PSX listen hardware

vbimport

#1

Hi to you, Truman also !!!

Its really great our old “power-team” still (almost) is complete and ready for more !! :slight_smile:

In the next days I hope I’ve time for another bunch of new cd marker pattern tests.

First another good news:


With SCEE we also can try following compression pattern:

original SCEE: 1 00110101 00, 1 00111101 00, 1 01011101 00, 1 01011101 00

compressed SCEE: 100110101001001111010010101110

Its just deleted the complete double “E” character and the last 100 value. This raises our chance to success by whole 50% if the first method wont work, and you know I have to try the SCEE 'cause at the moment theres no US station around here, at least no Playstation. :wink:

little info:
The PSX doesnt need any Lead-Out for booting, formerly tests did show this.
And thats important if we burn slightly shortened Lead-ins with a little empty space between the data:

Truman, is there an easy way to “patch” such additional feature button into your program? At the moment the data starts directly after the shortended leadin.

We would need a little feature which allows us to set the laser at the usual 0 start position for our PSX pregap/data writing after writing a leadin of ca. 9000 sectors. That would be perfect, so everybody could burn directly 1 session PSX backups with visible “SCEE paint” gap, and so wont cover any data area. Cause without that feature someone first has to burn the data track unclosed, and then had do plug off the PC at the right moment when the Leadin gets written (and thats not always easy, and 2nd, then no leadout was written).

And, something funny for your eyes:
Made a little new site where U can check out into what kind of crazy thing that “Experimental PSX” of mine has transformed. :wink: and a little view behind the scene. Have Fun!

http://the8ball.50megs.com/thAmOdificatn.htm

CU, Sam


#2

Sam.

Any chance of you publishing a description of how you wired up you playstation to your soundcard, and a link to the sound processing software? It’s the best testing tool we have, so it would be wonderful if others copied you. After all, imitation is the sincerest form of flattery.

I have had confidential correspondence about a writer mod, that showed some promise, but sadly the guy doesn’t want to publish. There is some evidence there that it’s possible to add a SCEx signal over the 22khz signal from a writeable disk.

This strengthens my theory that the PSX ignores a steady signal. It only detects transitions, between on and off, by looking for sudden increases or decreases in signal level.

This is why I am excited by semitransparent felt tip. A drop in signal level may work, while still leaving enough for tracking. The idea fits our results so far.


#3

@BlameTheEx, I’m still trying to find out where/how the PSX determines the position for SCEx signal.

It could well be that it searches where ever the lead-in TOC is written. What I mean is that even if we write the lead-in at a further distance it might still check there instead of from the original position.

@all, I think I need to either make a setup like Sam’s (yeah, eat in at Sam’s diner :)), or even better I was thinking to make a PIC that can decode the serial signal from Pin5 and pass it to the PC where a software could then display it in real time like an oscilloscope - but as bits instead of amplitude/freq against time.

I have some knowledge of electronics and I’ve already started, I have spent over a £100 buying a PIC programmer, some PICs and EEPROMs, resistors, breadboard and plug cables. At the moment I’ve only managed to flash an LED on a PIC 16F628 and interaction with digital input. I will be moving onto PIC 16F877 which has already built in hardware PC standard serial support. As I don’t have much time and experience, maybe someone else can do this.

@Sam, I’ve updated my cd program. It now includes the feature you requested. Please note, the calculation of lead-in length I previously described was wrong, check out the website for more info. Also I added a scramble feature in the sector viewer which will allow you to see the patterns of weak sectors, maybe later I will add the ability to edit image files, i.e. to synthesize weak sectors into lead-in.

I would do some experiments of my own, but i want to make the PIC PSX serial decoder - I think it’s more fun to do and also to see the SCEx signal as ASCII on the computer. Till then, we have some fun things to look forward to.


