Emax

Graham-

I’m sharing this out to a wider audience so I don’t have to type this out again- hope that’s ok.


There is a file out there (I think Dave Sotnick has it… may or may not be posted on the group- not sure as it’s been a while) of the parameter EEPROM 8MB STEREO unit. 

If you have socketed that EEPROM (it’s an 8 pin IC), you should be able to install a preprogrammed parameter EEPROM from an EMAX2 which had a higher amount of memory installed previously.
Ideally- to possibly increase the memory, you would pull your old IC out (CAREFULLY), put a socket in and save your data out of the existing IC in the computer as additional backup, so you could always fail back to the original data / EEPROM.

Where the unit has the proper new PAL set and memory ICs in it, and the new EEPROM when turned on in theory it supposedly would see the additional and not need a code.

There was quite a bit of traffic about this some while back- 
but without the proper PAL set, all that having the EEPROM would do is allow you to fix a unit where you already had the PALs and memory there, and had gotten scrambled megs.
Pop in a new, preprogrammed  EEPROM IC, and you are back in business with the full memory you had and not have to pay EPR.
Without different PALs, you are stuck at the memory level you have…. period.

In this scenario- a unit which never had max RAM, but had some expansion boards and some memory - you wouldn’t have all the proper PALs to make it max memory for the available possible hardware config.
So if these PALs make it that you could go to max memory as you might now have a higher PAL set….. you would just need to get the memory ICs (and in theory the code from EPR to make it rescan- or the file from the 8MB STEREO unit) and put in the preprogrammed IC, as described above.

So basically you have to evaluate and compare to the memory expansion guide:
1) How many expansion boards do I have, are they fully populated? if they are, you likely cant expand… if not fully populated with RAM, next step..

2) Confirm which PALs you have already installed, and with the newly available PAL files - can you get a PAL set which allows you to expand to a higher RAM level filling up the expansion board(s)?

- if so
get RAM,  install RAM (adding RAM without changing EEPROM or doing anything with the PALs should harm nothing at this point….
get EEPROM (I’d get spare EEPROMS, they are cheap ICs) and socket it, install EEPROM with original data and verify operation (this is your failback point, just in case)
get file, program spare EEPROM with max memory EEPROM
get PALs / GALS programmed in the appropriate set per the guide, install them, and swap out EEPROM to max memory EEPROM
power up and see if SUCCESS! 


Hope that is helpful….

Please note we don’t have the STEREO PAL. IP457, so if a unit is not stereo, we can’t make it into stereo- so you could add memory, but it would see it’s not stereo and revert to MONO (from my understanding).
Someone can correct me on that last if I am wrong...

-T



On Jan 19, 2016, at 10:11 AM, Graham Hunter <graham.hunter@...> wrote:

Ted,

Please forgive me for asking this, but are these files the ones we'd need to upgrade the memory without needing the code process?

Thanks,

Graham



[Non-text portions of this message have been removed]

I have an emax ii rack with 4mb and the expansion board. I have 32 empty slots. If I were to buy the 32 chips of KM41C464P-8 from alibaba or somewhere and install them, what is the next steps to take?
Thanks
Tom

Please look in the archive.
I posted this explanation just within the last couple of days.


As to the RAM- 
The -8 or -10 / -12 / -15 is the speed (80, 100, 120, 150ns)

Looking on UTSOURCE I can’t find a -8, it needs to match the other IC’s for speed….. but I’m not seeing that speed.
You might have to do an RFQ with a couple of the parts suppliers in Hong Kong / China


-T


On Jan 26, 2016, at 10:47 AM, schtom83318@... [emax] <emax@yahoogroups.com> wrote:

I have an emax ii rack with 4mb and the expansion board. I have 32 empty slots. If I were to buy the 32 chips of KM41C464P-8 from alibaba or somewhere and install them, what is the next steps to take?
Thanks
Tom





[Non-text portions of this message have been removed]

Yeah mine are showing the -8. I see them on eBay and alibaba. So those chips don't matter except for the speed being the same?

IF it’s a semiconductor reseller, you may want to contact them off the auction, as you need a large quantity, and that can lower the price.

