I have found one of the older mod boards which might be compatible for both 20/21 units. it has only one connector on it (21 pin) but on the other side it has a place for another connector which I believe would have been the 20 pin connection. I'm going to try to track down a scanner and get a good scan of the pcb traces, it may help. this 1 wire mod has a pic 16xxx and a peel 18cv8 pld, which probably cannot be copied. too bad, because the pcb would be easy to make. I'll post asap, if I can get a scan done.
20/21-pin differences
- Thread starter ExCyber
- Start date
there is no crystal. it has one resistor, one capacitor, 2 ic's. to have a look go here:
http://www.geocities.com/redhat58271/mod_bottom.html
and here:
http://www.geocities.com/redhat58271/mod_top.html
right click and save the pictures, they should be 800x1000 and have a reasonable amount of detail (the best i can do, anyway). i have not tried it, but i think that the other (unused) connection would unlock the 20 pin saturns. let me know what you think.
http://www.geocities.com/redhat58271/mod_bottom.html
and here:
http://www.geocities.com/redhat58271/mod_top.html
right click and save the pictures, they should be 800x1000 and have a reasonable amount of detail (the best i can do, anyway). i have not tried it, but i think that the other (unused) connection would unlock the 20 pin saturns. let me know what you think.
Alright.
I've nearly finished looking at 21 pin Saturns. Back to 20 pins...
I was just looking at a Saturn I have lying around with it's cover off and noticed something interesting. The crystal on the CD board has a frequency of 33.8668MHz.
Relevance?
The crystal missing from the 'modern' 21 pin modboard has a frequency of 8.467Mhz. That's one quarter of the CD board's crystal. Coincidence?
Doubt it.
ExCyber...
I've nearly finished looking at 21 pin Saturns. Back to 20 pins...
I was just looking at a Saturn I have lying around with it's cover off and noticed something interesting. The crystal on the CD board has a frequency of 33.8668MHz.
Relevance?
The crystal missing from the 'modern' 21 pin modboard has a frequency of 8.467Mhz. That's one quarter of the CD board's crystal. Coincidence?
Doubt it.
ExCyber...
It's probably the master clock for the CD reader, but I think this is interesting because AFAIK nothing else on the Saturn runs at that speed - the main system runs at 28.something, which leaves me to suspect that the CD side of the Saturn's CD interface is grabbing its clock from the ribbon connector.
Relevance?
The crystal missing from the 'modern' 21 pin modboard has a frequency of 8.467Mhz. That's one quarter of the CD board's crystal. Coincidence?
Doubt it.
Me too. Clock conditioning PLLs often take 4x the "real" clock speed of the device, so this is probably the basis for all CD timing. This raises the possibility that the CD reader actually clocks some component of the Saturn's CD interface, rather than being clocked by it; perhaps this was in anticipation of compatibility with faster drives?
OK.
So a mod board can get the signal it requires from the CD board that has a crystal at 33.8668 MHz or a built in crystal at 8.467 MHz.
Do you think that there would be any significant modification to the clock signal between the 33.x MHz crystal and the point that the mod takes it's signal?
Does a Model 1/20 pin saturn have a crystal on it's CD board?
So a mod board can get the signal it requires from the CD board that has a crystal at 33.8668 MHz or a built in crystal at 8.467 MHz.
Do you think that there would be any significant modification to the clock signal between the 33.x MHz crystal and the point that the mod takes it's signal?
Does a Model 1/20 pin saturn have a crystal on it's CD board?
Yes. AFAIK none of the traditional PIC line can run at anywhere near 33MHz, and it seems that if that was the frequency being used you could solder directly to one of the clock crystal pins rather than having to solder to a chip.
I believe so, but I'll have to dig out my M1 to check.
You've got yourself a version 7.0 mod there. With a 21 pin Saturn, it's jsut fine as it is, but you have to do a little extra to get it to work on a 20 pin.
First, desolder the sockets and move them to the other side form the W side to the G side. Now, take the 21 pin ribbon that came with the mod (leadsface up), and cut off the last one on the right, or cut the plastic in between the the last and the one before last and bend it up. Connect the ribbon from the cd drive to the "In" socket (to one side of course, make sure it is the side that doesn't pass thrugh to the cut end of the other cable) and the 21 pin cable that came with the mod t othe "Out" and the cut end to the motherboard.
That's not really what I'm trying to do.
I'm trying to work out if a fairly common 'Lik-Sang' type of mod (version ?) can be hacked into a 20 pin Saturn. The main issue at the moment is going to be finding a suitable clock signal on the CD board.
Even if we find one, who knows if it will have mod compatability issues like the '64 pin' model 2 Saturns? ???
I'm trying to work out if a fairly common 'Lik-Sang' type of mod (version ?) can be hacked into a 20 pin Saturn. The main issue at the moment is going to be finding a suitable clock signal on the CD board.
Even if we find one, who knows if it will have mod compatability issues like the '64 pin' model 2 Saturns? ???
I know, but I figured I would tell him, ince he was wondering abou the other side of the mod.
And also, with the Version 9.5 mods appeared the first 21 pin only compatible chips, they looked jsut like the one in the GameGizmop picture on their site, but the actual mods you recieve from them are slightly different, and are likely another more recent 9.x mod, same goes with the Lik-Sang ones.
And also, with the Version 9.5 mods appeared the first 21 pin only compatible chips, they looked jsut like the one in the GameGizmop picture on their site, but the actual mods you recieve from them are slightly different, and are likely another more recent 9.x mod, same goes with the Lik-Sang ones.
A scope could definitely help things, but I think what's really needed is a logging logic analyzer... I'm not sure that's the correct term; I mean a device that could be hooked up to the relevant pins and set to sample on the rising or falling edge of the clock (or both) so that we could look at the communication that's happening on a more complete level.
I'm thinking of using the CRO to try and hunt down a signal point on a model 1 CD board.
I'm going to try to identify the signal that is used on a model 2 board by the mod and see if it's present anywhere on the model 1 CD board.
While this may be a crude method of investigation, even if I had a logging logic analyzer, I wouldn't know what to do with it.
I'm going to try to identify the signal that is used on a model 2 board by the mod and see if it's present anywhere on the model 1 CD board.
While this may be a crude method of investigation, even if I had a logging logic analyzer, I wouldn't know what to do with it.
The idea is that you hook the probes up to the pins you want to monitor, hook a special one up to the clock pin to drive the sampling. Then you "record" what happens on the bus, dump that data to a PC and use some kind of viewer to get a scope-like readout of the signal transitions...
