DRUMULATOR & FPGA

Some time ago, I coded the whole processor part of the Drumulator in an FPGA. I still had to code the sound generation sequencer. I thought it was complicated to achieve, given the schematic in the service manual.

The sequencer looks like this:

This sequencer controls a set of registers that are used to generate addresses for sample ROMs.

I was not sure how to go about writing readable and simple code from these two diagrams. After having understood the general operation of this system, I finally decided to transcribe in VHDL what I had understood. Good idea since these two diagrams are coded in about fifteen short lines of code.

To carry out the tests, I contented myself with using an FPGA board whose two buttons I use to simulate two Drumulator sound buttons. The FPGA then generates addresses for the Drumlator board ROM address bus. It's as simple as that and it works great.

The adventure goes on...