Hi, I know that back in the most common places of the speech, but I have no bases and information sufficiency, to define such a thing. Step to the point I meant hypothetically overcloking my ps1, but keeping two frequencies, the original and freq. overclocking ... Crystal do I need or just a switch to be entrusted with the two roads. Thanks for your help.
The clock generation in the PlayStation changed quite a bit over time, so an exact answer depends on exactly which model you are talking about. In general, there are two clocks - one runs the CPU and the other the GPU. The second is probably best left alone, since all the video timing is derived from it. The main CPU clock is internally divided by 2, so the clock signal you need to supply the CPU chip is 67.7376MHz (at nominal clockspeed). In the models using the CXD8606Q CPU (which is everything except the PU-7 and some early PU-8s) this signal is on pin 4 of the CPU chip. You could try lifting this pin and switching over between the existing 67MHz clock and a new one, but it's quite possible you will glitch the clock and crash the CPU - all you can do is try. The other thing to note is that after being divided by 2 this clock is output to the GPU, Audio DSP and CD block - the most obvious effect of this is that the pitch of the audio will be wrong, since it derives it's 44.1kHz sample clock from the CPU clock.
In otherwords, it's not worth it. Doubt there'd be much improvement anyway, as all the systems rely on each other to run at the right speeds in order to function properly. Read speeds from the cd drive limit the loading times and the GPU shouldn't be touched so graphics won't be loaded any faster.
I know you, you do not it's worth it because everything turns smoothly already home, but the problem is if the method takes advantage of the 4 cpu pin and pin to 66 MHz clock, was interested to know how I could keep the two frequencies ... last time I tried, with a tangle switch, I only got the frequency to 66 MHz, and a black screen 33 ... so I grew doubt crystal added; or it is feasible without it. I was not interested in the simple connection between the source and pin cpu to 66 Mhz. - I apologize if I have not understood something, but the translation that comes to me, is not perfect.
The CXD8661 used on some of the later arcade games runs at 50mhz (from a 100mhz clock). They don't have use PS1 CD drives on the arcades, games are loaded from rom, hard disk or scsi/ide cdrom drive. Some of them use an SPU though and AFAICT that it's affected by the main cpu running faster.
Adding to what smf said, the NAMCO System12 board is a custom system you can always compensate for the clock speed change programming wise by changing the frequency values written to the registers of the sound chip. It's done that way with many Yamaha chips on arcade hardware. Chips designed to run at 3.57Mhz (NTSC color carrier) are either run at lower or slightly higher frequencies (using clock derived from video or CPU clocks as source) to save a bit by not needing to have multiple clock sources on board.
Of course the program being loaded from hard disk or another, has some different effect than a laser load but all running at a clock frequency twice before, I think you get results even if you do not satisfactory; but it is not what I want at the moment sapere..me had not noticed the first overclocking mod. I've done some time ago, and actually did not seem to have a lot of speed loading difference, but I can not say more because I have stopped playing the game right after the game logo, then I was no longer possible to continue with the mod.
I've done this mod and my main results are: - CPU overclock helps many 3D games. It appears the CPU is the bottleneck on 3D titles. - Sound pitch and CD loading speed increase with the CPU OC. Even the disk spins faster! - I tried feeding correct external clocks to the SPU but the chip glitched and froze. - The mod is simplest on older boards with the dedicated 67Mhz oscillator but it works on the later models as well.
Wow man, thank you for your direct impression. You have connected the only clock source to pin the CPU? The games run faster, but can not play or is jerky? ( works too fast).
The games I tested work fine but the sound is just too annoying to enjoy them. Also FMV run too fast. Memory cards and controllers work fine. The CPU ran at 40Mhz, by the way.
Oops, I think I made a mistake when writing that as I meant to say "it's not affected". i.e. the same frequencies produce the same sound (or close to it). It may be that instead of halving the 66mhz they divide the 100mhz by a third instead, which would be slightly different. Less likely (but possible) the game detects whether it's running from a 66mhz or 100mhz clock and writes the spu frequencies accordingly, but the detection doesn't work right in any of the emulators that handle the games and it writes the wrong values. This and the effect it has on all the different root counters is something that should probably be investigated at some point. Namco System 12 doesn't actually use SPU either btw, IIRC it's only ZN2 that has the 100mhz cpu and an SPU chip.
System 12 uses NAMCO's C352 custom sampler chip (same as used with System 22/ Super System 22) instead of using SONY's SPU. Actually PS1 based Namco hardware is fully customized instead of using a generic "COH" SONY board. They and Konami were the only companies which had access to that level of customization. All others had to use the Zinc (ZNxx) hardware.
I'm not sure if others had to use ZN, but it was certainly cheaper to. Namco and Konami were in the arcade hardware business, while ZN1/ZN2 were used by software publishers with console experience to bring out arcade versions. Namco and Konami had PlayStation based arcade hardware before the ZN1 board existed, so they were always going to have something different. In fact they both had PlayStation based arcade games out before the PlayStation itself existed, the GPU's on the first year or so of arcade boards are not compatible at all with the consoles. It's not known whether this was a deliberate attempt or whether they were just using up chips that had been obsoleted by a new design.
