IPM Invader, the Space Invaders clone.

IPM Invader

The purpose of this site is to document as much information on the little known Space Invaders rip off, IPM Invader. For those who are not aware of IPM Invader, it is the game that has a 'coffee break' after every 3 waves of invaders. This has always fascinated me and I enjoyed reaching the 'coffee break' when I was young.


Manufacturer	Year	Type	Players / Control	Monitor Information
IPM* / IREM	1978-79˜	Shooter/Space	2 Alternating / 2 way joystick	Raster. Vertical. screen aspect: 3 x 4. resolution x: 224 pixels. resolution y: 240 pixels. colors used: 8.

In this section I will be documenting all the technical data available to me on IPM Invader. Pin outs, schematics, manuals, pcb revision numbers, pcb sound boards, pcb cpu/rom boards and pcb pictures.

IPM Invader is also a Dual sync game meaning it has separate Horizontal and Vertical outputs, and many have been modified to composite negative Horizontal sync because they won't work on most monitors. Thanks Jomac.

I have managed to track down some pinouts thanks to a friend of mine. Thanks Geoff.
*Updated - 11 December 2013. Thanks to Andrew Welburn for some fine electronics work.

*Updated - 12 December 2013. Manual and Schematics finally found. Thanks DisQo and yohansen.

IPM Invader Pinouts
			(confirmed on M-11s-1 PCB)
Solder Side			Parts Side
-------------------------------------------------------
Ground	44	43	Ground
(+) 5 Volts	42	41	(+) 5 Volts
(+) 5 Volts	40	39	(+) 5 Volts
Coin 1	38	37	~~Test Switch / Coin?~~ (hangs the game if grounded)
N\C	36	35	N\C
N\C	34	33	N\C
N\C	32	31	Video Blue
Video Green	30	29	Video Red
1 Player Lamp	28	27	2 Player Lamp
Speaker (+)	26	25	Speaker (-)
(+) 12 Volts	24	23	(+) 12 Volt
(+) 12 Volts	22	21	(+) 12 Volt
H-Sync (negative)	20	19	-
-	18	17	V-Sync (positive) 62hz
P1 Start	16	15	P2 Start
P2 Fire	14	13	P1 Fire
P2 Right	12	11	P1 Right
P2 Left	10	9	P1 Left
N\C	8	7	Coin Counter
(-) 5 Volts	6	5	(-) 5 Volts
Ground	4	3	Ground
Ground	2	1	Ground

To download the pinouts click here.
To download the Manual (with schematics) click here.

Sound Which pot does what? [write to $a000]
BIT	POT	Sound
0	VR2	base shoot
1	VR1	base explode
2	VR3	invader hit
3	VR4	life extend (bonus)
4	VR5	fleet move - low tone
5	VR6	UFO hit
6	VR7	fleet move - high tone
7	VR19 volume VR10 controls frequency	UFO noise
-	VR8	Volume for all sounds

Credit: Andrew Welburn.

Thanks go to Carmel Morris for supplying me with photos of an original IPM Invader cocktail control panel.

Here are some pictures of a working IPM Invader board set.

I have recently translated the Japanese writing (katakana)that is located on the board connectors, and it says 'Su-ka-i Shi-yuu-ta'. Actual translation is: (Sky Shooter). A converted PCB set. Numbers on this board set are:

Top board (sound) = M-10S-E
Bottom board (cpu/rom) = M-10L-E

This pcb is now happily running IPM Invader.

Another board set that is not working is pictured below.

Numbers on this board set are:

Top board (sound) = M-10S-H
Bottom board (cpu/rom) = M-10L-C

Here are another 2 different board sets from another friend.

1st set
2nd set

Numbers on the 1st board set are:

Top Board (sound) = unknown
Bottom board (cpu/rom) = M-10-L

Number on the 2nd board set are:

Top Board (sound) = M-10S-E
Bottom board (cpu/rom) = M-10L-E

Finally I have a board set which is not working and it's a weird revision too.

Numbers on my board set are:

Top board (sound) = M-11S
Bottom board (cpu/rom) = M-11L

As you can see, there clearly were several hardware revisions when Irem was manufacturing these pcb's.

Will have manuals and schematics up shortly. I hope.

IPM Invader ROMS have been dumped for the mame project but due to the Irem skychut.c driver not being the best it could be, the game play is average at best in mame. I hope the skychut.c driver is improved in the future.

Some more images of IPM Invader (click for larger image)