#4

Sam, Truman, Blame,

I am more than willing to build any hardware and check any specific things you want done, as I have a bit more experience with micro controllers than just flashing LEDs :slight_smile:

Can build, document and send out the hardware to each of you three if you like.

Just say what you want-built / to-test

regards,
andrewm


#5

Great, I was getting a bit loss in the PICs. Sam and Blame, any ideas what is useful to build?

andrewm, my idea is this, since the SCEx signal is encoded as a normal inverted serial 250bps signal and modulated at 22kHz, is it possible to build a simple hardware device that we can log the digital signals onto the PC in real time.

What I mean are these hardware stages:

  1. Isolate pin5 from our circuit, e.g. put a resistor in series, like sam did - unless there’s a better way

  2. Simply amplify, e.g. with normal transistor - unless you wish to use opamp. The signal should be around 3.3V - 5V mark, as a CMOS or TTL signal that is compatible with chips

  3. Make a simple low pass filter, i.e. to cut off 22kHz freq. so as to convert 22kHz to DC (digital signal). A simple low pass filter can just be the correct resistor and capacitor

  4. use the chip max3232 or max232 to translate the low voltage digital signal into usable standard PC serial COM port.

All parts are available at www.maplin.co.uk - where I buy my stuff.

That’s it, in fact we don’t even need a PIC. Then we would need to write a software for this. But it should be simple now, since the signal is now converted into a standard serial COM signal.

I would make this but I don’t know how to calculate the correct values for the resistor and capacitor to make a suitable low pass filter.


#6

250BPS is not a standard baud rate that new PCs can do.

I have built a micro controller based circuit that converted from 250BPS to 2400BPS.

It sent this up to the PC opto isolsated.

It could monitor the digital signal at mod point 5 and the AM signal at pin 5 of CD ribbon cable.

The AM part was monitored by a PLL tone decoder, it was a bad choice on my part and I will build a better modulator if you all think that circuit sounds like a good idea.

BTW - what country is every one in. Where do I have to send these circuits to when I build them?


#7

Truman

Congratulations on your upgrade to moderator. Its well deserved.

Given how close we have come with the felt tip trick, I would plead with you to experiment with trying to persuade the PSX to seek the SCEx track at a different place. If the last read sector of the leadout was directly followed by a copy of the SCEx track, with original sector numbers, would the head seek, or stay where it is?

Truman/ andrewm

Pic hardware will be exciting once we have a solution and want to create a practical device.

I still think the best experimental tool we have is the pc sound card. Although a 96khz sampling rate would be nice. It gives us the ability to inject signals at a variety of volumes, and change them at ease. We can even use an external amplifier to get high voltages to drive a writer tracking coil via a high impedance resistor, that would provide fair isolation, at the expense of wasting most of the voltage.

There are 2 interesting frequencies. The SCEx is at 22khz, but we know that this frequency is not critical. In specification, a 1X speed writer is supposed to correct wobble below 5khz, and not above. This leaves the frequencies between 5khz and 22khz.Too high and you will be above the natural cut-off frequency of the tracking coils. Too low and you will be below the cut-off frequency of the SCEx line filter, or cause problems with the physical amplitude of the wobble forcing adjacent tracks to meet.

Perhaps all you need to do is find a tolerant writer, and inject a SCEx signal into the tracking coil via a high impedance resistor and/or a LC bandpass filter, at the right frequency, while the SCEx track is being written.

Sam

I still feal that it is the connection points used by a modchip that are the most definitive for testing, especially the pin used for the modchip’s signal out. Ideally we need a stereo signal, with the SCEx signal from disk blocking pin included. That would give us a clear idea of the relationship between signal from SCEx line, and triggered On/Off events.

There is no reason to create circuit diagrams. There are plenty of diagrams, pictures, and instructions on the net for fitting modchips. You just have to give the mod chip pin numbers used, the resistor, and where you fix the earth wire.


