[YamahaDX] Creating a RAM4 Compatible Cartridge

[[e-mail] [YamahaDX]]

Hi All,

I've been looking into the possibility of making a RAM4 compatible cartridge (For the DX7II etc) as it seems to be more popular than the RAM1 style I designed for the original DX7.

Is there anyone in the UK (or Europe?) who would be prepared to lend me an original RAM4 cartridge for a few days, with the intention of opening it to study the insides?

It would also be possible to glean most of the information I require from an ADP-1 adaptor.

The main information I need to establish about the RAM4:
Exact dimensions of the cartridge and its edge connector. Functionality of the CT0 and CT1 (cartridge type) pins.I already know from online photos that the connector has 34 pins as opposed to 28 but the pin lengths and spacings appear to be the same as the RAM1.

From the DX7II schematic I have the pin-out information.

CT0 and CT1 are used to tell the DX7 what type of cartridge is installed.
If I could discover whether these pins are connected to (GND, +5V or left floating) in the RAM4 that would help a lot. I suspect that this will be different in the ADP-1 adaptor, the RAM4 cartridge and the DX7II ROM cartridge.

As the RAM1 style cartridge will work in an ADP-1 adaptor my design would only need a new PCB outline with the new connector type to work basically. However I believe that the patches stored in the RAM4 cartridge from a DX7II have more information and therefore take twice the storage space. I take it the RAM4 holds 64 patches by default.

Original RAM1 (DTC4W): 2 x X2816A devices = 2 x 2048 x 8 bits = 32 kbits = 32 patches of 1k.
Original ROM cartridges (DCT8R): 1 x 2764-2 device = 8192 x 8 bits = 64 kbits = 2 banks of 32 patches.
My cartridge design: 1 x AT28C256 device = 32768 x 8 = 256 kbits = 8 banks of 32 patches.

Original RAM4: 2 x M5M5165 devices = 2 x 8192 x 8 bits = 128 kbits = 64 patches of 2k ?
My possible design: 1 x AT28C256 device = 32768 x 8 = 256 kbits = 2 banks of 64 patches.

Any thoughts?

[Daniel Forró [e-mail] [YamahaDX]]

Hi,

I’m in Japan so it’s not so comfortable to send cartirdge to you and back


I send you all I have about RAM4 and RAM5 cartridges - check your mail, maybe you will find something you haven’t yet.

I think RAM4 cartridge has more banks (at least 4, but OS can select 16 banks but they are not used) - they can be used for saving patches, performances, or fractional scalings or microtonal settings.

ROM cartridges for DX7 II D/FD could have two banks of patches (2x64), performances and fractional scaling.

It’s a question if your design would be enough attractive if it can have only double size of standard RAM4


Daniel Forro

Post by ***@goffart.co.uk [YamahaDX]
Hi All,
I've been looking into the possibility of making a RAM4 compatible cartridge (For the DX7II etc) as it seems to be more popular than the RAM1 style I designed for the original DX7.
Is there anyone in the UK (or Europe?) who would be prepared to lend me an original RAM4 cartridge for a few days, with the intention of opening it to study the insides?
It would also be possible to glean most of the information I require from an ADP-1 adaptor.
Exact dimensions of the cartridge and its edge connector.
Functionality of the CT0 and CT1 (cartridge type) pins.
I already know from online photos that the connector has 34 pins as opposed to 28 but the pin lengths and spacings appear to be the same as the RAM1.
From the DX7II schematic I have the pin-out information.
CT0 and CT1 are used to tell the DX7 what type of cartridge is installed.
If I could discover whether these pins are connected to (GND, +5V or left floating) in the RAM4 that would help a lot. I suspect that this will be different in the ADP-1 adaptor, the RAM4 cartridge and the DX7II ROM cartridge.
As the RAM1 style cartridge will work in an ADP-1 adaptor my design would only need a new PCB outline with the new connector type to work basically. However I believe that the patches stored in the RAM4 cartridge from a DX7II have more information and therefore take twice the storage space. I take it the RAM4 holds 64 patches by default.
Original RAM1 (DTC4W): 2 x X2816A devices = 2 x 2048 x 8 bits = 32 kbits = 32 patches of 1k.
Original ROM cartridges (DCT8R): 1 x 2764-2 device = 8192 x 8 bits = 64 kbits = 2 banks of 32 patches.
My cartridge design: 1 x AT28C256 device = 32768 x 8 = 256 kbits = 8 banks of 32 patches.
Original RAM4: 2 x M5M5165 devices = 2 x 8192 x 8 bits = 128 kbits = 64 patches of 2k ?
My possible design: 1 x AT28C256 device = 32768 x 8 = 256 kbits = 2 banks of 64 patches.
Any thoughts?

