Z*Magazine: 16-Mar-87 #43

From: Atari SIG (xx004@cleveland.Freenet.Edu)
Date: 07/09/93-11:04:30 AM Z

From: xx004@cleveland.Freenet.Edu (Atari SIG)
Subject: Z*Magazine: 16-Mar-87 #43
Date: Fri Jul  9 11:04:30 1993

ZMAGAZINE              MARCH 16, 1987
Publisher:Syndicate Services
Editor in Chief:Ron Kovacs
Editor/Coordinator:Alan Kloza
Columnist:Steven Godun

        Pearl Harbor, Hawaii

          (808) 423-2754

Xx This week in Zmag

<*> Part 2: Atari Emulator
    Text from the author of the
    Atari 800 Emulator Demo

<*> New Product announcement from
    Orion Systems

<*> Product review of Super Mario
    Brothers from Nintendo

<*> PCP Update. Get more out of
    your usage

<*> Battery Backup your Atari

<*> Atari news and more from the
    CHAOS BBS and John Nagy

<*> Note from the Editor
.......Continued from Zmag40.........

Current information about the ST 
Transformer as of 03/09/87

By Darek Mihocka (CIS 73657,2714)
Programmed by Darek Mihocka
additional programming and all night
testing by Ignac Kolenko hardware
supplied by:

Xanth Computer Systems
600 First Avenue
Seattle, Washington

The purpose of this document about
the ST Transformer is: - to explain
its purpose and give a history of its
development - to give the latest 
information about the ST Transformer 
- to discuss the legal problems with 
this program and why I can't release 
it to the public for all former Atari
400/800 owners - to find other 
programmers to work on this project.

For those of you unfamiliar with the
name, you have seen it as the Atari
800 Emulator Demo or the Apple ][

Part 1:The history

When Atari introduced the ST
computers, I was then the owner of 
an Atari 400, bought way back in 1981
with all my summer's earnings. Like
many other people I spent a
considerable amount of money on my 
system for software and disk drives.
About the only piece of hardware that
I could use on the ST was my FX80
printer. This is not too useful as
none of the software works. So I held
off buying an ST for over a year as I
waited for Atari to introduce some
kind of a device or program to allow
me to run old software. They never
did. I finally sold the 400 and
bought the ST anyway because after
using 68000 based in machines at my
university, I was impressed by its
power and already had a program in

The implementation:
The first project I decided to work
on was to somehow run the old
software so that all that money
didn't all go to waste. I considered
2 approaches:

 - the first approach is to write a
   program that reads a binary file
   from a 400/800 and convert each
   machine language instruction into
   a 68000 instruction. This would
   then create a file on the ST that
   would run about 10 times the speed
   of the original file!

 - how do you tell the difference
   between code and data?
 - how to handle self modifying code?
 - how to handle the  hardware

 - the second approach is to write an
   interpreter, similar to the way
   BASIC interprets a tokenized
   program, or the way that a real
   microprocessor executes code. You
   read in a byte of memory,
   determine which 6502 instruction
   it is, and execute it. The real
   6502 executes microcode. I would
   use 68000 instructions.

 - the overhead of processing each 
   instruction is greater than the
   time it takes to actually execute

 - how to handle hardware registers?

I chose the second approach because
it solves the first two problems of
the first approach, and shares the
third problem. The problem of speed
is also in both approaches. Software
running at ten times the speed is
usually unusable. This is similar to
the problem when some IBM PC software
is run on an AT or even worse, a
Compaq 386 (18 times faster). It is
always possible to use software
running slower. The unknown is how
slow the software would run. The
hardware problem can be solved by a
similar interpreter which checks
which register is being accessed and
does something accordingly.

First results:

The first version of the 6502
interpreter was written in Megamax C
in August. As it turned out, the
unknown speed was about 7% of the
speed of a real 6502. This does not
include the extra interpretation of
hardware. It was obvious that hand
coded 68000 code was needed. About a
month later, I had the hand coded
version sort of working at about 30%
of the speed. To make the hardware 
interpreter would be difficult, 
because of the dozens of hardware 
locations in a 400/800. I chose then 
to first do an Apple ][ hardware 
emulator, because there are only 2 
vital locations needed to get it to 
work: the keyboard and the screen.
The next month was spent debugging
the many bugs that crept into the
6502 interpreter and porting software
from . Finally it worked, at about
25% of the speed. 

