ROM Colour disambiguations
last updated October 20, 2014
|There's lots of confusion over Defender rom boards and the rom colours.||
I'll try to give you some idea of what its all about with the help of what i know from owning a LOT of defender pcbs and being involved in the dumping/verification of sets.
As a collector, having owned and sold maybe 10 Defender machines and selling maybe 40 pcb sets over the past 17 years, i knew of a white blue, green and red romset, but mame didn't reflect this. I had a rocky relationship with Mame in the beginning, a lot of devs were not interested in accuracy, just in getting new romsets into mame. When i made suggestions about correcting things, i was basically told, whatever was written in mame was sacred, and that i'd have to jump through a lot of hoops to provide evidence to support my case for the changes. Needless to say, that was time consuming and just not practical for me to prove what lot of collectors already knew. You could cobble a romset together from various sources and submit it, and it would be taken as gospel in Mame it seemed.
Thankfully things are different now, and now i spend a lot of my time trying to tidy up the problems Mame has inherited over a long history of ignoring basic naming conventions and submitting new drivers and mixed-romsets without any proof previously. These days at least, a photo is required to check the evidence for supporting naming conventions etc.. There are still a few common games that are not accurately dumped.. but we're getting there.
How can we accurately identify each rom?
Mame uses CRC's, in fact, so does a lot of test equipment, it is used to give a unique signature to a block of code. This signature means you dont have to compare byte-for-byte two large amounts of code side by side. If a CRC calculation sum performed on two blocks of code matches between them, you know they have to contain the same code.
|Mame Rom questions and chronology:|
- Until August 2008, Mame
only showed 3 Defender romsets, called Red, Green and White.
- Using this rationale, we submitted it to mame, and it got added, with the old 'white' romset becoming the new 'blue' romset, see below :
- So, at this point, August 2008, there were 4 Defender romsets now in Mame, white, blue, green, red (from oldest to newest) called "defendw, defendb, defendb, defender"
- This obviously caused some confusion, beause people already had defendw.zip in their mame collections, but the CRC's or filenames now weren't matching up, so it seems everything got re-named and by mame 0.135 (oct 2009) the rom zip file names had changed to what we see today, which is defenderw, defenderb, defenderg, defender. I have not yet found the version of Mame where the names actually changed. [to-do]
|Mame 0.126||the last version of mame without the 'Blue' romset (its there but called white)||6 Jul 2008||Source code|
|mywhite.rar||I dumped my white romset||8 Aug 2008||Me|
|Mame 0.127||The actual Defender White romset added - owned by Andy Welburn||19 Aug 2008||WHATSNEW.TXT|
whats the age of the romsets? see in the table the serial number stickers and their groupings
Which romsets came first?
|According to the
Defender theory of operation manual for the EARLY pcbs(16P-3001-300 Oct
1981) page 30 :- Table 4-1 :
"Table 4-1 shows the two versions of Defender currently available"
|Williams own naming:||description||Which Must mean romset|
|Defender "Version 1"||- IC1,2,3 is shown to be using 4K roms||BLUE|
|Defender "Version 2"||- (IC1, 4) shown as 2K roms||GREEN|
It is interesting to note
that in the Defender theory of operation manual for the LATER series
of pcbs, (16P-3001-301 Oct 1981) page 29, the table 4-1 is repeated
exactly as before, except the wording this time is:
|By this logic, we know that the white romset must pre-date the green and red.|
There's a few different types, but i have yet to see blue type 2
||WHITE||absolutely no sign of any pen marks|
||BLUE||oversized, quite often found with top and bottom of the label missing|
||BLUE||Mistaken for White in the past|
||GREEN||look at it carefully, its definitely green, not blue.|
||GREEN||Because of fading, this can look blue as well!|
||RED||- semi-glossy appearance|
- 1981 copyright
|There are no shared roms between red / green / white at all.|
|lower half of blue1 = green 1|
|upper half of blue1 = unique|
|green 1+4 = no match|
|RED code is unique, no matches with other sets|
|WHITE code is unique, no matches with other sets|
|green 3 is unique|
|green 4 is unique|
difference between blue and green rom sets :
Rom set types:
Serials - approximate serial numbers the roms have been seen on. This does not mean someone in the past hasn't swapped the roms around from other pcbs, but it should give a general idea of which romsappeared when in the chronology...
I dont think i've seen a Red romset on an 'early' rom pcb, if you find that, it could be that you've had the roms transferred over from another pcb, i certainly know that happened among shelf-stored collectors pcbs and repairs.
|colours||Earliest Serials Seen||comments|
|These are the serial number range of Pilot/prototype machines - none have contained any unique romsets so far, all have been repaired/swapped/upgraded over the years|
|Blue||439159 (me)||(yup! earlier than the white serial?!)|
|White||448815 (E.Thomas)||the only pcb i've seen|
This page is in progress, please
let me know what roms you have and what serial number your pcb is,
plus if you have high res images of your rom pcbs it would help!
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