Owners of the original 1998 E-mu Audity 2000 ROMpler with version 1.00 firmware have never been able to make use of E-mu’s MIDI based firmware update mechanism. E-mu did add that feature to the version 2.00 firmware, but if you have a version 1.00 your only option was to send your box off to an authorized service center. This hasn’t been possible for some 20 years, though…
There was, however, a big breakthrough a few years ago, when following the estate sale of a synth repair tech I was able to source both an Audity 2000 service manual and the holy grail–the official upgrade kit used by those service centers!
Until that point there had been no publically available information about what the upgrade process actually entailed. It turned out that the process required both a special boot ROM with the programming code and a Sound Flash SIMM with that containing the OS firmware image. The boot ROM is fitted in the usually empty PLCC32 socket on the Audity 2000 main board, and the Flash SIMM replaces the AP530-02 sample ROM. A jumper (W1) on the board tells the unit to boot from the PLCC socket instead of from the onboard flash memory, and then, when you power up, this alternate boot ROM reads the firmware image through the G.chip and updates the flash memory.
My thoughts, of course, turned to how I might replicate this upgrade kit. The Sound Flash SIMMs are very rare, and very expensive. While I already have experience in reproducing clone SIMMs, this would not be a cost effective upgrade method.
While I mulled over how to solve this problem I started doing what I could to reverse engineer the Audity hardware and firmware, as well as the special boot ROM from the upgrade kit. Eventually I was able to learn enough about the hardware to be able write my own ROM that was able to read the front panel buttons, write to the LCD and LEDs, and also write to the MIDI port. Being able to write to the MIDI port gave me the ability to dump the existing flash memory contents without having to desolder the ICs.
The “Eureka!” moment was realising that with more efficient compression algorithms now available than back in 1998 it was probably feasible to compress the entire 2MB firmware image into the 512kB boot ROM, and do away with the expensive Sound Flash SIMM. I tried out various compression algorithms, eventually settling on the XZ algorithm for which a library especially designed for low-memory embedded systems already existed.
After a few false starts, I’ve now been successful. What is presented here following several months of additional testing is a standalone boot image that can be programmed into an AM29F040B PLCC32 NOR Flash and will upgrade the firmware to 2.01–the final E-mu release. Both the update code and the compressed firmware come in at just under 400kB–easily fitting in the 512kB limit supported by the PLCC32 socket.
This is being made freely available, but the update code is copyrighted by myself subject to a no-commercial-exploitation clause. Pre-programmed ROMs may be distributed for no more than GBP 5.00 and reasonable postage costs. See LICENSE.txt in the zip file.
Please note that currently the upgrade ROM only supports units using either Intel or Micro 28F800 flash memory ICs. The Audity main board also supports AMD 8 Mbit flash ICs but I’ve never one seen one in the wild so that I can confirm the exact part number and hence from that its programming algorithm. The upgrade ROM has a menu to report the chip identifiers and checks these before proceeding. If you have a unit with AMD flash ICs please let me know what they are!
Operating instructions for the upgrade are in the zip file available below. Enjoy!
Download: audity-update-0.3.zip
