OK, I will have a go with it tonight. I'll also expain the situation with that OTP chip - I removed it from the board years ago, and then tried to dump it using the verify function on the Motorola programmer (well, by abusing the verify function - basically, I connected an EPROM emulator to the prog...

19h,20h --> INT3(yy,mm,dd,ver) 19h,22h --> INT3(<region string>) 19h,23h --> INT3(<servo amp string>) 19h,24h --> INT3(<signal proc string>) 19h,25h --> INT3(<decoder string>) 19h,60h,FCh,00h --> INT3(databyte) ;\upper 4 bytes on stack 19h,60h,FDh,00h --> INT3(databyte) ; (2A,66,10,86 on SC430917) ...

... so the GetID command will return four spaces as SCEx string (namely it does NOT return "SCEW", which is said to happen on Yarozes) (maybe the Yaroze does really return "SCEW", or maybe the Yaroze is just displaying "SCEW" in the MIPS BIOS, regardless of the GetID command). I don't have a Yaroze...

Still no luck with the SCPH-1000 - but I have managed to dump a few more machines from my stack of consoles:

OK, for reference, the reason the SCPH-7000 wouldn't dump (using the built in dump routine) was that PB0 (pin 16) was floating low, and once I pulled it up (I just shorted it to pin 17 using a scope probe during reset), the ROM dumped with no problems. The region string is indeed "for Japan" - and a...

Grounding PB0 and PB1 shouldn't output any serial data! Better try to wire both PB0 and PB1 to 3.5V. If you are lucky (=if RX is low) then you should see serial TX data on one pin. Otherwise you could try to drag RX to GND while searching the TX pin. Ie. while looking for TX at pin number "N", try ...

This looks interesting - I've just had a look at the machines I have here, and the oldest one is a SCPH-1000 with a 1-655-322-11 PU-7 board in it. I will see if it dumps. For reference, the CD CPU on this board doesn't have one of those "SC" numbers on it. The markings are as follows; Sony Computer ...

Oh, and incidentally, although the block diagram in the SCPH-550x manual shows the expansion port as being connected to the main data bus, it isn't - it actually goes to the same sub bus that the boot ROM / Audio DSP and CD controller are on. Well that's a bit annoying. The actual schematic is corr...

I haven't tried it on a PSone - but this works OK on a SCPH-900x series machine, so I can't see why it wouldn't work correctly on the PSone, too. On the PU-23, the other signals you need (like the expansion bus chip select) are brought out to test points, so it's a fairly simple soldering job. Altho...

Hmm, are we talking about these RAM chips? Sadly, they won't work - the first thing is that they are "KM48 C " rather than "KM48 V " - so they are designed to operate from 5V rather than 3.3V. The second is that the '0' at the end indicates that they are fast page mode devices - and the PSX memory ...

Great work TriMesh, can you recommend a good source for the RAM chips? Only place I can find is in the USA at they have a $200 minimum order. I got them from one of the suppliers in Shenzhen that deals with obsolete parts - they were not that easy to find, and took a couple of days to turn up. I wo...

i think it is not correct, from what i read in the handbook, if you set the RE you change the whole Endianness, in both kernel and userland. I don't know how the PSX handles it, but on the embedded MIPS CPUs I've used in the past, the RE bit only applies to user mode. If you wanted to change the de...

I discovered that the default Caetla setup sets the initial SP to 8MB - this is normally harmless because of the memory aliasing, but it means that the memory test blows up when you try to run the memory test under Caetla. This is a fixed version that relocates the stack. // // Quick and dirty RAM t...

Thanks for the ROM collection! I wasn't able to unzip the CAEFLASH.zip file and CAETLA30..38.zip's. Either that 10 files are corrupt, or I was doing something wrong. Did anybody else have that problem, too? Or got them unzipped okay? They seem to not be compressed, just raw binary files and an exec...

this thing is something unbelievable for me, but if you understand what to do - you get real result. I'm impressed! I left some of the technical details out because this was a "how to" - but you might be interested in them. First of all, I didn't think it was going to work, either - the biggest pro...

i think you'd better translate in English, else way i can understand less than the 5% of the content. Anyway, i am replacing the PSX bios with a piece of custom firmware, it should be interesting to use the CD-decoder 68hc05 in such a way, what do you suggest ? In my firmware i have the full contro...

It will refuse to run on a 2MB unit - the problem is that on a regular PSX the 2MB memory is mirrored 4 times - so if you try writing to memory above 2MB it will trash all the BIOS data in the machines low memory. This makes it ... unhappy. It's pretty quick and dirty anyway - but I'm sure it could ...

First of all, many thanks to Shadow for humoring me when I hassled him to do wiring checks on his DTL-H2000. It might have been possible to do this mod without that information, but it would certainly have been far more difficult. The question of if it's possible to upgrade the RAM on a retail to be...