There's a bug in the code of the left Magna Save button in Jungle Lord that messes up the lamps when you press the button during the light show when Stampede Mode is started. Jess Askey provided the fix, which is included in all the different home ROM versions floating around.

My other two games -- Alien Poker and Pin Bot -- also have bugs, but I have not upgraded these to the most up-to-date codes. Just yesterday I was finally ready to upgrade Pin Bot only to break both sockets on removing the original chips. The sockets have zero springiness left for maintaining contact or even holding the chips in place -- quite a funnily annoying failure mode, I ended up thinking. And now I have some board work on my to-do list, before I can even play again.

Ours is a great hobby

I found three bugs in the Pinbot L5 code. I have fixes for all of them and would *like* to release those but am not sure how. In the mean time, here's documentation:

Bug#1 Energy Value Limit. The Energy Value is supposed to be limited to 500K. Instead, it starts looping like this : 498-500-502-504-506-508-500-502-... The culprit is a subroutine starting at address $627A. This bug is largely cosmetic.

Bug#2 Solar Value Limit. There is a similar bug in the Solar Value limit, which is supposed to be limited to 5M. The buggy routine starts at $77CB.

Bug#3 Visor Open code. This is an interesting bug; I do not think that it affects game play on machines with fully functional visor mechs. It might well affect games with visor problems, though. The problem occurs when the visor is already open and the software, for one reason or another, decides that it wants to open the visor. In that case, what the code should do (as it does in the visor-closing routines) is simply ignore the visor open command. What it does, instead, is cycle the visor (close, then open). The underlying problem is that a BGT instruction (at $B769) is used to test a variable that takes on only the values 0 and -1 ($FF). Neither of those two values causes the BGT to branch. The bug can be fixed by replacing the BGT either with a BPL or a BEQ and updating the checksum byte at address $BFFF.

While making the “PEMBOT (no relation)” home ROM, I found and fixed the following bugs in the L-5 release of the Pinbot code. Earlier versions have additional bugs that I did not look into.

• When two switches are hit simultaneously during the chest skillshot (i.e. when one lit and one unlit targets are hit), the skillshot is only awarded when the left target is lit but not when the right target is lit, i.e. the skillshot is not always awarded when a lit target is hit.

• During multiball when one of the balls ends up in the shooter lane double scoring is disabled and should stay disabled until the ball is served again. However, double scoring is re-enabled erroneously whenever the other ball that’s still in play hits any switch.

• Timed shots are paused when a new ball is served. While timed shots are paused they continue making sound but do not blink, which makes it impossible to see which shots are active.

• Timed shots are paused on entering the ramp and re-started when the upper PF is exited via the right inlane or the shooter lane. However, the timers are not restarted on aborted ramp shots or when the ball exits the upper playfield over the side and the ramp thunderstorm F/X times out. As a result, you can trap such a ball and have an infinite amount of time to make the timed shots.

• Both the Solar and Energy value show weird behavior around their max value. The energy value, which should max out at 500K, shows the following sequence 498K, 500k, 502K, 504K, 506K, 508K, 500K, 502K, …

• When a game is restarted with the start button during balls 2 or 3 the current game is aborted. When open, the visor closes immediately and any locked ball is available as a “stolen lock” for the newly started game.

• During multiplayer games, after a ball has drained but before the bonus count begins, the lamp status of the next player flashes briefly on the playfield while the game checks to see whether the visor should be opened/closed for the next player.

• When the single eject is set on a timer, and the shot is enabled by making the right inlane, the corresponding lamp (25K, 50K, 75K, EB) starts blinking. When the shot is made, the corresponding lamp is lit. When the shot is left to time out instead, the corresponding lamp is lit as well. As a result, you cannot tell from the lit lamps whether the next award to be enabled with the inlane is the last one that is lit or the first one that is unlit.

• The timeout for entering initials after a high score is too short and you never get to hear the very nice ending of the high-score melody.