Skip Navigation.
Section 0

Polaris EPROM Code

Rev 11

Paul DeRocco [21030230] writes, "I've created Rev 11, which fixes a tiny bug I noticed in earlier code. It's a bug that only appeared for people who had bad membrane switch panels: if a short in the tails or connector caused one of the missing switch positions in the matrix to be spuriously invoked, the program would crash." [November 2014] Download (71kb).

Rev 9

Thanks to David Clarke [300831++] for this information.

David writes, " [28K] contains the 4 binary files for the four EPROMs for a Polaris. The firmware in the files is Rev 9. Each image gets programmed into its own 2764 EPROM and the put in the Polaris in the socket corresponding to the file name (e.g., Z10 into the socket labelled Z10, etc.).

"The current firmware version can be determined by pressing LF-D-2 and watching to see which of the numbered buttons flash. A common version of firmware in the field is '5' (i.e., the '5' button will flash)."

See the thread Polaris sys ex broken for what appears to be version "9 star." See also Chroma EPROM Code.

Installation Instructions

Material Required

P/N 306802301 Chroma Polaris Revision 9 EPROM's.

Make sure you save the customer's programs and sequences on cassette before you begin. Memory locations usually change when EPROM's are revised, making it necessary to totally reset the Polaris. All necessary software adjustments are outlined in the following procedure. Observe standard safety procedures for static sensitive IC's.


  1. Save the programs and sequences on cassette.
  2. Disconnect line power and open the Polaris.
  3. Remove four 2764 EPROM's from sockets Z10, Z11, Z12 and Z13. Carefully install two 27128 Revision 9 EPROM's in Z12 and Z13 making sure that the notched end of the EPROM goes to the pin 1 end of the socket and that no pins get bent. Sockets Z10 & Z11 remain blank.
  4. Move the jumper connector located near the left rear corner of the main board (next to C819 and Z19) so that the center pin shorts to the rear-most pin.
  5. Press LOWER FUNCTION – D - 12 STOP.
  6. Press LOWER FUNCTION – TUNE ALL. Move the master slider to maximum, then back off to about 1/4.
  7. Select A-1 in the Bank Select/Program Select section; now you should have a "scratch sound."
  8. The LED above the master slider must be off. If on, turn it off to establish the volume mode. The assignable volume must be on and set to about 1/4.
  9. Put a scratch program in the main workspace. (Select A-1)
  10. Press LOWER FUNCTION - A.
  11. Press 1 and move the master slider down to its minimum position. If already at minimum, move it up and back.
  12. Press 2 and move the master slider up to maximum.
  13. Press 3 and move the master slider down to minimum.
  14. Press 4 and move te master slider up then down to minimum.
  15. Press 5 and move the master slider to its maximum position.
  16. Press 7 and move both levers (not sliders) through their entire mechanical ranges. Set the master slider to 1/4.
  17. Press 8 and move the pedal through its range.
  18. Press 9. Select VOLUME on the Assignable Control and set the slider to 1/4. Play 6 different notes, 1 at a time. After releasing each note, move the MASTER slider up until you hear the note bleeding through, then back off until it just disappears. If this adjustment is not set properly, notes will decay abruptly or the velocity will be too sensitive. Playing 6 notes adjusts each of the 6 channels.
  19. Press B. Turn on LED's 1, 2, 3, 7, 8, 9, 10, 11 and 12. Turn off LED's 4, 5 and 6.
  20. Press C. Turn on LED's 1 and 2. Turn off all others.
  21. Press K. Turn on 1 and 7. Turn off others.
  22. Press LOWER FUNCTION to return Polaris to normal operation.
  23. LOAD programs and sequences from cassette.