But I assume you know that….

-T


On Jan 26, 2016, at 12:54 PM, schtom83318@... [emax] <emax@yahoogroups.com> wrote:

Yeah mine are showing the -8. I see them on eBay and alibaba. So those chips don't matter except for the speed being the same?





[Non-text portions of this message have been removed]

It would be best to get all the same brand and part chips if possible….


On Jan 26, 2016, at 12:54 PM, schtom83318@... [emax] <emax@yahoogroups.com> wrote:

Yeah mine are showing the -8. I see them on eBay and alibaba. So those chips don't matter except for the speed being the same?





[Non-text portions of this message have been removed]

I think you misunderstand what Scrambled Megs IS.

Scrambled Megs was specifically made available for the purpose of if the Emax 2 LOST it’s memory config, and you wanted to get it back.
And if you paid for 8MB upgrade, you certainly would want it back…..

Scrambled Megs only works if:
1) The memory chips are in place
2) The correct PALs are in place.

PALs are used as locking chips.
Emu sends a specific set of PALs with the memory upgrade to lock you into that amount of memory.

You can put in all the memory you want, and pay for a scrambled megs- but if the PALs are not the correct ones- the added memory will never be seen.

Otherwise, everyone would have bought a 2MB kit, and just got the DRAM themselves and updated to 8MB

Hopefully you see where I went with this.

-T


PS-  I  haven’t made any chips, these binaries came from E-mu, just in a proprietary format which I had to convert to a usable format….





On Jan 26, 2016, at 1:34 PM, schtom83318@... [emax] <emax@yahoogroups.com> wrote:

No I appreciate your help.  So what happened to the Scrambled Megs way of upgrading with a code or is it better to put the chips in that you have made.  I guess that would require me to buy a ic programmer?  I just want my dm (AW) samples to play.  





[Non-text portions of this message have been removed]

Tom-

I would suggest first that you verify the PALs that are available in the file (and looking at the guide, and the PALs currently installed on your board) are what is needed for your specific configuration possibility (either 6MB or 8MB) combination.
If you find the combination of PALs will do it - then buy memory and move on from there.


-Ted


On Jan 26, 2016, at 5:15 PM, schtom83318@... [emax] <emax@yahoogroups.com> wrote:

Awesome.  Thanks for the clarification.  So I'll look at getting some memory chips and then I look into figuring out how to make the pals with your post.  I appreciate it.


thanks
Tom





[Non-text portions of this message have been removed]

Great. Thanks.

Per page 2- It looks like since you have 4MB you don’t need any PALs, just the scrambled megs or an eeprom programmed with 8MB stereo already detected to add more memory (and the memory itself of course).

The empty sockets on the main board are not used.
The empty expansion board sockets (which are numbered )  should correspond to details in the memory guide page 6 and 7.
in other words- those numbered sockets which are empty should match the instructions in the memory guide for what should be filled.

Per page 1, the memory per 2MB is
Qty 16    of  44256     256K x 4 DRAM’s
 Whatever the memory speed of the chips -8, -10, or or faster.

For example, I would expect if you had some -8 on the expansion, you could put -8 or -7

Faster won’t cause you a problem, but slower could.


-T


On Jan 27, 2016, at 12:26 PM, schtom83318@... [emax] <emax@yahoogroups.com> wrote:

The PALs I have are:


IP431AEMU3593 in IC54
IP432AEMU4393 in IC55
IP433AEMU4193 in IC56
IP430AEMU2294 in IC57

thanks,
Tom





[Non-text portions of this message have been removed]

Hi all,

I have a 4MB Emax 2 and bought the ram chips to install. It appeared that I had all the PALs as I had the expansion board already running at 4MB without a problem. I then purchased an EEPROM programmer and managed to download the correct 8MB file for the EEPROM. 

