Casio CZ/ VZ/ FZ - Pro Series

Hi Everybody!

I've managed to get hold of the schematics for the very rare RA500 RAM
card, used in the Casio VZ1/10M/8M and the Casio PG guitar synths,
thanks to Steve at the EZ-VZ forum website. It will now be possible to
make one of these RAM cards yourself for about $20!!

I'm in the process of making up a step-by-step guide with photos, which
I will upload to the FILES section here when I've finished them. In the
meantime, for anyone who's good with electronics, I've uploaded the
RA500 card schematics there, along with datasheets and other info, so
you can start straight away!!

Cheers, Graham

Fantastic!  I'm glad that you're going to do a tutorial about it.  Not
only are you solving your own problem, but you'll give everybody else
the bug to do it too.  And that will keep all these synths around
longer.  I can't wait to see the outcome.  Hope it goes smoothly!


--- In CZsynth@yahoogroups.com, "gmeredith1" <gmeredith1@...> wrote:

>
> Hi Everybody!
> 
> I've managed to get hold of the schematics for the very rare RA500 RAM
> card, used in the Casio VZ1/10M/8M and the Casio PG guitar synths,
> thanks to Steve at the EZ-VZ forum website. It will now be possible to
> make one of these RAM cards yourself for about $20!!
> 
> I'm in the process of making up a step-by-step guide with photos, which
> I will upload to the FILES section here when I've finished them. In the
> meantime, for anyone who's good with electronics, I've uploaded the
> RA500 card schematics there, along with datasheets and other info, so
> you can start straight away!!
> 
> Cheers, Graham
>

It would be easy to make a larger capacity card: just get a bigger RAM chip 
(1 Mbit would give you 4 banks), and use DIP switches or something for the 
additional address lines.  Or, multiple chips could be stacked and switched 
using the CS line.  It just depends on what chips are available.  I think 
the only hard part would be finding a suitable connector.

Do you have a schematic for the ROM cards?  I think it would be possible (if 
not particularly pretty) to use a ROM card as a starting point (making 
changes to account for the difference in the way ROM/RAM cards are 
detected).  If the ROM chip has a CS line, it would probably be pretty 
simple to add a switch to choose either ROM sounds or RAM sounds.


>From: "gmeredith1" <gmeredith1@...>
>Reply-To: CZsynth@yahoogroups.com
>To: CZsynth@yahoogroups.com
>Subject: [CZsynth] Make your own Casio VZ/PG RAM card!!
>Date: Fri, 01 Jun 2007 02:17:00 -0000
>
>Hi Everybody!
>
>I've managed to get hold of the schematics for the very rare RA500 RAM
>card, used in the Casio VZ1/10M/8M and the Casio PG guitar synths,
>thanks to Steve at the EZ-VZ forum website. It will now be possible to
>make one of these RAM cards yourself for about $20!!
>
>I'm in the process of making up a step-by-step guide with photos, which
>I will upload to the FILES section here when I've finished them. In the
>meantime, for anyone who's good with electronics, I've uploaded the
>RA500 card schematics there, along with datasheets and other info, so
>you can start straight away!!
>
>Cheers, Graham
>
>

_________________________________________________________________
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Hi Scott,

I just got sent a photo of a ROM card opened up. There is not much 
difference with the RAM and ROM PCB, the RAM has more etchings and 
tracks in it for an extra chip that does switching of the CE (Chip 
Enable) pin, and also the WE (Write Enable) pin, both of which the 
ROM doesn't need. And a few other differences in the pin track 
layouts to the RAM chip, but that's it. I've uploaded a schematic for 
the RAM card in the FILES section on this site. 

Regarding having a larger chip, the schematics show already that it 
was made to accommodate a chip 2x as large as the one used, there is 
a spare address line not used on the connector. This is for the ROM 
chip, which is 2x larger than the RAM chip (which is why it has an 
extra bank of sounds) - The ROM is 512k and the RAM is 256k. It would 
require no more effort than dropping in a 512k RAM chip and hooking 
up the extra address line. As you say, an even larger chip can be 
installed and the highest address lines switched with a DIP switch to 
get extra banks.

