Re: 16 MHz 64k Zip Benchmarks

[pho@vmsa.oac.uci.edu]

I received this email from johnt@meaddata.com (John Townsend).  Replies
to questions such as these will be posted publicly on comp.sys.apple2
for everyone to benefit (saves on typing too).

> I now have a ROM 3 IIgs, and am planning to upgrade my Zip GSX as
> high as I reliably can.  I'd like more specific information about
> the modifications Long mentions above, especially the modification
> for >5V and the split cache.  Does the >5V mod only modify the power
> to the Zip board or to the whole IIgs system?  How much of a speed
> difference does it make?  Replacing the 74F00 is easy enough, but
> I'm not sure I wanna risk frying something else.  Did Long socket
> his oscillator, and what speed and size (wide or narrow) are his
> SRAMs?  My IIgs is completely full of cards, too, with slot 1=Audio
> Animator, 2=Zip GSX, 3=Video Overlay, 4=Vision Plus video digitizer,
> 5=SuperDrive controller, 6=PC Transporter, 7=RamFAST, and 7MB CV-RAM
> in the memory expansion slot; is this likely to increase system
> noise and significantly reduce the maximum speed I can get out of
> the Zip GSX?  Any other tips would also be appreciated.

The modifications required for 16 MHz are currently being withheld at
this time until I decide if I shall market it or release it to the
public.  The other stuff I can discuss.  Since the Apple II community is
such a great bunch I'm going to volunteer most of the info.  I'll let
you have the joy of figuring out the rest though =).

*DISCLAIMER*  Do any of the following modifications at your own risk.  I
will not be reponsible if you mangle your Zip.


Question:  Does the >5V only modify the power to the Zip board or to
           the whole IIgs system?

All the components on a Zip feed off of the +5 V line from the expansion
connector.  The Zip is designed so that you can disconnect the +5 line
from the CPU and connect the +12 V line and regulate it down to a
desired level.  Only the CPU gets the regulated voltage while the rest
of the board gets +5 V.

Parts needed:

(1) voltage regulator, part # LM317H or HS (looks like a small cylinder)
(4) 22 uF 16 V polarized electrolytic capacitors
(1) 1/4 watt 3.9k resistor
(1) 1/4 watt 1.2k resistor for ~5.6 V or 1.3k resistor for ~5.3 V

1.  Cut trace at T2 and T3.  You've just disconnected +5 V to the CPU.
2.  Solder 22 uF caps at C21 (this one negative at 6 o'clock), C16, C17
    and C19.
3.  Solder voltage regulator at Q2.  Pay attention to the orientation
    of the notch.  Use the drawing on the Zip as a guide.
4.  Solder 3.9k resistor at R7.
5.  Solder 1.2k or 1.3k resistor at R8.  A 2k potentiometer (adjustable
    resistor) would work even better.


Question:  How much of a speed difference does it make?

Severals benchmarks were recently posted to comp.sys.apple2.  At 16 MHz,
improvements in speed range from 200% to 600%.  Tasks done in memory
benefit the most, tasks involving disk I/O suffer from 1 MHz bus and
graphics kick butt.  If you can only see Rastan, Sword of Sodan Demo or
Out of this World on a Zippy Zip.


Question:  Did long socket his oscillator, and what speed and size are
           his SRAMs?

Information on crystal oscillator, SRAMs and sockets also recently
posted on comp.sys.apple2.  All my Zips have skinny sockets for the
static rams and socket for the crystal oscillator except for the 16 MHz
one.  I wanted to be sure about the connection so I soldered it directly
to the board.

Question:  My IIgs is completely full of cards, too, with slot 1=Audio
           Animator, 2=Zip GSX, 3=Video Overlay, 4=Vision Plus video
           digitizer, 5=SuperDrive controller, 6=PC Transporter,
           7=RamFAST, and 7MB CV-RAM in the memory expansion slot; is
           this likely to increase system noise and significantly reduce
           the maximum speed I can get out of the Zip GSX?

I've got the Zip, Sonic Blaster, RamFast Rev. D and 6 MB GS Ram Plus
running off of a stock ROM 01 power supply without any problems.  It's
possible that all your cards may increase system noise but I don't know
for sure.  I bet they're sucking your power supply silly though.  I
would suggest a heavy duty power supply and a good fan such as the
System Saver.  Avoid internal fans that blow hot air around inside your
IIgs.  A stock ROM 01 power supply is rated at 1 amp for +12 V and about
2 amps with a ROM 03 power supply.  Depending on how many cards draw
from +12 V you may have to get a larger power supply.

Long Hoang