Kawai SX-240 Tauntek Modded Firmware on two new Atmel ROMs OS upgrade kit ROMs SX240

Brand New
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10+ in stock
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Night Crew Digital Synth Repair Shop
Cambridge, MA, United States
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About This Listing

You will receive two BRAND NEW chips - never before used, new manufactures, will last much longer than reprogrammed 30, 40 year old chips. These are new never before used chips made by Atmel, an American company. THEY WILL SHIP "SANDWICHED" TOGETHER EXACTLY LIKE IN THE PICTURE, IN AN ANTI STATIC BAG, WITH INSTALLATION INSTRUCTIONS.
Part of the proceeds from your purchase are sent to Tauntek, the developer of this firmware.

  Someone recently suggested that adding CC support to the Kawai SX-240 was a worthwhile project, despite the relatively small number of units sold. Adding sysex patch save/restore also seemed like a good idea. The SX-240 uses two 8031 CPU's. The "master" handles patch and sequencer RAM and selection, keybed scanning, and the front panel switches and display.   The "slave" handles the sound generation DCO's and analog circuitry. Each 8031 contains one serial port, with rx and tx, both at the same baud rate.   MIDI input is fed to rx of the master CPU. The tx of the master is used to feed control messages to the slave CPU's rx input (at the rather slow MIDI baud rate). MIDI output must come from the slave CPU's tx, as the master's tx is taken. So one problem was how to get sysex dump data from the master to MIDI out.

    Anyway, after disassembling both code EPROMs and spending lots of time figuring out what did what, running Verilog simulations, scratching my head, etc, I started adding code and have added sysex patch and sequence save/restore, CC parameter change support for both upper and lower voices, MIDI note on/off for the lower voices, (upper voices were already supported) and non-volatile storage and power-up display of selected MIDI channel. I have programmed a Peavey PC-1600x to control both upper and lower voice parameters using CC's, for testing. I decided not to update the front panel display to reflect incoming CC changes.   This would have added complication, as a CC might be changing a lower parameter when the panel was selecting the upper ones for editing.   I wanted CC response to be as fast as possible.   Also, it seemed safer to simply change the parameter, to avoid getting the panel out of sync with the variables that control it.  

      Some details concerning program changes:

  If the upper voices are selected by the front panel and a program change occurs, either using the switches, or with a MIDI command, the lower program that was loaded when the new upper program was last saved will be loaded automatically. This is part of the original firmware, and can be disabled by holding the "Bank C" switch at power-up. (I don't see any mention of this feature or how to disable it in the owner's manual) Also, I have not changed the MIDI code that processes program changes.   As a result, the selected new program will be applied to either the upper or lower voices, depending on which is currently selected on the front panel. MIDI program changes are only detected on the MIDI channel used to send notes or parameter changes to the upper voices.   I may look at changing the MIDI program change firmware to change upper or lower based on the MIDI channel, but have not done so yet."

The original chips use unfavorable / problematic terms for designation. As a result your chips you receive will have abbreviations as pictured.

Product Specs

ConditionBrand New (New)
Brand New items are sold by an authorized dealer or original builder and include all original packaging.learn more

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