#8

@andrewm, you’re already ahead of us - wow! You’re right, 250bps is not possible on PC and opto isolated - yeah it stops us numpties from blowing things up!

Well, I’m from UK, london. But I think it is better if you could make a schematic diagram with component list on your webpage. This is so that any one with at least some simple electronic skill can build one and have some fun. I hope the device will be simple with easy to get components. Also could you post software - if not, I can try and write one.

Now, we’re getting somewhere. What we need is more action from more people.

@Blame, didn’t see your post up there. Thanks. Okay, I will do some tests on the PSX with write lead-in TOC at further pos and write track/TOC after leadout. But it would be much more tidy and professional if I had only to fire up an accurate logger program which the circuit from andrewm can give us - instead of recording audio and then trying to analyse the huge wave signal by eye!!

Your idea of inject SCEx signal into the writing process is what I’m also thinking.


#9

I never bothered to work out where or how the PSX seeks for the SCEx data. I will work this out on the weekend if people want me to. I have a suspision that it does this mechanically (sled stop switch).

Even if this is not the case, moving the sled stop switch in a PSX to 1/2 way out the disc, and using the truman tool to burn lead-ins there would give you a larger diameter to play silly buggers with felt pens.

Call me old fashioned, but I think that the analog signal generator and the 4066 that I used to inject signals to the AM demodulator might be a better idea than a sound card (96khs or otherwise). It might not be available to everyone, but just tell me what experiment you want run, and I will do it.

I dont like the idea of a high voltage through a resistor to the tracking coil of a CD Burner. Most CD burners use ROHM BA6xxx chips or something equivilent to drive the tracking coils. Simply injecting a low level signal into the filter network on the input to these chips works a treat for what we are looking to do (have already played here myself).

The modchip digital SCEx signal point (pin 5 on the standard old-crowe chips) is definitly the point of interest. If you have 20Khz on the ribbon cable pin 5 means NOTHING if the PSX’s own AM demodulator misses it.

@Truman

I will be using all sorts of hard to get chips, and I will also be using Atmel AVRs not pics, so it might be best if I just build things and send them to you. They will be pretty things on PCBs that you can show your grand kiddies one day if you like.

Also @ Truman

injecting signals into the tracking coils WHILE WRITING is the only success I have had at controlling the SCEx digital line. However as stated above, I injected the signal into the driver chip, not the coil (and in my case it was not a Rohm BA6xxx)


#10

WOW friends, our projects gets more and more fascinating now, almost 1 1/2 year after we’ve started it.

@Truman: My honour also for that you now had promoted to Moderator here, its great. Also a big thx for coding that cool icon :wink: into your newest version of CDReader.

Few days ago tried to burn such physical leadin <-> Data GAP test CD, but I didnt get it how I have to do that now - please can you advise me a little bit? As example:

I ve build an usual ISO with the CDReader ‘CD to image’ including full leadin sector files, lenght 8000 sectors. Now when I wanted to burn it with physical Gap and the new feature PG1 at 0 (Pregap sector 0 starts at 0:00:00 in expl.) my leadin ISO would be burned from -8150 (instead of -11xxx). But this way we dont get any physical GAP. The PG1@0 feature is superb, no question, but I wonder how we can create that physical Gap! Just again by skip sector file or is there another method without first burning usual data track unclosed with finally poweroff switched leadin burning (without leadout)?

For me that issue yet isnt any big problem, 'cause I need to burn the PSX Test CDs with my old Mitsumi at 1x speed anyway, because the lowest 4x (hardware limited) @ Liteon results in a bit too low “PSX readable quality”. My old PSX can read 4x Liteon written disx, but not very good, so I prefer to use the 1x burn with Mitsumi including power off switch broken lead-in without lead-out (psx dont need any leadout, even if the datatrack was broken by laser switched off, it still boots).

