Alesis DataDisk Refurb

Alesis DataDisk

Overview I picked up an Alesis DataDisk in May 2020 for £25, so I  can store and retrieve SysEx data from my hardware synths rather than having to power the computer on and use software. The 1U rack  connects up to my MIDI hub and uses a 3.5″ floppy diskette to store 800 KB of data.

The DataDisk was launched in late 1989 at a rather steep £299, but was quite popular for musicians touring and wanting to restore all their patches across multiple synthesizers. In the studio an Atari 520 was more effective with the right software, and that is what I used in 1990. The high cost of the DataDisk put me off buying one, until now!

Recap Complete

Refurb The DataDisk looks like an x-hire unit; connections have been hot glued and there is lots of wear to the casing and buttons. All the casing screws needed replacing with new ones, and the LCD mount has broken. It also needed a 9V external power supply, which is the same as used with the Quadraverb with a 4-pin plug, bought from eBay. I replaced the 16×2 LCD with a new OLED display and glued the mounting back together (two parts were broken) and unglued the ribbon cable.

The original LCD is 16×2 characters with 14 pins, here is the Quadraverb schematic which uses the same LCD. Note that there is no contrast potentiometer but a fixed contrast voltage of -0.6V at Pin 3. Pin 2 is the main GND connection and pin 5 is set low to enable write to the display. Pin 4 is the mode control for either data or an instruction and Pin 1 the +5V.

New OLED Display

I have fitted a new blue character OLED display, the Winstar WEH001602DBPP5BN which is available from Rapid Electronics. It has the same 14-pin connector and PCB size and is a drop in fit as Pin 3 is Not Connected. There is no contrast needed on an OLED display. To be extra safe the cable to pin 3 can be cut or the diode and resistor removed from the main PCB.  The new OLED fits on the same plastic mount but is thinner than the original and therefore the front of the OLED is set back 5mm from the bezel.

The three large 4700uF 25V axial electrolytic capacitors were replaced in the power supply along with 3x 4.7uF 50V and one 100uF 16V capacitor. The OS is 2.10 and does not need upgrading. There was no floppy drive in the unit, so I tried my spare diskette drive but it was not compatible, and I don’t want to hack one. There is not much space in the case left free for the diskette cable at the rear of the drive but there is plenty of room for a Gotek drive.

In the Studio I use the DataDisk with my MIDI polysynths to save and restore patch banks; the Wavestation, OB-6, XTk and D-05 using the iConnectivity MIO as the MIDI hub. All these synthesizers can initiate a SysEx dump of patch data, which the DataDisk simply listens for and then reads the data stream and puts it on the diskette. The DataDisk cannot handshake with my MKS-80, so I use the my MC-300 with the MFB-500 Bulk Librarian software which works perfectly.

The DataDisk can also initiate a SysEx Dump request, provided the Manufacturer and Device ID’s are known by the DataDisk software. You simply select these two parameters from the display, however the OS has not had an update for 30 years, and there is no free form editing of the Device ID which would be very useful – see below.

Storage Limitations the DataDisk is limited to 764 KB of patch data storage and a maximum of 53 files. In 1991 the storage limitation was not significant (a D-50 Patch Bank is 36 KB, the Wavestation is 64 KB and the XTk is 70 KB) but today synthesizers can generate much larger SysEx files, such as the OB-6 at 576 KB! Large SysEx files generated by fast PC’s may overwhelm the old synth processors, so I use pauses when sending to the Wavestation. The DataDisk uses a slow processor my today’s standards and therefore should not overwhelm the synths with SysEx, but maybe new synths will overwhelm the DataDisk, we will see!

Gotek Drive Setup It is easy to fit a Gotek drive and here is the setup, you need to customize the firmware:

  • Track Type: MFM, Two sides floppy, GAP3 auto GAP3
  • 80 Tracks, Sector IC Start: 1, Sectors size: 1024, 5 sectors per track
  • RPM: 300,  Bitrate: 250,000, Total sector: 800, Total size: 819200
  • HFE file interface mode: Auto (IBM PC 720kB)
  • Shugart device
  • Hardware Jumper settings: MO and ID0

File Naming The DataDisk reads the inbound MIDI SysEx message and extracts both the Manufacturer and Product ID’s. The Manufacturer ID is either one or three bytes with the DataDisk capable of recognizing the big manufacturers from the 1980’s using a single byte;

  • Sequential 01H
  • Roland is 41H
  • Korg is 42H
  • Waldorf is 3EH
  • Behringer is 00H 20H 32H

The DataDisk is over 25 years old and therefore has not kept up with more recently issued manufacturer ID’s in its ROM based look up table> If the manufacturer ID is not recognized the default is xxH. The Device ID’s are also a problem, as these single byte numbers correspond to a product name which the manufacturer has determined. Once again a look up table is needed and the DataDisk is stuck in 1991!

The DataDisk names the files with 3 set of characters:

  • XXXXXX is the manufacturers name
  • YYYYYY is the product model name
  • ZZZZZZZZ is the name of the file and can be edited

I may extract the ROM code and do an update if there is room in the ROM.

SQ Display

SQ Upgrade Alesis updated the DataDisk to a new SQ model in the Autumn of 1990 with a new firmware version 2.0 (and higher price of £349). SQ stands for SeQuencer as the upgrade enables the DataDisk to record and playback MIDI sequences, with the usual store and retrieval to floppy disk using DS/DD diskettes. MIDI sequences from a keyboard or a MIDI sequencer (like my Roland MC-300) can be recorded and then played back locked to the MIDI clock.

Sequence recording also allows SysEx to be recorded and played back with pauses, which is often how long data streams are managed.  MIDI data is recorded and played back in real time from the diskette with no copying to internal RAM, so there is no lag between hitting MIDI start and the notes being generated, this made the DataDisk as an attractive MIDI song player for live bands.

Buttons These are touch sensitive (multi-speed) versions and not the usual single click momentary buttons, therefore the best I can do is clean the surface of the buttons, and even polish them, but the damaged ones remained pale. A common issue with these buttons after 30 years of UV light.

Inside the DataDisk

Technical Bits  The DataDisk is based on an Intel 8031 microprocessor running at 12 MHz which does all the MIDI handling, front panel scanning and disk access work. It loads the OS from a 27C256 EPROM (32 KB)and uses 32 KB of static RAM as a work area. There is no battery as the RAM is only used during operation and no data needs to be saved across power downs.

A Sony MPF11W-10WP 3.5″ DS/DD diskette drive was used in the DataDisk, which can now be replaced with a Gotek drive – see above. Some hardware bugs were sorted out in the DataDisk manufacturing life, some to do with MIDI timing and signal levels. Mine has a few kludges.

OS Versions The latest OS versions are 1.03 (non SQ) and 2.10 (SQ) and there are many versions below this final numbers, so its well worth getting 2.10 which cures all the known bugs. It was released in November 1991. The service manual explains the version history and bugs, the OS EPROM is available on eBay.

 

 

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