#16025·mame

Apple IIe and IIgs joystick->keyboard emulation has directional error in some games

Author: AOcarsonCreated Aug 31, 2026Updated Sep 14, 2026

MAME version

0.289

System information

MacOS 15.7.9 and Windows 11 Apple Silicon M4 and Ryzen 9 x64 Default graphics for Mac, Integrated on Windows

INI configuration details

ini
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# CORE CONFIGURATION OPTIONS
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coin_lockout              1
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#
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paddle_device             keyboard
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dtd                       1

Emulated system/software

Apple IIe, IIgs

Incorrect behaviour

There are several games that seem to have an issue when using the keyboard to emulate an Apple joystick, when moving to the right or down. The main issue is found is with Boulder Dash II, Rockford cannot move down fast enough to not be crushed by falling boulders. When moving to the left or up, the sprite shows left or up and he moves quickly. When moving to the right or down, it shows to the right, facing the viewer, to the right, facing the viewer, to the right, and he moves in a halting motion. I have adjusted the increment, sensitivity of the X and Y axis, I have adjusted the centering, I have inverted the access and use different keys, it always ends up a problem, moving to the right and down.

Expected behaviour

The character should move the same speed right as left, and down as up, without the halting behavior currently seen.

Steps to reproduce

mame apple2e -gameio joy -flop1 ~/Desktop/Boulder\ Dash\ II.dsk

This does not come up using AppleWIN, or KEGS. I looked through the code for AppleWin joystick.cpp and noted that it has a special value assigned to maximize joystick input values when they are 255, it time it so that there is not a delay in the poling behavior.

This seems to be an issue with the joystick emulation on the keyboard, not an issue with the Apple IIe or IIgs emulation. The KEGS and AppleWin code have the modification below, and neither of those two emulators has an issue when playing this game and others, when moving to the right and down.

// This is from KEGS. It helps games like Championship Lode Runner, Boulderdash & Learning with Leeper(GH#1128) if (pdlPos >= 255) pdlPos = 287;

Is there a way to have a per-game patch so that the MAME joy device can be used to emulate and play these games? Thank you!

Additional details

Using a simple basic program (10 PRINT PDL(0), PDL(1) 20 GOTO 10), the paddle shows 128 as a default value, it moves to 0 with a left keypress, and to 255 with a right key press. It seems to be an issue when the joystick emulator reports instantly going to 255 and misses some timing loop.