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Reading out the ROM - Part 3

A project log for Reverse Engineering the Janome Memory Cards

Reading the ROM on the Janome MemoryCraft 9000 memory cards

esophagooseesophagoose 11/17/2022 at 07:110 Comments

Looking at the binary read out again, I notice a couple of issues:

1. Every 4 lines the text repeats itself - which is a 64 byte offset or that the A6 pin is not toggling

2. Every 8 bytes are repeating (half of the line), A3 pin isn't toggling

3. Sometimes the repeat parts aren't quite the same which indicates maybe a signal integrity issue (or power issue?)


Though I feel like I'm getting close. This memory card has the alphabet on there and this is close to that:


Found some incorrect pinouts in the firmware :(
Fixed that and still having issues but closer to an alphabet!

Every other letter is 0xF1.  Hmm .. pyembroidery makes is seem like I should be looking for 0x80 to indicate a control byte coming.

With the fixed pinout, I added A-1 back in and see saw the wrong deltas but the start of the file REALLY looks like a header: "832 DATA EXP L V1.0 R1.0"
I'll keep address A-1 in.

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