No, the switch board isn't anything to do with anti piracy. For starters it's the simplest part to copy.
The switch board is needed only because a few of the lines needed for CD function is not available on the parallel port so the switch board helps inject the signal from PS-IO and when PS-IO is removed, allow for normal CD games to work. So far I didn't find any issue with the single CD games I've tested but the multi-disc game isn't tested yet. I know some people will question the high cost of PS-IO compared to mod chip and CD-R blanks. Consider this: replacement CD drive won't be available forever and in 25 years easily working Playstation can cost a lot and spare working drive can cost a lot. PS-IO starts to look cheap by then. Also it benefits the game developer with direct USB connection from the computer, no need to burn CD-R every time you make some bug fixes and all.
Don't know about that, Playstations are dirt cheap, CD-Rs are dirt cheap.. I'd love all games on an SD card and all, but $150 to do that is pretty extreme.
The problem with this is that it also assumes that your SD cards will continue working for 25 years (they probably won't) and that SD cards will still be available (they probably won't). Ever try finding a 1GB non-sdhc card to buy these days? You know, for those devices which can't handle larger sizes (wii software hacking comes to mind, along with old GBA/DS flash carts)... I don't doubt that something else will come along which makes the current SD cards we're using in these devices obsolete :/
The PS-IO is also supposed to support a USB to PC connection for running games, so in this theoretical situation where you can't find an SD card that works you could use that. If you only play the occasional PS1 game then $150 or whatever it is doesn't make sense. But as wilykat said if you have any interest in developing homebrew, but also hacking or translations, it is far more appealing than needing to burn CD-Rs for every test. Although emulators have improved over the years so you can do a lot of testing with them. I'm just wondering when it will be available to the general public. I thought I read somewhere they once said sometime this November.
I suppose that it's expensive because it's produced in so few quantities too? Perhaps if it becomes a mainstream mod, it could become cheaper? I'm not very sure how interrupts are dispatched in the PlayStation, but I think that it has to be done by the kernel? Or is software allowed to go straight for the interrupt vectors? If the kernel has control over this, wouldn't it be possible to write a small software patch that gets installed by PSIO on boot, that will intercept the registration of the CD-ROM interrupt handlers and calls them whenever the PSIO hardware wants to assert a CD-ROM interrupt (via the PIO interrupt)? If so, then perhaps there would no longer be a need for the interrupt-routing board.
I think that he's referring to how games control the CD/DVD hardware. I already knew about that; it's hence why PSIO exists. But what I'm referring to here, is interrupt handling. It's about the very reason why PSIO is not exactly plug-n-play on consoles with the expansion port. How do games handle interrupts? If interrupt handler dispatching is done by the kernel, then it should be possible to re-route the CD-ROM interrupts in software as a kernel patch, hence removing the need for a hardware mod.
150 is A LOT... If it didn't require ANY soldering i would have given it a thougt, like this, i guess it's a no-way for me
I don't think it has to do with interrupts at all. The reason PSIO is not plug and play sounds like it is because it would require patching all software. The hardware modification approach apparently lets them make the system use their own set of simulated CD-ROM control registers. Whatever the exact details are, the basic concept seems to be that a hardware mod will function better. Yes it would be nice if it were plug and play but it just isn't possible without modifying game software which has it's own set of problems.
Revectoring the interrupt would be easy - the problem is that you can't just patch the resident code because most titles don't use it, instead relying on local copies of the relevant code (I.E. linked into the game) that directly hit the hardware. Since most games of any complexity are implemented using overlays, there will probably be multiple copies of this code located in different places in each overlay. To make it work without any hardware mods at all, you would need to do a number of things: 1) Hook the boot process and patch the resident code so that you can boot from the (relocated) CD controller. 2) Add an interrupt handler that revectors the expansion port int to the CD-ROM code 3) When you load any code in, patch it to fix up accesses to a) The CD-ROM controller registers b) The DMA controller for CD access (put the correct FIFO address in) c) Code that writes to the SPU to allow the use of the external audio input. So really I think the interrupts are the least of your problems.
PSIO is plugged into the expansion port, so that the CD-ROM device can be "replaced" in the R3000A memory space. The expansion bus allows the expansion device to have some control over the bus. The reason for the hardware modification is because it doesn't have "access to the CDDA and XA interrupt lines.", and so there's no way to emulate the CD-ROM interrupts. I remember cybdyn mentioning that somewhere around here, but I quoted his page here: http://ps-io.com/switch_board.html I'm referring to the only problem (isn't it just about the interrupts?) that PSIO has, since I would also like it to be fully PnP, even though I am not a PlayStation developer nor user. Even if this is not for PSIO, I would like the understanding of this matter to be complete, for any other project. Doesn't PSIO already take care of CD-ROM control itself because it replaces the CD-ROM registers in the R3000A memory space? If interrupts are handled by first registering a handler with the kernel, then the kernel only needs to be modified to allow the CD interrupt handlers to be run whenever the PIO interrupt is asserted.
No, it's not just about interrupts - the two signals that are routed out to the expansion port are the CS/ and INT/ lines from the CD controller. The job of the switch board is basically to connect them back to the CD-ROM drive when PSIO is unplugged or you boot a CD. When PSIO is active, the internal CD interface chip is disabled and all the accesses to the CD controller are redirected to the emulated CD controller in PSIO. That's why you don't have to patch the code - all the hardware registers are still in the same place.
I didn't think about the /CS signal. So it doesn't modify the device mapping? Would it be impractical to do so, meaning that the CD-ROM libraries in each and every game will reset the memory map for the CD-ROM device? The service is called the "SSBUSC service" in the PS2. I'm not sure if it's called the same thing in the PlayStation, but I know that it exists too.
It's much more limited, and CDROM_CS/ is one of the lines that you can't do anything with but change the cycle timing. Interestingly, even the page length bits (which work on the other chip selects) are ineffective for the CDROM (and the SPU, I think). It's not so much the title resetting the IO mapping as it being impossible to change in the first place. I did try remapping the Expansion 2 region (which is one that does have a base address register) to overlap the CDROM controller, and that didn't work either (in fact, setting it to any value except the default one appears to just deactivate the CS/ line). Maybe there are some magic values you can write that will get it to work, but I couldn't find them.
Ah okay, I didn't realize that there's no base address register for the CD-ROM device of the PlayStation. Thanks for clearing this up.
Do remember it is 150 AUD. Mine cost around $116 USD which isn't too bad. That translates to a little over 98 euros. Also, thanks for the update on OPL, sp193!
I must have missed this video first time I read the thread... I've done a bit of soldering on my Gamecube (many years ago) and that was just about okay with 4 wires with big points to solder to - but this thing looks ridiculously hard to install. The solder points are incredibly small... I can see a lot of people screwing this up. I suspect this is going to be sold through people who have experience modding systems so you can probably add another 50 euros/dollars to the final price - provided you can find someone who'll do it. Impressed it finally got done, having followed the progress over the years on/off - but ultimately disappointed with the final product. For the money you may as well just buy a load of old PS1 consoles cheap on eBay (how many could you buy for 150 - 200 euros? Quite a few) The video seems to make it look like a breeze to install... I'm no expert but I don't think it is unless you've been modding for a fair old while.
so who wants to buy one just to remove the header and start hacking wires into a psone slimline model? I know i'll be willing to do it.
