OP
OP
They also bothered to cut the bezel shelf (? Not sure what the terminology is) enough so that the start buttons could be fitted in their proper locations on the CPO.
Picked up a Bootleg?? Joust Cabinet
- Thread starter 64B1T
- Start date
mecha
Well-known member
I asked Eugene Jarvis if he's familiar with this science experiment
The wrinkly green on the edges of the blitter board also remind me of the same PCB defects found on Williams sound boards. And Williams certainly had the production manufacturing capabilities to quickly produce prototypes for stuff like this.
During development of Joust and Sinistar, there was an issue the software engineers discovered about the blitter chip. According to Sean Riddle:
The entire codebases for both Joust and Sinistar are littered with references to this bug every time some sort of graphic needs to be displayed on-screen (here's an example with comments by RJ Mical). It's very much possible that this hardware may have been used by the engineers to debug the chip and/or developing the revised blitter chip.
That marquee is really cool; from your description is sounds like it's handmade.
During development of Joust and Sinistar, there was an issue the software engineers discovered about the blitter chip. According to Sean Riddle:
The entire codebases for both Joust and Sinistar are littered with references to this bug every time some sort of graphic needs to be displayed on-screen (here's an example with comments by RJ Mical). It's very much possible that this hardware may have been used by the engineers to debug the chip and/or developing the revised blitter chip.
That marquee is really cool; from your description is sounds like it's handmade.
TexasHotshot
Well-known member
AAAAHH!! Those AA batteries, man!
OP
OP
Don't worry they're gone! I took photos before I touched anything is all.
mattosborn
Well-known member
That's what I figure. I have that CPU board shown in Joe's thread. Unfortunately it didn't come with any other boards.
HudsonArcade
Well-known member
The top and middle ports appear to have the same pinout, and the bottom is different.
I'm guessing that proto ROM board uses the defender(ish) pinout and the 3rd connector is used for a real ROM board with the joust/robotron style pinout.
HudsonArcade
Well-known member
It'd be worth documenting (especially interested to see if the SC1 bug is replicated on this board), but the SC1s are well enough understood to do an FPGA replacement, but it's really not worth the trouble to do it.
I'm betting that this is the SC1 since Joust has code to workaround the bug. I would imagine that if this was SC2, then a new version of Joust would have to be built with all the "EORA #$04" and "EORB #$04" instructions removed or replaced with NOP instructions.
mecha
Well-known member
Eugene is busy saving the world but I got some replies. anyone that's read the Defender later Theory of Operation may have seen where it references DMA and how it would be used in later games. he says the Special Chips were designed while making Robotron which everyone knows was done independent of Williams so I'm curious how those discussions went down lol
he said something about the mods turning Defender into Stargate generation hardware doubling the address space (I think that's the core difference is Defender needed bank switching to work)
@Lon if you're talking about John Newcomer or Pfutz given this was done during Robotron development it would probably make sense they don't know about it. I haven't gotten any confirmation about anything really. this is stuff from over 40 years ago after all and it intrigues me anyone remembers anything lol
he said something about the mods turning Defender into Stargate generation hardware doubling the address space (I think that's the core difference is Defender needed bank switching to work)
@Lon if you're talking about John Newcomer or Pfutz given this was done during Robotron development it would probably make sense they don't know about it. I haven't gotten any confirmation about anything really. this is stuff from over 40 years ago after all and it intrigues me anyone remembers anything lol
OP
OP
I think I caused some orientation confusion. I was referring to the top connector as the one closest to the edge/how it is installed in the cabinet. So of the two similar (possibly exactly the same?) pinouts, only one (the middle one) is used, connecting to the ROM board). Perhaps this was a spot to hook up a logic analyzer?
Makes sense that the one on the Robotron.co.uk site is a "Robotron Prototype" then. But honestly this raises even more questions. If this was some kind of Stargate Proto, and then a Robotron Proto / Vidkidz hack, then how and why did it end up as a Joust with a weird marquee? The plot thickens.
Did he mention if he ever did these mods or know who did?
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HudsonArcade
Well-known member
Hm... I would have expected bottom to CPU, middle to defender-style ROM board, top to Stargate-style ROM board (ie. Robotron/Joust - blitters).
I doubt they would have tried to probe there with the connector facing down instead of up.
Both games use bank switching, but they do it differently.
Both have unbanked ROMs at $D000-$FFFF
Defender bank switches the other ROMs in place of the RAM in a big block.
Later games bank switch the other ROMs on top of the IO space ($C000-$CFFF) one bank at a time.
OP
OP
Yeah the connectors facing down is super weird, and also weird that they're reversed from how you'd think they'd go.
