Turbo CD system card integration mod?

[cr4zymanz0r]

Since the CD system card is basically (to my knowledge) just adding more RAM and loading a ROM/bios to interact with the CD unit, is there a way to replicate this functionality internally with a mod? I know some of you may think this sounds highly impractical (and maybe it is), but sometimes it's fun to do stuff just to say it's been done.

Background: I'm thinking about getting a Turbo CD add-on for my TG16, but the US 3.0 system cards are very expensive. I know a common thing to do is do a region mod and import the JPN 3.0 system card, but I thought why not get more creative.

The Idea:
1.)The 1st and most necessary step would be to solder in the additional RAM into the system. Since the system card is used in the hucard slot, wiring this up to the hucard pins on the motherboard should be feasible. If we knew of a compatible RAM chip and the proper pinout to wire it up this, then this portion of the mod sounds theoretically feasible to me. (Maybe we could even bump it up to the arcade card level of RAM while we're at it)

2.) The 2nd step has an easy way and hard way option. The easy way would be to use a Turbo Everdrive to load the system card rom. The hard way would be putting the system card ROM into a EPROM chip or something similar and mod it into the system internally. This sounds feasible to me, but I'm unsure how you could make it ignore the system card ROM when a hucard game is inserted (like the Duo does). With the added RAM and integrating the system card rom, functionally it would make the system like a Duo with a detachable CD unit.

So does anyone with pretty in-depth TG16/PCE knowledge care to give their technical opinion on this? I'd love to mod in the additional RAM at the least. I have the soldering skills to do so, but I don't have the in-depth knowledge to know what RAM chip(s) I would need and where to wire them up.

[BlueBMW]

I know there is unused circuitry in the TG16 that looks like it could accommodate a built in game rom of some sort.  The trick is how do you tell the system to use the internal rom versus a hucard.  Its possible the existing circuitry detects the presence of a hucard and thus switches the bus to the hucard and not the internal rom.  I know the DUO systems do this... whether or not that function was built into the TG16 board or not I dont know.

[TheOldMan]

The trick is how do you tell the system to use the internal rom versus a hucard

That's the CART line on the HuCard. IIRC, 0 means use card, 1 means use internal rom.
Dunno if all that stuff us available on a turbo; you might have to add a gate or two, as well.

If we knew of a compatible RAM chip

Maybe this one? IS62C256AL-45ULI  => 32Kx8, 5V 45ns static ram.
Dunno if it's too fast or not; the tg uses 120ns ram internally, iirc.
Any of you electronics guys know?

(digikey : ICS => Memory. Possibly type = RAM. Was third one on the list when I checked. Pdf of specs is available, that's why I posted this info.)


Blue: Does this mean we need to work on a ROM/RAM card now ?

[Fidde_se]

This mod reminds me of the guy who had magical chase builtin, which were discussed a couple months ago.

[bust3dstr8]

Why don't you just solder in a cheap PCE 3.0 and add some glue logic to the /CE

[BlueBMW]

A ROM/RAM card would be slick

Maybe thesteve will chime in.  He seems pretty familiar with the internal data line workings of these consoles.

[Necromancer]

It's done in the Super CD add-on, so it should be doable.  But why stop at a Super CD syscard when you could do an Arcade Card and have something really special?

Alternatively, install a region mod and use a cheap PCE syscard, with the added bonus of being able to play all the great hueys denied to the US.

[OGHUGO]

This mod reminds me of the guy who had magical chase builtin, which were discussed a couple months ago.

Yeah, did anyone get a hold of the seller, or the buyer? interested in knowing how that was done..

[KalessinDB]

It's done in the Super CD add-on, so it should be doable.  But why stop at a Super CD syscard when you could do an Arcade Card and have something really special?

Alternatively, install a region mod and use a cheap PCE syscard, with the added bonus of being able to play all the great hueys denied to the US.

Yeah the region mod, however it's done, is pretty awesome.  But somehow the built-in cd booting (with Arcade Card) would be beyond awesome.  Wish I had the knowledge to make it happen.

[Fidde_se]

This idea coincide with that idea of builtin tennokoe huey card, which can be very much more advanced, if it's just a switch of cards then it's easy but if they should interact on the busses or have expanded memory like discussed a year ago then it is advanced, anyhow moving on.

This could be pretty simple, the component for it is just a little unusual, it could be done with circuits too, if one were to find a 2pol slide switch with has like 40 pins, it would just be about soldering the right cables to the right pin that lets the input of the huey switch between the either a card internally as input or the normal huey connector, it just a simple on to on switch it just that it does 40 pins in a row, well at least 38.

These kind of slide switches existed in the 60-80:s, but has since been replaced by circuits.
reminds me of that simple region switch that was used a couple years ago on the PCE.
it just used a lot less pins.

you could do I manually with 38pcs on to on switches too =) or 19 double pol...

Some one here should probably solve this one with a bunch of 4551 circuits in a matter of hours, at least in theory....