Today’s teardown target is an early 1990’s electronic organizer from Casio. Casio Digital Diary SF-4000, complete with a travel guide!
Interesting mix of keys- membranes plus some hard buttons
Complete with a Travel Guide!
Very solid and compact unit
With the back cover off, and individual coin cell covers removed. Note brass inserts for the screws!
Plastic label peeled off
The height of components was high enough that they had to recess them inside the plastic frame!
Batteries are in series, but with taps brought out to allow replacement without loosing memory contents
Another view of the holder
With the board exposed- not a lot of surprises here: a Hitachi HD62023C50 processor, NEC D43256-10L low power 5V SRAM (70mA active, 100uA standby, data retention specified down to 2V), 2MHz oscillator and a power supply. The main membrane keypad is connected in the lower left, while the display and the upper keypad is going through a flex on top.The board is two layer and very thin- you can see traces from the back showing through.
We have a serial port in the upper left!
Looks like the diodes are across each cells
The instruction label directed the user to replace batteries one at a time, so to keep RAM contents alive, there are MA151K diodes across each cells. That way with at least some batteries still present, memory contents is preserved.
Diodes on all battery inputs, voltage regulator
Here is the power switch. It will be eerily familiar to those following along at home- the same design was used in a Soviet Elektronika MK-51 calculator we tore apart a while back. I think I know who cloned whom!
Something looks very familiar here!
Even the footprint of the contacts is the same, with a minor detail- they are gold plated! MK-51 used tinned pads, good for probably a few cycles.
Unlike MK-51 clone, contacts are gold plated
On to the top assembly:
Two LCD drivers and keypads
The driver packages are rather strange- I’ve never seen anything like that!
The lead frame appears to be copper and soldered to the board.
Great Info!
Are These CPU’s Reprogrammable?
and what about old casio SF-series?
Can Somebody Mod These Machines?
Thank You
I actually haven’t got a clue! So far I’ve not been able to find the datasheet for the micro, but if I had to guess it’s most likely masked ROM. Seeing how it’s an early 90s design, it’s unlikely to be flash based, and i see no external storage.
Found one of these laying around and I’m trying to see if I can reprogram it. I could only find the data sheet for the Static RAM chip here http://pdf1.alldatasheet.com/datasheet-pdf/view/144315/NEC/UPD43256AGU-15LL.html but despite all my efforts I cannot find the controller’s data sheet. 🙁
tentei recuperar a minha casio digital diary, funciona em pleno, mas nao consigo trabalhar com elas por desconhecimento do seu funcionamento, preciso de um manual de funcionamento donde conste:
– Gravar e apagar dados;
– Tem o calendario de 1988, como actualizo?.
Obgd
I have the manual (in English)
I want to download an user manual pdf for Casio Digital Diary SF-4000
I have forget my passwrd CASIO SF 4000 ;HOW I CAN OPEN MY CASIO AND CREATE A NEW PASSWORD?
Either find a way to hack the controller (which would take a lot of work) or open the back panel and push the reset button (but it will erase all data). Maybe you could use the serial to try and pull data off but I believe it may need a specially designed cable: http://www.imslsoft.com/cable.htm and http://www.pfranc.com/pclink/myidea.htm
need 4 screw for the back panel. battery housing
Hello
How can I change from German to English on the Casio SF400 please.
Regards
Janet
I forgot the password. Any way to recover without loosing ph numbers especially? Would be most grateful
I collect these units… I have one brand NEW inbox with its Travel Guide.
It has a very old logic which is partly kept in successor models but this one feels like dealing with an early 80s PC and it’s a good feeling. Not super practical, keys are pretty “resistive” to touch but it does its job and does it reliably (as long as you refresh the batteries in the appropriate way). The interior keypad design has charm.