famicom disk other port on ram adpater

[cadillake]

i found this link on a forum and look like a cool stuff if some one tried to do it will be cool

links: http://ayasuke.exblog.jp/8672106/

http://ayasuke.exblog.jp/7417029

sorry me English

[arfink]

I have contemplated hacking an FDS RAM adaptor for some time now, though I have not done so simply because I didn't have a Famicom. I'll have my first in less than a week, and I intend to get right down to business with hacking etc. Unfortunately I don't know any Japanese at all, so I can't make much of that website besides the pictures and a few acronyms. I recognize the development board he is using, and that's about it. However, the FDS data protocol is well documented at places like NES Dev so a project to do, for example, an arduino or propeller MCU based FDS backup/hacking device would be perfectly possible.

[Xious]

Does anybody have a pinout of that port, or a schematic of the RAM Adapter?

-Xious

[satoshi_matrix]

Just what could hacking of the FDS RAM cart accomplish?

[ericj]

I believe it would allow you to write or dump disks or you could emulate the disk drive through it. I think someone on Tototek.com has the pinout. I remember someone was tearing apart a Hacker Pro ram adapter to see how it worked.

[arfink]

Just what could hacking of the FDS RAM cart accomplish?

I would say, backups and disk writing would only be a fraction of what it could do. Running FDS games without a disk drive comes to mind. Running FDS homebrew. Converting other games to FDS format. Dumping disks.

[ericj]

Besides converting games to fds format, I said the rest of what you just said. FDSLoader can do pretty much all of that right now, except loading and dumping game doctor formatted disks. Many cart games can be manually converted to run on the FDS, but most require a game doctor to work. Since there are already reliable ways to dump and write disks (Pasodisk w/ the Chameleon Set, MGD1, and FDSLoader, and some other more obscure ways), I'm not really sure what the benefit would be to hacking the ram adapter to do this. FDSLoader can already emulate the disk drive, at least for correctly formatted FDS images. It would be nice to have a USB device, though, instead of having to rely on DOS and a parallel port.

[kyuusaku]

This port is just a 7-bit open-collector parallel port. The Hacker Intl hardware uses it for nibble-wide access to access 32 KiB of RAM. Instead of developing for this port, I would suggest using the Famicom's expansion port, which while less versatile is more available and obviously can be used in projects without a RAM adapter.

[ericj]

kyuusaku, didn't I read on Tototek that you were trying to disassemble a Hacker Pro ram adapter? If so, did you ever get all the epoxy off it to see the pcb?

[kyuusaku]

Yup I was trying to, I don't remember even posting about that, must have been forever ago. It's still disassembled XD I would like to finish removing the epoxy but it's in between the chip legs and I already scratched a bit of the PCB trying to get it off ( This stuff is SUPER tough, I'm not sure how I even chipped it before, maybe with a drill... Not only did they glop on the epoxy but they also filed off some of the chip names! The only two I couldn't make out logically have to be counters for the RAM's address lines, and the only chip that would make sense would be the '393. So here's an IC list for the Hacker thing:

-62256 (32k x 8 sram)
-125 (4 x 3-state buffers)
-14 (6 schmitt trigger inverters)
-257 (8:4 multiplexer with 3-state output)
-173 (4-bit register)
-123 (dual monostable) -- seems unnecessary/out of place, I guess it's used to speed up reads/writes
-393? (dual 4-bit ripple counters)
-393?

The data bus must be 4-bits so the 173 register holds the most significant nibble during writes.

The 125 is used to drive the open-collector bus during reads. The 125 is fed by the 257 multiplexer which is attached to the RAM's 8-bit data bus.

Since there are only 7 free bits on this port, and the data bus is 4-bit, there are only 3 control signals...

-One must be an address clock/data strobe
-One must be R/W or bus direction (enabling either the register or multiplexer outputs)
-One could be a reset signal for the address counters, though this is technically unnecessary since data will repeat every 32768 clocks)
-One could instead control the data register and multiplexer which would be faster than using the least significant address line for that.

I still dunno what's up with the monostable.

[b1aCkDeA7h]

That other port is also on the side of a Twin Famicom. Supposedly, it's to allow you to plug in a RAM adapter and use the Sharp Twin's disk drive with a regular or AV Famicom. However, that other port is too small for the standard RAM adapter plug.

[kyuusaku]

Whoever said that is very wrong, not only is it like impossible since the port is software controlled and the FC is not fast enough to play FDS Loader, it wouldn't even make sense from a marketing perspective. Since the regular FDS has one, does that mean it should allow someone to use a FC+FDS on another FC? XD

The port is good for a few things:

-simple peripherals that use very little or no power, like a system link cable
-peripherals that have their own power supply (such as the Hacker thing)

And nothing high speed either, at most you could get like 30KiB/s interfacing to hardware, using 4 data bits. Probably  a system link cable would be like 5KiB/s with the software handshaking.