I socketed the EEPROM and then programmed the necessary file to the EEPROM. All seemed well and it checked out as the 8MB version when I checked the memory. So far so good. Then it all went wrong. Once I switched off the unit it failed to boot up again. The firmware appeared to be confused. Fortunately I had kept the original 4MB EEPROM, however I had cut the legs in order to reduce chance of damaging the PCB whilst socketing this chip. I managed to solder it to a prototype chip holder and downloaded it's contents. I then copied this onto a brand new chip and inserted it into the socket. Much to my delight the unit came back to life although only finding the original 4MB even though the extra RAM was still installed. 

To me it appeared that what was happening here is that somewhere in the keyboard a record of what system was last booted was being held. I am not sure how or why this was possible, but it appeared that if the system was not updated via scrambled megs, it would know that the EEPROM was switched and refuse to boot. Maybe some sort of checksum was stored and this was detected on startup. Anyway it didn't work for me but was a lot of fun trying and I learnt quite a bit in the process. I hope this is useful to anyone else trying to do this. 

Regards

Tony

Sent from my iPad

On 27 Jan 2016, at 23:04, "Ted Summers djtbs1@... [emax]" <emax@yahoogroups.com> wrote:

> Per page 2- It looks like since you have 4MB you don’t need any PALs, just the scrambled megs or an eeprom programmed with 8MB stereo already detected to add more memory (and the memory itself of course).
> 
> The empty sockets on the main board are not used.
> The empty expansion board sockets (which are numbered ) should correspond to details in the memory guide page 6 and 7.
> in other words- those numbered sockets which are empty should match the instructions in the memory guide for what should be filled.
> 
> Per page 1, the memory per 2MB is
> Qty 16 of 44256 256K x 4 DRAM’s
> Whatever the memory speed of the chips -8, -10, or or faster.
> 
> For example, I would expect if you had some -8 on the expansion, you could put -8 or -7
> 
> Faster won’t cause you a problem, but slower could.
> 
> -T
> 
> On Jan 27, 2016, at 12:26 PM, schtom83318@... [emax] <emax@yahoogroups.com> wrote:
> 
> The PALs I have are:
> 
> IP431AEMU3593 in IC54
> IP432AEMU4393 in IC55
> IP433AEMU4193 in IC56
> IP430AEMU2294 in IC57
> 
> thanks,
> Tom
> 
> [Non-text portions of this message have been removed]
> 
>

Tony, I believe it could be possible,  a configuration back up may also be stored in the os if you booted from the hard 
drive 
Sent from Yahoo Mail on Android 
 
  On Wed, Jan 27, 2016 at 7:36 PM, tonykirby100@... [emax]<emax@yahoogroups.com> wrote:       

Hi all,
I have a 4MB Emax 2 and bought the ram chips to install. It appeared that I had all the PALs as I had the expansion board already running at 4MB without a problem. I then purchased an EEPROM programmer and managed to download the correct 8MB file for the EEPROM. 
I socketed the EEPROM and then programmed the necessary file to the EEPROM. All seemed well and it checked out as the 8MB version when I checked the memory. So far so good. Then it all went wrong. Once I switched off the unit it failed to boot up again. The firmware appeared to be confused. Fortunately I had kept the original 4MB EEPROM, however I had cut the legs in order to reduce chance of damaging the PCB whilst socketing this chip. I managed to solder it to a prototype chip holder and downloaded it's contents. I then copied this onto a brand new chip and inserted it into the socket. Much to my delight the unit came back to life although only finding the original 4MB even though the extra RAM was still installed. 
To me it appeared that what was happening here is that somewhere in the keyboard a record of what system was last booted was being held. I am not sure how or why this was possible, but it appeared that if the system was not updated via scrambled megs, it would know that the EEPROM was switched and refuse to boot. Maybe some sort of checksum was stored and this was detected on startup. Anyway it didn't work for me but was a lot of fun trying and I learnt quite a bit in the process. I hope this is useful to anyone else trying to do this. 
Regards
Tony

Sent from my iPad
On 27 Jan 2016, at 23:04, "Ted Summers djtbs1@... [emax]" <emax@yahoogroups.com> wrote:


    
Per page 2- It looks like since you have 4MB you don’t need any PALs, just the scrambled megs or an eeprom programmed with 8MB stereo already detected to add more memory (and the memory itself of course).