[[e-mail] [YamahaDX]]

Hi Daniel,

Thanks for the info (or should I say "arigato"!).

I've seen nearly all the RAM4 info before, inckuding the incomplete schematic.
The RAM5 photos and information are interesting however I still can't quite see the connections for CT0. It appears to go to the mode switch and the level 1-2 switch.

It's a shame the photos of the insides of the RAM4 are so low resolution. Some nice high resolution photos would be great. Anybody?

It might be possible to use two 256kbit devices. That would give the same capacity as a RAM5, i.e. four times the RAM4.

Ant.

[Daniel Forró [e-mail] [YamahaDX]]

I understand more languages, including arigato :-) Thank you for saying thanks :-) In my native tongue it’s “děkuji”.

I supposed you would have most of that.

Can try to make RAM4 hi-res pictures today. One of my cartridges can be opened quite easily.

Higher capacity would be great! RAM5 clone, wow


Daniel Forro

Post by ***@goffart.co.uk [YamahaDX]
Hi Daniel,
Thanks for the info (or should I say "arigato"!).
I've seen nearly all the RAM4 info before, inckuding the incomplete schematic.
The RAM5 photos and information are interesting however I still can't quite see the connections for CT0. It appears to go to the mode switch and the level 1-2 switch.
It's a shame the photos of the insides of the RAM4 are so low resolution. Some nice high resolution photos would be great. Anybody?
It might be possible to use two 256kbit devices. That would give the same capacity as a RAM5, i.e. four times the RAM4.
Ant.

[[e-mail] [YamahaDX]]

I have uploaded a few higher resolution pictures of my RAM5 on google drive:
https://drive.google.com/open?id=0BysIHN85jAaoNUZGMGw3OVZaUUU https://drive.google.com/open?id=0BysIHN85jAaoNUZGMGw3OVZaUUU
Let me know if you need a specific close up, or measurement (electrical or mecanical).

[[e-mail] [YamahaDX]]

Additional info:

The resistor networks are hard to photograph, they are marked as follows:
5-pin : BI L61C472
8-pin : BI L81C472
10-pin : BI L101C472
Pin marked with a dot (common?) is near the edge of the board for all resistor networks.


Transistor is 2N3904

[[e-mail] [YamahaDX]]

Hi Antoine,

The photos are great - thank you. The backlit ones are a nice touch.
I shall attempt to create a schematic of the RAM5 when I get a chance.

If I need some more connection information I'll let you know, but most should be possible to work out.

It looks as if the CT1 signal connects to the multi-bank mode switch and also to the select input of the 74HC257 data MUX. That makes sense as moving the mode switch would then change the cartridge type.

I wonder if the majority of users would want multi-bank mode or single-bank mode.

Ant.

[[e-mail] [YamahaDX]]

Glad I could help.

I think those with instruments that support the multi-bank mode would prefer it, as the banks can then be selected from the front panel (and maybe even from MIDI?) instead of by sliding tiny switches, but I think not all instruments compatible with the RAM5 support the multi-bank mode.

[Daniel Forró [e-mail] [YamahaDX]]

MIDI Bank selection is not supported on Yamaha DX/TX instruments, it was later MIDI innovation


Daniel Forro

Post by ***@yahoo.com [YamahaDX]
Glad I could help.
I think those with instruments that support the multi-bank mode would prefer it, as the banks can then be selected from the front panel (and maybe even from MIDI?) instead of by sliding tiny switches, but I think not all instruments compatible with the RAM5 support the multi-bank mode.
--
Antoine

[Daniel Forró [e-mail] [YamahaDX]]

So I have tried to make some pictures from near distance but my cameras were not able to do it so it’s not usable
 Sorry!

