I was thinking about if it was possible to move a whole game to another position in memory. Taking a disassembly and place that after another game and then assemble all the code again…
I have done it with some Fairchild games and it worked out very well. There’s a good disassembler for Fairchild that also replaces all the real addresses with labels instead, so you’re free to move it to any place on the memory map.
If there are absolute addressing in the Virtual Boy game it will of course not work unless these are altered.
Then you could make a menu and have it jump to the right location. This would perhaps make it possible to place all the American released games on one 128 Mbit cartridge.
It looks like it’s possible to cram four 32 Mbit eproms in one cart, when looking at the FlashBoy circuitboard.
You would have to place the smaller games inside the empty space of the large ones to make it fit, but I know nothing about how this work. I have noticed there must be some header last in the cartridge rom, how will this be affected?
Alternatively you could cram all versions of the commercial games into two carts and top them off with the nicest and most practical homebrews. The homebrews would of course be a lot easier to move anywhere on the memory-map, right?
It would be nice if someone with a FlashBoy and programming tools as well as skills could make a test. Disassemble Mario’s Tennis and Panic Bomber, place one after the other in memory, add a tiny “menu” – it doesn’t even require any graphics, just wait for button A or B, pressing A jumps to where Mario’s Tennis starts and pressing B makes a jump to where Panic Bomber starts.
Assemble all of it and try it out…
Perhaps it could even be tested with Reality Boy. I guess the final rom-image of 1MB plus menu code has to be padded to a 2MB rom and header changed appropriately to work with FlashBoy…
Mario’s has a gap from $7DC90 to $75D5F, if there was only a jump added somewhere in the beginning to that address and the menu code was “hidden” in that free space and the final rom was shortened with as many bytes as that initial jump would take you could perhaps even make it work without padding – if run in Reality Boy, or add a 1MB game as well or two more 512kB games – so you could have four games on your FlashBoy at ones – or even more if you crammed in some of those small homebrews.
Possible? Feasible?
If the roms can be freely moved around in memory it seems both possible and feasible to me. It would simplify the hardware side of making a true Multi-Cart. Just put all of it on a large eprom or bank of eproms.
The other way to go would otherwise be a large memory of some kind, most likely not an eprom as there are none large enough at reasonable cost that would hold all games. So let’s say a SD micro card – it’s small, cheap cards will easily hold all available data for the Virtual Boy and there are already finished routines to read and write to them with both PIC-processors and Atmel AVRs.
Then some kind of memory that the selected program would be copied to, perhaps the same type of eprom that the FlashBoy has or if there is large enough ram…
A menu program would be loaded into the active memory when cartridge is inserted – unless it was permanently stored in some other small memory. In the menu you would choose program – in an automated list created by the micro processor after reading the file names of the contents of the SD micro card.
Biggest problem with the second approach is speed, it will take a little time to transfer the data from the card to the eprom/ram.
Any thoughts on this, any constructive critisism?
I laid out the flash roms, needed caps, the connector and the dipswitches, put a voltage regulator there but it’s not hooked up yet and tried routing. It seems possible…
This is the pcb adapted for a new connector, haven’t checked it it fits yet though but it’s still in the planning phase so.
Anyway, it seems like it’s possible to make a 32 slot multi-cart with dip-switches.
I need to check to sort out the voltage level converting, check that I have large enough traces for the needed current and correctly hook up the regulator. But even if I need to solder jumpers manually it seems feasible.
Attachments:
Sure, just desolder an eprom, put it in your TSOP56 adapter and reprogram it with your eprom programmer…
The PCB is quite full as it is, I’m not sure it would be possible to add support for it to be reprogrammable. Perhaps it would be possible to route VPEN and /WE to cartridge connector pins and then it would be possible to reprogram by connecting the cartridge to an eprom programmer. But I guess that’s too much work for most people and there’s no physical room for a USB-interface.
This is meant to be the whole collection in one cart.
I guess you need a FlashBoy as well.
Here’s an almost working version, the second one is for the original connector. The dip-switches I chose was apparently not in the parts library for the 3D rendering:
Paper cutouts in an original shell (yes they’re up-side-down for a better view).
Attachments:
Both the upper versions are for a standard 2mm 2×30 connector. The connector can be seen in the upper paper-cart-picture. I don’t know if it works yet, it looks like it could… It would help production not having to desolder connectors but cart shells are still needed so it won’t save on any carts, and as I mentioned before, the connectors are probably more expensive than getting a batch of brand new boxed cart.
I finished routing the version with ram, it looks like it’s possible.
It would be fun to have a prototype made and try it out.