The empty sockets on the main board are not used.
The empty expansion board sockets (which are numbered ) should correspond to details in the memory guide page 6 and 7.
in other words- those numbered sockets which are empty should match the instructions in the memory guide for what should be filled.

Per page 1, the memory per 2MB is
Qty 16 of 44256 256K x 4 DRAM’s
 Whatever the memory speed of the chips -8, -10, or or faster.

For example, I would expect if you had some -8 on the expansion, you could put -8 or -7

Faster won’t cause you a problem, but slower could.

-T

On Jan 27, 2016, at 12:26 PM, schtom83318@... [emax] <emax@yahoogroups.com> wrote:

The PALs I have are:

IP431AEMU3593 in IC54
IP432AEMU4393 in IC55
IP433AEMU4193 in IC56
IP430AEMU2294 in IC57

thanks,
Tom

[Non-text portions of this message have been removed]

I wonder if you got to the 8MB point and then did a copy software to floppy. boot from floppy (verify 8M) and wrote that to the hard disk, if that would save the 8MB size?

Just a thought that may be worth trying.
The fact that you DID get it to see 8MB at least for a moment is promising….. but maybe Gary is right…there may be a config backup held on the hard drive in case something happens to the EEPROM IC….hmmm.

-T




On Jan 27, 2016, at 6:23 PM, Gary Doty djrgary@... [emax] <emax@yahoogroups.com> wrote:

Tony, I believe it could be possible,  a configuration back up may also be stored in the os if you booted from the hard 
drive 

Sent from Yahoo Mail on Android <https://overview.mail.yahoo.com/mobile/?.src=Android>
 

Hi all,

I have a 4MB Emax 2 and bought the ram chips to install. It appeared that I had all the PALs as I had the expansion board already running at 4MB without a problem. I then purchased an EEPROM programmer and managed to download the correct 8MB file for the EEPROM. 

I socketed the EEPROM and then programmed the necessary file to the EEPROM. All seemed well and it checked out as the 8MB version when I checked the memory. So far so good. Then it all went wrong. Once I switched off the unit it failed to boot up again. The firmware appeared to be confused. Fortunately I had kept the original 4MB EEPROM, however I had cut the legs in order to reduce chance of damaging the PCB whilst socketing this chip. I managed to solder it to a prototype chip holder and downloaded it's contents. I then copied this onto a brand new chip and inserted it into the socket. Much to my delight the unit came back to life although only finding the original 4MB even though the extra RAM was still installed. 

To me it appeared that what was happening here is that somewhere in the keyboard a record of what system was last booted was being held. I am not sure how or why this was possible, but it appeared that if the system was not updated via scrambled megs, it would know that the EEPROM was switched and refuse to boot. Maybe some sort of checksum was stored and this was detected on startup. Anyway it didn't work for me but was a lot of fun trying and I learnt quite a bit in the process. I hope this is useful to anyone else trying to do this. 

Regards

Tony

Sent from my iPad

On 27 Jan 2016, at 23:04, "Ted Summers  <>djtbs1@gmail.com <mailto:djtbs1@...> [emax]" < <>emax@yahoogroups.com <mailto:emax@yahoogroups.com>> wrote:

>  
> Per page 2- It looks like since you have 4MB you don’t need any PALs, just the scrambled megs or an eeprom programmed with 8MB stereo already detected to add more memory (and the memory itself of course).
> 
> The empty sockets on the main board are not used.
> The empty expansion board sockets (which are numbered ) should correspond to details in the memory guide page 6 and 7.
> in other words- those numbered sockets which are empty should match the instructions in the memory guide for what should be filled.
> 
> Per page 1, the memory per 2MB is
> Qty 16 of 44256 256K x 4 DRAM’s
> Whatever the memory speed of the chips -8, -10, or or faster.
> 
> For example, I would expect if you had some -8 on the expansion, you could put -8 or -7
> 
> Faster won’t cause you a problem, but slower could.
> 
> -T
> 
> On Jan 27, 2016, at 12:26 PM,  <>schtom83318@... <mailto:schtom83318@...> [emax] < <>emax@yahoogroups.com <mailto:emax@yahoogroups.com>> wrote:
> 
> The PALs I have are:
> 
> IP431AEMU3593 in IC54
> IP432AEMU4393 in IC55
> IP433AEMU4193 in IC56
> IP430AEMU2294 in IC57
> 
> thanks,
> Tom
> 
> [Non-text portions of this message have been removed]
> 
> 






