Intellivania: Castlevania for the Intellivision!

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Flecko
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Intellivania: Castlevania for the Intellivision!

Post by Flecko » Tue Dec 10, 2019 3:19 pm

I just stumbled across this this morning, and couldn't resist sharing. This looks like an amazing port/demake of Castlevania.
Check it out:

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Re: Intellivania: Castlevania for the Intellivision!

Post by Jubatian » Thu Dec 12, 2019 9:34 pm

Wow, on that system with the limitations it had (as far as I could figure with a bit of research), pulling that off is quite something indeed! The Uzebox's typical resolution is pretty high comparatively (Alec's WIP of the same game). The audio is great for such an old system predating the C64.

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Re: Intellivania: Castlevania for the Intellivision!

Post by Flecko » Thu Dec 12, 2019 10:32 pm

I had an Intellivision as a kid...and it was definitely primitive by any standards. It had some really good games (Bump N' Jump, Shark! Shark!, Beauty and the Beast...to name a few.)

But what is in that video blows all of it out of the water. I have no idea how it was accomplished.

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Re: Intellivania: Castlevania for the Intellivision!

Post by Jubatian » Thu Dec 12, 2019 11:52 pm

I think it was rather the lack of tools at that time. There were no home computers, not even a C64 as even that would be released years later, and of course no knowledge base at all, techniques we take for granted when creating games and stuff. Such as they may have designed the sprites on graph paper, then typing it all up in some machine language monitor they had designed for whatever prototypes they had built. Even building a game using only Commodore Basic on the real machine is at least a magnitude more advanced than they likely had to work with initially.

Today it is a whole lot easier to devise means to pull off complex games with complex audio on the same piece of hardware, also with those cartridge-based systems, there is some flexibility in designing the cartridge itself. The graphics system as far as I could see is pretty advanced (especially considering the age), a 8x8 pixel 1bpp tile-based solution capable to provide X/Y scroll in HW (1 tile, then copying is necessary like on the VIC of the C64, so a bit tricky), with 8 single-color 8 pixels wide sprites, with HW capability to double their size (vertical resolution is apparently fixed at 96 pixels, double scanning).

I found a quite cool little demo video of this:



Sprites apparently can even use the full resolution.

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Re: Intellivania: Castlevania for the Intellivision!

Post by rv6502 » Fri Dec 13, 2019 3:42 am

And it's a 16bits system!

But the ROMs were 12 bits wide to save cost which was possible thanks to the opcodes being only effectively 10bits long with 6 reserved bits.

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Re: Intellivania: Castlevania for the Intellivision!

Post by Jubatian » Sun Dec 15, 2019 11:44 pm

rv6502 wrote:
Fri Dec 13, 2019 3:42 am
And it's a 16bits system!

But the ROMs were 12 bits wide to save cost which was possible thanks to the opcodes being only effectively 10bits long with 6 reserved bits.
Yes, that's also rather interesting, a quite unique CPU, in some regards it might do better than the 6510 due to being 16 bits. Otherwise it is not quite as fast by the clock counts in this Wiki, however it was clocked at almost twice the rate of the typical 6510 based machine (C64). The Wiki actually is quite interesting, I would say, tempting, to start experimenting with the thing :)

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Re: Intellivania: Castlevania for the Intellivision!

Post by Jubatian » Mon Dec 16, 2019 10:49 pm

Just a find, there were some quite strong titles apparently even back then!



I barely believe this was actually released in 1982, the design of this game is just so good. Comparatively Intellivania doesn't stand out that much, not that it isn't awesome :) - just that it seems that some managed to get this machine show off its capabilities pretty well.

What it lacked compared to an Atari VCS (which looks primitive in comparison) is sprites, due to the design it seems like it is impossible to multiplex sprites (such as possible on the C64), limiting the dynamics. A similar problem to what the Uzebox has (due to different HW constraints, but the effect is the same).

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Re: Intellivania: Castlevania for the Intellivision!