@Blame:

About the circuit diagram: The biggest problem isnt create one, but finding out how that connections have been made exactly! I forgot it already ggg Have to open the PSX again or find the needed info somewhere into our huge 1.st thread. I also attached some 4.7k resistor somewhere, but where?? ;-)))

OK that was history, I did ya all that favour:

!
http://the8ball.50megs.com/SCExConneX.htm

About the stereo pin recording:

For the moment I only could offer:


Pin5 CD Unit - in combination with - Pin5 Modchip Subcode Puffer Line

Pin5 CD Unit - in combination with - Pin6 Modchip SCEx Input Line

@AndrewM:

Its fantastic that you’re back again with such good offers about help, ICs, circuits etc. For the moment I evtl. only could connect a cardreader unit into the PSX in combination with programmable smartcards like Fun (AVR - AT90S8515) or PIC/PIC2 16F84 16F876 -877. But I suggest, its better for now, you only work something out with Truman, otherwise it could became too confusing.

btw as it seems we’re all in “SCEE country” :wink: This also make alot thing easier, yet. :wink:

And: Doubt this info helps, but there exists alot cardwriter programs which use serial interface. Maybe theres a way to receive directly some modified impulses over Com2 by a little “receiver - proggie”.

@Blame & Andrew:
About the “leadin at different position” test:

Little idea: Perhaps also give it a try with a larger leadin at the usual position. I dont know how far above the usual 0:02:00 position the datatrack still boots.

And another interresting thought:

If the PSX looks at 1x for a frequency between around 8 khz and 30khz (as I can remember thats Andrews test results on his wobble page):
If we manually slow down the speed to 0.5 speed, we would have the double amount of felt tip pattern space, if the laser still accepts also halven frequency (should be around 10 kHz then if it was around 20 before and normally).

CU, Sam


#11

I’m trying to prevent the other main PSX thread from becoming too long again so I’ve moved these discussions in to this new thread.


#12

@SAM

Smartcards are easy to program, but limited pins available.

I will do everything will AT90S2313 and supply a programmer that hooks into the RS232 port on your windows box so you can burn any new/beta/development code into the chip if you like.

Also @SAM

Your getting close to an answer there.

x almost marks the spot.

You three guys can chat to me in private if you want to know my latest info. Just dont want to make it public yet (thank you blame for honouring those wishes .


#13

How it seeks the Wobble

Did a few experiments tonight to work out what it does.

AFAICT

Power On
Move sled till sled switch closes
Focus
Spin up to 1x
Seek to Wobble area using sector numbers

What I have not found out yet is WHAT sector numbers it seeks too. Might be -ve numbers . Might be TOC.


#14

Andrewm / All

Hoho. After andrews test, it looks like we CAN create a second SCEx track. Still one question remains a bit of a puzzle:

What happens after the faked SCEx sector has been read? can we persuade the PSX to look for tracks below this fake track, when its expecting to find them above?

As a last resort we could start all the normal tracks after the second SCEx track. A bit messy, but with an 80 minute CD there should be room. Perhaps this could be done by duplicating the first sector before the SCEx track many times to pad the SCEx track out to a more favourable diameter?

The felt tip trick is looking more likely all the time. Who have believed it?

Regarding injecting the signal in writer. There are 2 problems here.

The first is the very short commercial life of a writer. They are obsolete within months. A solution that can’t be applied generally is going to be a problem. That is why i have advocated injecting directly to the tracking coil. Its less likely to be model-specific.

The second is that the signal must not interfere with normal wobble correction. I have assumed this means that the signal injector must present a relatively high impedance below 5khz, and if it uses the writers own amplification, it must not overload it.

All

Just in case of arguments. I have been arguing for injection of a SCEx signal into the writers tracking coil for some time, but I very much doubt that the idea was original to me. In theory the idea is simple. The devil lies in making it work. 95% at least of the credit should go to whoever succeeds in that. 5% inspiration, 95% perspiration.

Sam

Thanks for the circuit diagram. I am sure it will help others set up rigs.