Cheers, Graham



--- In CZsynth@yahoogroups.com, "Scott Nordlund" <gsn10@...> wrote:
>
> It would be easy to make a larger capacity card: just get a bigger 
RAM chip 
> (1 Mbit would give you 4 banks), and use DIP switches or something 
for the 
> additional address lines.  Or, multiple chips could be stacked and 
switched 
> using the CS line.  It just depends on what chips are available.  I 
think 
> the only hard part would be finding a suitable connector.
> 
> Do you have a schematic for the ROM cards?  I think it would be 
possible (if 
> not particularly pretty) to use a ROM card as a starting point 
(making 
> changes to account for the difference in the way ROM/RAM cards are 
> detected).  If the ROM chip has a CS line, it would probably be 
pretty 
> simple to add a switch to choose either ROM sounds or RAM sounds.
> 
> 
> >From: "gmeredith1" <gmeredith1@...>
> >Reply-To: CZsynth@yahoogroups.com
> >To: CZsynth@yahoogroups.com
> >Subject: [CZsynth] Make your own Casio VZ/PG RAM card!!
> >Date: Fri, 01 Jun 2007 02:17:00 -0000
> >
> >Hi Everybody!
> >
> >I've managed to get hold of the schematics for the very rare RA500 
RAM
> >card, used in the Casio VZ1/10M/8M and the Casio PG guitar synths,
> >thanks to Steve at the EZ-VZ forum website. It will now be 
possible to
> >make one of these RAM cards yourself for about $20!!
> >
> >I'm in the process of making up a step-by-step guide with photos, 
which
> >I will upload to the FILES section here when I've finished them. 
In the
> >meantime, for anyone who's good with electronics, I've uploaded the
> >RA500 card schematics there, along with datasheets and other info, 
so
> >you can start straight away!!
> >
> >Cheers, Graham
> >
> >
> 
> _________________________________________________________________
> Don't miss your chance to WIN $10,000 and other great prizes from 
Microsoft 
> Office Live http://clk.atdmt.com/MRT/go/aub0540003042mrt/direct/01/
>

>I just got sent a photo of a ROM card opened up. There is not much
>difference with the RAM and ROM PCB, the RAM has more etchings and
>tracks in it for an extra chip that does switching of the CE (Chip
>Enable) pin, and also the WE (Write Enable) pin, both of which the
>ROM doesn't need. And a few other differences in the pin track
>layouts to the RAM chip, but that's it. I've uploaded a schematic for
>the RAM card in the FILES section on this site.

I think that was probably my ROM card, actually.

>Regarding having a larger chip, the schematics show already that it
>was made to accommodate a chip 2x as large as the one used, there is
>a spare address line not used on the connector. This is for the ROM
>chip, which is 2x larger than the RAM chip (which is why it has an
>extra bank of sounds) - The ROM is 512k and the RAM is 256k. It would
>require no more effort than dropping in a 512k RAM chip and hooking
>up the extra address line. As you say, an even larger chip can be
>installed and the highest address lines switched with a DIP switch to
>get extra banks.

Referring to the service manual... apparently a 2-bank RAM card was never 
released.  When the VZ detects a RAM card, the highest address bit is 
disabled (unless someone wants to modify the OS).  To access both banks (as 
it would be useful to have 192 online patches), the VZ needs to detect a ROM 
card.  In this mode, it would be impossible to write patches, and likely it 
would have to be switched off when changing this to avoid crashing things.  
But, if it can be determined how the VZ detects the card type, it could make 
things a little more interesting.  From the diagram, it seems like only the 
CD (Card Detect?) pin could determine this... but my scan only shows the 
component side of the board, and that pin connects to something on the other 
side.  This pin is grounded for a RAM card, so inside the VZ it's probably 
just pulling down a high value.  But if that's the case, I'm not sure what a 
ROM card could do differently.... I can take my card apart again if 
necessary (though it's sort of damaged enough already...)

