Flash based HuCard project

[NightWolve]

https://shop.retrogate.com/everdrive/turbo-everdrive-v2-buy



Description
The Turbo EverDrive v2,4 is a flashcart for the TurboGrafx-16 and PCEngine, which loads the ROMs in the console itself. The handling of the flashcart is very simple. Plug your microSD card into your Turbo EverDrive v2,4 and plug your Turbo EverDrive into the HuCard slot of your system.
 
Features

PCEngine and TurboGrafx-16 systems are supported.
FAT32 file formats are supported.
Supports microSD cards up to 32GB.
Instant loading.
Street Fighter II mapper support.
On board reset button.
4Mbyte of ROM memory.
Cart may not work properly with region modded systems.
USB port for developers (optional).

[elmer]

https://shop.retrogate.com/everdrive/turbo-everdrive-v2-buy

Yes, I'd just buy a Turbo EverDrive, too ... and did. 

I recently put a PC engine GT back to life by changing its capacitors and found it would be interesting to design a Flash based Hucard so that games could be downloaded through USB.

But perhaps he really does want to design his own ... some people enjoy doing that kind of thing. 

[Vimtoman]

I agree it's great to see someone having a bash at it.

[thesteve]

you know, if you run the system bus through a PIC you could just have it running a loop untill the rom is ready and then going active
would require likely a slightly bigger chip then GameOofYou used as it would need to map the system bus and program the chip, whereas his only programs the chip
also doing that you could run lower voltage flash as it would be buffered

[Pierre95]

@elmer

The documentation at http://archaicpixels.com/HuC6280 does not specify the state of the address bus when /RESET is low but the documentation says:

/RESET terminal
A program is started by reading lower address from the physical address 0x001FFE and upper address from the physical address 0x001FFF when a RESET input becomes Low.

Which can be interpreted as "the processor outputs the physical addresses 0x1FFE and 0x1FFF when /RESET is low" So the address bus is probably not at high impedance when /RESET is low. But as you say elmer, it should be verified through experimentation.

@NightWolve, yes the Everdrive is a great product but for educational purposes, I find it interesting to design a similar hardware.

[Pierre95]

Hello,

Line A20 of HuC6280 is named XCE on the Hucard connector. This line is used as the ROM chip select. This is OK for 1MB or smaller ROMS as all ROMs fit this size, except street fighter II which is 2,5MB. This means this ROM requires some memory banking to allow reaching the extra segments which dos not fall in the 21 bits addressable space, right?

I am a bit confused about the addressable segments.

Here http://emu-docs.org/PC%20Engine/pce_doc/pce_memory.html

It is written Hucard storage goes till F6h =1968KB

But here http://www.db-elec.com/home/technical-info/tg16/memory-map

it says the space between 80h and F7h is unused (reserved for CD ROM) so what is the truth about that?

Also here: http://emu-docs.org/PC%20Engine/hw.html

It seems segments 01 of ROM is unused, but when looking into a ROM file through hexeditor, there is data in this segment...

[elmer]

I am a bit confused about the addressable segments.

I recommend that you ignore everything on emu-docs.org, they don't seem to have a clue, and are just plain wrong.

Try this instead ... http://www.archaicpixels.com/Memory_Map

HuCard space is just the lower 1MB of the processor's 2MB of address-space.

If you've not already seen it, this is the document that you should be looking at ...

Charles MacDonald's TurboGrafx-16 Hardware Notes
http://www.romhacking.net/documents/302/

"Street Fighter II" fits 2.5MB into the 1MB of HuCard address space by adding a secondary banking mechanism to switch the contents of the top 512KB region of the HuCard address-space.

[Pierre95]

Thanks a lot elmer, both links are really helpfull.