If only we knew a way to persuade the PSX to run at 1/2 speed! Possible, but that has to be considered one of the lower probability chances.

Truman

So you live in london! Me too. Let me know if you need a PSX as a test rig. I have spares.

Don’t knock sound cards too much. Low tech is all most of us can afford, and Sam’s has given us good data. As for analysing the results by eye. It the end, we have to use our eyes to check data with any proposed method. The beauty of inputting to a computer is that we can use software to process the data. Without software high pass filters we would never have had the conclusive proof we have now. Could not your “logger program” be more flexibly created in software?


#15

Blame,

Nope - The disc will only read ABOVE the fake leadin. Unless you write your own code to tell the sled to move back home and remove the lump of blu-tac that was stopping it before)

Even with this and the felt pen trick, it is not realy a “no mod” solution. You have to pull apart the playstation to jam a bit of blue tack in the switch mechanisim.

As far is injecting goes.

I was playing with the tracking coils 3 years ago before the neo-wanker episode. I gave up then without trying all the ideas I had. That one idea I am playing with now is way promising though.

The writer I am using WAS OBSOLETE 10 years ago. I am not doing this part of the experiment to make a “here-you-go/turn-key CDR mod-chip to burn bootable PSX’s in any modern CDR drive”

After I have done this, I am sure someone else in tiawan will take the ball and run with it. In fact from what I have seen in the past - give it 2 weeks and PSX burning CDR drives will be for sale in the shops.

Also - the coil-amp in my CDR unit uses a digital 1 bit stream to drive the tracking coils. No worries about impedence affecting the natural tracking response below 5Khz there.

**** ALSO ****

It IS possible to make the PSX spin at slower than 1 speed :slight_smile:


#16

andrewm/Truman/Sam

Ok so we cant chuck the fake SCEx track after the leadout. However there is plenty of room with a 80 or even 99 mim CDR to put all the data tracks after a wide fake SCEx track.

I have been thinking. Perhaps the safest, and easiest, way to do it is to duplicate the entire leadin, including the SCEx track, a few times. Truman, is it possible to do this with your program?

I believe that the start up sequence goes:

  1. find the leadin mechanically.
  2. Check leadin.
  3. Check leadout.
  4. If playstation game disk, go back to SCEx track and look for SCEx.
  5. Go to first data track.

Hopefully the additional leadins will be ignored when moving from leadin to leadout, as there sector numbers are too low. Presumably the PSX will land on the first SCEx track it finds on the way back, I.E the outermost. After that there is no reason why the PSX should read any but data tracks.

andrewm

PSX at lower than 1X speed? If this is possible with software, then i am sure Sam would be delighted with the details. The idea would be to run the SCEx track at a lower speed, and thus effectively make one revolution last for the entire SCEx signal. 1/2 speed would be ideal, but any significant reduction might be enough.

Regarding your experiments on tracking coils. I have identified several possible problems, but do you know which ones stopped you in practice?

A digital stream to drive tracking coils??? Well, if you found it, I have to believe you. Still. I am amazed. Tracking is a matter of feedback, and its so much easier to do that with a simple amplifier. Are you sure it was true digital (higher volume represented by a larger binary number), rather than an on/off gate using pulses. More or longer pulses representing greater volume? Regardless with such a system, I am interested in how you avoided interfering with the tracking while injecting your SCEx signal.

Misstracking when reading the resulting CD is the most likely problem. The cause will be ether loss of tracking control while writing, or possibly, excessive wobble forcing tracks to cross, or at least get too close, due to using a low modulating frequency. I expect the result of misstracking will be the dreaded “Square waves”, that the PSX so unfortunately interpretates as “SCEx line signal ON”.


#17

@BlameTheEx, hi, thanks for the offer of spare PSX - you’re a nice person, but I have one already which I’m doing tests on.

