NS BASIC Tech Note                                      September 27, 1996

28. Hardware Tidbits                   
--------------------------------------------------------------------------
Contributed by Jonathan Kipling Knight (KKnight-COS3© Kaman.com), Colorado
Springs, CO.


Here are some technical tidbits on the MessagePad 120 hardware.  Most of 
this
information you can't find very easily and has been uncovered through some
tinkering.

1) How to wake up your MessagePad through the serial port.

The MessagePad has the ability to wake up just by activity on the serial 
port.
This can be accomplished by raising the Data Terminal Ready line ( DTR, 
pin 7 on
the DIN8 connector ). This usually occurs when attached hardware is ready 
to do
something.  For example, when a modem hears the phone ring or when a 
desktop
computer is connecting to the MessagePad.

2) The chips inside.

	Chip, Company, Purpose, Comments
	-----------------------------------------------------------------------
	P610ARM, ARM, Inc., Processor, Speed of 20 MHz
	LO2, Apple, Newton OS ROM, Version 2.0
	HI2, Apple, Newton OS ROM, Version 2.0
	Z85C30, Zilog, RS422 serial	external clk, up to 32.3 MHz
	28F008SA, Intel, Flash memory, 8 MegaBits = 1 MB (ads say 8 MB)
	?, ?, Static memory, 4 chips of 512kB each = 2 MB
	AD7880AR, Analog Devices, A/D converter, 12 bit analog to digital 
converter
	LIC 7645, Apple, RUNT, Memory management
	LT1271CQ, Linear Tech, Switching reg., 3.5V to 30V input, 60kHz	switch
    LTC902CS, Linear Tech, ?, can't find what it is.

3) Future microphone?

The Newton OS 2.0 comes with a built in global function named 
GetRecordVolume(). 
I think you can assume this means Apple was thinking ahead to future 
hardware
revisions or to other companies that provide Newton PDAs with record
capabilities.

4) Battery charging.

There is button in the center in the battery compartment.  If depressed, 
the
MessagePad thinks there is a nicad battery pack in the compartment.  When 
in
nicad mode, the MessagePad will trickle charge the batteries with whatever 
power
source is plugged in.  I found that I didn't need to buy Apple's nicad 
pack. 
Place tape over that switch and put Renewal Alkaline batteries or your own 
nicad
batteries in the compartment.  The MessagePad will then recharge them 
anytime you
plug it into the wall.  When charging, the battery indicator in the Extras 
drawer
will change from "Battery" to "Charging".  You may be wary about charging 
Renewal
Alkaline batteries in the MessagePad but I've tried it - it works.  The 
Renewals
don't even get warm and will charge fully in a few hours.  One advantage 
is that
Renewals don't have the memory effect like nicads.

5) Cheap voltage regulator.

Here's how to build a cheap voltage regulator for the required 7 VDC for 
the
MessagePad.  Most of the parts can be found at Radio Shack and almost any
electronics store.  A cheap car adaptor can be found at many auto parts 
store. 
Once you get all the parts you can solder everything together according to 
the
schematic on the back of the Regulator package.

	Part		Quantity	Store
	LM317T		1	Radio Shack
	0.1 microfarad	2	Radio Shack
	220 Ohm		1	Radio Shack
	1 kOhm		1	Radio Shack

With this put together, you could adapt the MessagePad to any DC power 
source up
to 28 Volts.  This means car batteries, 9V batteries, solar cells, and 
almost any
DC "wall wart" transformer.  Before you put it all together, a word about
polarity.  The plug that goes in the MessagePad has positive on the inside,
negative on the outside.  For the standard Apple AC adaptor, the yellow 
wire is
positive and the white wire is negative.  Also, you'll notice two small 
contacts
open on the back, bottom right of the MessagePad.  The left is positive 
and the
right is negative.