Current Brother/Bernina domestic sewing and embroidery machines have a slot for a memory card, and a USB host connector into which a standard Flash stick can be plugged.
Older machines only have a card slot, and transferring embroidery instructions from a PC (e.g. prepared using Inkscape/Inkstitch) to the machine relies on having a special memory card and a card writer... both of which are scarce and expensive.
I have seen a number of questions before relating to these cards and readers, but it seemed that nobody made much progress. I now have a sacrificial card (not part of a burnt offering) over which I have been waving test probes and magnifier.
The card is 40-pin, not 41-pin as sometimes reported. The connector is an AMP 175564 with 1mm pitch, it's comparable with a single row of a PCMCIA connector. One of the "ears" at the end is slightly thinner than the other, and this identifies pin 1.
Most of the pins connect both to the chip (a die under an epoxy blob) and to tracks cut when the PCB was guillotined to size. The pin layout corresponds roughly to the die, i.e. it's either an ASIC or Brother selected a type of chip when they first specified the slot and has been able to continue sourcing it.
I've not got an extender so so far at least haven't been able to tack testgear onto it, and without having done that I'm not going to guess which power connection is Vcc and which 0V.
This is where I'm at with pin functions:
1 to pin 40 (presence detection?)
2 power (also pin 39), copper fill on front of PCB
3 power (also pin 38), copper fill on back of PCB
4 n/c
5 unpopulated R, other end off-board
6 R, chip, off-board
7 R, chip, off-board
8 R, chip, off-board
9 R, chip, off-board
10 n/c
11 R, chip, off-board
12 R, chip, off-board
13 R, chip, off-board
14 R, chip, off-board
15 R, chip, off-board
16 R, chip, off-board
17 n/c
18 R, chip, off-board
19 R, chip, off-board
20 R, chip, off-board
21 R, chip, off-board
22 R, chip, off-board
23 R, chip, off-board
24 R, chip, off-board
25 R, chip, off-board
26 R, chip, off-board
27 R, chip, off-board
28 R, chip, off-board
29 R, chip, off-board
30 R, chip, off-board
31 R, chip, off-board
32 R, chip, off-board
33 off-board
34 R, chip, off-board
35 R, chip, off-board
36 R, chip, off-board
37 R, chip, off-board
38 power (also pin 3)
39 power (also pin 2)
40 to pin 1 (presence detection?)
So that's about 29 logic connections plus power, which I think is compatible with there being an IDE controller (without DMA etc.) plus storage under the blob.
Contributed in the hope that this is useful to somebody at some point.
MarkMLl