I was searching the forums and came across this thread. I couldn't resist reviving it, since I have more info.
There are 3 official ROM sets for Defender: Blue, Green and Red (released in that order). They all differ to some extent, and all have separate Instruction Booklets (the smaller format).
A collector told me he estimated Red ROM machines outnumbered the Blues/Greens by a 7:1 ratio. And that the Green ROMs strongly outnumbered the Blues. An estimated total of 55-60.000 units were produced.
Blue ROM set
- Runs the game on 10 ROMs (#4 and #5 not used).
- Early series CPU
- The ROM board has different jumpers than the Green and Red ROM boards.
- The attract mode reads: "LANDER 100"
- Instruction Booklet #16P-3000-103 (no date) reads:
Function #18 = Starting Difficulty: 0=LIB; 1=MOD; 2=CONS (Factory default=0)
Function #19 = Progressive Wave Difficulty Limit, 4-25, e.g. 5=LIB; 10=MOD; 15=CONS (Factory default=10)
Function #20 = Background Sound: 0 = OFF; 1 = ON
Green ROM set
- Runs the game on 11 ROMs (#5 not used)
- Early series CPU
- The attract mode reads: "LANDER 100"
- Instruction Booklet #16P-3001-103B (March, 1981) reads:
Function #18 = Starting Difficulty: 0=MOD; 5=CONS (Note: no LIB setting) (Factory default=0)
Function #19 = Progressive Wave Difficulty Limit, 1-30, e.g. 01=LIB; 10=MOD; 20=CONS (Factory default=10)
Function #20 = Not Used
Red ROM set
- Runs the game on 11 ROMs (#5 not used)
- Later series CPU (which made it possible to flip the screen for the cocktail version)
- The attract mode reads: "LANDER 150"
- Instruction Booklet #16P-3001-103 R-T (July, 1981) reads:
Function #18 = Starting Difficulty: 0=LIB; 5=MOD; 10=CONS (Factory default=5)
Function #19 = Progressive Wave Difficulty Limit, 5-30, e.g. 5=LIB; 15=MOD; 25=CONS (Factory default=15)
Function #20 = Not Used
Note: difficulty never progresses beyond 30 (for function #19): a game set to 05-30, will play exactly like a game set to 05-00 (=100). Difficulty 30 is max.
For hardware differences between the CPUs/ROM boards, see here:
www.robotron-2084.co.uk: Williams Video Games Hardware Identification and Compatibility:
http://www.robotron-2084.co.uk/techwilliamshardwareid.html#defender
Gameplay differences between the ROM sets.
The ROM sets are not equally hard to play. On any given setting, the Blue ROM set is harder (=faster), than the other two ROM sets. This is mostly felt on easy/default settings (B/G=00-10; Red=05-15), but goes all the way up to max (99-99), though here the difference between the Greens and Blues is hardly noticeable anymore. On the Blue and Green ROMs difficulty can be set to escalate all the way up to max/99 (or actually 00, to be exact), whereas on the Red ROMs difficulty stops at 30 (function #19): 30 is max (even though you can set it to 99-99, it will play exactly like a 99-30 setting). This difference in difficulty between the Blue/Green ROMs and the Reds is not as huge as the figures seem to imply: between difficulty 20-30 the Baiters are becoming a real problem, and effectively stop most players from marathoning Defender – on any ROM set. The Baiters are not getting much harder after 30-35 (on any ROM set), and are not the biggest difference between the Blue/Green ROMs and the Reds – the Landers are. Around difficulty 65 they're lifting humanoids so fast the game can't handle their logic very well any more: they very often take an extra lap (or two) through the ceiling, and out through the floor again. Landers also often get stuck when trying to lift humanoids, spraying bullets like crazy. And 'Space' is monstrous: the 'Dateline' seems to be following you everywhere, so often when you turn on the Mutants, they're going the other way – fast. The usual strategies don't work anymore. Hyperspace mostly feels like a suicide-button – it's really the last way out.
The difficulty settings for playing 5-man Defender, i.e. the Twin Galaxies Tournament Settings (aka 'TGTS'), are the default settings for the Red ROMs: 5-15. There's no mentioning of what ROM set to play, but the Reds are implied by the 5-15 default setting (because default on the Blue and Green ROMs is 00-10). But the Blue/Green ROMs set to 5-15 are noticeably harder than the Red ROMs on 5-15 (and the Blues clearly being harder than the Greens). So if you're trying to improve on your TGTS score: be sure to play the Red ROMs.
I've requested an 'Extreme Settings' track for Defender at Twin Galaxies (aka 'TGES'). Read it here (and feel free to comment):
"Defender TGES/TGXS – maximum difficulty: 99-99/20K –Green ROMs (important)":
http://forums.twingalaxies.com/viewtopic.php?f=22&t=13405&p=188138&hilit=+TGES/TGXS+#p188138
It has a link at the bottom to a maximum difficulty sample game (Blue ROMs), but you can see it directly here:
YouTube: "Defender arcade game – 909K on hardest settings":
http://www.youtube.com/watch?v=yrkx...DvjVQa1PpcFOzst1gYu76TQVkvLPEzVFgacHvMuJkcPk=