Daniel Forro

Post by Daniel Forró ***@yahoo.com [YamahaDX]
I understand more languages, including arigato :-) Thank you for saying thanks :-) In my native tongue it’s “děkuji”.
I supposed you would have most of that.
Can try to make RAM4 hi-res pictures today. One of my cartridges can be opened quite easily.
Higher capacity would be great! RAM5 clone, wow

Daniel Forro

[[e-mail] [YamahaDX]]

Hi all,
had some spare time the last weeks and so -inspired by EEPROM-Cartridge for DX7- I rummaged around in some old folders on my computer (there was a project started some time ago) and have done a "quick and dirty"-prototype that's still not working:

dimensions - good, pcb fits original dx7s rom-cartridge case (without IC sockets) and contacts seem in the middle of the track
formatting - works
saving single sounds - works partially (they sound wrong but the names are shown correctly)
saving complete bank - doesn't work
service menue read/write - error
I've created some breakout points and jumpers on the board to experiment a little with the lines but till now had no success.

Any ideas?
Best Regards, clem!

[[e-mail] [YamahaDX]]

You're using 28C256? Those are EEPROM, and I'm not sure what the original RAM4 cart used, whether it was battery backed SRAM/DRAM or something else. If it wasn't EEPROM then it's possible that write timings are off, or maybe you've got one of the address lines wired up wrong.

[Bruce Wahler [e-mail] [YamahaDX]]

Almost all memory cards in the '80s used battery backed static RAM --
dynamic RAM uses too much power during standby.  Most EEPROMs require
MUCH longer write times, on the order of milliseconds (vs. 100's of
nanoseconds).  If the user attempts to write another byte of data before
the write cycle is finished, the EEPROM aborts the first write, leaving
behind corrupted data.

To protect against these problems, most EEPROMs use a system where the
data written to the memory is read as the ones-complement (inverse)
until the EEPROM has actually completed its program cycle --

ex:

* Write 28H (0x28) to the EEPROM
* Read the EEPROM
* Value read is D7H  [11010111b vs. 00101000b]
* Continue reading the EEPROM until the value is 28H
* Write the next byte
* etc.

Of course, this requires software to perform the loop-and-test routine;
and to time out if the correct value is never read from the EEPROM.  I
wouldn't expect that the DX has this software, since EEPROM was a new,
expensive technology; I doubt that Yamaha planned for its use.

Regards,

-BW

Bruce Wahler
Ashby Solutions.com™
***@ashbysolutions.com
http://music.ashbysolutions.com
http://halfmoon-switch.com
http://ashboys.com
978.597.7008

Post by ***@yahoo.com [YamahaDX]
You're using 28C256? Those are EEPROM, and I'm not sure what the
original RAM4 cart used, whether it was battery backed SRAM/DRAM or
something else. If it wasn't EEPROM then it's possible that write
timings are off, or maybe you've got one of the address lines wired up
wrong.

[[e-mail] [YamahaDX]]

Yamaha did in fact use EEPROM. Without more info from the OP it's hard to know why his cartridge isn't working. It could be a design issue, a soldering issue, bad memory chips, bad connections at the socket (most likely if you ask me), etc.

[Bruce Wahler [e-mail] [YamahaDX]]

Yes, but are you sure that it's EEPROM in the cartridge?  Both my RAM4
and RAM5 have a backup battery.  That wouldn't make sense with EEPROM,
but it would with static RAM.

Regards,

-BW

Bruce Wahler
Ashby Solutions.com™
***@ashbysolutions.com
http://music.ashbysolutions.com
http://halfmoon-switch.com
http://ashboys.com
978.597.7008

Yamaha did in fact use EEPROM.  Without more info from the OP it's
hard to know why his cartridge isn't working. It could be a design
issue, a soldering issue, bad memory chips, bad connections at the
socket (most likely if you ask me), etc.

[Grant B [e-mail] [YamahaDX]]

Yes I'm sure. Yamaha used EEPROM in the original DX7 RAM cartridge. You
may be able to see it via Google images or in the service manual.  Other
people have pulled this off so it's probably just some error the OP has
made.  Many of the 3rd party RAM carts for the DX7 were SRAM though, so
one imagines the algorithm is timing and not command based.

Also, FWIW the SRAM they used on the main board is very unique too. You
can't pop a 6116 in there and have it work.  They were in a world of
their own when they built the original DX7. Even the cartridge male
connectors (not the PCB trace versions) were different than Kawai and
Roland, who used a common part.

Post by Bruce Wahler ***@ashbysolutions.com [YamahaDX]
Yes, but are you sure that it's EEPROM in the cartridge?  Both my RAM4
and RAM5 have a backup battery. That wouldn't make sense with EEPROM,
but it would with static RAM.
Regards,
-BW
Bruce Wahler
Ashby Solutions.com™
http://music.ashbysolutions.com
http://halfmoon-switch.com
http://ashboys.com
978.597.7008

Yamaha did in fact use EEPROM.  Without more info from the OP it's
hard to know why his cartridge isn't working. It could be a design
issue, a soldering issue, bad memory chips, bad connections at the
socket (most likely if you ask me), etc.

