project sd2snes

Here’s another preview: v0.1.7 preview 2
It addresses some issues reported with v0.1.7 preview (and some others).

• Satellaview works again. BSX alters the original interrupt vectors at run time. The original interrupt vectors are now saved per hook call, not only once when loading the ROM.
• In game buttons now work with MSU1, too.
• Automatic hook method choosing: NMI is default but switched to IRQ when no NMIs are triggered. If both occur, NMI has priority. This should enable the in-game buttons for games that previously did nothing.
• The hook routine saves some CPU time when auto joypad read is enabled by the game – it will just reuse the result instead of doing its own controller scanning. Also the controller is now only scanned every 8 frames. This helps alleviate some glitches, e.g. Secret of Mana now starts up correctly. There are still some glitches left which can’t be eliminated fully.
• Auto region patching works again without having to delete the sd2snes.cfg.
• BSX now emulates Type 1 memory packs instead of Type 2. Apparently the BSX BIOS is buggy with Type 2 packs when they contain HiROM games that are supposed to be run from PSRAM. So, at least Bomberman works now, and probably others too.
• Fixed BSX PSRAM shadowing for HiROM.
• Files and directories with “hidden” or “system” attributes are now actually hidden from the file browser.

NOTE: Satellaview is broken at the moment because it doesn’t work with the NMI vector patching. I’m working on it.
At last here’s the v0.1.7 preview. Cx4 blew up in my face when I tried to insert the cheat/in-game hook engine and ended up taking days to get working. 😐
Here’s what’s new (mostly copied from the status post):

• In-game button combinations are in effect. See the table below for the key mapping. Note that some games show glitches with the in-game functions in place. I added an additional feature to temporarily disable them in case of game glitches (e.g. Secret of Mana hangs at the Squaresoft logo, displaying only garbage). I’m not entirely happy with the button choice but it will do for now. 😉
• When running a game from the recent games list, the selected entry is now moved to top of the list.
• LED blink codes for file system errors – e.g. in case the SRM file cannot be saved this will tell you that something’s gone wrong. The blink codes are yet to be listed.
• Also the sd2snes will retry saving until it works so you have the chance to swap out the SD Card. In that case the directory structure must be present where the sd2snes expects to save the file.
• “Screen saver” – in the menu, the screen is darkened after some idle time to reduce wear on CRT and plasma screens.
• Memory sharing between SNES and the sd2snes CPU is greatly simplified (The FSM is reduced to only 5 states instead of 18) and timing is more relaxed. This should help with stability on a wider range of consoles.
• On-the-fly file browsing. Also shows a little “loading…” window when loading directories/files.
• Windows are now blue so they stick out better in front of yellow directory listings.
• Cx4 data ROM is now embedded in the FPGA configuration – no more need for the external file cx4.bin.
• Initial Satellaview clock is back to 18:00:00 from 18:05:30.
• SD cards can be hotswapped. Currently there is no automatic refresh of the file list so tapping reset on the SNES or changing the directory is necessary to get the new contents.
• The status line is moved upward a few pixels so hopefully it doesn’t get eaten by overscan.
• Navigation: When scrolling page-wise with the right D-pad arrow, the end of the file list is now aligned to the bottom of the screen.
• Navigation: The shoulder buttons can be used to jump to the beginning/end of a directory listing.
• Bugfix: some compatibility issues with a number of games. (Super Play Action Football (S-RTC interference), GP1 Part II (WRAM initialization), Human Grand Prix (mapper detection bug))
• Bugfix: properly initialize FPGA state machine (on some consoles the menu failed to start at all)

v0.1.7 final will contain menu items for various configuration settings and a cheat interface.
Please let me know if any games are broken that worked before, even with the in-game functions disabled.

In-game button mappings:

Buttons	Function
L+R+Select+Start	Reset game
L+R+Select+X	Reset to sd2snes menu
L+R+Start+B	Disable cheats
L+R+Start+A	Enable cheats
L+R+Start+Y	Permanently disable in-game hooks (in case they interfere with game operation).
L+R+Start+X	Temporarily disable in-game hooks (~10 seconds - if you need to get past a glitch but don't want to lose in-game buttons)

Sorry to keep you waiting! Turns out I have some sort of GUI-code-a-phobia so the cheat interface isn’t done yet.
I’m currently updating the secondary FPGA configurations (cx4, obc1, bootstrap) with the updated in-game command interface and simplified memory sharing. So with a bit of luck I might be able to release a preview version (with everything but cheat support) this weekend. 🙂

Here’s what I’ve been working on in the meantime:

• More refactorings of the menu ROM. This will facilitate further UI development (sub-menus etc.)
• NMI+IRQ hook routine – these are required for WRAM cheats and in-game reset. The latter is in working state as of now. I’d like some input on which key combinations would be desirable 😉 (some conflicts can arise with existing SNES mods, see below). There is now a dedicated memory area in FPGA block RAM mapped to $2a00-$2aff which is used for the hook routine and command exchange between a running game and the sd2snes main CPU.
• Game loading handshake between SNES menu and sd2snes CPU – this is a technical prerequisite for error handling (such as missing supplementary files, write-protected SD Card, etc.)
• LED blink codes for file system errors – e.g. in case the SRM file cannot be saved this will tell you that something’s gone wrong. Also the sd2snes will retry saving until it works so you have the chance to swap out the SD Card etc.
• “Screen saver” – the screen is darkened after some idle time to reduce wear on CRT and plasma screens.
• Memory sharing between SNES and the sd2snes CPU is greatly simplified (The FSM is reduced to only 5 states instead of 18) and timing is more relaxed. This should help with stability on a wider range of consoles.
• Fixed some compatibility issues with a number of games. (Super Play Action Football (S-RTC interference), GP1 Part II (WRAM initialization), Human Grand Prix (mapper detection bug))

To do for the upcoming release:

• Cheat management – technical prerequisites for cheats (ROM+WRAM) are met, now to code the GUI for it…
• Finish on-the-fly file browsing
• Decide on key combinations for in-game functions. (en/disable cheats, kill cheat engine, reset game, reset to menu)

About key combinations:
I wanted to use combinations that don’t interfere with my SNES IGR mod. This mod uses L+R+Select in combination with Start, A, B, X, or Y to perform different operations. In that scenario I still had the four directional buttons left to put other functions on. However 😀 With borti4938’s release of the feature-enriched uIGR these are now taken.

