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Space Invaders Test ROM: Documented and Modified

Space Invaders Test Rom

I have a Space Encounters PCB with RAM errors I've been fixing and thought it would be nice if the Space Invaders Test Rom available on the web would work for Space Encounters as well. After burning one and trying it out, I found out it kind of does (at least for the ram tests). The main problem is that Space Encounters has a hardware special effect that allows the screen to fade up to an all white screen. When the machine is powered up this is on by default and must be turned off by the program. Since Space Invaders doesn't have the feature it doesn't account for it and the text on the Space Invaders Test ROM is unreadable because of the white screen.

While looking at the code of the Space Invaders ROM in order to fix this problem, I decided I'd learn quite a bit about the hardware / software interaction of the 8080 PCBs by documenting its code.

In order to create the Space Encounters Test ROM, I had to convert the Space Invaders Test ROM for use in TASM, the assembler I use for development. In the process, I cleaned things up a bit and it now can be assembled into an exact copy of the original ROM.

So here it is: Space Invaders Test ROM Documented and ready for the Telemark Assembler (TASM)

To assemble this file: (MS-DOS)

  1. Download and decompress TASM.
  2. Save the file in the TASM directory changing the .txt extension to a .asm extension.
  3. Type on the DOS command line: tasm -85 -b -f00 si_test.asm
  4. The resulting .obj file can be renamed invaders.h for use in MAME.
  5. The .obj can be burnt to a 2716 EPROM or (if your board's strapping requires it) doubled and burnt to a 2732 EPROM.

In case anyone is interested in my (now outdated) first pass at this (it includes the op codes and memory addresses):
Here it is: Original Space Invaders Test ROM Documented

Here is the zip containing the original binaries ready for burning to EPROMs:
Space Invaders Test ROM

The Space Encounters test ROM is now completed and can be found here.


Modified Space Invaders Test ROMs

Modified Space Invaders Test ROM

Frederic Rodo & Fabrice Girardot have modified the Space Invaders Test ROM adding many new features. They have given me permission to distribute these updates and they can be downloaded below. Marc Deslauriers submitted an update which fixes incorrect RAM failures that were occurring with v1.2. Thanks to all who have contributed to this project!

1/29/2022 Update: I have added three sub-directories to the zip files for v1.2 and v1.3.

The binaries directory contains ROM images for 2716 and 2732 EPROMs as well as for MAME. The test ROM binary file is test.h. To emulate the ROM in MAME, uncompress the invaders.zip file in the mame/roms directory. Then replace the invaders.h file in this directory with the one from the mame directory in the test rom zip file.

The manuals directory contains the documentation for the test ROM. I have upgraded the RAM chart with the original, higher quality version.

The source directory contains all the source files. Build using the UNIX command line.

Space Invaders Test ROM: Version History
ROM
Version
Date Download Author Notes
v1.3 3/27/2019 Binaries,
Manual
&
Source

Marc Deslauriers

[Email]

  • Properly initialize ram test to prevent spurious failures.
v1.2 10/14/2017 Binaries,
Manual
&
Source

Frederic Rodo

spectroman or
frodo13 on forum

[Email]

  • Modify the test RAM to display all rams in error at one time.
  • Correct a display bug on INPORT test
  • Simplify the shifter matrix
  • Add manual
v1.1 9/17/2017

Source

Binaries

Fabrice Girardot

[Email]

  • Fix a small cosmetic bug on bad ram display
  • Refactor makefile
  • Add binaries in zip file for easy compiling on Linux
  • Add .png file for bad RAM identification
  • For those able to read French, there is a discussion about the bad ram display bug here.
v1.0 10/12/2013

Source

Binaries

Frederic Rodo

[Email]

  • Compute CRC32 check of all the roms
  • Add cross-hatch pattern for adjusting the screen
  • Add test for the game's shifters
  • Proper text display for the SI's portrait monitor orientation
Original Version 11/16/2007

Source

Timothy Shiels

[Email]

  • Exported raw opcodes using MAME debug
  • Documented and formatted code for assembly by the Telemark Assembler (TASM).
Original Version May 2001

Binaries & Documentation

Paul Sommers

  • Dumped EPROM and documented its use.
Original Version 1978

Taito

  • Included in Space Invaders Tatio TV revision 1 and 2.
    MAME: sitv1 and sitv2
  • Original code tests RAMS, INPORT, SOUNDS & WATCHDOG

The original Space Invaders Test ROM was written for the Taito board set, not the Midway set, but works on both.

 

Modified Space Invaders Test Rom

Phil Murray has modified the original Space Invaders Test ROM code to ease in troubleshooting the game's audio PCB. Individual sounds can be selected with the left and right buttons. The selected sound can then be played by pressing the fire button.

He has given me permission to distribute this modification and it can be downloaded below.

The test ROM binary file is test.h. There are two versions: _716 (2k) and _732 (4k). The 4k version is just a doubled 2k image. Burn the one appropriate for your PCB to an EPROM.

To emulate the ROM in MAME, uncompress the invaders.zip file in the mame/roms directory. Then replace the invaders.h file in this directory with the one from the mame directory in the test rom zip file.

Space Invaders Test ROM- Sound Modification Branch: Version History
ROM
Version
Date Download Author Notes
[SM]v1.0 1/14/2022

Source

Binaries

Phil Murray

  • Add ability to select sound to be played with left and right buttons.
  • Add ability to play selected sound by pressing fire button.