[Grant B [e-mail] [YamahaDX]]

I should mention that it's possible I may have misunderstood the OP's
project. If he's trying to make a DX7 cart, then yes EEPROM. If he's
trying to make one of the larger carts for the later models then perhaps
they will only work with SRAM.  I'm not familiar with the later
cartridges, so you may be correct about that.

GB

Post by Grant B ***@jps.net [YamahaDX]
Yes I'm sure. Yamaha used EEPROM in the original DX7 RAM cartridge.
You may be able to see it via Google images or in the service manual. 
Other people have pulled this off so it's probably just some error the
OP has made.  Many of the 3rd party RAM carts for the DX7 were SRAM
though, so one imagines the algorithm is timing and not command based.
Also, FWIW the SRAM they used on the main board is very unique too. 
You can't pop a 6116 in there and have it work.  They were in a world
of their own when they built the original DX7. Even the cartridge male
connectors (not the PCB trace versions) were different than Kawai and
Roland, who used a common part.

Post by Bruce Wahler ***@ashbysolutions.com [YamahaDX]
Yes, but are you sure that it's EEPROM in the cartridge?  Both my
RAM4 and RAM5 have a backup battery.  That wouldn't make sense with
EEPROM, but it would with static RAM.
Regards,
-BW
Bruce Wahler
Ashby Solutions.com™
http://music.ashbysolutions.com
http://halfmoon-switch.com
http://ashboys.com
978.597.7008

Yamaha did in fact use EEPROM.  Without more info from the OP it's
hard to know why his cartridge isn't working. It could be a design
issue, a soldering issue, bad memory chips, bad connections at the
socket (most likely if you ask me), etc.

[[e-mail] [YamahaDX]]

It might be to do with the write cycle timing of the particular EEPROM they originally used - i.e. the firmware was written to support that particular chip, not the one used in the new homemade cartridge.

Short of finding some of the original type of chip, you might have to settle for just being able to write single patches.

Presumably, it starts writing the next one too soon, when you save a bank, because the firmware thinks the EEPROM is ready for more when it isn't I haven't looked at the datasheets. It might be a busy flag, one one pin of the chip, or the firmware might just be waiting for a set amount of time.

Perhaps writing a single patch works because the EEPROM buffers writes (but only so many)?

Andy

[[e-mail] [YamahaDX]]

Thank you for your feedback.
Yes I'm trying to use EEPROM - two AT28C256 - the type that that works in aerobaticant's cart for DX7.
To eliminate soldering problems I have build two prototypes, first with AT28C64 and the second is the one in the pic.
The CT1/CT2 (to GND) coding is explained in the TX802 Service manual and can be checked with Service-Menue.
I have double checked the order of the adress-lines, because the order of the lines differ between SRAMs that Yamaha used for RAM5 and EEPROMs (Byte and Page adresses). - Maybe I misunderstood something here?
And last tried to connect D7 to both of the CT lines in the hope that Yamaha implemented DATA-Polling in the firmware (BTW it is DX7s 1.2).
So the next attempts will be:
-trying to mount one or two EPROMs (for this I read out the OTP-EPROM of the DXs7 ROM Cartridge I will upload it soon) to verify the base of the design. But before I can do that, I must find someone who can erase my EPROMS.
-finding faster EEPROMs - eventually 28HC with 85ns will do it, but this needs another cartridge layout with smd parts
- or patching the firmware for slower write cycles.
Best,
clem!

[[e-mail] [YamahaDX]]

Thank you for your feedback.
Yes I'm trying to use EEPROM - two AT28C256 - the type that that works in aerobaticant's cart for DX7.
To eliminate soldering problems I have build two prototypes, first with AT28C64 and the second is the one in the pic.
The CT1/CT2 (to GND) coding is explained in the TX802 Service manual and can be checked with Service-Menue.
I have double checked the order of the adress-lines, because the order of the lines differ between SRAMs that Yamaha used for RAM5 and EEPROMs (Byte and Page adresses). - Maybe I misunderstood something here?
And last I tried to connect D7 first to CT1 and then to CT2 line in hope that Yamaha implemented DATA-Polling in the firmware - no effect. Connection to D5 for toggling made no effect either (BTW it is DX7s 1.2).
So the next attempts will be:
-trying to mount one or two EPROMs (for this I read out the OTP-EPROM of the DXs7 ROM Cartridge I will upload it soon) to verify the base of the design. But before I can do that, I must find someone who can erase my EPROMS.
-finding faster EEPROMs - eventually 28HC with 85ns will do it, but this needs another cartridge layout with smd parts
- or patching the firmware for slower write cycles.
Best,
clem!

