User`s guide

at full speed (set ON) or "normal" speed (set OFF)**.
SW2-8 sets Defeat Speaker Delay. To play 'old Apple' music and
effects correctly, the switch should be OFF to permit the delay.
**Note: Whether or not a particular card can work without a slow-down is
something you can determine by experimentaton. This is easiest using the
ZipGS CDA accessed via the Desk Accessories menu (OpenApple-Control-Escape).
The CDA settings are not permanent. Once you find the settings you like,
you can turn OFF the computer and set the switches on the board to match
the settings that work best.
____________________________
From: Todd P. Whitesel
002- Why should Appletalk Delay be disabled with a ZipGS?
Because it saps performance every time an interrupt occurs.
The Appletalk delay was originally called the "Interrupt Delay" but they renamed
it at the last minute because somebody actually tried an 8/64 on an Appleshare
network and it dropped packets like crazy.
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.
Why the Appletalk delay is not a complete solution: a full-size Appletalk packet
that you'd get from a file server takes about 14 ms to transmit. The Appletalk
delay covers the first 1/3 of the packet, the VBL interrupt covers at most
another third of the packet, but nothing is guaranteed to keep acceleration off
for the whole packet. If you speed the Zip up more, say to 10/64, it starts
dropping long packets no matter what.
This latter problem was why I originally wrote ZipTalk. It required a slot delay
to be enabled (in, say, slot 6 or 7), and before each appletalk packet was
received I tweaked that slot -- slot delays are 50 ms, so the Zip stays
unaccelerated way past the end of the packet and everything works. (I also
patched packet sending, to be safe.)
In system 6 Apple fixed things correctly in the appletalk drivers. I removed the
code from ZipTalk and released what remained as ZipFix. As of 6.0.1, the cursor
flicker problem was fixed by apple in the control panel, so now you only need
ZipFix for the GS/OS SET_SYS_SPEED hook, which nobody seems to use.