which Zip GS delays are actually necessary?
A: "CPS Follow" should always be enabled. If you disable it you will have problems with Disk ]['s and System 6's AppleTalk driver and anything else that expects the Zip to slow down to 1 mhz when the GS is instructed to slow down to 1 mhz. For instance, border text demos (like the FTA XMAS demo) won't work if you have this disabled. Expect weird things to happen if you play with this one.
"Counter Delay" I would recommend leaving enabled. This causes the Zip to deaccelerate (actually all it does is temporarily ignore that any data can be read from the cache instead of the motherboard) for about 5 milliseconds any time you read one of the Video Counters -- this is really only there so that one of the self-tests will pass. Which way you set it shouldn't be fatal.
"AppleTalk" or "Interrupt Delay" should always be disabled. This option slows the accelerator down 5ms for every interrupt, including the 60 Hz VBL interrupt, which means a minimum of 300ms slowdown every second. The only reason most people needed it was for AppleTalk under System 5. System Software 6.0 fixed the problem but requires "CPS Follow" to be enabled for the fix to work.
"Speaker" and "Paddle delays" are intended to let old 1-bit sounds and Paddle access work the way they do on an unaccelerated IIgs. I recommend leaving these on unless you feel like experimenting. They shouldn't be fatal but some program might react very negatively, so be prepared.
"Bank C/D cache enable" should be left at the default setting. This tells the Zip if it's OK to cache bank-switched RAM (the old language card area). Zip's own documentation says "there is no know software requiring this" but that is why it's there, in case somebody ever finds software that doesn't like it.
Todd Whitesel
Q: Can I basically mix and match parts when upgrading my accelerator? That is, could I hypothetically stick in the new 65c816 CPU and run it with my existing crystal & SRAM?
A: Yes. You can always put faster CPU's or RAM's in. Just don't expect them to actually run faster unless you change the crystal too.
Todd Whitesel
Q: What are the most likely ways of actually damaging an accelerator with upgrade experimentation? Are there any?
A: When you run a chip too fast 1) it malfunctions and 2) it gets warmer.
#1 is why the chip is speed rated. Logic inside the chip happens at a finite speed which is dependent on a lot of things, so the chip is tested to see what speed it runs safely at. It is very difficult for a chip to get physically damaged if it is run too fast; it will just get very confused and you won't be able to make it do anything coherent until you run it at a safer speed.
#2 is a simple consequence of electronics principles and CMOS. The current used by a CMOS chip is roughly proportional to the clock speed you run it at, so naturally the amount of heat that is given off will increase as you force it to use more current (conservation of energy, folks, the stuff has to go somewhere). The kind of chips that are used in a Zip will not be in danger of overheating.
Todd Whitesel
Q: Is there is a way to name an icon something unrelated to the filename of the application on disk. e.g. File on disk is called: /hard1/apps/util.system. I'd like the icon to appear with a name of "Copy II Plus". Is there a way to do this?
A: Actually, there is a roundabout way you can set things up to get the same effect as this. Follow these steps:
1) Create a "dummy" text file with little or nothing in it. Save it as "Copy.II.Plus" somewhere.
2) Load your Copy II Plus icon into an icon editor and make a copy of it. Edit the icon "attributes" of that copy. Set the file type to $04 (ASCII Text file), set the file name to "Copy.II.Plus" and set the Application path to /HARD1/APPS/UTIL.SYSTEM. Now save that icon.
From this point on, whenever you double click on that text file called "Copy.II.Plus," Finder will launch UTIL.SYSTEM for you! You can put the text file anywhere you want, it doesn't even have to be on the same drive.
This simple form of aliasing can be quite useful, but it's also very limited due to the amount of work required to set one up. Also, certain applications will actually load that "dummy" text file when you've double clicked on it, and present it to you when you get to the application.
Lunatic Johnathan Bruce E'Sex
Q: I'm trying to change the color of the content region of a window. I don't want to print blank lines just to get the background color. Is there an easier way to do this?
A: Create the window invisible (fVis bit clear in the frame bits); then SetPort to your window and use SetBackPat to set your window's port's background pattern to whatever you want (horizontally-solid patterns only, please--see the GS technotes). Then use ShowWindow to make your window visible.
David A. Lyons, Apple Computer, Inc.
Apple II System Software Engineer
Q: The Apple IIgs GS/OS Reference, page 43, alludes to an enhanced ProDOS 8 QUIT call, which contains a pathname to an application to be launched. However, I find no mention of this enhancement in the ProDOS 8 Technical Reference. How do I use this call?
A: The enhanced ProDOS 8 QUIT call allows you to quit to another application if GS/OS or ProDOS 16 has been booted. The enhanced ProDOS 8 QUIT call requires either of the following four-count parameter blocks:
Standard:
dc.b $00 ;quit type
;normal
dc.w $0000 ;null
dc.b $00 ;null
dc.w $0000 ;null
Extended:
dc.b $EE ;quit type
;enhanced
dc.w path ;addr of
;launch
;pathname
dc.b $00 ;reserved
dc.w $0000 ;reserved
path str 'myprog.sys16'
GS/OS patches ProDOS 8 to get control on a QUIT and launches the next program if the quit type is $EE. The code to do this is not part of ProDOS 8; it doesn't fit in the kernel, and it can't go in the quit code because program selectors swap that out. The enhanced Quit call, therefore, works only when GS/OS has been booted.
Q&A Technical Notes

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