BOM for a500hdd board
http://nuclear.mutantstargoat.com/hw/amiga/a500hdd


U1	40pin ATA connector - male 2x20 pin header, 2.54mm pitch.
U3	74HCT04 hex inverter - SOIC-14
U4	See NOTE below.
U5	74HCT00 quad nand - SOIC-14
U6,U7	74HCT08 quad and - SOIC-14
D1	red LED - 0805
C1-C4	0.1uF (100nF) capacitors - 0805
R1-R16	68 Ohm resistors - 0805
R17	330 Ohm resistor - 0805

NOTE: as it's extremely difficult to source edge connectors large enough for the
Amiga500 side expansion port, the U4 footprint is actually for a right-angle male
86 pin header (2x43). This allowed me to make a custom card-edge connector by
splicing together big ISA connectors, mounted on a pin socket adaptor
board once, and use it for multiple expansion experiments.

Soldering an edge connector directly to this board is also easy enough (easier
than making the adaptor board). Just bend the bottom row of pins and solder them
directly to the outer row of pads, then pass a single-row pin header through the
back row of pads to reach the straight upper row of pins.

UPDATE (dec2019): currently a good source for the correct card edge connectors
is this: https://www.aliexpress.com/item/33029711948.html