Patch for Cubit on Laser 128 Posted

screenshot_0_Q-Bit_0

Steve Nickolas has posted a patch which fixes the Apple II game Cubit on the Laser 128 computer.  Cubit was a 1980’s clone of the popular Arcade game Q-Bert and was long the bain of those users who purchased the Video Technology produced Laser 128 Computer.  A single memory location jump was causing the game to stop mid-stream as explained by Steve below:

My experience has been Cu-bit breaks on a Laser due to firmware
incompatibilities because it jumps to an undocumented entry point.

It’s a one-byte patch.

Context:

78D8-   4C 76 40    JMP   $4076
78DB-   CA          DEX
78DC-   E0 00       CPX   #$00
78DE-   D0 EB       BNE   $78CB
78E0-   4C A4 76    JMP   $76A4
78E3-   20 33 FB    JSR   $FB33    <– derp!
78E6-   20 58 FC    JSR   $FC58
78E9-   A9 02       LDA   #$02
78EB-   20 C1 FB    JSR   $FBC1
78EE-   A0 00       LDY   #$00
78F0-   B9 AC 7A    LDA   $7AAC,Y

On the Laser, that JSR causes the code to go off into lala land.

The fix is to change that line to 20 2F FB (JSR $FB2F), which does the
right thing on both Apples and Lasers.

The patch:

*78E4:2F

The game is playable on the Virtual Apple II website at:
http://www.virtualapple.org/q-bitdisk.html

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About the Author

billm

A.P.P.L.E. Chairman of the Board and Club president — Bill worked for the founder, Val J. Golding and A.P.P.L.E. from 1981 to 1982. In 1999, he began archiving the materials which were distributed and sold by A.P.P.L.E.. That project led to the group that remained of A.P.P.L.E. Bill was involved in the financial industry in Tokyo and has over 20 major office infrastructure projects to his name. In March 2001, he retired to write books and to spend more time pursuing personal interests. As the president of the users group, Bill is in charge of distribution of Call-A.P.P.L.E. magazine as well as the organization of this web site. Bill currently resides in Tokyo, Japan and Shelton, Wa splitting time between the places.