This is the version that you have 
seen as the Apple ][ emulator.

First Problems:

One problem with all emulators is
inherent in their design: to emulate
the software of another machine, you
must transfer that software. When I
approached Apple about this, they
told me that what I am doing is
illegal, since I copied the ROMs of
Ignac's no name ][ clone, which had
ROMs probably derived from an Apple.
I approached Apple Canada about
getting the real ROMs from them, plus
the code for Apple DOS, and anything
else they'd want to let me try. As it
turned out, they saw my project as
software piracy and told me to forget
it. I guess they didn't want to
expand to the ST market anyway. After
the Apple told me they weren't
interested, I decided to stop
spending more time on Apple
emulation. I ported over my copy of
the Translator disk's image of the
Revision B ROMs. I chose those ROMs
because they are made to run with 64K
of RAM, which is what the 6502
interpreter sees when it is
executing. I also ported a copy of 
Atari Basic to use as a test file. 
After only a few days of hacking the 
Apple ][ routines, I got a very 
primitive version of the Atari 
emulator working. It only supported 
a few graphics modes and still had a 
major 6502 bug, but it sort of
worked. I uploaded it to my BBS and 
to Atari's BBS as the Atari 800 
Emulator Demo.

Part 2: the Atari 800 emulator

What happened then was a big shock.
I got a phone call from one of the
Atari BBS sysops telling me that
Atari was not pleased with what I had
done. They too considered my program
as piracy. I was told that I would be
contacted within a few days to
discuss the emulator. No one ever 
called back, and I have never been 
able to get through to anyone that 
would discuss it with me. The 
secretaries usually screwed me around
on the phone. Attempts to reach
someone willing to talk on Compuserve
also failed.

What I currently have is a program
that appears to execute 6502 code 
according to the 6502 specs at about 
20% of the speed. This includes the 
overhead of the hardware interpreter.
The hardware supported so far

 - graphics modes 0,1,2,3,6,6+,7,7+,
   and 8
 - most display lists, no matter how 
 - most keyboard keys, including
   caps, inverse, and BREAK.
 - the color registers, and a few
   other miscellaneous locations
 - most read and write DOS operations
 - 1 joystick port
 - printer output - 

Runs most BASIC software I've 
downloaded from BBSs and tested.

Not supported yet:

 - GTIA modes
 - player missle graphics
 - sound registers
 - a combination of the two mentioned
   approaches, where parts of the 
   operation system are hand coded to
   68000 code and executed directly, 
   not interpreted. This is already 
   done for the D: and P: drivers,
   but I plan to eventually do the
   whole operating system which would
   result in a significant speed

Part 3: Legal Problems

According to Apple and Atari, it is
illegal for me to distribute the
emulator any more because I had
included the ROMs with the demos.
That is the reason I have not
released anything in over 2 months.
I respect their legal right, but I
also believe that Atari has an
obligation to all the tens of
thousands of 8 bit owners who helped 
build the Atari empire. The only 
people who can make a perfectly legal
emulator are Atari themselves. I have
spent about 500 hours of my time
planning, programming, and testing my
program. This may seem like a lot,
but it works out to about 10 weeks of
full time work, or about 2 to 3 weeks
work for a team of Microsoft caliber 
programmers, which I assume Atari
has. With their technical knowledge 
of both the 8 bit and the ST
computers, I don't see why Atari 
couldn't have released an fully 
implemented emulator 18 months ago. 
They were quick to introduce the CP/M
emulator. I've compared the code of
my program and theirs, and it is
quite similar. So they are half done
already. Until they do, I will keep
working on my program until it is
functional enough to run most
software that can be downloaded. Once
released, it will be up the
individual used to copy their ROMs
over to the ST. Atari says that's
illegal. For as long as the people do
it for their own use, I do not see
this as being illegal. I do not have
access to high priced lawyers, so I
am hoping that Atari will finally
talk to me and come to an agreement
that will benefit us all.

