Famicom Disk System emulation

Discuss emulation of the Nintendo Entertainment System and Famicom.

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Re: Famicom Disk System emulation

Post by abridgewater » Mon Apr 08, 2019 10:09 am

byuu wrote:Not for the audio portion, though. I had to just reuse the Wiki formulas for that. I suck at FM synthesis. I do have 6-bit signed integers in higan though, so I would like to try and rework that code sometime to use those instead of the strange over/underflow manual checks to work with 8-bit integers that's there now.
I'm a bit unfamiliar with precisely what you're trying to do here, but... Can you "just" scale all of your 6-bit values by 4 (shift left two bits) and treat as 8-bit, with appropriate compensation for divide/multiply if necessary?

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Re: Famicom Disk System emulation

Post by Near » Mon Apr 08, 2019 7:10 pm

I certainly could, yes. I just figure that if I have native 6-bit types, I may as well allow the over/underflow behavior to occur naturally.

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Re: Famicom Disk System emulation

Post by Pokun » Sun Apr 14, 2019 8:49 am

byuu wrote:I haven't *yet* added write protection. Is that just a physical switch on the floppy disk like regular 3.5" disks have?
Not a switch, QDs have two plastic tabs (one for each side) that are broken off to enable write protection (just like on tapes), so you need to tape over the slot to disable write protection again. Although games might not work if it's enabled, Nintendo's version of the disks nevertheless always has these tabs, so I see nothing wrong in emulating them.

The tabs are checked by a physical lever inside the disk drive which can get dirty and upset, and throwing unwanted write protection errors even if you press on it with your finger. Never happened to me though.

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