[Grant B [e-mail] [YamahaDX]]

Well this might help. Once upon a time I started reverse engineering the DX7.
I didn't get far, but I did do the cartridge write code. My comments were not
complete so reading the data sheet for the EEPROM might fill in the questions
I had left. The function and sram names are my own designations.

GB


;-----------------------------------------------------
; Write data to cartridge
; $00FB ;Destination pointer
; $00F9 ;Source pointer
; Location "CartByteCount" returns zero on success.
;-----------------------------------------------------
CartWritePatch: ;LD83F:
ldaa #$80 ;Byte counter (128 bytes per patch). Size of patch.
staa CartByteCount ;$2179
LD844: ldx SrcPointer ;$00F9 Get Source pointer
ldaa $00,x ;Read byte value
anda #$7F ;Allowed values 00-7F only.
inx ;Incr and save source pointer.
stx SrcPointer ;$00F9
ldx DestPointer ;$00FB Get dest pointer
bsr CartWriteByte ;LD85C Write the value to EE. A holds byte, X holds addr.
bcs LD85B
inx
stx DestPointer ;$00FB
dec CartByteCount ;$2179
bne LD844
LD85B:
rts


;---------------------------------------------------------------
;CartWriteByte -
;ACC A - value to write
;---------------------------------------------------------------
CartWriteByte: ;LD85C:
tst $00,x
tst $00,x
tst $00,x ;Curious TSTs before cart access.
tst $00,x
tst $00,x
cmpa $00,x ;Is byte already there?
beq LD88C ;Yes, done success.
staa $00,x ;No, overwrite with new value.
cmpa #$FF ;Special value? Maybe last test val or erase?
bne LD874 ;Not special value (never writes $FF?) so read back.
jsr Delay_15ms ;LD8E7 - If $FF then after the write delay and exit?
rts


;---------------------------------------------------------------
;Read back after the EEPROM write with a timeout.
;Returns CF=0 on success otherwise CF=1.
;---------------------------------------------------------------
LD874: ldab #$64 ;Loop timeout value = 100
LD876: jsr Delay_x7 ;LD8D1 Delay 100us??
LD879: tst $00,x
tst $00,x
tst $00,x ;Curious TSTs before cart access.
tst $00,x
tst $00,x
cmpa $00,x ;Read back. Is value written OK?
beq LD88C ;Yes, done.
decb ;No. Anymore loops left?
beq LD88E ;No. Exit failure.
bra LD876 ;Yes. Go around again.

LD88C: clc ;Return success.
rts

LD88E: sec ;Return failure.
rts
;---------------------------------------------------------------

[[e-mail] [YamahaDX]]

I found someone, who erased my EPROMs and the first test with a new-burned EPROM with the uploaded bin-file was succesful. So I can state, that the base-design of my cartridge works. Data-Lines, Adress-Lines, Chip-Enable and Out-Enable seem to be OK.
Now the next step will be to find faster EEPROMS... And a new cartridge design with PLCC-EEÜROMS or SOIC-EEPROMs with a DIP-adapter.
Best,
clem!

[charles copp [e-mail] [YamahaDX]]

I know someone who can make cartridges
for the dx , he has made some for the
roland m-16 but multi bank
want me to ask about a dx7 cartridge
multi bank?

[[e-mail] [YamahaDX]]

Hi all,
RAM6 for DX7II is ready and running. It is a 32 Bank RAM Cartridge with 1 512x8k SRAM and DS1210 as watchdog. The resistor-networks are on the Backside.
Hereis a pic of a multbank cartridge
best regards clem!

[[e-mail] [YamahaDX]]

Hi all,
RAM6 for DX7II is ready and running. It is a 32 Bank RAM Cartridge with 1 512x8k SRAM and DS1210 as watchdog. The resistor-networks are on the Backside.
Hereis a pic of a multbank cartridge


Hi all,
RAM6 for DX7II is ready and running. It is a 32 Bank RAM Cartridge with 1 512x8k SRAM and DS1210 as watchdog. The resistor-networks are on the Backside.
Hereis a pic of a multbank cartridge

[[e-mail] [YamahaDX]]

Hi all,
now I have finished my DIY RAM6 SRAM Cartridge for DX7II/FD/D/S TX802 and DX11. It is a 32 (16x2) multibank cartridge and it seems to work fine.
Now I have saved different sounds on the cartridge but IÂŽm wondering if anyone here in the forum has made sysex dumps of bank 3 and four of their ROM cartridges with fractional scaling and microtuning data.
Best clem!

