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VDP or equivalent for Capcom Commando hardware
#387303 - 07/29/20 11:48 PM
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I'm looking for detailed info on Capcom Commando hardware, used on 1942, 1943, Commando, Black Tiger and others.
https://www.system16.com/hardware.php?id=788
Surprisingly, I'm not finding anything related to the VDP used: which one was actually, how much VRAM, specs, etc.
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Re: VDP or equivalent for Capcom Commando hardware
[Re: DavidLynch]
#387305 - 07/30/20 02:16 AM
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A lot of older arcade hardware doesn’t have a “VDP” as such. Video hardware was often built up with TTL logic chips, or sometimes mask-programmed gate arrays (ULAs).
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Re: VDP or equivalent for Capcom Commando hardware
[Re: Vas Crabb]
#387308 - 07/30/20 04:51 AM
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ULAs reminds me of ZX Spectrum 
How can we get specs like number of colours, sprites per line, etc.
Thank you.
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Re: VDP or equivalent for Capcom Commando hardware
[Re: DavidLynch]
#387309 - 07/30/20 06:07 AM
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By looking at the schematics.
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Re: VDP or equivalent for Capcom Commando hardware
[Re: MooglyGuy]
#387310 - 07/30/20 06:17 AM
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Re: VDP or equivalent for Capcom Commando hardware
[Re: DavidLynch]
#387311 - 07/30/20 09:02 AM
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One could argue that the details are all there, one needs only to be able to understand the schematics.
Philosophy aside, the simple fact is that if you can't read schematics, and you can't understand MAME's code, you're not going to have much luck in tracking the information down.
To answer your question more directly though, Commando hardware had a fixed 256-color palette supplied by a set of PROMs that were different depending on the game running on the hardware (either Commando or Space Invasion).
It had three layers of graphics: "text" for things like scores and, well, text, "tiles" for the background layer, and then sprites on top of that. The text layer is limited to the topmost 64 colors of the palette (indices 192 to 255), the background tiles are limited to the bottom-most 128 colors of the palette (indices 0 to 127), and the sprites are limited to 64 colors (indices 128 to 191).
Text-layer tiles are 8x8, tile-layer tiles are 16x16, and sprite tiles are 16x16.
Text-layer tiles, tile-layer tiles, and sprites could be independently flipped on the X or Y axes.
The layer drawing priority is always in the order Text -> Sprites -> Tile, from front to back.
The text layer and tile layer contain 1 kilobyte, each, of tile RAM to indicate tile indices, and 1 kilobyte, each, of attribute RAM to indicate tile attributes (such as the color palette and flip bits). Both are arranged in a 32x32 grid of text tiles or tile-tiles.
Since the tile layer uses 16x16 tiles and 32*16 gives you a usable size of 512x512-pixels, the tile layer can also be scrolled independently in the X and Y directions.
The screen has an overall timing of 256x256 pixels, but the topmost 16 lines of pixels are reserved for the vertical-blanking interval, so only 256x240 pixels are usable.
Hopefully that's a sufficient amount of information.
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Re: VDP or equivalent for Capcom Commando hardware
[Re: MooglyGuy]
#387320 - 07/31/20 02:18 AM
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That's pretty much a perfect and complete description.
Thank you for taking the time for doing this, and I hope that it could help others too.
(Sorry if it's redundant: what's the specific component (or set) that generates the image?)
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Re: VDP or equivalent for Capcom Commando hardware
[Re: DavidLynch]
#387330 - 07/31/20 01:10 PM
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There is no one specific component that generates the image, it's the co-operation of all of the underlying chips that comprise the video section of the board.
Can you narrow down your question to a set of questions pertaining to specific aspects of the hardware that I described?
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Re: VDP or equivalent for Capcom Commando hardware
[Re: MooglyGuy]
#387333 - 07/31/20 04:25 PM
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Thank you again, MooglyGuy.
Sure.
The set of components that were responsible for the very good graphics performance of this hardware, specially if compared to the systems that we were able to have at the time, like home computers from the 80's.