Part 4: Programmers Wanted

Most of the emulator is written in
68000 code, with C code handling the
less critical routines. It has been 
suggested that I write my program 
for the Amiga, because its superior 
graphics would make it easier to 
implement player missle graphics and 
the other features. Since I have 
never programmed the Amiga, I cannot 
make the Amiga version. What I would 
also like to do is write hardware 
emulators for other computers, like 
the Commodore 64, VIC 20, Color 
Computer, Sinclair, etc. Anyone 
proficient in 68000 programming that 
would be interested in writing those 
modules starting sometime next fall 
or winter should contact me.

Until then, keep an eye out on your
local BBS for the ST Transformer
which I hope to have released in
June. I will update the situation on
the board I hang out on, Megabaud 
416-243-9519. Anyone having any 
suggestions on the program or who 
can help me with the legal questions 
can reach me on Compuserve or write 
to me before May 1 ,1987 at 5023 
148th Ave. N.E. #G207, Bellevue, 

[ED.] In addition to this text sent
in by Darek. I would like to add that
I have spoken to this gentleman 
myself and feel that he is entitled
to some type of official response
from Atari Inc. In the weeks ahead
and until we feel that Atari is
looking into this matter, we will
update you on a weekly basis and
next week, we will supply you with
a few names and addresses to send
off letters to. If we can produce a
loud enough voice as 8 bit owners,
we can perhaps persuade Atari to

Xx PCP Update
   BY:Steve Godun

Info from Mark Asbell (El Paso, TX)
Thanx to The Vault BBS 303-796-0539

Many computer users across the
country use a service called PC
Persuit (henceforth referred to as
PCP).  This article is provided to
those who want more from PCP.

Did you know that PC Persuit has many
functions that aren't stated in the
user manuals OR in the PCP
Newsletter?  When I found out what
PCP could do, I was curious as to why
none of this isn't stated anywhere.

Anyway, back to business.

Most people who use PCP are quite
familiar with the "ATZ" command and
the "OK" prompt.  Most people think
that that's all PCP has to offer.
WRONG!  There as an entire section in
PCP accessed by a single keystroke
that can help you a lot!

By simply pressing CONTROL+E (for
"E"nhanced?) and RETURN, you will see
"HELLO:I'M READY".  This is the
doorway to the "extra" commands. Most
of the commands you will never use,
but many of them you will.

For example, to dial a number in
"regular" PCP, you would have to type
"ATDTXXXXXXX", and then you would see
either "CONNECT" or "BUSY",  In the
"enhanced" PCP, all you have to type
is "Dxxxxxxx".  Enhanced PCP will
tell you what is happening by posting
"DIALING...", and then either "BUSY!"
(and return you to the command
prompt)", "RINGING...", and/or
"ANSWER TONE:ON LINE".  It will also
say such things as "CONNECT FAILURE"

Other features in Enhanced PCP are
redial last number (up to 9 times)
and the ability to disconnect from a
BBS on your side (very helpful when
the BBS is running an Avatex modem
which will not hang up by itself).
For a complete list of these and more
commands, type a question mark (?)
after the "HELLO:I'M READY" prompt.

To subscribe to PCP, you may call
PCP's 24 hour online guide and signup
BBS at 1-800-835-3001.  Fee is $25
per month, flat rate.  More info is
available on the PCP BBS.

Supplied by the CHAOS BBS-
Reprinted From
by permission.

Compiled by John Nagy

reality, on the other hand...  for a
while, anyway.  Two problems are are
the major hangups:  negotiations for
GEM for the machine, and FCC
acceptance.  Neither area has had any
positive movement, despite ATARI's
optomistic projected "spring '87"
release of the $500 do-it-all PC
compatible.  The GEM interface, owned
by DIGITAL RESEARCH Inc., would make
over 700 ST titles directly portable
to the machine, but according to DRI,
no agreement is near on the licensing
of the interface.  Additionally, FCC
type acceptance is neccesary for any
commercial computer product, a
process that can take literally
forever, but never less than about 40
days.  ATARI hasn't even APPLIED for
approval, since there is not yet a
finished production model.  Industry
observers note that the announcement
has seriously turned down the
purchases of the ST machines, and
that the lost sales cannot be made up
for within the ATARI line because the
new machine isn't ready.  This is
themselves out of business a few
years ago.  They announced that a
great new machine would be out
shortly, which killed sales of their
available product, and then couldn't
produce the new product due to lost
revenue and production problems.
Can't ATARI learn from history?