[Tom Butcher [e-mail] [YamahaDX]]

Cool! Is it a one-off or will you be offering some for sale?

Post by ***@yahoo.com [YamahaDX]
Hi all,
now I have finished my DIY RAM6 SRAM Cartridge for DX7II/FD/D/S TX802 and DX11. It is a 32 (16x2) multibank cartridge and it seems to work fine.
Now I have saved different sounds on the cartridge but IÂŽm wondering if anyone here in the forum has made sysex dumps of bank 3 and four of their ROM cartridges with fractional scaling and microtuning data.
Best clem!

[[e-mail] [YamahaDX]]

I have a handful of spare PCBs, maybe I sell or better swap them after some more testing later in Central-Europe. Shipping costs for "GREATER" America are out of proportion to the costs for the PCB I think.
Best clem!

[[e-mail] [YamahaDX]]

Ha ha. I got that. ;-)

[Ewan Colsell [e-mail] [YamahaDX]]

if you have spare pcbs, i'd love to make one of these!

i have a half made pcb i have cut to size and was going to etch myself, but
maybe life is too short.

Ewan.

Post by ***@jps.net [YamahaDX]
Ha ha. I got that. ;-)

[a b [e-mail] [YamahaDX]]

Hi Ewan,
you are on the list. The pcb needs a little bit more testing. I think it will take 2 weeks. BTW: The PCB will be 20 EUR + shipping (3-5 EUR).
Best, clem!


Am Donnerstag, 12. Juli 2018, 17:46:02 MESZ hat Ewan Colsell ***@yahoo.it [YamahaDX] <***@yahoogroups.com> Folgendes geschrieben:

 

if you have spare pcbs, i'd love to make one of these!

i have a half made pcb i have cut to size and was going to etch myself, but maybe life is too short.

Ewan.
On 10 July 2018 at 18:17, ***@jps.net [YamahaDX] <***@yahoogroups.com> wrote:

 
Ha ha. I got that. ;-)


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[Tom Butcher [e-mail] [YamahaDX]]

Hey y’all,

I recently got one of those awesome DTronics DT-7 programmers for my 6-op DXes. I’d love to find a clean scan or copy of the algorithm diagrams and hopefully also one of the envelope diagrams to print out and place near it. Any of you have something like that?

t

[Florian Anwander [e-mail] [YamahaDX]]

Hello Tom

Post by Tom Butcher ***@gmail.com [YamahaDX]
I recently got one of those awesome DTronics DT-7 programmers for my
6-op DXes. I’d love to find a clean scan or copy of the algorithm
diagrams and hopefully also one of the envelope diagrams to print out
and place near it. Any of you have something like that?

here we go:
Loading Image...

btw: here my first try of the DT7:
https://vimeo.com/283518980

[Florian Anwander [e-mail] [YamahaDX]]

Aah, sorry, I overlooked the request for the envelope.

Then this is the one to go for:
Loading Image...

Post by Florian Anwander ***@mnet-online.de [YamahaDX]
Hello Tom

Post by Tom Butcher ***@gmail.com [YamahaDX]
I recently got one of those awesome DTronics DT-7 programmers for my
6-op DXes. I’d love to find a clean scan or copy of the algorithm
diagrams and hopefully also one of the envelope diagrams to print out
and place near it. Any of you have something like that?

http://powerfx.assets.s3.amazonaws.com/images/uploads/fm-synth-algorithms.png
https://vimeo.com/283518980

[[e-mail] [YamahaDX]]

I found someone, who erased my EPROMs and the first test with a new-burned EPROM with the uploaded bin-file was succesful. So I can state, that the base-design of my cartridge works. Data-Lines, Adress-Lines, Chip-Enable and Out-Enable seem to be OK.
Now the next step will be to find faster EEPROMS... And a new cartridge design with PLCC-EEPROMS or SOIC-EEPROMs with a DIP-adapter.
Best,
clem!

