W7v2 EPROM's

[► Evil E. ◄]

I would like to know a little bit more about the EPROM chips that are inside a W7 version 2. Can someone here parhaps enlighten me a little on this subject ? (how many are there, what manufacturer/model/type number, how many pins, where are they located inside the machine, ...)

I've been reading some disturbing things about the lifespan and EPROM "bit rot" (an decay effect similar to "Compact Disc bit rot" from what has been described) in some threads here on this forum. So I'm thinking of buying myself an EPROM programmer that allows me to read, back up, erase and reprogram the EPROM's to prevent my beloved machine from turning into a very expensive paper weight.

Would a TOP853 USB EPROM programmer be capable of reading and writing these EPROM's ?

[Derek]

Unless anybody can contradict me with real experience, I think EPROM bit rot is akin to the alleged 10 year lifespan of CDs. All of my CDs (accumulated since 1986) are still working 25 years on. I.e. it's all scaremongering.

With EPROMS you need to ensure that the window is properly covered (assuming the innards of your synth ever see daylight). Uncovered EPROMS will supposedly naturally erase over time, but I never saw that i practice when I was an engineer. And I quite often had EPROMS uncovered for lengthy periods of time on development boards. I was too lazy to waste a label on the basis that I could reprogram them if needed.

Having said that, it doesn't hurt to have an EPROM programmer to take some backups.

[► Evil E. ◄]

With EPROMS you need to ensure that the window is properly covered (assuming the innards of your synth ever see daylight). Uncovered EPROMS will supposedly naturally erase over time, but I never saw that i practice when I was an engineer. And I quite often had EPROMS uncovered for lengthy periods of time on development boards. I was too lazy to waste a label on the basis that I could reprogram them if needed.

I never opened my W7 (no need to) up until now, and when I'm not using it it's tucked away in its original box in dark storage.
So the IC's should still be okay, unless the time factor has an influence on them, of course...

Having said that, it doesn't hurt to have an EPROM programmer to take some backups.

Agreed. But then I need to know what EPROM programmer model can handle these IC's, hence my request for information.

Here's some more info about the W7v2 inner guts :



WARNING : NAKED SYNTH PARTS DISPLAYED BELOW
Look away NOW if you are over-sensitive to synth-pr0n !!!



Here is the Yamaha W7 version 2 motherboard :

W7v2 motherboard

As you can see, the W7v2 is (as standard) equipped with the WEMB02 "Vintage Sound Expansion Wave/Voice board", sitting on 4 raiser pins in the middle of the motherboard. On the right of the expansion board are 2 IC's that I think are the ones I'm looking for. These are the only 2 IC's I found that can be removed/replaced. They are both 32-pin IC's and contain the following printed text :
© 1995 YAMAHA / XQ452B0 / M534001C-37 / 5462361
© 1995 YAMAHA / XQ453B0 / M534001C-38 / 5482352

W7v2 removable IC's (ROM's ???)

Unfortunately, I cannot seem to find any information about these 2 IC's on the webbernet, so I have no idea if these are indeed the EPROM's.
As you can also see, these 2 IC's don't have any wipe window, so I have doubts that they are EPROM's (maybe EEPROM's, PROM's or ROM's ???).

Do these 2 IC's hold the firmware of the synth, or are they something completely different ? If they do then could I reprogram them and what EPROM programmer do I need to buy to accomplish that ? At what voltage do these operate ? And if I wanted to replace these chips with other reprogrammable equivalents, what EEPROM model/types do I need to replace them with ?

P.S. : underneath the motherboard shown above there's another fairly large PCB to be found. This one is connected to the surface controls/display of the synth, and is covered with some plastic foil and a thin aluminum/metal sheet on the bottom side (antistatic and EMI shielding ?). From what I could see, this PCB doesn't seem to have any IC's underneath the protective cover, but I'm guessing there are some to be found on the side pointing towards the top of the synth. But I haven't dared touching this one yet...

[Miks]

Since your W7 is opened up now you should try to locate those eproms containing the firmware.. but keep in mind that mostly the internal waveforms (samples) are stored to eproms too. But these are very often OTP (one time programmable) which means they have no window to be erased by using UV light so they look like an ordinary IC. My SY99 has (among others) several OTP which have 42 (!) pins. Before ordering an eprom programmer you have to make sure that it can handle ALL of the required pins!!! That's why one of my programmers can handle up to 48 (!) pins...

If you're interested what type it is: look here...

http://www.yamahaforums.co.uk/forum/vie ... =45#p26639

It's the link with the BX48 in it...

regards,

Miks

UUhhh, I was a lil' bit late...

Well, those IC are M534001C, a 524,288-Word x 8-Bit MASKROM which means they had been pre-programmed by the manufacturer with the data given by Yamaha. I'm not familiar with the W7 but I think there's a good chance that they contain the OS (firmware). They can easily be read out by an eprommer... and then stored away (as a file) for future handlings...
And therefore the eprom programmer you mentioned in your first post should satisfy your needs.

BTW: what type is that IC on the left side of your opened synth, the one with the sticker on it...?

[mikesblunt]

Hi All

Having been directed here by EVIL, I see the pics of his W7v2 and from these it is apparent that it contains OTP's (one time programmable) devices, whereas the W7 contains EPROM's.
OTP's are effectively fuse link devices and have no data decay mechanism whereas EPROM's have a vaguely defined data retention life of around 10-30 years.
EPROMS do die. My Philips LCR meter (electronic test equipment) suffered this some time ago but so far neither of the W7's in my family have fallen over.
Rest easy all of you who have these OTP's, they do not suffer from data rot.