Actually, maybe this should be verified.  If anyone has a RAM card, I would 
appreciate it if this could be tested:  When a RAM card is inserted and the 
CARD button is pressed multiple times, does it switch banks between CARD (1) 
and CARD (2)?  If it does, that means it is actually using the highest 
address bit, but since it's not connected, it's still just looking at the 
same data.  Seems like it would be bad design to do it this way, but it's 
possible.  I suspect a RAM card just shows up as CARD, with no indication of 
bank.

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Hi Scott,

Thanks for the sacrificial ROM scan!

Regarding card detection, all that the VZ does to detect a card, 
whether a ROM or RAM, is check to see if pin 44 is low (grounded). If 
so, then the software allows the the data lines to be read, again, 
either RAM or ROM. 

To activate the RAM, pin 32 connects a high signal from the VZ port 
to the CE (Chip Enable) pin on the RAM chip, via a NOR gate chip, 
which pin 35 (high) also operates.  The ROM chip is disconnected from 
both these pins, as it is always enabled.

So the only difference between the 2 cards seems to be the extra 
address line RA15, which is connected to the highest address line A15 
on the ROM chip, but not connected to anything on the RAM chip. I 
don't know what means the VZ has to display "no bank", as you say, it 
would be interesting if someone could put in their RAM card and 
switch through the banks and see what it displays. 

In any case, I don't think the VZ sees any difference between a ROM 
and a RAM, except that it will fail to write to a ROM because the 
ROM's write line is not connected (and wouldn't work if it was, 
anyway.). This being the case, using a larger RAM  chip will give you 
an extra bank WITHOUT DIP switch selectors for extra address lines, 
because you can use RA15, which is disconnected on the RAM card, but 
is utilised on the ROM, being 2x larger than the RAM. For even more 
banks, you will need DIP switch selectors though.

Cheers, Graham




--- In CZsynth@yahoogroups.com, "Scott Nordlund" <gsn10@...> wrote:
>
> >I just got sent a photo of a ROM card opened up. There is not much
> >difference with the RAM and ROM PCB, the RAM has more etchings and
> >tracks in it for an extra chip that does switching of the CE (Chip
> >Enable) pin, and also the WE (Write Enable) pin, both of which the
> >ROM doesn't need. And a few other differences in the pin track
> >layouts to the RAM chip, but that's it. I've uploaded a schematic 
for
> >the RAM card in the FILES section on this site.
> 
> I think that was probably my ROM card, actually.
> 
> >Regarding having a larger chip, the schematics show already that it
> >was made to accommodate a chip 2x as large as the one used, there 
is
> >a spare address line not used on the connector. This is for the ROM
> >chip, which is 2x larger than the RAM chip (which is why it has an
> >extra bank of sounds) - The ROM is 512k and the RAM is 256k. It 
would
> >require no more effort than dropping in a 512k RAM chip and hooking
> >up the extra address line. As you say, an even larger chip can be
> >installed and the highest address lines switched with a DIP switch 
to
> >get extra banks.
> 
> Referring to the service manual... apparently a 2-bank RAM card was 
never 
> released.  When the VZ detects a RAM card, the highest address bit 
is 
> disabled (unless someone wants to modify the OS).  To access both 
banks (as 
> it would be useful to have 192 online patches), the VZ needs to 
detect a ROM 
> card.  In this mode, it would be impossible to write patches, and 
likely it 
> would have to be switched off when changing this to avoid crashing 
things.  
> But, if it can be determined how the VZ detects the card type, it 
could make 
> things a little more interesting.  From the diagram, it seems like 
only the 
> CD (Card Detect?) pin could determine this... but my scan only 
shows the 
> component side of the board, and that pin connects to something on 
the other 
> side.  This pin is grounded for a RAM card, so inside the VZ it's 
probably 
> just pulling down a high value.  But if that's the case, I'm not 
sure what a 
> ROM card could do differently.... I can take my card apart again if 
> necessary (though it's sort of damaged enough already...)
> 
> Actually, maybe this should be verified.  If anyone has a RAM card, 
I would 
> appreciate it if this could be tested:  When a RAM card is inserted 
and the 
> CARD button is pressed multiple times, does it switch banks between 
CARD (1) 
> and CARD (2)?  If it does, that means it is actually using the 
highest 
> address bit, but since it's not connected, it's still just looking 
at the 
> same data.  Seems like it would be bad design to do it this way, 
but it's 
> possible.  I suspect a RAM card just shows up as CARD, with no 
indication of 
> bank.
> 
> _________________________________________________________________
> Get a preview of Live Earth, the hottest event this summer - only 
on MSN 
> http://liveearth.msn.com?source=msntaglineliveearthhm
>