There are four large carriage bolts on the right side of the cabinet facing in, arranged in a rectangle. Do you think it's possible that at one point some other piece of development hardware was mounted to those, on the inside of the cabinet? Because as of now I can't see any purpose for them being there.
mecha
Well-known member
much of the time when I ask him these things he kind of doesn't know lol maybe it's a secret
I think he may have told me the Special Chips were originally intended to use +12V, which is why the Special Chip rom boards have the 2 filter caps and where the +12V would have gone is dummied out but I think the traces are still shown in the schematics. it's why the power header was a couple pins bigger. I think the larger issue was they ran out of independent pins on the power supplies and they may have found out in testing that it would spell disaster later (reliability; general oops)
I only mention this cause it's fascinating this prototype blitter board uses +5V. when you really take everything into consideration they made seismic leaps with the technology in a little over a year.
taulpaul
Well-known member
I didn't see this mentioned, but it is using the optical joysticks?
OP
OP
No, and it doesn't use regular Joust sticks either.
It's using regular wico sticks with the up and down switches removed, restricted by a slot cut into the wood.
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OP
OP
I'm gonna make a Devils Advocate argument that this is in fact, an extremely sophisticated bootleg.
1) There are just three of these these hacked up Defender boards I can find references to. However, they seem to span a wide range of Serial numbers. 40,000 Serial numbers from lowest to highest, and two different REVs of the base defender board (X0, and X1). So it's not like they pulled three random Defenders off the line to tool on. Also interesting, this specific one in the linked thread (image copied below) appears to have a different REV of the daughter card, which indicates to me that it was in production for long enough for whoever made it to switch PCB processes. Interestingly the leftmost (or upper on mobile) version of the daughter card looks more like the actual Williams protos as seen below.
Mine also doesn't look like it was put together by the same person as the other two. Different technique and wiring choices. Mine is definitely the kludgiest one.
2) Defender bootleg ROM Boards are out there. And they have the similar "organic" traces that this set has on the ROM board. This post is from UKVAC and indicates that someone local was "churning them out". The version that is in this set is much cleaner, but still didn't have the proper angled traces which seem typical of Williams boards. I haven't found any references to Stargate Bootlegs, much less Joust/Robotron bootlegs, but I don't see why at least Stargate wouldn't be possible.
3) Williams Prototype Boards still seemed to contain REV Information, and seem to typically lack a solder mask. Shown are actual Williams prototype ROM Boards from this FS thread.
4) This is apparently an image of an actual Williams Special Chip 1 Prototype. Found this as a dead link to the robotron-2084.co.uk website. Luckily it was preserved on the internet archive. Doesn't look like what I've got on this set, and looks more like the williams prototypes as shown above. Looks like it has two clusters of chips: One cluster with 16 chips and four off to the side, and another cluster of 30 chips with one off to the side, for a total of 51 chips... The Blitter board in this set only has 44 chips. I wonder what functionality is different, if any.
5) The Marquee, as interesting as it is, does have "Discolorations" where the normal part numbers would be. If it was created prior to the production marquees, why would these spots be present? It's definitely not a scan, otherwise the colors would be similar or at least off by the same amount, but it is very odd still.
6) I Found another Defender Cabinet that had a sophisticated Joust conversion. @TexasHotshot you weren't wrong in seeing one. This one even has Sideart. It's interesting that it seems to have the exact same choices in controls and buttons. Red, presumably wico sticks, and 2x color matched non-lit buttons on each side. There are no shots of the PCBs, but I have to wonder....
7) This boardset, and others like it, despite having non-williams ROM labels, had production, and actually latest version code on them. Other prototype boards from Williams, even early protos, seemed to have descriptive ROM information on them. Actual Labels. These did not...
8) This game has been played HARD. There are no coin counters to go off of, but the bald patches on the CPO and the massive amount of cigarette burns definitely give the impression that it was on location. Why would a dev unit have been placed in an arcade?
Clearly, whatever entity that created the daughter card for the defender hack also created the Special Chip/Blitter eliminator present on this set, as well as the Stargate-esque ROM board that it uses. They are all very similar in style and manufacture. I have NO IDEA why any sane human being would go through that much effort to do so without the funding of a corporate empire behind them. It is weird though that with a greater than five number of these boards out there, that nobody seems to know definitively where they came from, other than a couple retrieved from "Ex Williams" employees, who also either didn't know or didn't convey what their origins were.
It's also bonkers that if this thing does turn out to be a bootleg, that means someone completely reverse engineered the special chips in the 80s, and then that was kept under wraps for 40 years...
Very disappointing if true, would love to be proved wrong but I guess you've got to give all the options a fair shot... At this point if it did turn out to be a proto, it's a very very weird one that deviates a bit from Williams's norms.