Regards, Mike

[Miks]

Maybe one should read out the data, store it away, and at regular intervals have the EPROMS erased and written new so the bit rot didn't get a chance?
Having a second set of EPROMS will make the swap easy, and you're not 'out of synth' if something goes wrong writing those eproms new.

[► Evil E. ◄]

keep in mind that mostly the internal waveforms (samples) are stored to eproms too. But these are very often OTP (one time programmable) which means they have no window to be esased by using UV light so they look like an ordinary IC.

OTP PROM's... I'm learning more new stuff each day...

My SY99 has (among others) several OTP which have 42 (!) pins. Before ordering an eprom programmer you have to make sure that it can handle ALL of the required pins!!! That's why one of my programmers can handle up to 48 (!) pins...

If you're interested what type it is: look here...

http://www.yamahaforums.co.uk/forum/vie ... =45#p26639

It's the link with the BX48 in it...

Thanks for the heads-up about the pins, Miks. That thread contains very interesting reading material.

Those IC are M534001C, a 524,288-Word x 8-Bit MASKROM which means they had been pre-programmed by the manufacturer with the data given by Yamaha. I'm not familiar with the W7 but I think there's a good chance that they contain the OS (firmware).

Yeah, I had a feeling that those 2 might be the ones I was looking for. Thanks for confirming my thoughts, Miks !!! It makes sense to me to have the firmware in removable IC's, like the BIOS firmware chip(s) in PC's.

They can easily be read-out by an eprommer... and then stored away (as a file) for future handlings...
And therefore the eprom programmer you mentioned in your first post should satisfy your needs.

That is great news !!!

BTW: what type is that IC on the left side of your opened synth, the one with the sticker on it...?

I think that's the beast that makes it all work, the CPU itself. It's a 64-pin H8/325 4K2 (HD6473258P12). A model based on the Hitachi H8/300 CPU architecture, from what I can find on the net. I found a document online that has quite a lot of technical data on it : (http://www1.futureelectronics.com/doc/R ... 58P10V.pdf).
Here's a close-up picture of it :

H8/325 4K2 HD6473258P12 (XQ456A0)

I have no idea why that sticker is on there, though, or what "XQ456A0" means (Yamaha seems to have a lot of "XQ" stickers for parts, maybe it's a Yamaha part reference number ?). I don't think it covers an erase window. This seems to be the chip that controls the whole synth (32KB ROM, 1KB RAM, lots of I/O ports, clock timers, ...).

It runs at 5V if I read the technical document correctly. So does this mean that the rest of the W7 also runs at 5V (including the 2 removable PROM's) ?

I see the pics of his W7v2 and from these it is apparent that it contains OTP's (one time programmable) devices, whereas the W7 contains EPROM's.

Aha... So Yamaha chose to upgrade the W7v2, and that these 2 IC's are in fact the ones I was looking for. Thanks for confirming my thoughts, Mike !!!

Judging from the pictures I attached, do you believe that Yamaha made any other changes to the W7v2 (compared to the W7v1) ?

OTP's are effectively fuse link devices and have no data decay mechanism whereas EPROM's have a vaguely defined data retention life of around 10-30 years.

That is actually good news for me and other fellow W7v2 users. That means that they won't go bad. That's 1 machine less in my setup I have to worry about in terms of firmware corrupting.

EPROMS do die. My Philips LCR meter (electronic test equipment) suffered this some time ago but so far neither of the W7's in my family have fallen over.
Rest easy all of you who have these OTP's, they do not suffer from data rot.

Once again, Mike, thanks a lot for your assistance and your technical expertise. This is very much appreciated, and very interesting stuff to know !!!

Question-time again : what EPROM/EEPROM models/types would be compatible with the M534001C ? (for backup and - worst case scenario - replacement purposes)



Just an idea for the webmaster/admins :
Maybe it's interesting to post pictures and information of all different Yamaha gear models/versions, as a reference for fellow Yamaha gear users ? Things like EEPROM/EPROM/PROM locations/models/types/operating voltage, compatible replacement EEPROM models/types, battery type, ... and everything else that might come in handy if some fellow Yamaha gear owner wants/needs to DIY, modify, upgrade or repair his/her machine(s). I think it would make an awesome addition to the site.

[Miks]

Hi,

regarding your question for the right eprom: you can take a 27C4001 C-MOS type eprom. This is nothing special and you can get it (nearly) everywere. A good source may be eBay where some people are offering used items like this, often they have been erased and tested before they are up for auction. If you don't own a UV eprom eraser you schould buy from someone who erased the eproms before selling.

And thanks for the picture of the W7 CPU... now it's clear to me. The label is the Yamaha part number and needed for ordering a new one if the CPU fails.

best,

Miks

[chrispoacher]

Hi,

Did anyone get eprom dumps of the Yamaha W7 version 2 Roms after??

I'll happily pay someone for a set or for the downloadable .bin files.


Chris

email me via the Contact: "balloon" icon below my Avatar on the right . . . .

[tvirostek]

I have the ROM images for both V1 and V2.

I also have the rom image for the SUB cpu, but it's the same between V1 and V2 despite having different part numbers. The SUB CPU is a OTP microcontroller (H8/325) but it reports the same version (1.00) despite having two different part numbers on the two CPU boards that I have.

Tom

edit: The SUB CPU software is actually in 2 parts. The EPROM and the on-board micro controller ROM. The EPROM is the one mentioned above. A special adapter board would be needed to check the MCU ROM, but it appears to make no difference between the two versions (XP612C0 and XQ456A0). They may have the exact same code with different part numbers, just like the EPROM.