stupus' Epoch Cassette Vision & Super Cassette Vision collection

[Kurt_Woloch]

Anyway, a cute system with its pastel coloured cartridges. Is it properly emulated? I understand something like a multicart does not yet exist, or at least I haven't seen anything about a such. Then again I love the oddball systems almost more than I love the mainstream systems so not odd that I would get to like it, in particular when the common cartridges before shipping are much cheaper than e.g. NES cartridges for which there ought to exist tons and tons of games but prices anyway are kept moderately high.

 

Sorry for hijacking or reviving yet another thread, but I've been reading up on the Cassette Vision lately, and I see some facts about it scattered on various internet sites which, if brought together, could lead to a deeper understanding of the system and its cartridges...

 

First, while the Super Cassette Vision has a MAME driver for it, the Cassette Vision doesn't. The primary reason being that the console itself doesn't contain much hardware, rather each cartridge has a special chip on it which contains all ROM and RAM and other circuitry needed for this game. But this chip on each cartridge is actually part of a chip family which, to my understanding, still could be emulated if properly understood.

 

I've read through the following interview with one of the designers of the Cassette Vision, Masayuki Horie, and it has quite a bit of useful info on it:

 

http://shmuplations.com/epoch/

 

The Cassette Vision cartrdges all use a variant of a NEC microcontroller which was first used in the dedicated Epoch consoles "TV Vader" and "TV Baseball". The chips are called uPD77X, with the part after the 77 changing from game to game... each game had its own variant. For instance, TV Vader's variant was called D774C (as written on top of the chip). This can be seen here:

 

http://discreteconsoles.blogspot.co.at/2015/10/nec-upd774c.html

 

All the games had similar graphics, so I guess the graphics capabilities didn't change fundamentally. Judging from the screenshots and videos, I'd guess the possible resolution is about 56 x 56 to 60 x 60 pixels, though not all of it may be visible on screen, similar to the Channel F. According to the interview mentioned above, the screen is entirely made up of sprites, and there are 21 of them in total. From the screenshots, it can be seen that the sprites are probably 8x8 pixels in 1 color out of 8 or 16, but there seems to be an ability to draw them as diagonals, but doing so exposes a transparency glitch where black triangles appear at the left or right of sprites drawn this way, filling a square halfway made up by the diagonal instead of the background being transparent.

 

Now according to the interview above, the microcontroller internally uses a 48-bit architecture, so the instruction format is probably a strange one. But there is one variant of it that was more exposed, the D779C 300. This one wasn't used in any Epoch Cassette Vision cartridge, but in the Hanimex HMG-7900 console. The chip is called "programmable", but according to the pinout, it doesn't exactly expose address and data busses like real CPU's do. There is a discussion about that console there:

 

http://forums.bannister.org/ubbthreads.php?ubb=showflat&Number=103713

 

According to that thread, the Hanimex console doesn't have any video memory... which actually doesn't surprise me since I think all the video "memory" is contained in the D779C chip, and I think it's rather a memory map where every location means a specific thing. This would be similar to the TIA of the Atari 2600 and the video chips used in the Interton VC-4000 and the Odyssey^2. What they have in common is that they all have various memory locations (at most 256 of them) controlling the display, but they have to be externally fed with data because they don't access external RAM by themselves. Instead what they display is entirely defined by those on-chip memory locations.

 

On the Hanimex console though, it seems that the cartridges actually contain the CPU (an 8049 this time) which sends commands to the D779C built into the console. Which commands I don't know since I neither have any of the binaries for the D779C (which then could be disassembled) nor any cartridges. But by carefully tracing the disassembly and figuring out which commands get sent, one could at least figure out what each command does, and further, if it's actually setting register values in the D779C, figure out what the respective registers do. Sean Riddle seems to have also decapped and visually dumped the Cassette Vision chip for "Monster Mansion", which is a D777C 009 and actually contains two areas of ROM. I suspect one area might be the code, and another might be the graphics which are read separately (similar to CPU and CHR ROM's on NES cartridges).