ATr a long seige
of difficulty in negotiations with
ATARI, Detroit's 400-plus member
M.A.C.E.  club threw up their hands
and pulled out of the effort,
cancelling a planned August '87 show
for the Southfield Civic Center. 
Before the body was cold, the
competing Detroit area ATARI club,
MAGIC about 90 memeber strong,
contacted ATARI and took up the
torch.  They even got SANDY AUSTIN,
ATARI's user group contact, to come
to Detroit to discuss it.  Hard
feelings abound, with some M.A.C.E. 
members crying FOUL, since they had
not been able to even get Sandy to
return some of their calls.  What
next?  Film at 11:00.  In CHICAGO,
union costs may make the ATARIFEST
planned for there simply too
expensive to hold.  Requirements of
unioned employees only to carry all
equipment, set up anything
electrical, etc.  have driven
projected costs through the roof.
Again, we will tell you more when we
know it.

ANTIC MAGAZINE's publisher Jim
Capperell wrote to Detroit's M.A.C.E.
to notify them that they had to
remove any and all ANTIC programs
from their BBS.  He reaffirmed that
they are copyrighted, and to exchange
them is PIRACY.  Despite previous
"understandings" about such things,
it now looks like ANTIC wants to play
hardball.  Nothing was said in the
letter about library inclusions of
ANTIC material, but that is probably
next.  This will be quite a blow to
many smaller clubs that have had
almost nothing else in their club
library but ANTIC and ANALOG
material.  ANALOG went on record last
year saying that their materials
could not be disrtibuted BEFORE THE
PUBLICATION DATE of the magazine, a
very reasonable policy.  Even a
six-month "cooling" period would be
understandable...  does ANTIC really
think they are likely to sell their
older disks if the programs can't be
gotten elsewhere?  More likely, they
will simply fade altogether.  Looks
like ANTIC wants to be like SOFTSIDE
magazine...  hard to deal with, then
gone altogether.

8-bit DOS ON A CART:  Spartados from
ICD is not the only player in the
DOSCART game anymore...  and the
competition is coming from MICHEAL
DOS 2.5 on a cart and added true
double density support and a ramdisk
handler.  Although it is memory
-greedy (16k when resident), the cart
can be switched out manually. 
Another switch handles BASIC in or
out.  This looks like a basement
operation, as plans and code for
eprom burning yourself are available
for $5, and we don't have a price on
finished carts.


P.O.  Box 104013

.......Super Mario Brothers.......
For the Nintendo Entertainment
System, (C)1986 Nintendo, Inc.

Review by Steve Godun

"One day the kingdom of the peaceful
mushroom people was invaded by the
Koopa, a tribe of turtles famous for
their black magic.  The quiet, peace
loving Mushroom People were turned
into mere stones, bricks, and even
field horsehair plants, and the
Mushroom Kingdom fell into ruin.

"The only one who can undo the magic
spell on the Mushroom People and
return them to their normal selves is
the Princess Toadstool, the daughter
of the Mushroom King. Unfortunately,
she is presently in the hands of the
great Koopa turtle king.

"Mario, the hero of the story (maybe)
hears about the Mushroom People's
plight and sets out on a quest to
free the Mushroom Princess from the
evil Koopa and restore the fallen
kingdom of the Mushroom People."

So begins the instruction manual for
"Super Mario Brothers".  This gives
you the general idea of the whole
game, but there is more to it than
that.  This game (the fifth in the
popular "Donkey Kong" series) plots
you as the hero Mario (or, in two
player mode, as Luigi) trying to get
through several "worlds" of bricks,
coins, fire pits, and a host of
assorted baddies ranging from the
easily killed "Little Goomba" to the
dreaded "Bowser, King of the Koopa",
who can only be killed by several
direct hits of your fireballs.

