I have been doing some research on the pinouts on the internal drive on the fds. I have noticed some similarities to the 3.5" floppy drive for a pc. Would it be possible to replace the internal drive with a 3.5" drive with 3.5" floppies? From what I would see is that you would have to make a connector or hard wire the drive in the fds. I haven't found any information on if it’s possible or if anybody has tried. So I guess I am looking for some feedback on the idea.
FDS disks are basically read and written like cassette tapes, it wouldn't work.
I suppose it would work if you completely rewrote the low level firmware on the floppy drive, FDS bios, and possibly RAM carts themselves. That and some extensive harware modifications. Good luck.
Of course, if you make a FDSLoader cable, you are doing exactly that, in a way, sort of. A bit bulkier than just throwing a floppy in though, of course.
-Rob
rbudrick wrote:
I suppose it would work if you completely rewrote the low level firmware on the floppy drive, FDS bios, and possibly RAM carts themselves.
And it still wouldn't work for games that access the disk directly instead of using the BIOS, possibly for copy authentication. (What percent of games are those again?) Otherwise, someone would have probably rewritten the BIOS a long time ago.
I don't believe that many games do any low level disk stuff themselves. I just think that it would be quite a task to write your own BIOS, make your own RAM adapter, etc. First off you can't replace the BIOS in the RAM adapter cause it's not a ROM chip, it's built into some other chip. I'm sure there is a slew of hardware issues to work out to use a floppy drive instead. You'd be better off making your own original NES Disk System that loaded game files similarly to the FDS but from 3.5" floppy disks. Besides that way you could make your system much better by having more RAM, like 128K or more PRG and 64K or more CHR allowing you to have banking abilities that many games using CHR-ROM had. But you'd have to do all this cheaply if you want anyone interested in buying it. And ofcourse then you need software, so you'll have to make good games or hack alot of licensed games. In the end it's just not worth it.
I base my opinion that not many games do low level access because simply HLEing LoadFiles() from the FDS Bios makes most FDS games work on my emulator. I didn't ever add any low level drive emulation. Wasn't interested in all that work.
MottZilla wrote:
First off you can't replace the BIOS in the RAM adapter cause it's not a ROM chip
I was thinking it'd be for emulators and PowerPak.
Bunnyboy so far has said there will be no FDS love for the PowerPAK. ='( Although I suppose with it lacking the sound channel capability it is just as well.
MottZilla wrote:
Bunnyboy so far has said there will be no FDS love for the PowerPAK. ='( Although I suppose with it lacking the sound channel capability it is just as well.
Man, that's a bummer. Can't this be emulated in hardware in a similar fashion to the way he did the mappers in the PowerPak?
-Rob
There are several reasons:
- The FDS BIOS is copyrighted until after you are dead. It would have to be rewritten anyway to access a disk image in bankswitched RAM.
- PowerPak has a 72-pin connector. The 72-pin connector has no audio pins.
Does anyone know how many free I/O there are on the PowerPak? Perhaps we could come up with a DAC and mixing circuit internal to the PowerPak. Also how many DAC bits are necessary to support the existing sound chips? I'm not sure either if there's enough logic left over for some of the big sound chips.
I think it would be OK to distribute a program to patch the official BIOS and join it with a FDS ROM for use with a mapper on the PowerPak.
If your DAC is mono and clocked over 1 MHz, you really only need one output. You toggle a bit at rates in the hundreds of kilohertz, and then you run the output through a low-pass filter circuit. It's called
pulse-density modulation, and all SACD players use it.
I've tried a second order delta sigma DAC for CD audio and it sounds pretty bad; I suppose for 4-8 bits low quality expansion audio it'd be fine (especially if you use two output bits) but then you have the logic overhead which could be an issue. I've never tried to implement MMC5, so I'm not sure how much logic is left over after that with the Game Genie etc, maybe there's plenty.
Here's what I'd do:
Rig up a very small Mini-ITX motherboard (or smaller, if you can manage it-- like those ISA cards that contained a tiny Pentium or 486/etc. PC), and power it from the FC supply (you'll need to replace the brick with something with a lot more current, I imagine).
Hardwire the DB25 Parallel Port header to the FDS drive controller IC as specified by FDSLOADR. Attach your floppy drive. Make a standard format for all your disks so that they are bootable to DOS and automatically run FDSLOADR on startup.
It's a little wacky, but I'd love to see it.
I'm working on the reverse of this project; building an internal PC FDS drive from an FDS drive unit, wired internally to the motherboard's DB25 header. Wish me luck.
An ITX computer seems really wasteful since a microcontroller could deliver the same performance for a fraction of the price. Give it a 7-segment, a few buttons and a SD card slot and you have a complete FDS emulating system, but one that still relies on Nintendo parts.
I'd rather see the PowerPak thing though, no more loading or disk errors or new hardware to be built unless you want expansion audio.
Can't you just output the audio on one of the expansion cartridge pins that goes to the expansion port? And doesn't one of the expansion port pins goto the audio mixing thing? So you just need a jumper. I forget but I recall a topic like this before.
MottZilla wrote:
Can't you just output the audio on one of the expansion cartridge pins that goes to the expansion port? And doesn't one of the expansion port pins goto the audio mixing thing? So you just need a jumper. I forget but I recall a topic like this before.
Sure but why make people mod their consoles if you don't have to?
tepples wrote:
There are several reasons:
- The FDS BIOS is copyrighted until after you are dead. It would have to be rewritten anyway to access a disk image in bankswitched RAM.
- PowerPak has a 72-pin connector. The 72-pin connector has no audio pins.
Both are easily worked around. For #1, there are alternative bioses out there. On top of that, he could always leave that out and you could find it yourself and load it onto the cart. For #2, the mod to the expansion port could easily be done. On top of this, FDS audio isn't necessary and only optional.
There's got to be better reasons than this why he isn't going to do it. I wonder if someone else did it, whether he'd sell it.
kyuusaku wrote:
MottZilla wrote:
Can't you just output the audio on one of the expansion cartridge pins that goes to the expansion port? And doesn't one of the expansion port pins goto the audio mixing thing? So you just need a jumper. I forget but I recall a topic like this before.
Sure but why make people mod their consoles if you don't have to?
Well in BunnyBoy's case, to make money, of course.
-Rob
You don't even need to mod the expansion port; a simple jumper pack that connects the output and input pins (plus any caps/resistors) is all you'd need. There's evidence that Nintendo planned to do this with the MMC5. As I recall, though, the main problem with that option is finding/making a connector that'll fit the NES's oddball expansion slot.
On irc I suggested a sollution......alligator clips! they have the correct resistor ect in between the two halves then you just clip them onto the pin (obiously you'd need to cover one side of the alligator clips or it'd short but you get my point)