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Re: VDP or equivalent for Capcom Commando hardware
[Re: DavidLynch]
#387339 - 07/31/20 08:35 PM
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The graphics performance of Commando was nothing special for the time, as far as arcade machines went, particularly for 1985. Compared to contemporary computers like the Amiga, it was actually on the fairly weak side.
The thing about it is that the hardware was pretty much entirely bespoke for Commando and Space Invasion, although it has an obvious functional lineage to the year-earlier 1942 hardware.
That said, arcade machines tended to lead the top of the pack in the 80's and early 90's for pretty much two reasons: First, the hardware was typically developed with a specific game in mind, and any subsequent games released on the same hardware were then tailored to that hardware. Second, arcade operators would drop multiple thousands of bucks on a new arcade cabinet with no questions asked, because for the most popular games they could make their money back within a few weeks to a few months. As a result, arcade manufacturers could and did use technology that was wildly out of reach of the average home computer or home game console that had to meet a price point just a fraction of what a single arcade cabinet would cost. Most of the cost of the cabinet was never really the wood-working, or the controls, or the CRT. It was the beefy PCB - sometimes multiple ones - riddled with enough components that a lot of them couldn't even hope to fit in a compact home computer or game console profile.
I could do a deep dive into how the hardware for Commando works, but I'd need a link to the schematics so I can ensure that I'm not just talking out my posterior. Think you can oblige?
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Re: VDP or equivalent for Capcom Commando hardware
[Re: MooglyGuy]
#387351 - 08/02/20 07:09 AM
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> The graphics performance of Commando was nothing special for the time, as far as
> arcade machines went, particularly for 1985. Compared to contemporary computers like
> the Amiga, it was actually on the fairly weak side.
Amiga was a powerful machine but (IMHO) it lacked many of the best titles - maybe we can't say the same of Sharp X68000, for instance.
Almost all home computers at the time were highly limited. Colors, simultaneous sprites and others led us to admire even more the arcades with their big PCBs.
Anyway, probably the best developers and artists were in the arcade business.
> The thing about it is that the hardware was pretty much entirely bespoke for Commando
> and Space Invasion, although it has an obvious functional lineage to the year-earlier
> 1942 hardware.
1943's quality is really good, specially at the time - scenario layers, sounds, the whole thing still is a work of art
>
> That said, arcade machines tended to lead the top of the pack in the 80's and early
> 90's for pretty much two reasons: First, the hardware was typically developed with a
> specific game in mind, and any subsequent games released on the same hardware were
> then tailored to that hardware. Second, arcade operators would drop multiple
> thousands of bucks on a new arcade cabinet with no questions asked, because for the
> most popular games they could make their money back within a few weeks to a few
> months. As a result, arcade manufacturers could and did use technology that was
> wildly out of reach of the average home computer or home game console that had to
> meet a price point just a fraction of what a single arcade cabinet would cost. Most
> of the cost of the cabinet was never really the wood-working, or the controls, or the
> CRT. It was the beefy PCB - sometimes multiple ones - riddled with enough components
> that a lot of them couldn't even hope to fit in a compact home computer or game
> console profile.
Good points - I agree
> I could do a deep dive into how the hardware for Commando works, but I'd need a link
> to the schematics so I can ensure that I'm not just talking out my posterior. Think
> you can oblige?
I'm asking all of this because to my understanding I've always seen hardware - processors/chipsets - dedicated for sprites, tiles, etc., and the schematics that I've provided in a previous post wasn't detailed enough, at least for me, a tech savvy but not on a dev level...
So, I was surprised to what Vas Crabb said previously here on how features was obtained at the time:
> A lot of older arcade hardware doesn’t have a “VDP” as
> such. Video hardware was often built up with TTL logic
> chips, or sometimes mask-programmed gate arrays (ULAs).
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Re: VDP or equivalent for Capcom Commando hardware
[Re: DavidLynch]
#387455 - 08/11/20 01:40 AM
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> I'm looking for detailed info on Capcom Commando hardware, used on 1942, 1943,
> Commando, Black Tiger and others.
>
> https://www.system16.com/hardware.php?id=788
>
> Surprisingly, I'm not finding anything related to the VDP used: which one was
> actually, how much VRAM, specs, etc.