"Super Mario Brothers", for those of
you who haven't visited an arcade
since the days of Pac-Man, is one of
the hottest games today. This arcade
-to-home cartridge comes extremely
close to the arcade game, but small
differences between the cart and the
arcade machine makes the difference.
Its main fault lies in the 20-page
instruction manual, which I will tell
you about later.

To give you a general example of the
quality of this cartridge, my scores
at the arcade version of this aren't
all that hot, but after playing the
cartridge a few days, my arcade
scores soared!

Playing the game is fairly simple.
Using a controller in port 1, you
controll Mario/Luigi's movements
across several "worlds", which are
divided up into 4 rounds. Your on
-screen character can walk, run,
duck, jump, swim, throw fireballs,
and climb (only experienced players
will know when to climb).  Covering
each world are many dangers, traps,
and bonuses.  Dangers include things
like attacking turtles (both by land
and by air), fish (in the water and
in the air), nearly indestructable
beatles, and mutant fireballs. Traps
like pits and rotating "bars" of fire
hinder your progress, while things
like mushrooms, flowers, and stars
increase your powers.

What is most interesting about this
game is how you lose a life.  When
you are in "regular" Mario mode, any
baddie or trap will kill you. 
However, if you happen to uncover a
magic mushroom, you become Super
Mario.  You grow to twice the size
(very handy for reaching those high
placed coins), but nothing else
happens to you.  If you are REALLY
lucky, you will find a Fireflower.
This baby will turn you into Firey
Mario, and now you can now hurl
fireballs at your enemy to wipe them
out.  If, while you are Super Mario
or Firey Mario, you hit a baddie, you
don't die.  You simply revert back to
regular Mario and continue on. A pit,
however, is always fatal no matter
what stage you're in.

You can pick up coins along the way
for points and for free men (100
coins=1 free man).  There are a few
other ways of getting free men, but I
won't reveal them.  If you happen to
find a star (known as "Starman"), you
can pick it up and become
indestructable for a few moments
(but, of course, pits can still kill
you). Secret tunnels, hidden prizes,
and warp zones complete the package
of surprises.

That was the good stuff...Now for the
bad.  The major flaw here is the
manual.  There is no excuse for poor
documentation.  If Nintendo was lazy
enough to put out such a great game
with lazy docs, then that hints at
their customer relation work, doesn't
it?  Anyway, the manual is VERY
incomplete.  What starts to look like
clever hints that attract your
attention soon appear to be
ommisions, misprints, and even
outright errors.  For example, the
manual states "At the end of an area,
fireworks may go off, and for each
explosion you get 500 points.  The
reason (for this) is a secret; see if
you can figure it out."  I bought
"Super Mario Brothers" when I bought
the system, and it took me about a
month and a half to figure out why
they go off.  That's REALLY annoying,
and I can't see why they don't just
tell you in the first place!  If it's
just a ploy to get you to play more,
it isn't needed; The gameplay of the
game is good enough to keep anyone at
it for a VERY long time!

Another part of the manual says
"Pressing the RESET switch...will
cause the hi-score to be reset."
This is not true.  Pressing RESET
simply resets the game to the title
page and the hi-score is still
intact.  A typo?  Maybe.

Overall. this cart is a masterpiece
of programming.  If you like the
arcade game, you'll love the cart.
The $25 list price isn't that bad,
especially since I spend more than
that on the arcade game.

...130XE/800XL Battery Backup...
by:Peter Hunter

This Battery Backup system is
designed to work with the Atari
130XE, or 800XL computer.  If you are
running a BBS on an expanded memory
Atari, this will allow you to run the
message bases in the Ram-Disk without
fear of losing them due to those
little power "blips" and long
outages.  The little 10 second power
losses are the most frequent cause of
heartache to a BBS SysOp.

Well!, fear no more.  This hardware
project has been several months in
the making and testing.  I have been
using it on my BBS (BBS: EXPRESS!)
for about 3 months now and the Great
thing about it is you don't even have
to open the case on your computer as
it requires no alteration to your
computer what so ever.

