Trim V-REF to 2.56V for any quantization scale.
Some people have reported that pulse outputs do not trigger 281 envelopes. To fix that wire 1M resistor from each pulse output banana to a ground. you can find a ground at a square pin of a LED next to each of banana jacks.
DOWNLOADS:
ATTINY88 FIRMWARE REV1.0
ATTINY84 FIRMWARE REV1.1
BOM REV1.1
LOW FUSES SHOULD BE SET TO E2