[Non-text portions of this message have been removed]

Just to clarify my Emax 2 does not have a hard drive fitted. I have a brand new hard drive for it but never installed it due to the noise it generates. Yes they are noisy even when brand new! ;o) I just use the SCSI linked zip disks which I find easy when transferring samples via EMXP. 

In my view something is wrote to the EEPROM at some point whilst the machine is powered up. It may be that this is then checked again at the next power up to check it is the same. This may be over complicating it, however if EMU went to the trouble of making self destruct floppy disks. (obviously not literally) then to write some sort of a checksum code into the EEPROM would not have been beyond the realms of possibility. It may be that it checks the amount of memory and writes a code. If the memory has changed the code would change. Therefore there would be a mismatch of codes at the next power up? Just a theory really but that may explain why it worked until next power up. 

Regards

Tony

Sent from my iPad

On 28 Jan 2016, at 05:06, "Ted Summers djtbs1@... [emax]" <emax@yahoogroups.com> wrote:

> I wonder if you got to the 8MB point and then did a copy software to floppy. boot from floppy (verify 8M) and wrote that to the hard disk, if that would save the 8MB size?
> 
> Just a thought that may be worth trying.
> The fact that you DID get it to see 8MB at least for a moment is promising….. but maybe Gary is right…there may be a config backup held on the hard drive in case something happens to the EEPROM IC….hmmm.
> 
> -T
> 
> On Jan 27, 2016, at 6:23 PM, Gary Doty djrgary@... [emax] <emax@yahoogroups.com> wrote:
> 
> Tony, I believe it could be possible, a configuration back up may also be stored in the os if you booted from the hard 
> drive 
> 
> Sent from Yahoo Mail on Android <https://overview.mail.yahoo.com/mobile/?.src=Android>
> 
> 
> Hi all,
> 
> I have a 4MB Emax 2 and bought the ram chips to install. It appeared that I had all the PALs as I had the expansion board already running at 4MB without a problem. I then purchased an EEPROM programmer and managed to download the correct 8MB file for the EEPROM. 
> 
> I socketed the EEPROM and then programmed the necessary file to the EEPROM. All seemed well and it checked out as the 8MB version when I checked the memory. So far so good. Then it all went wrong. Once I switched off the unit it failed to boot up again. The firmware appeared to be confused. Fortunately I had kept the original 4MB EEPROM, however I had cut the legs in order to reduce chance of damaging the PCB whilst socketing this chip. I managed to solder it to a prototype chip holder and downloaded it's contents. I then copied this onto a brand new chip and inserted it into the socket. Much to my delight the unit came back to life although only finding the original 4MB even though the extra RAM was still installed. 
> 
> To me it appeared that what was happening here is that somewhere in the keyboard a record of what system was last booted was being held. I am not sure how or why this was possible, but it appeared that if the system was not updated via scrambled megs, it would know that the EEPROM was switched and refuse to boot. Maybe some sort of checksum was stored and this was detected on startup. Anyway it didn't work for me but was a lot of fun trying and I learnt quite a bit in the process. I hope this is useful to anyone else trying to do this. 
> 
> Regards
> 
> Tony
> 
> Sent from my iPad
> 
> On 27 Jan 2016, at 23:04, "Ted Summers <>djtbs1@... <mailto:djtbs1@...> [emax]" < <>emax@yahoogroups.com <mailto:emax@yahoogroups.com>> wrote:
> 
> > 
> > Per page 2- It looks like since you have 4MB you don’t need any PALs, just the scrambled megs or an eeprom programmed with 8MB stereo already detected to add more memory (and the memory itself of course).
> > 
> > The empty sockets on the main board are not used.
> > The empty expansion board sockets (which are numbered ) should correspond to details in the memory guide page 6 and 7.
> > in other words- those numbered sockets which are empty should match the instructions in the memory guide for what should be filled.
> > 
> > Per page 1, the memory per 2MB is
> > Qty 16 of 44256 256K x 4 DRAM’s
> > Whatever the memory speed of the chips -8, -10, or or faster.
> > 
> > For example, I would expect if you had some -8 on the expansion, you could put -8 or -7
> > 
> > Faster won’t cause you a problem, but slower could.
> > 
> > -T
> > 
> > On Jan 27, 2016, at 12:26 PM, <>schtom83318@... <mailto:schtom83318@...> [emax] < <>emax@yahoogroups.com <mailto:emax@yahoogroups.com>> wrote:
> > 
> > The PALs I have are:
> > 
> > IP431AEMU3593 in IC54
> > IP432AEMU4393 in IC55
> > IP433AEMU4193 in IC56
> > IP430AEMU2294 in IC57
> > 
> > thanks,
> > Tom
> > 
> > [Non-text portions of this message have been removed]
> > 
> > 
> 
> [Non-text portions of this message have been removed]
> 
>

