Pac-Man Zip mod

mecha

Well-known member
Joined
Apr 19, 2007
Messages
24,333
Reaction score
7,039
Location
MKE, Wisconsin
anyone familiar with this modification on Pac-Man boards to turbo the entire game with a button?

I can decipher where the wires go but that white glob I would venture there's some caps inside or something.

IMG_20250813_180329474.jpg
 
Is this your board? Can you post what all the wires are connected to?
it's from the Pac-Man at work. it needs edge surgery and caps. so I put a better board in the game.

according to gamefixer it's the old turbo mod before the fast roms. my grandpa had a Ms. Pac-Man mini with probably this mod but without the Zip button, the whole game just ran twice as fast all the time. which was annoying cause the ghosts were just as fast. 🤣

I was hoping someone could share what's under the white glop.

Maybe the "little black box mod" near the bottom of lawnmower man's page?

I can check this out later. thank you
 
Looks like it wires identical to the Zoom button mod, not sure what's inside the puck.
 

Attachments

  • IMG_6029.jpg
    IMG_6029.jpg
    474.4 KB · Views: 17
  • IMG_6031.jpg
    IMG_6031.jpg
    686 KB · Views: 20
  • zoom page1.jpg
    zoom page1.jpg
    68.7 KB · Views: 20
  • zoom page2.jpg
    zoom page2.jpg
    27.4 KB · Views: 17
  • zoom power flyer.jpg
    zoom power flyer.jpg
    89.4 KB · Views: 15
Looks like it wires identical to the Zoom button mod, not sure what's inside the puck.
that looks like the exact mod, just minus the puck and engineered a lot hackier. oh, and called Zip instead of Zoom. I'm certain the button says Zip. lol
 
Think it was a East vs West Coast thing. We got the Zoom, others got Zip.

I've have a Pac cocktail with a Zip button I've never opened up, I can take a peek tomorrow.

HnTA55L.jpg
 
I was hoping someone could share what's under the white glop.


I can check this out later. thank you

Some sort of TTL is under the Glop.

It gets +5 and GND from the big cap
It's getting a Clock from pin 2 of 9C (Which is tied to VBLANK)

It's replacing VBLANK on pin 11 of 8C. According to the instructions, you're supposed to cut the pin and solder the wire to the pin.

You pick one of these which probably controls the speed of the "Zoom": The document says "Yellow", but in your pic it looks grey.

It's getting 16V from pin 10 of 5S
It's getting 32V from pin 11 of 5S
It's getting 64V from pin 12 of 5S

I don't know enough about the design side of things to say which TTL it is, but it looks like that when you press the button it short-circuits the VBLANK (i.e. it fires sooner than it normally does) which generates an IRQ. Which then speeds things up.
 
Last edited:
Some sort of TTL is under the Glop.

It gets +5 and GND from the big cap
It's getting a Clock from pin 2 of 9C (Which is tied to VBLANK)

It's replacing VBLANK on pin 11 of 8C. According to the instructions, you're supposed to cut the pin and solder the wire to the pin.

You pick one of these which probably controls the speed of the "Zoom": The document says "Yellow", but in your pic it looks grey.

It's getting 16V from pin 10 of 5S
It's getting 32V from pin 11 of 5S
It's getting 64V from pin 12 of 5S

I don't know enough about the design side of things to say which TTL it is, but it looks like that when you press the button it short-circuits the VBLANK (i.e. it fires sooner than it normally does) which generates an IRQ. Which then speeds things up.
Yes, the game speed is paced by IRQ which is normally VBLANK or 60Hz. When you press the button it switches one of the other vertical counter signals to IRQ to speed up the game play. You can do this with several different ttl parts 74LS00, 74LS02 etc.
 
Yes, the game speed is paced by IRQ which is normally VBLANK or 60Hz. When you press the button it switches one of the other vertical counter signals to IRQ to speed up the game play. You can do this with several different ttl parts 74LS00, 74LS02 etc.
This would mean ramping up the full game from 18.432Mhz to 60Mhz (Pac + Ghosts) rather than Pac only?

Thought I recalled a kit BITD speeding up Pac Man only.
 
This would mean ramping up the full game from 18.432Mhz to 60Mhz (Pac + Ghosts) rather than Pac only?

Thought I recalled a kit BITD speeding up Pac Man only.
Sort of, the clock speed stays the same but the "game clock" controlled by the IRQ interrupts is normally 60Hz but would change to 120Hz or 240Hz. But yes, all motion objects would speed up. You could make just the player speed up but that's a bit more complicated than this solution. The way the code is written the processor runs through the program to update all its "tasks" like moving the objects, checking for player death, updating score etc. then it HALTS and waits for the next interrupt to come in and start the process over. Kind of interesting how the processor is under control of the TTL state machine rather than the other way around. Obviously it one of the early implementations where game hardware was changing from logic state machines to CPU driven. pretty interesting.
 
Back
Top Bottom