[Xious]

That thing about connecting a second FDS is a tidbit of mis-information spread like a disease via Wikipedia pages on the Sharp Twin Famicom. I wasn't aware that the hacker-pro used it--I underbid on a couple of them and haven't held one in my hands yet--and I was pretty sure it was some kind of data port, but I wasn't sure what the original concept behind it was until more recently by reading about the FDSLoader stuff. it does seem that Pasofami uses it though, with a custom bootstrapping disk or something like that, to run FDS games in the emulator using actual disks. (From what I saw in a blog+video.)

I think I'm right in my understanding that you can R/W to the FDS RAM-Adapter memory ranges using the port, but I'm not sure how (pinout unavailable at present?). I'm guessing here, but I'd figure that it was probably used by some SW companies when developing FDS titles for debugging or for loading data directly into the RAM adapter from a computer. I wonder what NCL had in mind when they included it. Perhaps some way to connect the FDS and the Family BASIC set or something along those lines, that never materialized.

Certainly, connecting a second FDS has little (really no) practical value, even if it would be possible. The only advantage would be less disk swapping, which is pointless, as few games came on more than one disk, except Doctor Disk games, which Nintendo wouldn't have planned to authorize. (It's rather like emulating a PC on a Mac, then running a Mac emulator therein: Aside from just being silly, it serves no logical purpose.)

Depending on the capabilities of the port, it could be used in developing an FDS peripheral, such as my suggested Family BASIC FDS attachment, although that could be done within ROM or with disk handling routines in BASIC on disk. The DA-15 port has $4017 and $4016 address lines, so developing something to connect to the RAM-Adapter port would be a completely different type of peripheral.You can't do direct memory reads of FDS games loaded into the RAM-Adapter via these address ranges, so it is certainly possible to do something unusual and interesting with the FDS Expansion bus, but I'm at a loss for anything good to do with it until I have factual data on what it does.

-Xious

[kyuusaku]

it does seem that Pasofami uses it though, with a custom bootstrapping disk or something like that, to run FDS games in the emulator using actual disks. (From what I saw in a blog+video.)

It's dumping the disks, not accessing them in real time.

I think I'm right in my understanding that you can R/W to the FDS RAM-Adapter memory ranges using the port

No. You'd be hard pressed to find a peripheral port that can take over the CPU bus with 7 pins. The 2A03 doesn't even have a mechanism for that. This port is entirely software defined, bits you write to $4026 appear on the port. If you want to read back data from the port, set the bits high and read $4033. If you don't get it read about computer buses and open-collector buses.

I'm not sure how (pinout unavailable at present?)

Keep looking, it's out there, you may have to consult a technical document.

The DA-15 port has $4017 and $4016 address lines

Please don't confuse memory-mapped I/O @ $4016 and $4017 for address lines... An address line is a single bit of a binary number making up a memory address that the CPU is currently accessing. Here are the address lines: A0, A1, A2.... A15. Again, read about computer buses.

so developing something to connect to the RAM-Adapter port would be a completely different type of peripheral.

Actually it wouldn't be, if you develop a peripheral for the FC expansion port (2 outputs and 4 inputs that aren't also used by the controllers), the RAM adapter port is more than capable of interfacing with the device (which has 7 bidirectional).

You can't do direct memory reads of FDS games loaded into the RAM-Adapter via these address ranges

This doesn't make sense.

so it is certainly possible to do something unusual and interesting with the FDS Expansion bus, but I'm at a loss for anything good to do with it until I have factual data on what it does.

You have factual data on what it does... It's 7 memory mapped signals, figure out what you want to do with them.

[Xious]

No. You'd be hard pressed to find a peripheral port that can take over the CPU bus with 7 pins. The 2A03 doesn't even have a mechanism for that. This port is entirely software defined, bits you write to $4026 appear on the port. If you want to read back data from the port, set the bits high and read $4033. If you don't get it read about computer buses and open-collector buses.

I'm not sure what my statement had to do with taking over the CPU. I'm talking about reading and writing to where the FDS RAM-Adapter retains the loaded game data. I didn't know what memory address ranges are accessible via this post, so I was only guessing from what I've read or seen elsewhere.  I'll have to look into $4026 and $4033 and see what documentation is out there.

Please don't confuse memory-mapped I/O @ $4016 and $4017 for address lines... An address line is a single bit of a binary number making up a memory address that the CPU is currently accessing. Here are the address lines: A0, A1, A2.... A15. Again, read about computer buses.

Sorry. Data lines for the $4016 and $4017 memory address ranges. Specifically, read for $4017 D0 through D4, along with $4017 and $4016 Read-Enable and $4016 reads on D1 only, but writes three bits (D0, D1 and D2).

You can't do direct memory reads of FDS games loaded into the RAM-Adapter via these address ranges

This doesn't make sense.

Well, you can't do data reads outside the $4017 and $4016 memory address ranges on the DA-15 port.