Hi Tom,
I bought them from ebay and from memory they were from a seller in the USA. It was a little while ago now. I can check the chip numbers for you when I get a minute but am not at home just now. They were all new old stock and are actually the same as were used in vintage computers of the time. 
Have you got all the other things you need to do the upgrade or are you going to purchase the scrambled megs code? 
Regards
Tony

      From: "schtom83318@... [emax]" <emax@yahoogroups.com>
 To: emax@yahoogroups.com 
 Sent: Thursday, 4 February 2016, 15:29
 Subject: Re: [emax] Emax2 Memory Files
   
    Tony,
Can you tell me what memory chips you bought and where you got them?  I need to by 32 of them to get mine to 8mb.
thanks,Tom  #yiv1669300320 #yiv1669300320 -- #yiv1669300320ygrp-mkp {border:1px solid #d8d8d8;font-family:Arial;margin:10px 0;padding:0 10px;}#yiv1669300320 #yiv1669300320ygrp-mkp hr {border:1px solid #d8d8d8;}#yiv1669300320 #yiv1669300320ygrp-mkp #yiv1669300320hd {color:#628c2a;font-size:85%;font-weight:700;line-height:122%;margin:10px 0;}#yiv1669300320 #yiv1669300320ygrp-mkp #yiv1669300320ads {margin-bottom:10px;}#yiv1669300320 #yiv1669300320ygrp-mkp .yiv1669300320ad {padding:0 0;}#yiv1669300320 #yiv1669300320ygrp-mkp .yiv1669300320ad p {margin:0;}#yiv1669300320 #yiv1669300320ygrp-mkp .yiv1669300320ad a {color:#0000ff;text-decoration:none;}#yiv1669300320 #yiv1669300320ygrp-sponsor #yiv1669300320ygrp-lc {font-family:Arial;}#yiv1669300320 #yiv1669300320ygrp-sponsor #yiv1669300320ygrp-lc #yiv1669300320hd {margin:10px 0px;font-weight:700;font-size:78%;line-height:122%;}#yiv1669300320 #yiv1669300320ygrp-sponsor #yiv1669300320ygrp-lc .yiv1669300320ad {margin-bottom:10px;padding:0 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You’re looking at the wrong item(s).
Emax 1 and Emax 2 don’t have a circuit to flash / update the main EPROMS.

In addition, parameters like that aren’t stored in the boot / system EPROMS, they are held in the 9306 Parameter EEPROM IC 24.

Kind of like the PRAM in a MAC, but this you don’t ordinarily want to unset. When it becomes unset, then it’s Scrambled Megs…like what you describe.



-T


On Feb 6, 2016, at 5:09 PM, midipuppies@... [emax] <emax@yahoogroups.com> wrote:

I'm working on three 8MB Stereo machines that have lost their memory size allocation.

I have one working 8MB Stereo unit that I copied the EPROMS from (IC19 and IC20) and wrote those binaries to the other machines.
They still give the memory size error message, and show incorrect memory sizes, so something else has been overwritten besides the EPROMS.