[[e-mail] [YamahaDX]]

RAM6-Cartridge for DX7II (32 Bank) with 512x8 32 Pin SRAM

[[e-mail] [YamahaDX]]

If they *did* manufacture both EEPROM and SRAM based cartridges for the same machines there must be a way for the keyboard to detect what type of memory has been inserted. Either there must be a line dedicated for this detection, or some code in the main BIOS (how to do this programmatically?).

[[e-mail] [YamahaDX]]

There are two lines CT0 and CT1 that identify the cartridge type.
The RAM1 cartridge does use EEPROM, as does the 8 bank catridge I have designed.

The RAM4 and RAM5 cartridges both use SRAM.

[Ldcovino [e-mail] [YamahaDX]]

Good morning, group.  I have two dx7s.  One has the thick power cord, and battery voltage is supposed to be 3.0.  Right now it's at 2.8.  At what point in terms of voltage do I need to change out battery? 

On my second DX7, I have a lamp cord for a power cord, and that DX has a battery voltage reading of 4.5.  What is supposed to be? Obviously it has a higher voltage requirement than the other one. Other than that, both appear to be the same. 

Thanks for your assistance as always..... 

Regards, 


David Covino 




-----Original Message-----
From: ***@yahoo.com [YamahaDX] <***@yahoogroups.com>
To: YamahaDX <***@yahoogroups.com>
Sent: Mon, Dec 4, 2017 8:28 am
Subject: Re: [YamahaDX] Creating a RAM4 Compatible Cartridge

You're using 28C256? Those are EEPROM, and I'm not sure what the original RAM4 cart used, whether it was battery backed SRAM/DRAM or something else. If it wasn't EEPROM then it's possible that write timings are off, or maybe you've got one of the address lines wired up wrong.

[Barry Carson [e-mail] [YamahaDX]]

If your DX7's have the original batteries, it's pretty certain they need to
be replaced no matter what the display says the voltage is. My original
DX7 always said 2.8 but the battery was deader than a door nail. It's not
a hard job if you're careful...

Good morning, group. I have two dx7s. One has the thick power cord, and
battery voltage is supposed to be 3.0. Right now it's at 2.8. At what
point in terms of voltage do I need to change out battery?
On my second DX7, I have a lamp cord for a power cord, and that DX has a
battery voltage reading of 4.5. What is supposed to be? Obviously it has a
higher voltage requirement than the other one. Other than that, both appear
to be the same.
Thanks for your assistance as always.....
Regards,
David Covino
-----Original Message-----
Sent: Mon, Dec 4, 2017 8:28 am
Subject: Re: [YamahaDX] Creating a RAM4 Compatible Cartridge
You're using 28C256? Those are EEPROM, and I'm not sure what the original
RAM4 cart used, whether it was battery backed SRAM/DRAM or something else.
If it wasn't EEPROM then it's possible that write timings are off, or maybe
you've got one of the address lines wired up wrong.

[Ldcovino [e-mail] [YamahaDX]]

Thanks, Barry.  The 3.0 battery has been changed several times over the years, but the 4.5 V DX& is likely the original, and I don't know what the proper voltage for a new battery should be.  Is there a manual out there for this type of DX7?  I suspect the electronics are a little bit different....  Thanks!


L. David Covino CFE ALHC



-----Original Message-----
From: Barry Carson ***@gmail.com [YamahaDX] <***@yahoogroups.com>
To: YamahaDX <***@yahoogroups.com>
Sent: Mon, Dec 4, 2017 9:28 am
Subject: Re: [YamahaDX] Question of battery voltage....


If your DX7's have the original batteries, it's pretty certain they need to be replaced no matter what the display says the voltage is.  My original DX7 always said 2.8 but the battery was deader than a door nail.  It's not a hard job if you're careful...   

On Mon, Dec 4, 2017 at 9:23 AM, Ldcovino ***@aol.com [YamahaDX] <***@yahoogroups.com> wrote:
 

Good morning, group.  I have two dx7s.  One has the thick power cord, and battery voltage is supposed to be 3.0.  Right now it's at 2.8.  At what point in terms of voltage do I need to change out battery? 

On my second DX7, I have a lamp cord for a power cord, and that DX has a battery voltage reading of 4.5.  What is supposed to be? Obviously it has a higher voltage requirement than the other one. Other than that, both appear to be the same. 

Thanks for your assistance as always..... 