Post by rv6502 » Tue Dec 17, 2019 2:27 am

Jubatian wrote:
Sun Dec 15, 2019 11:44 pm
Yes, that's also rather interesting, a quite unique CPU, in some regards it might do better than the 6510 due to being 16 bits. Otherwise it is not quite as fast by the clock counts in this Wiki, however it was clocked at almost twice the rate of the typical 6510 based machine (C64). The Wiki actually is quite interesting, I would say, tempting, to start experimenting with the thing
The 6 general purpose 16bits registers sure are nice.

They say 1 Mhz on that page but I don't think that's right.
Wikipedia says it's two 2Mhz clocks which would still make it slow in comparison

MOS6502: LDA addr,X is 4 cycles
CP1610: MVI, ADD, MVI sequence is 26 cycles

Even if by cycles they're counting both 2Mhz clocks effectively making it "4Mhz" similar to how a Z80 is clocked, that'd still be 6.5 equivalent cycles.

Z80s were usually clocked at 4x the speed of 65xxs of the time making the Z80 a pretty fast CPU.

So, I dunno.

Professionally I would definitely prefer working with a CP1610 than the 6502.

"How many general purpose registers?"
MOS: "None"
"What do you mean, none?"
MOS: "Well, you got an accumulator, that does math... but not addressing."
"What about X and Y?"
MOS: "Weeeeeell, those are only half an address, and you can't add arbitrarily to them. You can't even push/pop them directly..."
"Ooookaaaay..."
MOS: "And you can't index the stack directly.."
"Really selling it here..."
MOS: "And the stack is at a fixed 256 bytes area."
"The features just keep pouring in, don't they?"
MOS: "But it's really fast! Check the cycle count!"

(and was cheap too so there's that.)

The Intellivision is so feature & memory limited that it doesn't really matter tho. There's only so little to do :D

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Re: Intellivania: Castlevania for the Intellivision!

Post by Jubatian » Tue Dec 17, 2019 7:08 pm

rv6502 wrote:
Tue Dec 17, 2019 2:27 am
The Intellivision is so feature & memory limited that it doesn't really matter tho. There's only so little to do :D
There are a few things, though, which could be done. Simple AI may be rather calculation heavy, probably involving some recursive constructs (such as tree traversing). Flight of a Dragon is not only about graphics and free-dimensional scrolling, it also has a rather CPU intensive physics engine. Such could work even in the graphical limits of the Intellivision, as for memory, it really only needs the coordinates of the actors, and some info on the playfield (which may be pulled off of the tiles themselves). There are also some puzzle games which require significant calculation, but not much in storage apart from the playfield (like Kye as a notable example of something which can be implemented that way).

But sure, the Atari VCS is a bit more interesting in that regard that you can keep trying as its graphics is so simple that you have to race with the beam to build anything sensible :) - while on the Intellivision due to how the HW is constructed, you can't do much to the display during active video.

The clock is NTSC colorburst / 2 (1.789773MHz). There are some interesting stuff in the CP1610's design, I particularly like the hackwork realizing instructions with immediate operand. But it indeed likely demands some good utilization of the fact that it is a bit RISC-like 16 bits architecture to compete with a 6510.

EDIT: And another interesting game: Worm Whomper. Not something very spectacular, rather from technical standpoint, the basic worms actually seem to be soft-sprites, most likely done in a manner very similar to how Uzebox sprites are typically done. So something where that CP1610 had quite some stuff to do!

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Re: Intellivania: Castlevania for the Intellivision!

Post by uze6666 » Thu Feb 20, 2020 3:50 am

Wow, that is really awesome. I love so much to see creative folks finding news ways to squeeze out even more juice out of the same old cpu released 40 years ago. Just like the Uzebox community did over the years!! When I compare Megatris released in 2008 with the technical feats of Lee, Jubatian and CunnigFellow well, I feel this little Atmega644 still has more juice to offer. :D

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