At first I thought about offering it
to Antic, or Analog for a hardware
project but then decided to release
it as a SHAREWARE type, hardware
plan. As you already know, Shareware
really isn't Public Domain material. 
If you use these plans and they work
for you, any donation you care to
make will be appreciated and!, might
encourage me to design a battery
backup for the MIO board by ICD,
which would certainly be cheaper than
a UPS, transverter type system for
about $200.00 and up.

Plans For Battery Backup are
Copyright (c) 1986 by:

Pete Hunter Auctioneers Inc.
2760 W. Whiteside
Springfield, MO  65807

These plans can be built for about
$25.00 from Radio Shack Parts. The
Author accepts no responsibility for
them due to inability to control
user design techniques and

Send all inquiries or donations to:

Pete Hunter
2760 W. Whiteside
Springfield, MO .. 65807

This circuit diagram was written with
TextPro and should be viewed same or
similar type program to be shure that
some of the control arrow symbols are
displayed properly.

        | 12 Volt  |
   -<<<<o Battery  |
  Ground    o--o---o+Positive
            |  |
            |  D1
         R5 /  -    Voltage Regulator
            \  |    276-1770
            /  |    7805             
            o--o  |______|
     1N5400    |  |   V1  |          
     276-1101  |  |In     |Out    +5v
    |       |  |  | Gnd|      |  |
    |       |  |  |    |      |  |
    |  C1   |  |  =C4  |      \  =C5
    o--|(---o  |  |.1uf|    R4/  |
    | .01uf |  |  |    |      \  |
T1  |       |  |  |    |      |  |
o)|(o       |  |  |    |      |  |
 )|(--Gnd. |  |  o----o--o---o  |
o)|(o       |  |       |  |   |  |
   |       |  |       |  |   |  |
1   |  C2   |  |+    R1\  \   \R3|
1   o--|(---o  =C3     /  /R2 /  |
7v  | .01uf |  |4700   \  \   \  |
    |       |  |uf     |  |   |  |
    |       |  |       |  |   |  |
    o-->|---o  o-------o--o---o--o-
     276-1101                   Gnd.
     1N5400    Gnd.                 

Power Plug connection to computer.
Pin Configuration

           7.   .6   
          3.     .1    
           5.   . 4   

1. +5 Volts
2. Shield
3. Ground
4. +5 Volts
5. Ground
6. +5 Volts
7. Ground

If you can't find a 7 pin, DIN plug
like what is on your Atari power
supply you can get a 5 pin, DIN plug
from Radio Shack..#274-003 for the
power plug....

If you use the 5 pin plug be extra
careful as it is the same plug that
goes into the Monitor Jack.  If you
plug 5 volts into the Monitor Jack
I am sure you would have problems so
paint the plug red or something like
that if you use the 5 pin plug.  Any
of the terminals that are marked +5
or ground will power the computer.

NOTE*  All part numbers given are
Radio Shack Part Numbers. Other parts
of equal value may be substituted.

Parts List:
T1..Transformer..273-1515..18vct (2A)
V1..276-1770..5v regulator
Heat Sink for above..276-1367
D1,D2,D3..276-1101..1N5400 Diodes
R1,R2,R3..271-1301..10 ohm resistors
R4..271-012..100 ohm resistor
R5..Optional...See text!
C1,C2..272-131..0.01uf capacitors
C3..272-1022..4700uf..35v capacitor
C4,C5..271-135...1uf capacitors

This power supply can be assembled
without a PC board  by using a 5 lug,
terminal strip. Be extremely cautious
as you will have 117 volts present.
The 2,  117v wires on the transformer
should be taped and insulated to
prevent electrical shock. A PC board
and plastic or metal case may be used
if desired.


Some electronic experience is MOST
ESSENTIAL to build this project.

DON'T EVEN attempt it if you don't
have the qualifing experience.  Get a
friend or someone knowledgeable in
this area to help.  Most "HAM" Radio
operators would be able to help.