The hardware for many pre-cps1 capcom games were reverse engineered by Jose Tejada (jotego) for his FPGA recreations last year and this year. The ones you mentioned are included in his work "942, 1943, Commando, Black Tiger"
He was trying to do all of the pre-cps1 hardware that had something in common with cps1. Like some games have the 384x224 resolution. Some games have the same sound chip. Etc. He recently finished CPS1 and is doing some other stuff while he works on the DSP chip needed for qsound.
This is all done at the logic level because that's how FPGA stuff is done. He uses the "many files to implement a thing" approach that all of the professional ic designers favor. It makes it hard to read for me, but maybe you can do better.
This is his main repo: https://github.com/jotego/jt_gng
The video hardware (and other things common to multiple games) is in here: https://github.com/jotego/jt_gng/tree/stable/modules
And he's on twitter here: https://twitter.com/topapate/
Edited by SoltanGris42 (08/11/20 01:41 AM)
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Re: VDP or equivalent for Capcom Commando hardware
[Re: SoltanGris42]
#387459 - 08/11/20 02:20 AM
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No offense to you, but you're a little late to the party on this thread.
And not to minimize jotego's work, but saying that he "reverse-engineered the hardware" is ridiculous. Reading the published schematics for these boards and transcribing them into VHDL or Verilog isn't reverse-engineering any more than looking at the published audio schematics for various arcade boards and transcribing them into a netlist is reverse-engineering.
What he did for CPS1 and a number of other systems? Absolutely reverse-engineering. Reading schematics? No.
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Re: VDP or equivalent for Capcom Commando hardware
[Re: MooglyGuy]
#387460 - 08/11/20 02:48 AM
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> No offense to you, but you're a little late to the party on this thread.
>
> And not to minimize jotego's work, but saying that he "reverse-engineered the
> hardware" is ridiculous. Reading the published schematics for these boards and
> transcribing them into VHDL or Verilog isn't reverse-engineering any more than
> looking at the published audio schematics for various arcade boards and transcribing
> them into a netlist is reverse-engineering.
>
> What he did for CPS1 and a number of other systems? Absolutely reverse-engineering.
> Reading schematics? No.
I suppose you're right. The pre-cps stuff probably didn't require much more than schematics. I just figured the hdl might provide information to the original poster in a different form that maybe he would find interesting.
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Re: VDP or equivalent for Capcom Commando hardware
[Re: SoltanGris42]
#387463 - 08/11/20 04:57 AM
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> I suppose you're right. The pre-cps stuff probably didn't require much more than
> schematics. I just figured the hdl might provide information to the original poster
> in a different form that maybe he would find interesting.
You may be right, I just doubt that someone who can't read a schematic or grok MAME's codebase would necessarily be able to read HDL either.
Again, don't get me wrong, jotego's work with the earlier Capcom games is amazing and I don't want to minimize the amount of effort that goes into translating schematics into code. After all, it helped solve a MAME bug related to sprite handling in 1942 after something like 20 years. I just don't think it's necessarily reverse-engineering in the strictest sense. Now, what he's pulling off with CPS-1 and hopefully with CPS-2, that just blows the hell out of my mind.
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Re: VDP or equivalent for Capcom Commando hardware
[Re: MooglyGuy]
#387470 - 08/11/20 05:03 PM
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Great discussion here - I'm even missing a like button
I wasn't aware of jotego's work. Following from now on.
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Re: VDP or equivalent for Capcom Commando hardware
[Re: DavidLynch]
#387471 - 08/11/20 05:27 PM
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Oh yeah, jotego's absolutely brilliant.
The thing about FPGA-based emulation is that at its worst it's no better than a run-of-the-mill software-based emulator running on a PC; but at its best, it's essentially as if you were running the entire emulation of a CPU-based machine through MAME's netlist system, in terms of emulating every last detail of the hardware.
Many people act like emulation via FPGA is a magic bullet, but in reality it would just be a cheap parlor trick if not for people like jotego doing their best to ensure that the experience is more like the best-case situation than the worst-case.
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