It's very hard for us to make a universal dev cart, because of the existence of variety mappers and cart structures. It's almost impossible to include all of them on one cart.
But I thinks we have some other ways. Maybe we're able emulate all kinds of mappers and carts if we use a powerful MCU to control it.
For example, we may be able to write the whole INES data(include the header) into the external Flash ROM.
When the controller is powered, it reads these data the kind of mapper, then emulate the cartridge.
As we know, a console emulator can receive inputs from players, process it and return the correct result to players. A cartridge emulator is the same - it receives the request from console, then do some works to make it able to send response like a real cart.
This is called a PowerPak.
Actually, what he describes is more what Memblers was doing with
Squeedo, using a 20 MHz PIC microcontroller as the MCU. But even a fast processor can't emulate some mappers fast enough; for that you put an FPGA on board, as the
PowerPak does.
blargg wrote:
Actually, what he describes is more what Memblers was doing with
Squeedo, using a 20 MHz PIC microcontroller as the MCU. But even a fast processor can't emulate some mappers fast enough; for that you put an FPGA on board, as the
PowerPak does.
It may sound off topic but instead of always trying to emulate existing mappers, I would like to know why new ones for our own needs are not developed (or are they)?
Since this is mostly for our own custom development, I don't see the issue unless of course you want to use an existing rom that use that specific mapper on your dev cart.
p.s. I'm not a hardware guy by the way so don't be too hard on me
Sorry if I put the thread in another direction, if this is the case.
The powerpak is not suited for development because of all the steps needed to go from compile->test
Now a powerpak with onboard memory, an usb connection and no menu to try out what you uploaded... that would own for development. Both for existing mappers and ones you make up your self (as long as they fit in the FPGA in the pp)
Yes, I think programmable controller can also provide us the possibility to customize it for our programs.
The only problem is, if we use a software emulator on PC for debugging, we must hack the emulator in order to make it able to support our own "mapper".
And about the performance issue.
Well, if a 20 MHz PIC is not fast enough, what about a 32-bit ARM processor?
About the products from RetroZone.
They sounds great.
But it's difficult for me to get it in P.R.C.
Our customs are very strict and these products' compatibility with Chinese Famicom clones is unsure. After the original Famicom's production discontinued, these clones are the only product that we can get easily.
So, are there any other alternatives?
I might recommend your own Dr. PC Jr.
ccovell wrote:
I might recommend your own Dr. PC Jr.
Well, just like the original Famicom, it's production discontinued.
And most of it's clone have no floppy drives nor internal storages.
Miliardo wrote:
Yes, I think programmable controller can also provide us the possibility to customize it for our programs.
The only problem is, if we use a software emulator on PC for debugging, we must hack the emulator in order to make it able to support our own "mapper".
I forgot about that part completely. You lose the ability to test it in an emulator, which is a big lost. In that case, we need to have access to an emulator that allows to add 3rd party plug-in for our own custom mapper. That would be nice.
Unlike the DS scene, where the best available emulator is the apparently abandoned freeware version of NO$GBA, the NES scene has very high quality
Free emulators such as Nintendulator, Nestopia, and FCEU*. So yes, it would be possible to hack a new mapper into a decent emu.
Yes, it's true that it is pointless to restrict to officals mappers the day a homebrew game is large enough to use the feature of a custom made mapper and the day emulators emulate it. Unfortunately this day has not come yet. As for today, almost all homebrew games that have been completed use mapper 0 so I guess it's too early to talk about new mappers.
If I would ever devlopp an "advanced" RPG for the NES, I'd definitely like to try to replace the PRG-ROM with an EEPROM that the 6502 can partially overwrite (re-programm) so you'd save data to EEPROM and remove the need for SRAM+Battery. This would also fix the problem of dead batteries.
But a too advanced game would require the SRAM anyway because internal 2kb wouldn't be enough so in that case it may be just better to stick with the battery thing, unless the custom mapper has it's own internal RAM (like the MMC5).
There is always chances that games developped today using common official mappers could be mass producted using cheaper/more advanced custom-made mappers in the future when they will become well known.
In fact, there're still some companies in China, which develop their own illegal Famicom games.
And they used some customized or rare mappers, with some modern flash rom chips that can storage up to megabytes of data.
Anyway for the real core gamers, their game is just nothing but some joke. Because their game always use the names of famous titles on later platforms.And most of them have lots of terrible design.