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!Help_Joy
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1993-03-29
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The Arc_Welder Joystick Interface
---------------------------------
Copyright I.Haylock 1993
This interface is designed to enable two joysticks to be
connected to the Archimedes via the Parallel printer port.
The Draw file provided shows the layout of the interface
on Veroboard. The only track cutting required is between the
pins of IC1 & IC2
The interface is designed to use the switch type joystick
normally found on the Atari or Amiga computers.
Software
--------
JoyMod
This module is supplied to drive the interface and follows the
Acorn standard for joystick interfaces. Simply copy this module to
the games directory and add the line :
RMEnsure Joystick 0 RMLoad <Obey$Dir>.JoyMod
to the games run file.
If the game follows the Acorn guidelines the program should now
run using the joysticks. Two games that I know of that use this SWI
are !SWIV and Spheres Of Chaos. If you have either of these games
they may be used to test if your joystick port is actually working.
To use the module in your own programs Use SWI "Joystick_Read"
to read the joystick
This requires R0 to contain the number of the joystick you wish to
read i.e 0 for joystick 1
1 for joystick 2
And returns with :
Byte 0 of R0
&C0=down &00=rest &40=right
Byte 1 of R0
&C0=left &00=rest &40=right
Byte 2 of R0
&01=fire &00=rest
Joy_Key
Not many games as yet appear to use the Joystick SWI, so I have
written a module which traps keyboard scans and uses the joystick to
emulate key presses. To create the module simply run the program
'Key_Emulate' and you will be asked to press the keys required for each
joystick position. When this is completed the program will generate a
module called 'Joy_Key' in the currently selected directory. Copy this
file to the games directory and add the line :
RMEnsure Joy_Key 0 RMLoad <Obey$Dir>.Joy_Key
to the games run file
If the game is compatible with the 'Joy_Key' module the game should
now work using the joysticks. Not all games work and I have a list at the
end of this file of those that I know work and those that don't.
Limitations
-----------
The interface will NOT work with the A5000 or any Arc using
the same chipset to control the Parallel port :-(
(If someone tells me the new address for the port I will alter
the software to use this new address, but until then......)
Component List
--------------
IC1-IC2 = 74HC151
C1-C2 = 0.1uF
R1-R10 = 100k
R11 = 1k
2 x Male 9 Way D Connector
1 x Male 25 Way D Connector
Vero Board Approx 10.5 cm x 5.5 cm
(Tracks Running Width-Wise)
Compatible Games
----------------
I have tried some games with the Module and the following appear
to work ok :
AdAstra
ArchieMan
Elite
Enter The Realm
Gods
James Pond
Legend Of The Lost Temple
Mad Professor Mariarti
Man United Europe
Nevryon
Pacmania
Quazer
Spheres Of Chaos
Swiv
Twin World
All these games were run on a 2 Meg A3000 running RO 2 and RO 3.11
and caused no problems.
Non Compatible Games
--------------------
These games I've tried and do NOT currently work with the software:
Rotor
XRun
Yaig
Zelanites
Enhancements
------------
Using the same layout as in the draw file leaves enough room on the
veroboard to fit extra resistors and links to enable the unused inputs
of the MUX's. This means there are then two spare inputs available on
each MUX, enableing three independant fire buttons to be used.
This requires modifications to the wireing of the joystick and the
software, but isn't difficult so I may get around to it one day.
One reservation I have is that the extra overheads caused by scanning
for the extra inputs may cause flicker in some games,
i.e Manchester United Europe,
as my original software caused a line to appear across the picture in this
game, I have speeded up the software to remove this, but adding the new
routines may bring the fault back.
_______________________________________________________________________
Disclaimer
----------
Building this port and connecting it to your computer must be at
your own risk. If you do go ahead and build this Interface port and
blow your computer up don't blame me.
Having said that any problems you have with the software I can be
contacted on Arcade as user 'Garrard' user number #989