So far this is my new proposal for key combinations (UPDATED 2014-06-24):

Buttons	Function
L+R+Select+Start	Reset game
L+R+Select+X	Reset to sd2snes menu
L+R+Start+B	Disable cheats
L+R+Start+A	Enable cheats
L+R+Start+Y	Kill in-game routines (in case they interfere with game operation).

Updated to reflect some of your suggestions. Already looks better to me. I steered clear of L+R+Start+X because it’s similar to L+R+Select+X. 😉

Just a little fun post inbetween. Ingo Korb of sd2iec fame (that’s the project that got me started on sd2snes in the first place!) had the chance to take thermal images of a running SNES+sd2snes. Some people, including myself, found that the sd2snes gets quite hot in the SNES. However the heat actually comes from outside the sd2snes, that is from inside the cart slot! The SNES’s linear voltage regulator produces a lot of heat that gets radiated into the cartridge slot (among other places).

These images illustrate it quite nicely. There are little hotspots where the chip dice are but most of the heat comes from below / behind.

This is a little call for feedback. In order to simplify the general usage of file lists – such as ROM lists, cheat lists, skin lists… – in terms of programming I would like to generalize directory access.

The sd2snes currently scans the entire card on startup and rebuilds an internal database if any change to relevant card contents is detected. This takes place so the file browser can always show the current state on card. Said database contains the entire directory structure and takes up quite some “ROM” space. I would like to replace this “deep scanning” by a simple “list a single directory” function which can also be used to list other kinds of files under different circumstances. This would mean that a folder will be loaded on the fly when you open it, instead of all folders being preloaded at startup.

The current state of implementation has one advantage: browsing the card is fast. There are no delays when changing directories.
The downside is that you have quite a lengthy “Loading …” screen at bootup because of the full card scan. And if something is added/removed/renamed the database rebuild can take a long time.

The advantage of proposed on-the-fly file list creation is that there is almost no loading time at startup. I could even ax the “Loading …” screen altogether. There will be no lengthy “rebuilding database …” either every time you change something on card. Files could easily be manipulated on the fly, too – some people asked for a file deletion feature – without having to rebuild the entire database. Also the database creation code is a complex mess and I want to get rid of it… 😉
The disadvantage is that there will be slight delays while browsing (as a folder is read and sorted on demand) – if a single folder contains several thousand files this can amount to a few seconds.

So um, would you mind if I changed file handling to the latter?

It’s been a while~ Firmware v0.1.6 is out with these changes:

• OBC1 support (yeah, did it anyway :)). Metal Combat: Falcon’s Revenge now works.
• Menu: Start button now brings up the 10 most recently played games instead of only one
• Menu: File browser now ignores files with the “hidden” and “system” attributes
• Partial-size BS-X games should now load correctly
• Fixed a PSRAM mapping bug in BS-X support that caused sprite corruption or worse on some games (notably Treasure Conflix)
• Map SRAM to the whole bank instead of just the lower half on LoROM games <=16Mbits. Fixes saving in some games, at least Ys III - Wanderers from Ys.

Grab it here.

Next up will be cheat support and possibly advanced SuperCIC utilization.

I’ve added an FAQ to address some questions I’ve been getting over time. I’d rather not give any time estimates for implemented features since that didn’t work so well in the past… 😉 All I can say is that SuperFX is too much for me to handle at the moment so I’m going to target some lower hanging fruit for now.

So I’ve been getting a lot of questions pertaining to current progress, understandably. 😉
SuperFX is still crawling along, I’ve gotten a basic CPU core control unit and partial instruction decoder to work which can run test code in simulation fine, albeit limited. But it doesn’t deal with the different memory delays, stalling and parallelism yet; also the SNES interface, plot logic and other supplementary stuff are still missing.
The SuperFX uses pipelining which is a thing I haven’t fully understood yet, so that’s going to take some brain work and likely multiple complete rewrites of the CPU core. I’d rather not give an estimated time of completion for that at the moment… 😉 Implementing pipelining properly is important because game code is laid out to take advantage of it and will not run correctly otherwise.

Besides the SuperFX, kogami has discovered a BS memory mapping bug, a regression that snuck into firmware 0.1.5 where I rewrote the BS memory mapping based on my own RE efforts. Also some graphical corruption has been found when using the “Run previous game” feature (Start button). I expect to make a bug fix / minor release addressing these issues (possibly others) in a couple of weeks.

Firmware v0.1.5 is out with these changes:

• Menu: Files are now sorted by their entire file name instead of the first 20 characters only
• Menu: Ignore input from non-standard controllers (Super Scope, Mouse etc.)
• SPC player: fix soft fade-in (first note cut off) on S-APU consoles (1CHIP / some Jr.)
• More accurate BS-X memory map
• Correctly map SRAM larger than 8192 bytes (HiROM) / 32768 bytes (LoROM), fixes Dezaemon, Ongaku Tsukuuru – Kanadeeru
• minor memory access timing tweaks (should help with occasional glitches on some systems)

Download it here.