1) There are just three of these these hacked up Defender boards I can find references to. However, they seem to span a wide range of Serial numbers. 40,000 Serial numbers from lowest to highest, and two different REVs of the base defender board (X0, and X1). So it's not like they pulled three random Defenders off the line to tool on. Also interesting, this specific one in the linked thread (image copied below) appears to have a different REV of the daughter card, which indicates to me that it was in production for long enough for whoever made it to switch PCB processes. Interestingly the leftmost (or upper on mobile) version of the daughter card looks more like the actual Williams protos as seen below.
Mine also doesn't look like it was put together by the same person as the other two. Different technique and wiring choices. Mine is definitely the kludgiest one.
2) Defender bootleg ROM Boards are out there. And they have the similar "organic" traces that this set has on the ROM board. This post is from UKVAC and indicates that someone local was "churning them out". The version that is in this set is much cleaner, but still didn't have the proper angled traces which seem typical of Williams boards. I haven't found any references to Stargate Bootlegs, much less Joust/Robotron bootlegs, but I don't see why at least Stargate wouldn't be possible.
3) Williams Prototype Boards still seemed to contain REV Information, and seem to typically lack a solder mask. Shown are actual Williams prototype ROM Boards from this FS thread.
4) This is apparently an image of an actual Williams Special Chip 1 Prototype. Found this as a dead link to the robotron-2084.co.uk website. Luckily it was preserved on the internet archive. Doesn't look like what I've got on this set, and looks more like the williams prototypes as shown above. Looks like it has two clusters of chips: One cluster with 16 chips and four off to the side, and another cluster of 30 chips with one off to the side, for a total of 51 chips... The Blitter board in this set only has 44 chips. I wonder what functionality is different, if any.
5) The Marquee, as interesting as it is, does have "Discolorations" where the normal part numbers would be. If it was created prior to the production marquees, why would these spots be present? It's definitely not a scan, otherwise the colors would be similar or at least off by the same amount, but it is very odd still.
6) I Found another Defender Cabinet that had a sophisticated Joust conversion. @TexasHotshot you weren't wrong in seeing one. This one even has Sideart. It's interesting that it seems to have the exact same choices in controls and buttons. Red, presumably wico sticks, and 2x color matched non-lit buttons on each side. There are no shots of the PCBs, but I have to wonder....
7) This boardset, and others like it, despite having non-williams ROM labels, had production, and actually latest version code on them. Other prototype boards from Williams, even early protos, seemed to have descriptive ROM information on them. Actual Labels. These did not...
8) This game has been played HARD. There are no coin counters to go off of, but the bald patches on the CPO and the massive amount of cigarette burns definitely give the impression that it was on location. Why would a dev unit have been placed in an arcade?
Clearly, whatever entity that created the daughter card for the defender hack also created the Special Chip/Blitter eliminator present on this set, as well as the Stargate-esque ROM board that it uses. They are all very similar in style and manufacture. I have NO IDEA why any sane human being would go through that much effort to do so without the funding of a corporate empire behind them. It is weird though that with a greater than five number of these boards out there, that nobody seems to know definitively where they came from, other than a couple retrieved from "Ex Williams" employees, who also either didn't know or didn't convey what their origins were.
It's also bonkers that if this thing does turn out to be a bootleg, that means someone completely reverse engineered the special chips in the 80s, and then that was kept under wraps for 40 years...
Very disappointing if true, would love to be proved wrong but I guess you've got to give all the options a fair shot... At this point if it did turn out to be a proto, it's a very very weird one that deviates a bit from Williams's norms.
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This thread was an entire story in itself and those are my favorite kind of threads
HudsonArcade
Well-known member
much of the time when I ask him these things he kind of doesn't know lol maybe it's a secret
I think he may have told me the Special Chips were originally intended to use +12V, which is why the Special Chip rom boards have the 2 filter caps and where the +12V would have gone is dummied out but I think the traces are still shown in the schematics. it's why the power header was a couple pins bigger. I think the larger issue was they ran out of independent pins on the power supplies and they may have found out in testing that it would spell disaster later (reliability; general oops)
I only mention this cause it's fascinating this prototype blitter board uses +5V. when you really take everything into consideration they made seismic leaps with the technology in a little over a year.
By the time defender came out, no logic was using +12V -- they probably just used the same power connector as the ROM board, which also doesn't use +12V.
Defender's 6-pin power connector may have originally been intended to support TMS2708/TMS2716 and would have also needed -5V, but later ROM boards just had the 4-pin power connector, which is pretty much as small as you can go and have the keying on the connector still be useful.
bitburn
Well-known member
The picture of the blitter board shows a date of July 15th 87. Meaning it was developed in 87, also in European date format. Interesting the photo is on a plane. I wonder if that huge book is the design document for the board.
