Editing Psion netBook (section)

=== PC Card slot current, and what the board change did ===

Psion Teklogix published the actual limits, which explain a great deal of otherwise mysterious card behaviour:<ref name="psionfaq">Psion Teklogix, netBook customer FAQ, hosted at [[Psion netBook Documentation]]. Psion's own PC Card slot current limits: 800 mA on the netBook after the September 2002 main logic board change, 300 mA before it, 200 mA on the Series 7. Also confirms the Series 7's 133 MHz clock and ROM-resident operating system.</ref>

* '''netBook built from September 2002: 800 mA''', supporting 3 V and 5 V cards. A '''main logic board design change''' that month raised the available power, which is what allows GPRS cards such as the Option GlobeTrotter to work.
* '''netBook built before that change: 300 mA.'''
* '''[[Psion Series 7|Series 7]]: 200 mA''' — the hard number behind that machine's reputation for refusing cards a netBook runs happily.

Psion's stated reason is thermal: PC Cards are designed either for machines with cooling fans or for machines without, and the netBook is in the second group.<ref name="psionfaq" />

Two independent sources agree on the timing. Psion date the board change to '''September 2002'''; the community record has '''revision 10 beginning in week 35 of 2002''' — the same month.<ref name="psionfaq" /><ref name="lindsay" /> That convergence is worth noting, because it means the manufacturing week in the serial number is a reliable way to predict what a machine's PC Card slot will do.

A teardown in December 1999 found an '''SA1100''', an '''ASIC manufactured by NEC''' and a '''Philips CPLD''' with five visible JTAG programming pads on the underside of the board.<ref name="newell">Craig Newell, [http://netwinder.osuosl.org/users/c/craign/public_html/netbook/insides/index.html "Disassembling the NetBook"], 14 December 1999. Source for the disassembly sequence and the identification of the SA1100, the NEC ASIC and the Philips CPLD.</ref>

The board also carries '''two unfitted DRAM sockets and what appears to be an unfitted Flash ROM site'''. At least one owner soldered Hitachi HM5165165LTT-6 devices to them to make a 32 MB Series 7 mainboard, noting that low-power parts are essential because the DRAM is powered continuously.<ref name="lindsay" />