The best part of a year after building my MB-6582 and I have finally installed the last of the SIDs. It has 4x 8580s and 4x 6581s. At some point in the future I plan to build a second one and have one all 8580 and the other all 6581.
This circuit will operate the NAND gates outside of the input voltage range.Each of the 4 gates on the top half of the drawing will be driven with a negative voltage spike each time the LED is turned OFF.How long it lasts will be a matter of chance and luck.