Psion Siena Teardown

[Stephen Hill]

I thought I would do a small teardown of my Psion Siena PDA. I used to own one as a young teenager until it broke. I then bought one recently on eBay for £1.

The Psion Siena is a PDA with 512Kb to 1Mb of memory powered by a 16bit NEC V30H microprocessor @ 7.68 MHz.

Here is what the Siena looks like fully assembled:


This is the main keyboard pcb:


Here is the front and back of the LCD:



Here is the back of the main pcb, nothing at all to see:


And now the main pcb:


Chips on the main pcb:

• NEC V30H - http://datasheets.chipdb.org/NEC/V20-V30/NEC_uPD70116.pdf
• LH5PV16256 4M bit Pseudo-Static RAM - http://www.datasheetcatalog.org/datasheet/Sharp/mXrwtws.pdf
• Psion Vine V4.20F/ENG - Not sure what this chip is for. Possibly the firmware memory.
• Matra Harris Semiconductors - CMRD69K1KE7
• MAX3212CAI - http://datasheets.maximintegrated.com/en/ds/MAX320-MAX322.pdf
• LP324 - http://www.ti.com/lit/ds/symlink/lp324.pdf
• 74HC00D - http://www.nxp.com/documents/data_sheet/74HC_HCT00.pdf
• Sharp 20VZ51 - http://sharp-world.com/products/device/lineup/data/pdf/datasheet/pq20vz51j00h_e.pdf
• Max757 - http://www.datasheetcatalog.org/datasheet/maxim/MAX756-MAX757.pdf
• 3V3704I - http://www.farnell.com/datasheets/70132.pdf
• 7.68Mhz Crystal
• 3.6864Mhz Crystal

This is the processor:


I was also very surprised to see a 6 layer pcb:


I was able to view the main 7.68Mhz clock on the scope but not the 3.68Mhz clock. Maybe the 3.68 is only used for serial communication? Here is the main clock:


The device runs from two AAA batteries. When idle it consumes about 10mA and when running flat out it consumes about 40mA.


I hope you enjoyed this small teardown. If you have any questions, you know what to do.

Cheers
Stephen

[Stephen Hill]

Hello!

[IanB]

The Siena was the forgotten child of Psion devices. Large form factor but small screen.

[baljemmett]

The Siena was the forgotten child of Psion devices. Large form factor but small screen.

Considerably smaller than the Series 3c that begat it, though...

I finally had to retire my Siena earlier this year after the keyboard failed again (think it was on its third), which was a shame since it's done great service since 1996.  I was given a 3c years ago that I still have lying around somewhere, but it suffers from the icky degraded rubber covering common to the model; picked up a Revo on eBay to see if that could fill the gap, but again it's rather bulkier.

Add to that having just changed mobile phones from a Symbian device to an Android, and recently receiving my buyout cheque from Motorola in respect of my Psion shareholding, there's been a definite downward trend in my association with the company

Maybe I'll take a leaf out of Stephen's book and whip the covers off my machine, see if the keyboard can't be coaxed back into life somehow!

[munchausen]

Hello,
first post here, I just registered to reply to this topic. Interesting pictures - I was looking for some pics of the siena internals so thank you (think these are the only ones on the net EDIT: found some more here http://old-organizers.com/MorePicts/MP160.htm - also other psions).

Some thoughts about the parts...

• NEC V30H - http://datasheets.chipdb.org/NEC/V20-V30/NEC_uPD70116.pdf
• LH5PV16256 4M bit Pseudo-Static RAM - http://www.datasheetcatalog.org/datasheet/Sharp/mXrwtws.pdf
• Psion Vine V4.20F/ENG - Not sure what this chip is for. Possibly the firmware memory.
• Matra Harris Semiconductors - CMRD69K1KE7
• MAX3212CAI - http://datasheets.maximintegrated.com/en/ds/MAX320-MAX322.pdf
• LP324 - http://www.ti.com/lit/ds/symlink/lp324.pdf
• 74HC00D - http://www.nxp.com/documents/data_sheet/74HC_HCT00.pdf
• Sharp 20VZ51 - http://sharp-world.com/products/device/lineup/data/pdf/datasheet/pq20vz51j00h_e.pdf
• Max757 - http://www.datasheetcatalog.org/datasheet/maxim/MAX756-MAX757.pdf
• 3V3704I - http://www.farnell.com/datasheets/70132.pdf
• 7.68Mhz Crystal
• 3.6864Mhz Crystal

NEC V30H - The CPU is not a standard NEC V30H - looking at the data sheet a standard one would have only 52 pins as a QFP. Psion have a tendency towards producing custom CPU designs using other peoples cores and adding peripherals, and often have a large ASIC or two as well (this is what they did for the 5mx and revo too). At first I thought maybe the MHS chip might be the CPU, but I think you're right, particularly as the 7.68MHz crystal is nearby. EDIT: This certainly is the CPU. It is the same as in the 3a/3c (not sure about series 3 - will have a look in my spares box tomorrow). 3mx processor looks the same but of course it is 5-10x faster (can't remember exactly).

Perhaps the MHS is actually another processor, as it appears to have the 3.6MHz clock next to it. Perhaps a display controller? EDIT: Had a look around and the other series 3 devices do not have this. So really not sure... could still be a display controller as the siena has a different LCD to the others.

The VINE chip looks like a mask ROM to me, especially since it has a version number on it.

What I find really interesting is something I've also seen on other Psions  - multiple connectors for the RAM. The pads either side of the RAM IC and underneath it look to be connected to the main address bus as well. Perhaps the 1MB model used both of these with two larger footprint chips. If you wanted to do some modding, this would be the place to start. (You can see the same for the ROM as well).

Some dreaming... it's a pity the full CPU specs aren't available... the NEC V30 doesn't have much more than a bus normally, but by the large pin out it looks as though psion have added a lot of peripherals. On the revo/series 5/5mx there is an unused SPI port that could potentially be used to add SD memory (and access it from Linux, not sure whether it could be achieved in EPOC). This could be really useful for the siena as the biggest problem with it was the lack of storage. Though I don't know if a software solution could be made for this in sibo anyway.

Something occurs to me as slightly odd - the 3a/3c/3mx came in 2MB models. But the NEC specs say that the address space is 1MB! Perhaps there is a newer revision of the core.

One other thing - the siena certainly was very small compared to the other series 3 machines. The adverts often pictured a guy with one in his shirt pocket!

[amyk]

Something occurs to me as slightly odd - the 3a/3c/3mx came in 2MB models. But the NEC specs say that the address space is 1MB! Perhaps there is a newer revision of the core.

Probably accomplished via bankswitching. The V30 is basically an 8086 (with some extra instructions and features like 8080 emulation) and has the same 1MB (20-bit) address bus.