Re: AppleTalk on IIGS - Questions...

[Marsha <menacechgo@aol.com>]

[posted and mailed]

"M. Pender" <mpender@hotmail.com> wrote in
news:Ygzxb.2800$a54.1933@nwrddc03.gnilink.net: 

>  I think I've found the problem--when I removed the ZipGS card
> Appletalk worked properly.  There are several DIP switches on the card
> and one is probably set wrong.

A GS can boot from AppleShare 2.0 and 3.0.x, boot support code was 
removed in later versions.

re. switches, from http://apple2.org.za/gswv/a2zine/faqs/Csa2ACCEL.txt
This first paragraph was for general use, not including booting as that 
relied on the ROM code as mentioned in the second paragraph.

<<AppleTalk or Interrupt Delay should always be disabled (SW1-3 set to 
ON). The desktop will run much slower if you enable it. The only reason 
most people needed it was for AppleTalk under system 5, and now there is 
an init on tybalt that fixes that. System 6 fixed the problem but 
requires CPS Follow to be enabled for the fix to work.
>>

<< With "Appletalk delay" on, every time an interrupt occurs your Zip 
will disable acceleration for 5 ms, just like it does with the paddles 
and the speaker and the others. This is a significant effect because with 
VBL interrupts going you have one every 16 ms, so your Zip spends nearly 
1/3 of the time not accelerating you.

Why this "fixes" appletalk: in system 5 and earlier (including the ROM 
appletalk code), there are software timing loops which assume 2.8 mhz 
operation. As you speed the system up, it gets more and more likely to 
drop incoming packets because it thinks they are being sent too slowly to 
be correct, when in reality the appletalk code is timing out too fast.
>>