Emax

The 9306 EEPROM also has a bit (or bits) that determine whether the Emax II has stereo or 
mono sampling capability. So you need to match that as well as the memory configuration 
bits for each binary image. The Emax II EEPROM should have the SCSI boot ID, headroom 
adjust, and wheel and slider calibrations as well, but they are easily re-programmable once 
the new EEPROM is installed.

The main problem with reading the EEPROM in a device programmer is it first needs to be 
desoldered from the main board. This should not be a huge problem but does risk damage 
or corruption of the EPROM data, so take care if you want to try this! Another alternative is 
just to probe the EEPROM clock and data pins during boot up with a logic analyzer and 
manually program the data that is read into a fresh EEPROM. 

Anyone planning to change the EEPROM on their Emax II will need to desolder their old 
EEPROM and at that stage it would be a good idea to install a socket so the new EEPROM 
can be easily installed and later removed if necessary.

I was actually going to do something like this last year and I got a tube of NOS 9306 
EEPROMs but my device programmer would not write to them for some reason. I could 
read from them and the analyzer indicated all the right timings were being met for both 
read and write operations but they would not store the data. If you find a cheap source 
of 9306 I am interested in some too.

/Tristan

Sunday, November 8, 2009, 4:02:20 PM, you wrote:

>
  
That makes more sense,I have never heard of the 27C64 being reprogrammed in circuit. If anyone has a 6 or 8 meg machine, and can read the 
eeprom, send me the .bin file, I have a spare 9306 I can reprogram, to test in my machine. If it works, I'll see if I can get a bunch of eeproms, and 
program them for 4/6/8 meg machines.

--- In emax@yahoogroups.com, "esynthesist" <esynthesist@...> wrote:
>
> I thought these configurations parameters (memory size, calibration settings, ...) are written to the 9306 eeprom instead of the two normal eproms. 
So I guess the eeproms must be reprogrammed, not the eproms. Am I wrong ?
> 
> ///E-Synthesist