I wonder if its stored somewhere in the O.S. as well. Since the HD's are not working on the broken machines, I'm using a floppy to boot them. I have no idea where I got that floppy, as I've owned pretty much every configuration of Emax at some point, but that would explain why this isn't working.






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OK-  It’s not a question, or a maybe…..you just CONFIRMED with your description that you have Scrambled Megs, because the 9306 IC24 lost all parameter data (ie- the calibration, memory size are all held in there.
If it was me, I would change out that 9306 so you know it’s a new IC which shouldn’t lose it’s programming.

There is some sort of checksum generated and written to the 9306 during the memory upgrade procedure.
If you read the Scrambled Megs procedure- you basically get a challenge code from your Emax2 which you then provided to E-Mu (now to EPR), and they give you the response code (kind of like the old copy protection on many video games back in the 80s - you had to have the manual or you couldn’t play the game as there were many challenge codes contained in the manual).

As far as EPR- they got the Scrambled Megs recovery system directly from E-mu to provide the service as E-mu didn’t want to do it anymore…besides that they are E-mu factory authorized repair.
But hey, do what you want.

-T


On Feb 7, 2016, at 9:44 AM, midipuppies@mac.com [emax] <emax@yahoogroups.com> wrote:

Never mind my question about the 8MB image, it is on here. One of these machines has the EEPROM socketed, so I was able to read/write to it.


I still can't get the machine to recognize 8MB. Looks like 4MB. Keep in mind that this is/was a factory 8MB stereo keyboard, so no PALs or RAM have been changed around. I still think there's more to it than that EEPROM. 

I don't think I want to chance the $60 or whatever it is at EPR.

So to sum up what I have tried here:

This particular 8MB Stereo Emax II one day displayed a "Warning Need To Recalibrate!" message. After that, the memory size error followed, and the rest is history.

I have now reprogrammed both EPROMS with known good images, checked all connections to daughter board etc, and most recently erased and re-imaged the EEPROM with the 8MB image from this group.

If I am missing something, please let me know. 





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In response:
"I've never seen an IC kind of work.”

I would hazard to say you’ve never worked in electronics repair industry then. 
In 16yrs experience I certainly have. Thats where the term “flaky” came from. Intermittent and often not easily explainable faults…
NTE had a reputation for making semiconductors in the 80s and 90s that would easily fail as their new parts spec didn’t hold up over time or was lower than the OEM part, even though their cross ref said it was an equivalent part.
If there was any way to get another brand quickly and NOT use NTE, we would do it.
I can’t say whether that’s true now. But that is why I buy from mouser and digi-key and avoid buying from the local shop.
Much as I like the staff there, NTE is not my goto brand and that’s what they stock… cuz it’s cheap.

But remember that there is a MTBF # hours on any part.
EPROMS 20yrs old can lose their programming and fail. It’s not unheard of…. In point of fact- 10 yr old EPROMs in Pinball machines could fail if the AC fan in the cabinet failed and the board ran hot all the time. As heat over time affects semiconductors.
This is probably less prevalent today, as electronics tech is much more robust than it was 20-30 yrs ago.

One or two people copied the Emax parameter EPROM and put in the copy into their machine and it worked.
But I tried it some time back and it didn’t work for me.
So I don’t think it’s as simple as all that.
Maybe the challenge code for some batches of machines was the same, so if you had two machines in a short serial number sequence or maybe the exact same rev EPROM, they would have the same challenge code, but one with different rev EPROM and or serial grouping would end up with a different code.

There isn’t enough data available to make a determination on that. 


-T





On Feb 7, 2016, at 12:42 PM, midipuppies@... [emax] <emax@yahoogroups.com> wrote:

I fully understand the adjust features element. I upgraded my original Emax II over the phone with E-mu in 1992.


I was under the impression that inserting the 8MB binary into that EEPROM is the same as what the keyboard would do if the correct adjust features code was put in. Is it possible that the chip itself is not working properly? I've never seen an IC kind of work.





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