>In any case, I don't think the VZ sees any difference between a ROM
>and a RAM, except that it will fail to write to a ROM because the
>ROM's write line is not connected (and wouldn't work if it was,
>anyway.). This being the case, using a larger RAM  chip will give you
>an extra bank WITHOUT DIP switch selectors for extra address lines,
>because you can use RA15, which is disconnected on the RAM card, but
>is utilised on the ROM, being 2x larger than the RAM. For even more
>banks, you will need DIP switch selectors though.

This may be the case, and I notice on mine that it does appear to try to 
write to the ROM card before giving an error message.  But I was thinking 
that this might not be a great idea- the ROM chip doesn't have the WE pin, 
and what are I/O pins on a RAM chip are just outputs.  I would assume that 
the VZ just blindly tries to write the data by asserting WE and then sending 
the data (if it hasn't got any way to tell), but on a ROM chip this results 
in output connected to output, basically a short circuit.  There are 1K 
resistors on the I/O lines, but it still seems like it's not the best way to 
do things, and I think any decently-engineered product wouldn't do that.

But regardless.. how, then, would it give an error message after trying to 
write to a ROM card?  If the VZ doesn't differentiate between RAM and ROM 
cards, there's no way to reliably detect a write error.  Even comparing the 
data on the card with the internal VZ RAM after the write isn't a foolproof 
way to do it.

However, now that I think about it a little more, there are ways to detect 
the difference in software.  If there's some unused portion of the memory 
space, it's easy to tell if the highest address bit actually does something: 
If ROM card address 0x0000 (bank 1) contains the value "10101010" and 
address 0x4000 (bank 2) contains "01010101", 0x0000 XOR 0x4000 = "11111111". 
  On a RAM card, it would simply refer to the same byte, so 0x0000 XOR 
0x4000 = "00000000" (regardless of what data is present).  Whether the VZ 
does it on start up or just before attempting to write is a different issue, 
but it would thwart the 2-bank RAM card idea.

At any rate, if a RAM card indicates CARD (1) and CARD (2), this would 
confirm that the highest address bit is being used, just not connected to 
anything, and that RAM and ROM cards are indeed detected the same, at least 
on startup (and thus a 2-bank RAM card can probably be used, unless it 
detects before attempting to write).

_________________________________________________________________
Get a preview of Live Earth, the hottest event this summer - only on MSN 
http://liveearth.msn.com?source=msntaglineliveearthhm

I suspect that the VZ doesn't use software to detect the difference 
between a RAM and a ROM card. There are other conditions that must be 
met other than just the WE pin, before writing can commence. 

It may be that the VZ looks for a completed circuit between the CE, 
CE1 and RA19 pins on the card before writing, all of which connect to 
the NOR gate chip and then go to the CS pin on the RAM chip, but are 
all not connected in the ROM chip. 

Also, CE1 on the RAM chip is permanently high, but not connected on 
the ROM chip. Without all those conditions being met, the VZ perhaps 
will not go into transmit mode. The "write fail" message may appear 
as a result of a negative scan result of CE, CE1  and RA19 lines, not 
because of failed data transmissions. Maybe. 

