Can you emulate a Vectrex ROM on the Vectrex?

[garryg]

Confused? Ok I shal explaine...

I was looking a a dead vectrex rom (Scramble) and I was looking at an unused Arduino Uno, and I thought: Hmm, I'm sure I've seen a demo of a vectrex rom being streamed to a vectrex through an Arduino, so this being the case...

Should it be possible to de-solder the dead Scramble ICU and wire up an Arduino pretending to be the ROM?

Obviously this would need to be powered, but is there a good reason why this isn't at least feasible?

[jfmateos]

I think it would be difficult for the Arduino to ouput the data at the Vectrex pace... but you could do it with a faster uC

[Rapetou33]

jf : what would be the result?

[jfmateos]

Probably the vectrex would just run mine storm and ignore the cartridge.

[kokovec]

I've done it with a PSOC but it's kind of a waste of a ucontroller

[garryg]

Mar 18, 2016 15:21:16 GMT -5 Rapetou33 said:

jf : what would be the result?

The result would be a 'cartridge' running on a Vextrex that is not only re-writeable, but could also be used to store in-game and save game data, as well as using cheep Uno clone hardware instead of having to make relatively expensive Vectrex cartridges...

Basically using Uno hardware instead of a dedicated cartridge. I just wondered if it would be worth while looking into this, or if someone already  knows why it can't be done?

Doing this with something bigger, and more expensive than, a cheep Uno clone would would basically defeat the point though.

[mountaingoat]

There is a video on someone hooking up a dual port SRAM, one side to a Vectrex, the other to an Arduino:

www.youtube.com/watch?v=iuyp2dIJGT0

This seems safer, the Arduino won't have to keep up with the timing of the ROM, just load the SRAM once and maybe tweak some memory locations. Could be pretty cool, replace some vector lists or music during gameplay from the Arduino side.

[kokovec]

This is what I ended up doing with the 3D engine I built.
It had two 32K SRAM chips.
It gave the Vectrex an extra 17K of RAM which was nice.

[mountaingoat]

Which chip did you use?

I need to find a DIP one to try - don't dare to try to solder an SMT one ;-)

[kokovec]

I like using Cypress chips although I usually use SMD.
I have a couple of these on hand...
www.jameco.com/Jameco/Products/ProdDS/1921320.pdf

[mountaingoat]

Very cool, thanks for the info.

[thomas]

Well, yes, you can emulate a ttl chip with a microprocessor, even possibly some of the Arduinos. I've built a 'multicart' around a microprocessor
simulating a rom/ram chip and am using it for almost half a year now. Emulating just a rom on a given Vectrex is easy. Getting it to work on a bunch
of different Vectrex units is harder. Getting it to work on all of them and adding nice extensions and a communication channel between the 6809 and the uProc
is even harder still. Really hard to nail down reliably. That's because you emulate not only the bus protocol of a 6809 asynchronously but also try
to find the cycles for those additions.

And if you are wrong even for a cycle in a million it'll crash, so better know what you are doing..

Anyways, I've done it for the Vectrex, have the T-Shirt to prove it plus a 'multicart' that provides sw extensions to carts like load/storing of data,
page swapping beyond 2 pages and I've also got on top of that a high-score saving extension plus versions of every original Vectrex game out there plus a
lot of home-brews to use that one.. This is what you end up with once you wander this path, so let this be a warning: it's a time-sink.. but worthwhile..

[garryg]

Thanks for all the replies, at least I now know it is possible although it sounds like a lot of work that I probably don't have the time (and or knowledge) for right now