First wire the line cord to the 2,
117 volt power supply leads on the
transformer and insulate them by
taping etc.  You may also want to put
a 1/2 amp fast/blow fuse inline on
one side of the power cord for
protection. You can tell which side
of the transformer to hook the 117v
line to because the low voltage side
has 3 wires coming from it and the
117v side only has 2 wires.

Assemble the rest of the circuit as
per the diagram. Look the circuit
over very carefully before starting
and if it is in a text file on disk
I strongly recomend dumping it to the
printer,  or drawing it out on paper
before starting the assembly.

If you use a metal case for your
power supply don't let the regulator
or heat sink get against it.  Some
people like to bolt the heat sink to
the case for extra cooling but it 
will cause a short with this
particular type of regulator.  If
extra cooling is needed bolt it to a
piece of scrap aluminium and keep it
insulated from the case.  A plastic
case REALLY is better for our

At the top of the diagram you will
find "D1" and "R5"...This is the
diode that allows the current to flow
from the battery to the computer upon
power failure. The resistor "R5" is a
"BYPASS" "current limiting" resistor
to allow the power supply to charge
the battery.  You may or may not want
"Charger" capabilities.  If you use a
Motorcycle, or Car battery you will
probably want to charge it a small
amount. A 140 to 150 ohm,  1/2 watt
resistor will allow about a 100
milliampere charge rate. A 700 ohm,
1/2 watt resistor would allow about a
20 milliampere charge. In order to
determine other charge rates and the
proper combination of resistors I
suggest you purchase an "Ohms Law
Calculator" from Radio Shack for the
small price of about 50 cents. It is
a small, sliding, cardboard chart
similar to a slide rule.

In summation of the charging system:
If you don't want to attempt to build
it just delete "R5" from the circuit
and charge the battery manually, with
a separate battery charger. You can
insert a DC Amp Meter in series with
"R5" to determine the amount of
current that is actually going to the
battery.  The Diode "D1"will only let
the current go in one direction which
is from the battery to the computer.
No voltage will be allowed to go
"upstream" from the computer to the

If you use lantern type batteries,
they are not designed to be charged
so delete "R5" from the circuit
should you decide to use this type. I
recommend a Motorcycle, Garden
Tractor, Car Battery, or Gel Cells be
used as these will keep the computer
going for several hours. If you use
Gel Cells be sure they are at least 5
Amp hour batteries. A 12 Volt battery
IS NECESSARY even though we are only
ending up with 5 volts to the
computer.  The 7805 regulator needs
at least 3 volts above it's operating
voltage to work properly.  Thus the
12 volts as 8 volt batteries are in
short supply.  Anything other than 12
volts are not recommended because
that is what I designed the circuit
to work with.

If you have trouble,  questions, or
suggestions please call me at my BBS
in Springfield, MO....

The Auctioneer BBS
417/887-4969...24 hours or!, write to
me at the address at the top of the

Please feel free to share these plans
with your friends, or other BBS'.
They are intended for public
distribution and may be shared or
distributed freely.

Good Luck!
Hope you enjoy the project!
Xx Editor Comments

You will notice a slight difference
in this issue as compared to recent
past releases. Our editor Alan Kloza
had a major problem this week with
his hardware and I have taken on the
job of compiling this weeks edition.
It has been a few months since I sat
down behind the keyboard and put
together a regular Zmag issue. I
hope Alan gets his hardware repaired
soon, as his talents have been missed
this week.

A new file was uploaded the Zmag
Headquarters this week. I have 
renamed it to ZPRINT7.BAS and it is
available on the Syndicate. This
file will print out your Zmag issues
in three columns on any Epson or
compat printer. 

ZREAD31 has also been released and
is written in Turbo-Basic. This file
contains the updated Zmag BBS systems

Look for ZREAD4 in the very near
future. This will be an ARC file 
with a font and other files for
updating later. Details will be
here in the weeks ahead.

Welcome to Spring!!
ZMAGAZINE 43  MARCH 16, 1987 
Please contribute!!
(c) Syndicate Services 1987
These articles can be reprinted as
long as the following appears at the
top or bottom of the text.

Reprinted by permission ZMAGAZINE
New Jersey (c)Copyright 1987

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