 

On the Hanimex console meanwhile, I guess the on-board 8049 in the cartridges run the game and access the D779C via Port 1 (bit 7 for clock, the other bits send commands) and the controllers via Port 2, which also receives acknowlegdes from the D779C. The commands don't seem to be sent very often according to the logic analyses (at most 1 command per scanline).

 

So maybe disassembling the code of the Hanimex games could be the key to knowing how the graphics work, and knowing that could make the emulation of the other custom chips for the Cassette Vision feasible.

[pacman000]

Wait,

 

 

Horie: The VCS Invaders game wasn’t part of the original Atari console; it was made at our request. The fact that a big American company like Atari listened to our request like that was, in and of itself, groundbreaking. I was amazed, and when the chip arrived in my hand, it was a very moving moment for me.

 

Is this true? Did Atari license Space Invaders at Epoch's request?

[Scooter83]

This is cool. I have both systems and looking to expand my collection of each. What would be the must haves / must plays to get going for someone in the US?

[carlsson]

Out of those 16 SCV games I listed on the previous page, Wheelie Racer and Nebula stand out for me. I am participating in the games tracker and thus keep a detailed minute count on every video game I've played since I joined in July 2013. So far I've tracked 426 minutes of SCV gameplay, of which Wheelie Racer makes up for 162 mins (38%) and Nebula 105 mins (24%). The other 14 games individually clock in at 0 (*) to 24 minutes each.

 

Of course YMMV but a lot of those games are ports from other systems, sometimes with a bit of SCV character/twist to them, but rarely I have found the difference to be significant enough to play e.g. Miner 2049er, Boulder Dash or Elevator Fight (Elevator Action) on this system instead of one of the original ones. I don't mind a sports game every now and then, but as I don't understand baseball, find old style golf games rather dull and Super Soccer is significantly non-superior to me, those rather are games filling out the cabinet than getting played.

 

(*) Milky Princess, because I don't read Japanese and wouldn't count play time in a game where I have no clue which choices I am doing.

Edited June 11, 2018 by carlsson

[Dillweed]

Alright, who's the one that bid $165 dollars on the Elevator Panic I was looking at? I know I had to be one of you guys.

Edited July 18, 2018 by Dillweed

[+stupus]

I just posted scans of the insert for elevator panic to the 2nd post of this thread as was requested by dillweed.

Enjoy!

[Dillweed]

Thanks, man! This will help with the project I am doing.

[+stupus]

First off.....does anybody have a skykid manual they would sell to complete my super cassettevision collection!?!?!

 

Second, when I analyzed my 2nd copy of star speeder I got so I could obtain the 2nd to last manual I need I saw this!?!?

 

 

The 2 carts are different colors. I always thought each game had a corresponding distinct color for its shell?

Any variants I got always had the same color shell. The yeno games I have also use the same color as the epoch version.....

anybody else ever seen the same game in 2 colors?

if not maybe I have some 1 of a kind error????

Thanks

[carlsson]

I also go by colours when determining which game is which. A bit of miscolouration may be in order but not that extreme. I'm willing to think the left cartridge is rarity (Comic Circus?), as I seem to remember it normally is baby blue.

[+stupus]

At first I thought maybe they didn't always use the same color shell per game. But I think your right that this is a case of them putting a game in the wrong shell. It's definitely not just discolored.

I guess now I have a weird variant I have to keep lol

[Dillweed]

It could be due to sunlight, I've come across oddities like that too.

[virtvic]

I have just bought the French super cassette vision and will probably get the 4 multi carts for it, to have the full set of games, but I was wondering - has anyone made a single cart pcb for these that you can burn your own roms onto eprom for it? 
 

i know not all the games can be done due to battery back ups and extra ram on board, but the standard games should be doable?

[carlsson]

I believe Rolo has an adapter for his CoCo/Dragon multicart that is suitable for the SCV. It lets you replace the EPROM but perhaps the capacity is less than with the other multicart solutions presented in recent years.