Having said that, if none of that is true, and the VZ  is able to 
blindly "write" to a ROM, the 1k resistors will indeed be protection 
against any data signal, I would think. But I think the above 
scenario is the case, rather than this one. That being true, IF it is 
true, then the extra data line RA15 may be availiable for a bigger 
RAM. In any case, I will be trying this out as soon as I get my VZ10M 
in about 6 weeks. In the meantime, I'm going to breadboard up a 
prototype card. I've already located a source for the standard RAM 
chip:

http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?
langId=-1&storeId=10001&catalogId=10001&productId=279857&pa=279857PS

And a 16x one here:

http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?
langId=-1&storeId=10001&catalogId=10001&productId=280049&pa=280049PS

Both very cheap.

Here's the NOR gate:

http://www1.jaycar.com.au/productView.asp?
ID=ZC4827&CATID=33&keywords=&SPECIAL=&form=CAT&ProdCodeOnly=&Keyword1=
&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=884

Cheers, Graham




--- In CZsynth@yahoogroups.com, "Scott Nordlund" <gsn10@...> wrote:
>
> >In any case, I don't think the VZ sees any difference between a ROM
> >and a RAM, except that it will fail to write to a ROM because the
> >ROM's write line is not connected (and wouldn't work if it was,
> >anyway.). This being the case, using a larger RAM  chip will give 
you
> >an extra bank WITHOUT DIP switch selectors for extra address lines,
> >because you can use RA15, which is disconnected on the RAM card, 
but
> >is utilised on the ROM, being 2x larger than the RAM. For even more
> >banks, you will need DIP switch selectors though.
> 
> This may be the case, and I notice on mine that it does appear to 
try to 
> write to the ROM card before giving an error message.  But I was 
thinking 
> that this might not be a great idea- the ROM chip doesn't have the 
WE pin, 
> and what are I/O pins on a RAM chip are just outputs.  I would 
assume that 
> the VZ just blindly tries to write the data by asserting WE and 
then sending 
> the data (if it hasn't got any way to tell), but on a ROM chip this 
results 
> in output connected to output, basically a short circuit.  There 
are 1K 
> resistors on the I/O lines, but it still seems like it's not the 
best way to 
> do things, and I think any decently-engineered product wouldn't do 
that.
> 
> But regardless.. how, then, would it give an error message after 
trying to 
> write to a ROM card?  If the VZ doesn't differentiate between RAM 
and ROM 
> cards, there's no way to reliably detect a write error.  Even 
comparing the 
> data on the card with the internal VZ RAM after the write isn't a 
foolproof 
> way to do it.
> 
> However, now that I think about it a little more, there are ways to 
detect 
> the difference in software.  If there's some unused portion of the 
memory 
> space, it's easy to tell if the highest address bit actually does 
something: 
> If ROM card address 0x0000 (bank 1) contains the value "10101010" 
and 
> address 0x4000 (bank 2) contains "01010101", 0x0000 XOR 0x4000 
= "11111111". 
>   On a RAM card, it would simply refer to the same byte, so 0x0000 
XOR 
> 0x4000 = "00000000" (regardless of what data is present).  Whether 
the VZ 
> does it on start up or just before attempting to write is a 
different issue, 
> but it would thwart the 2-bank RAM card idea.
> 
> At any rate, if a RAM card indicates CARD (1) and CARD (2), this 
would 
> confirm that the highest address bit is being used, just not 
connected to 
> anything, and that RAM and ROM cards are indeed detected the same, 
at least 
> on startup (and thus a 2-bank RAM card can probably be used, unless 
it 
> detects before attempting to write).
> 
> _________________________________________________________________
> Get a preview of Live Earth, the hottest event this summer - only 
on MSN 
> http://liveearth.msn.com?source=msntaglineliveearthhm
>

I'm looking forward to the results of your work Graham.