Namco Custom Chips

Galaga, and most Namco licensed boards of the era, use a number of Custom ICs to provide functionality (and I guess to try and confuse the bootleggers of the day 🙂 )

These ICs often just need cleaning, but as they are very fragile it’s good to know what they do when diagnosing a board.

Here’s a table from multigame.com of each numbering, and it’s purpose

Number Short Name Description
54xx   Sounds Generates Explosion Sounds (possibly a custom Z-80?) [Mux 4 Channel Audio Generator]
53xx   Steering Input [Custom 4Bit Micro/Handles Steering/sw/read]
52xx   Audio Processor [Audio Processor 4 Bit Voice]
51xx   Input Player controls, DIP switches, etc [Custom 4 bit I/O – Coins]
50xx   Sound Sequencer [Sound Sequencer]
13xx   Horizontal Scroll [Horizontal Scroll]
12xx   Sprite Position [M.OBJ. Position]
11xx   Playfield Shift Register [Datashift Playfield Register]
10xx   Micro Buffer Data [Micro Buffer Data]
09xx   Sprite Ram Buffers [M.OBJ Ram Buffers]
08xx   Bus Controller (basically the same as Pacman’s “285” Sync Buss Controller) [Multi-CPU Bus Controller]
07xx   Clock Divider (generates horizontal and vertical timing pulses divided down from master clock) [Sync Generator]
06xx   Bus Interface [Custom 50’s Controller]
05xx   Star Generator (tapped pseudo-random feedback shifter– makes scrolling starfield)
04xx   Bus Interface Motion object and scratch RAM to CPU bus interface [M.Obj Controller]
03xx   Buffer, Playfield Data [Buffer, Playfield Data]
02xx   Custom Shifter Custom shift register for data from graphics ROMs [Shift Register]
00xx   VRAM Addresser (basically the same as Pacman’s “284” VRAM Addresser) [Video Ram Addresser]

There is also a very interesting document archived on the web of what each of these chips actually does on each pin, and I guess then how to recreate them.

I’m attached it here – Namco [Custom Chips] [English] – so that I have it available going forwards

and here’s an example of the replacement chips that Jrok and others are making – very cool

Jrok Custom 51

and the standard Galaga custom chips versus replacements

Original:

Standard Galaga CPU Board

Standard Galaga CPU Board

Replacement:

Jrok GAL Replacements

Jrok GAL Replacements

Reference:

Namco Custom Chips

http://www.multigame.com/NAMCO.html

Reverse engineering a Namco custom chip

http://forums.arcade-museum.com/showthread.php?t=204010

Replacement Namco custom chips by Jrok

http://www.jrok.com/hardware/custom_ic/custom_51_install.html

Mike’s arcade sells the above Jrok chips

http://www.mikesarcade.com/cgi-bin/store.pl?action=search&category=Components