Regards, 


David Covino 




-----Original Message-----
From: ***@yahoo.com [YamahaDX] <***@yahoogroups.com>
To: YamahaDX <***@yahoogroups.com>
Sent: Mon, Dec 4, 2017 8:28 am
Subject: Re: [YamahaDX] Creating a RAM4 Compatible Cartridge

 
You're using 28C256? Those are EEPROM, and I'm not sure what the original RAM4 cart used, whether it was battery backed SRAM/DRAM or something else. If it wasn't EEPROM then it's possible that write timings are off, or maybe you've got one of the address lines wired up wrong.

[Bruce Wahler [e-mail] [YamahaDX]]

The battery voltage of that cell should be around 3V.  A 2.If you are
actually reading 4.5V -- a BIG if, read below -- then it implies that
the reading might be coming from the 5V power supply, and the blocking
diode might need replacing.

That said, the only battery reading I would trust would be from a
quality voltmeter measured across the battery itself, with the AC power
cord unplugged for at least a couple of minutes to bleed off any stored
charge.  The battery is only supposed to be in the circuit when power is
off, but it depends on the blocking diode to make this happen properly.

Regards,

-BW

Bruce Wahler
Ashby Solutions.com™
***@ashbysolutions.com
http://music.ashbysolutions.com
http://halfmoon-switch.com
http://ashboys.com
978.597.7008

Post by Ldcovino ***@aol.com [YamahaDX]
Thanks, Barry.  The 3.0 battery has been changed several times over
the years, but the 4.5 V DX& is likely the original, and I don't know
what the proper voltage for a new battery should be.  Is there a
manual out there for this type of DX7?  I suspect the electronics are
a little bit different....  Thanks!
L. David Covino CFE ALHC
-----Original Message-----
Sent: Mon, Dec 4, 2017 9:28 am
Subject: Re: [YamahaDX] Question of battery voltage....
If your DX7's have the original batteries, it's pretty certain they
need to be replaced no matter what the display says the voltage is. 
My original DX7 always said 2.8 but the battery was deader than a door
nail. It's not a hard job if you're careful...
Good morning, group.  I have two dx7s.  One has the thick power
cord, and battery voltage is supposed to be 3.0.  Right now it's
at 2.8.  At what point in terms of voltage do I need to change out
battery?
On my second DX7, I have a lamp cord for a power cord, and that DX
has a battery voltage reading of 4.5. What is supposed to be?
Obviously it has a higher voltage requirement than the other one.
Other than that, both appear to be the same.
Thanks for your assistance as always.....
Regards,
David Covino
-----Original Message-----
Sent: Mon, Dec 4, 2017 8:28 am
Subject: Re: [YamahaDX] Creating a RAM4 Compatible Cartridge
You're using 28C256? Those are EEPROM, and I'm not sure what the
original RAM4 cart used, whether it was battery backed SRAM/DRAM
or something else. If it wasn't EEPROM then it's possible that
write timings are off, or maybe you've got one of the address
lines wired up wrong.

[Daniel Forró [e-mail] [YamahaDX]]

CR2032 = 3 V.

Service manual is available, for example here:

https://groups.yahoo.com/neo/groups/YamahaDX/files/DX7s%20/

Daniel Forro

Thanks, Barry. The 3.0 battery has been changed several times over the years, but the 4.5 V DX& is likely the original, and I don't know what the proper voltage for a new battery should be. Is there a manual out there for this type of DX7? I suspect the electronics are a little bit different.... Thanks!
L. David Covino CFE ALHC

[Ldcovino [e-mail] [YamahaDX]]

Thank you, Daniel.  I'll check it out.  Appreciate the assistance. 


L. David Covino CFE ALHC



-----Original Message-----
From: Daniel Forró ***@yahoo.com [YamahaDX] <***@yahoogroups.com>
To: YamahaDX <***@yahoogroups.com>
Sent: Mon, Dec 4, 2017 10:49 am
Subject: Re: [YamahaDX] Question of battery voltage....


CR2032 = 3 V.

Service manual is available, for example here:

https://groups.yahoo.com/neo/groups/YamahaDX/files/DX7s%20/

Daniel Forro



On Dec 4, 2017, at 23:33, Ldcovino ***@aol.com [YamahaDX] <***@yahoogroups.com> wrote:

Thanks, Barry.  The 3.0 battery has been changed several times over the years, but the 4.5 V DX& is likely the original, and I don't know what the proper voltage for a new battery should be.  Is there a manual out there for this type of DX7?  I suspect the electronics are a little bit different....  Thanks!


L. David Covino CFE ALHC