Results:

I just did the test with writing extra track+extra leadout after the original leadout. The game boots but the PSX totally ignores the extra track+leadout - the head never reaches that area. The extra track was from another game (with short track).

I also think the same startup sequence, but a little bit more detail:

  1. Move head mechanically to hit the sled switch, which will determine the physical starting position
  2. Based on this physical starting position, move the head mechanically forward to a fixed position, i.e. where approx the lead-in should normally be
  3. Check TOC in leadin:
  • scan/analyse sub-channel to determine whether TOC is valid
  • find the end of the leadin
  • TOC will also determine if disk is a data/audio cd
  1. Check leadout: there’s an entry in the TOC which gives the position of the leadout in MSF sector - this will be used to calculate and move the head to approx location of the leadout
  2. If playstation game disk, go back to SCEx track based on physical starting position and look for SCEx.
  3. Go to the first track.

The thing is blame - I have a feeling the PSX calculates the approx move positions based relative to the current physical position and is based not entirely on scanning the sector numbers. Everytime it needs to move by a large distance I suppose it first does a physical circular linear calculation using the sector numbers as a parameter for the relative distance and moves the head. This just applies to the first approx move position - after it does a search by scanning the sector numbers.

This means that if we insert sectors, i.e. additional leadins, the head will still move to the same approx position, in which case it won’t find a leadout and may refuse to boot - unless of course we also extend the leadout start time given in TOC. I will try and do some tests to confirm this.

andrewm did a trick to fool the physical start position by putting blu tac to extend the tip of the sled switch. This makes the head start a little forward from where it should be. The PSX thinks that this is the physical starting position. This is sort of proof that PSX does use physical positioning - it won’t find a leadin written at further distance without this trick.

I will try to implement in my tool, a repeat the leadin/tracks at chosen different positions by user - but i’ll need some time to write/debug/test.

@Sam, I’m not entirely sure what you mean by physical gap - since the feature does this it calculates the correct starting write location so that the data will be written so that pregap 1 is at 00:00:00 (MSF). I think you mean can I implement a feature that will allow you to type in a number to automatically create a physcal gap between leadin and pregap 1.


#18

@Blame

The OA8845 and OA8844 (datasheets still available) are a Servo Signal Processor and Digital Servo Driver from philips that are used in the CDR drive I am playing with.

The OA8845 does the closed-loop feedback kind-of thing. Then it sends that to the OA8844 as a 1.84 Mhz PCM style one bit digital stream.

MOST CDR units use a BA6xxx style driver from ROHM and do NOT have a digital stream to interfere with. But honestly, interfering with the BA6xxx chips would have been easier to do. Just a couple of op amps buffering and mixing on the low side.

As you know the signal I was injecting was above 6khz so out side of the frequeny of the normal loop filter.

Checking for miss tracking is most easily done on a music disc. Burn a copy of Madonna The first album and do your signal injecting all the way through the disc. Start off only injecting a small signal, then increase the volume. Pull out the burnt copy and play it in the PSX. Depending if it starts to jump/skip at “Holiday” or “Burning for you” lets you know approx how much signal you can inject and get away with it.

I tried this with a Nine Inch Nails album but it was too difficult to audibly detect the music skipping or jumping :slight_smile:

Also @Blame (and Sam will have interest)

My experiments came to an end in tricking the CD to spin not at 1X speed and still boot. (even with pin 13 of the 6805G3 floating and relying on a modchip to inject SCEx into it).

The fact that these experiments failed indicated to me that the PSX does look for some kind of valid CD before checking the SCEx signal.


#19

@Andrew, whats possible to slow down the speed at scex search? btw that idea with the Music CD wobbling is cool. Just where and how to inject it into new writers…

Is there a way to “bushound” the PSX so we can read what exactly is searched for - as example what kind of data the laser reads first at leadin search - the formerly question if the laser checks the subcode or sectorheaders or if its all done by physical ranges.

