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Does this electronic organiser have UART?

Ask QuestionAsked todayActive todayViewed 107 times1This question was migrated from Information Security Stack Exchange because it can be answered on Electrical Engineering Stack Exchange. Migrated 14 hours ago.

This is a question about finding the UART, or whatever alternative, so I can get access to an old electronic organiser from the year 2000.

I know this is a hardware question, but it is technically reverse engineering and I will have to do some exploiting to gain access to the file system, and probably make the changes I want.

I have been unable to identify the UART. If this does not have one, are there any other alternatives?

There appears to be a serial number next to one of the round circles.

I think the three holes to the left of the top epoxy are them? They are touching it and are in a straight line which, from experience, is how UART ports are shown.

Here is a link to what an electronic lrganiser is, although it is different to my one.

enter image description here
enter image description here

uartassemblyhardwarejtagreverse-engineeringShareEditFollowFlagedited 2 hours agoasked 14 hours agoquestioner922 bronze badges

  • 1What is a “reorganiser”? – evildemonic 14 hours ago
  • 2@evildemonic Sorry, Electronic Organiser, let me update post: en.wikipedia.org/wiki/Electronic_organizer – questioner 14 hours ago
  • 3I would guess if there’s some eeprom or flash it would the the chip under the top epoxy blob, the bottom one is probably a processor of some kind as it appears to be driving the LCD. Have you got a scope? – Colin 14 hours ago
  • 1@Colin What type of scope? I have a multi-meter. I personally think it is the three holes lined up by the epoxy blob furthest away from the LCD screen, as that seems to be the convention on most electronics to line up RT, TX, and the other one could be VCC or GND. – questioner 13 hours ago 
  • 1@questioner An oscilloscope, you’re going in a bit blind without one, and with one you could look for signals which look like serial, or for something that looks like addresses or data being moved. – Colin 11 hours ago 
  • 2The three holes to the left of the epoxy blob are just vias to the other side of the board. They are uncovered simply because they are close enough to the pads that they become exposed by the gap in the soldermask intended for the pads. They are most likely connected to the buttons on the other side – Tom Carpenter 11 hours ago 
  • 1@TomCarpenter They are in a perfect line, touching the epoxy blob… seems like they are to me? – questioner 7 hours ago
  • There are lots of vias in a line. Doesn’t mean they are a connector. There are also lots of vias that go to the epoxy blob. – Tom Carpenter 7 hours ago
  • 1@TomCarpenter What about that serial number under one of the circles for the battery? – questioner 6 hours ago
  • 1PCB identifier. Effectively a part number, not a serial number – Tom Carpenter 6 hours ago 
  • Ah, me ok boomer used to call them “FiloFax” which is perhaps UK’s 200 years old sort of paper diary, and oh yes, I am still using Filofax. Anyway, fast forward to 1980’s when Apple Newton PDA rose and fell, and 1990’s when Casio Organizer rose, got very popular, but also fell flat. Anyway, here is the 70+ page Casio friendly manual which we can read together. Casio SF-R20 Digital Diary/PDA/Organizer/Filofax User Manual manualslib.com/products/Casio-Sf-R20-694195.html. Happy reading. 🙂 Cheers. – tlfong01 6 hours ago   
  • 1@tlfong01 But why would this be applicable to mine, if it is a different product? – questioner 4 hours ago
  • @questioner, Ah your PDA PCB shows 匯業 year 2000. So I guess 匯業 was OEM of this PDA on or after 2000. So the similar Casio model might be a reference to check out if it is using IrDA of similar. If you can show us a photo of the panel, then it is easier for us to do Google image search. – tlfong01 3 hours ago   
  • Or check out this one with a cable for PC Sync: Casio SF-5790SY Digital Organizer (1996-1999) youtube.com/watch?v=e7cs8n0QEpI – tlfong01 3 hours ago    
  • 1Do the manuals explain how to find UART though? It seemed more like an instruction manual. I will post a picture of it in a few minutes below the original picture. – questioner 3 hours ago
  • 1@tlfong01 Updated with a picture, and please see my above comment. – questioner 3 hours ago 
  • Does it go with any PC-Sync cord? yingkee.hk/phottix-3-5mm-male-to-locking-pc-sync-cord-40cm – tlfong01 3 hours ago   
  • 1@tlfong01 No, it has no ports. – questioner 3 hours ago
  • Ah, no port no hope. 🙂 i.imgur.com/YdbYCI4.jpeg. Cheers. – tlfong01 3 hours ago   
  • BTW, Page 56/57 of my Casio PDA manual shows the port for data transfer of O2O, or O2PC. – tlfong01 3 hours ago    
  • 1@tlfong01 But why can’t we find the UART port? – questioner 3 hours ago
  • 1There is no guarantee that this has a serial port. Nor is there any guarantee that the serial port would allow you to reprogram the device. I am guessing that smaller, elliptical blob is mask rom containing the non-modifiable code for the system. During development they probably installed EEPROM on the pads there. But then switched to chip-on-die mask rom after they finalize the code. (We used to call that gold mastering at one place where I worked). Devices like this were sometimes developed in assembly language and highly optimized for code space. – mkeith 2 hours ago
  • 1It could also be possible that the smaller blob is the processor and the larger, round one is just a video driver. If so, it wouldn’t hurt to probe the exposed pads around the smaller, elliptical blob with an oscilloscope. – mkeith 2 hours ago

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1 Answer


It’s quite difficult to say, that chip on board is obviously a no-name and impossible to identify.

However, for example, many of these used Epson microcontrollers which actually have a serial port; if it is used or not depends on the on-board software: maybe there’s something for manufacturing test or similar.

Probe with a scope carefully and see if you see something like serial data around but I think there will not be much.

Also, these thing didn’t have a file system but only a battery backed RAM array so it’s now totally empty anywayShareEditFollowFlaganswered 14 hours agoLorenzo Marcantonio68799 bronze badges

  • 1It ran out of battery life years ago. I would be more interested in adding my own software, than accessing stored information on it (which is gone now anyway). I also wanted to check if the password feature encrypted data, or was just a screen which could easily be bypassed etc… – questioner 13 hours ago 
  • 1That second oblong blob is probably the read only memory that contains the system code. I would guess that it is mask ROM. (Actual ROM where the ones and zeros are permanently encoded in silicon and cannot be erased or re-written). – mkeith 2 hours ago
  • 1@mkeith Which one is the second one? – questioner 1 hour ago
  • 1Oops. I am missing a comma. The smaller more oblong blob is the one that could be a ROM (or it could be a uProcessor, too). – mkeith 1 hour ago

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