The purpose of this site is to document as much information on the little known Space Invaders rip off, IPM Invader. It is the game that has a 'coffee break' after every 3 waves of invaders.
GAME SPECIFICATIONS
Manufacturer
IPM* / IREM
Year
1978–79
Type
Shooter / Space
Players / Control
2 Alternating
2-way joystick
2-way joystick
Monitor Information
Raster • Vertical
Aspect: 3×4
Resolution: 224×240 (240×224 rotated)
CPU: MOS 6502 @ 2.5 MHz
Colors: 8
Aspect: 3×4
Resolution: 224×240 (240×224 rotated)
CPU: MOS 6502 @ 2.5 MHz
Colors: 8
* IPM Corp. was renamed Irem Corp. in 1979. MAME lists IPM; most arcade databases list IREM.
IPM Invader is a Dual sync game (separate H & V outputs). Many boards have been modified to composite negative Horizontal sync for modern monitors.
| SOLDER SIDE | PIN | PIN | 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 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 |
SOUND POTENTIOMETERS
Which pot does what? (Write to $a000)
BIT 0 VR2 — Base shoot
BIT 1 VR1 — Base explode
BIT 2 VR3 — Invader hit
BIT 3 VR4 — Life extend (bonus)
BIT 4 VR5 — Fleet move (low tone)
BIT 5 VR6 — UFO hit
BIT 6 VR7 — Fleet move (high tone)
BIT 7 VR19 — Volume
VR10 controls frequency
UFO noise — VR8
Volume for all sounds
UFO noise — VR8
Volume for all sounds
Credit: Andrew Welburn (andysarcade.net)
Thanks to Carmel Morris for original IPM Invader cocktail control panel photos.
PCB REVISIONS & PHOTOS
Click any image to view at full native resolution. Images are not enlarged beyond their original file size.
Working board set
RUNNING
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.
Non-working board set
NOT WORKING
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
Numbers on the 1st board set are:
- Top board (sound) = unknown
- Bottom board (cpu/rom) = M-10-L
2nd set
Numbers 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.
Thanks to Andrew Welburn for electronics work.
MORE IMAGES
Additional IPM Invader photos from the live archive (click any thumbnail for the full-size image at native resolution).
ROMS & EMULATION
IPM Invader ROMs have been dumped for the MAME project
(romset ipminvad, driver irem/m10.cpp).
MAME currently lists the game as IMPERFECT — gameplay is generally accurate, but sound and colour emulation are still incomplete.
See the current MAME status for details.
Manual & Schematics: Available in the Downloads section
(thanks to DisQo and yohansen).