@All: I dont know how its with orig. disx, but my tests already did proof it that the PSX dont need any leadout nor complete datatrack to verify a disc as valid. I burned a PSX Video CD and did cut of the “sector write stream” by powering off the PC, so that Data area just had around 3000 an A HalF! sector without leadout and it still did boot with chip.

Important: Before we find a way to burn a wobble, we must know definitivle if/how/when etc. the PSX can or cant read the CDRs wobble. I dont think the pits-lands are so strong covering or confusing the wobble underneath the laser wont check it anylonger. Another question: does exist some simitransparent color which filters out the “wavelenght for the wobble” but not for the datatrack?

@Truman: Thanx for your new tests. My question was just about to create any physical “viewable” Gap inbetween leadin and pregap1 - dont know if there is already a different method to burn it with your tool without skip sektor file. Perhaps if you wanna like to create such special multi leadin feature then theres a possiblility to add such feature which leaves the PG1 at 0 as it is, but shifts the leadin for a inputable value/disctance x further in direction of the CDRs physical beginning.

Yesterday bought a very cheap spindle of 50 Sony CDRs, would be really ironic if we beat it just with the help of some of those (test-)disx! eggg

CU, Sam


#20

Sam/All

There can’t be any “wavelength of the wobble”. For one thing the laser has only one wavelength. The reason why semitransparent ink can work is a bit more complicated. It all comes down to how the PSX works. Your own tests showed me that the PSX doesn’t exactly detect wobble. Rather it detects sudden increases or decreases of wobble which it converts to “wobble on” and “wobble off” events. This means that a sharp reduction of the wobble counts, EVEN WHEN IT IS ONLY A PARTIAL REDUCTION. Enough of the track remains to prevent misstracking. I would imagine the track can’t be read, but as the SCEx track isn’t read, who cares? Err… of course I have been wrong before.

The conclusive tool for testing what the PSX accepts would be a stereo input connected to the points used by pins 5 and 6 by a mod chip. This would show us signal coming in, and how the PSX converts to “ON” and “OFF” events.

Your leadout free boot is interesting news. I think we would be very unlucky if a copy with duplicated leadins didn’t boot.

Truman.

Well, easiest thing is to try an extra leadin and see. You never know. Still if the PSX is so determined on distances being correct, then its going to get harder.

The question i was asking was a bit tricky. Exactly how is the track jump done? I am sure you are right in your assumption that it makes a large jump to the approximate position, and then checks sectors. Still how does it know where it is jumping from? Maybe it uses the last sector that has been requested to be read. However it is possible that it reads another sector before making the jump, or it habitually reads a few sectors beyond what was requested, for buffering. If so, You can play tricks by mislabelling the sectors after the last requested sector before jumping to the leadout.

Alternately You can do something like this. I believe that the PS exchange disk is short. Assuming so. You make a psxchange/game hybrid. Take a copy of psexchange, cut at the last sector READ in the leadout, and join to the first sector in the SCEx track of the game. The rest of the game tracks are copied after its SCEx track as normal. The PSX will read the leadout, then find its already on a SCEx track, and make no jump.

Second hand PSX units go for £5 to £10 now so its a small offer, especialy as I wasn’t planning on letting you have controlls or video lead. You may still be tempted to say yes. It might be nice to have an unchipped testing box.

andrewm

Ah, I fear I had a word definition problem. PCM is what i expected. I just didn’t think of that as digital.

Regarding tests in general, if they don’t result in a boot, it’s important to find out exactly what happened. Have you been making some equivalent of the pins 5/6 stereo test i have been suggesting? “wobble ON” and “wobble OFF” events can be the direct result of the additional wobble, or just misstracking. Can the wobble be created without misstracking? It’s important to know as misstracking probably can’t be controlled to produce a SCEx signal.

Much of what you are doing privately is already in the public domain, and has already been discussed in our threads. Could you email me and say what bits you want to remain secret?