Apple II joystick game problems

[+eebuckeye]

Why is it that I can play some games perfectly with my joysticks and others will not work or only partially work (like only left and up working)? I calibrate in game if there is an option but some games do not calibrate and work great while others have no calibrate option and do not work correctly.

 

Some games ask either Apply joystick or Joyport and I always select Apply joystick. What is the joyport? Is it better than Apple joystick? Does it work with all games?

 

Thanks!

[ianoid]

Most Apple II joysticks have a trim control, usually knobs or sliders for each axis (X and Y). The common designs have them easy to reach, but occasionally they require a flat head screw driver. They may require frequent adjustment for different games.

Edited January 12, 2016 by ianoid

[+eebuckeye]

Yep.. I am aware of that... strange that I don't change it and some games (without calibration) work great. I even try to adjust in game and nothing seems to work.

[cybernesto]

The Joyport was used to attach digital Joysticks to the Apple II. See https://en.m.wikipedia.org/wiki/Joyport

Are you using an official Apple Joystick? Some compatible Joysticks used some tweaks to come into the valid range of the Apple joysticks but did not provide the complete value range because the potentiometers were not 150k, which is a pretty rare value.

But maybe it is possible to patch the games to make them compatible with a wider range of joysticks. Do you have a list of the games that present this problem?

[MarkO]

The Joyport was used to attach digital Joysticks to the Apple II. See https://en.m.wikipedia.org/wiki/Joyport

Are you using an official Apple Joystick? Some compatible Joysticks used some tweaks to come into the valid range of the Apple joysticks but did not provide the complete value range because the potentiometers were not 150k, which is a pretty rare value.

But maybe it is possible to patch the games to make them compatible with a wider range of joysticks. Do you have a list of the games that present this problem?

You can't patch the Games...

 

The Apple Paddles and JoyStick use a "strange value", because Woz didn't use an Analog to Digital Converter ( ADC ) to read the Potentiometer... There is a Capacitor that is Charged in a given interval, and that is sensed to achieve the reading....

 

You need to make the Hardware reproduce the 0-150K Ohm range.

 

MarkO

[+eebuckeye]

Ms. Pacman is a game that works in all directions except right. Jumpman is another where the controls are not working correctly. Both of these games just select joystick with no calibration.

 

Other games that have calibration or even others that do not work fine. I have tried three different joysticks with one being an Apple joystick. All of them act the same.

 

Any ideas? Thanks!

[trash_44fr]

You can try the MECC Computer Inspector disk.

There is a graphical joystick calibration utility. Great to see what's going on...

[+eebuckeye]

Yep.. I just found that last night! It shows everything working great.. all directions and buttons.

 

Any idea why a few games might have direction problems? I do not see anyway to calibrate in Ms. PacMan for example.

[Osgeld]

You can't patch the Games...

 

The Apple Paddles and JoyStick use a "strange value", because Woz didn't use an Analog to Digital Converter ( ADC ) to read the Potentiometer... There is a Capacitor that is Charged in a given interval, and that is sensed to achieve the reading....

 

You need to make the Hardware reproduce the 0-150K Ohm range.

 

MarkO

 

most of the old machines didnt use a ADC for joystick, almost every single one of them used the same arrangement of quad 555 timer up until the IBM PC (it may have changed in later PC compatibles) cause it was cheap, simple and 555's are tanks. Each axis is connected to a 555 that's wired up in monostable mode

 

Output starts low, the computer basically pushes SW1 to reset the timer and output goes high, R1 controls the charge rate of C1, and when C1 reaches 2/3 of VCC (5 volts in most computers) the 555 trips, discharges the cap through pin 7 and output goes low again. The raitio of the RC (R1 and C1) determines how long the output stays high, meanwhile the computer is polling the output and counts how many cycles the output is high, simplfied, 0 cycles is dead hard left, 255 is dead hard right

 

Why did Woz use a screwball pot? Probably HP, he designed the early apple's while interning there and they used 150K ohm pots on a lot of their analog test equipment, and once your in production its easy to get any part you please so why break compatibility later on.

 

What you can do about it, now we all know whats going on is you can increase the capacitance of C1. and you can do that by just adding a cap to the middle pin of the pot inside your joystick, to ground, also inside your joystick. This will put a capacitor effectively in parallel with C1, which will increase its total capacitance, since the capacitance is larger you can use a smaller pot and still get the same results on the output.

 

How do you know what capacitance to use, maf of course

((original_potentiometer_value * internal_timing_capacitor) / new_potentiometer_value) – internal_timing_capacitor

so we know some things

original_potentiometer_value = 150K

internal_timing_capacitor = 0.022 uF according to the apple //C schematics I have on hand, and should be the same for all apple II computers

new_potentiometer_value = well lets say we want to use a PC joystick which is 100K

 

SO

 

((150,000 * 0.022) / 100,000) - 0.022 = 0.011uf

 

0.010uF is a extremely common value (or 10nF or cap code 103) which will give 99% of full range when added from the middle contact of a 100K pot on one lead and ground on the other

 

simple eh?

 

now whether this has any effect on the OP's problem I dont know, but its fun to explain

Edited January 16, 2016 by Osgeld

[cybernesto]

You can't patch the Games...

Of course you can! Most games use a simple CMP instruction to check if the PDL values are within some boundaries. If they exceed a value, then up, down, left or right are recognized. This is also the case for Ms. Pacman. If eebuckeye had just one non-Apple joystick, he could perfectly patch the game to change these values and make it compatible with his system. But, unfortunately, that's not the case.

So, eebuckeye, if you have the same behavior with all joysticks and the MECC utility shows your joystick is perfectly centered and it covers the complete value range, there must be something going on with the game... Maybe you picked up a patched version from someone with a skewed joystick? [emoji1]

Have you tried the Ms. Pacman version from 4am? It is as original as it can be. It works on my //c even when I use my homemade digital joystick adapter without problems. I have also been able to use it with a Computek analog joystick and the Apple joystick without recentering.

[+eebuckeye]

I have tried two different images and I have an Apple joystick and 2 different Kraft joysticks with the same issue.. very odd.. and it is not just one game... but the joystick diagnostic program works great.

[Great Hierophant]

 

most of the old machines didnt use a ADC for joystick, almost every single one of them used the same arrangement of quad 555 timer up until the IBM PC (it may have changed in later PC compatibles) cause it was cheap, simple and 555's are tanks. Each axis is connected to a 555 that's wired up in monostable mode

 

Not really (with the exceptions of the Tandy 1000s and Amstrad PC-1512 and 1640), all gameports rely on a 558 quad timer just like the Apple II. They are often seen on sound cards, even very late ISA ones. There is even an early Sound Blaster Live! PCI with a discrete 558.

 

Most speed adjustable PC gameports would have a dial which appears to be a variable capacitor.

[Osgeld]

that's what I said

 

almost every single one of them used the same arrangement of quad 555 timer

 

a 558 is just 4 555's in a chip

Edited January 18, 2016 by Osgeld