The Psion 3a serial port. ================================================================ This is designed as ready response to FAQs on this subject, but not guaranteed to be 100 percent right. I have no connection with Psion, not am very technical. Much of what is here was contributed by others in response to my original questions. I have an Archimedes and some experience of PC, but no nothing of Macs, which are not covered. Alan Roblou (zebra) - 01 Mar 1994 The six holes: ============== The socket with the six holes in the side of the Psion 3/3a is NOT a serial port. It is the port through which the Psion is connected to a serial port. The real serial port is the "soap on a rope" that you get when you buy a 3-link for a PC or an A-link for an Archimedes. The socket on the side of the 3/3a is not a socket at all but six pins covered by a little flap which folds back when the link connector is inserted. The pins give - a was told - AIUI, TTL levels only. It was explained that "This interface is basically a pair of signals over which we run a Psion Proprietary Synchronous Serial Protocol (PPSSP) at 1.536 MHz. The soap part of the "soap on a rope" contains an Asic which is basically a UART. The PPSSP can be used to send/receive data to registers in the Asic. This is best imagined as talking to a normal IBM/PC 16450 UART, execpt that instead of the data being sent in parallel over the ISA bus, its sent serially. The other 4 signals are power, ground, interrupt and external wakeup signal.The soap box contains driver circuitry as well as software. So your Psion 3/3a does not come with a serial port, but with the means to talk to a serial port, which is the soap on the rope dangling on the end of a short lead. The soap on the rope ==================== As noted above, this is the real serial port. It terminated with a female socket with nine holes. These are the serial port connections, entirely comparable to a normal nine-pin serial port, but arranged a little differently. To this connector you can attach a normal null modem cable, which is what comes with the 3-link and A-link packages, or any other cable .. for instance a cable to a 25-way connector for a modem. For versatility you might find it best to use to just to attach a short connector cable terminating in an ordinary nine-pin serial port connector. Here are the connections for that titchy round port: Pin Direction Signal 1 < DCD 2 < RX 3 > TX 4 > DTR 5 - SGround 6 < DSR 7 > RTS 8 < CTS 9 < RI Viewed head on to the pins of the male connector you would use they are : 7 8 9 3 4 5 6 2 1 If you DIY you need a small soldering iron, tweezers a magnifying glass and a third hand Differences between 3-link and A-link: ===================================== As far as I can work out there is no difference except for the label, the connections in the final link from the soap on rope to your computer, and the price (the A-link is a bit cheaper). With tha 3-link you get transfer software to go into your PC called MCLINK, and a fairly good manual. With the A-link you get software for your Archimedes, written by Computer Concepts, and a fairly sparse manual. The Archimedes end works as a window which converts file types. Crucially, the software at the Psion 3/3a end of the link is already in the Psion in all cases. There is no difference. It exists as "Drive C" on the ROM of the 3a (it may be in the soap in rope in the 3, I am not sure), and becomes active when you connect the soap on rope. You have to install it the first time - like any other application - and it only comes to life thereafter when you prepare to use the serial port. The details of this end are NOT explained in the A-link application, but you can get the manual from Psion for #6. Software: ========= MCLINK comes with the 3-link. I havn't used it but hear it is a bit tricky. RFM looks like being the successor to MCLINK and is available in an alpha version in the file list. It is brilliant. It allows a PC to treat the Psion at though it were another drive. You can use it with Laplink and shift files around as easily as moving them from floppy to hard disk on a PC. PocketFS for the Arc is tricky at first (especially if you have a modem which has been using the serial port) but fine after you get used to it. You can either transfer files by tugging them into a window, in which case they get converted by file type, or open the files on he 3a as though they were another directory on the Arc. (The applications on the Acorn Pocket Book are a bit different from the Psion3, so you have to make some adjustments if you use the 3a, but crucially it will still convert Word files to plain text and Spreadsheet files to Lotus123-like .WKx files) Inside the Psion is COMMS software, as mentioned which will allow the 3a to be used as a terminal and up and download files. It gives you the basic settings and will capture incoming streams as well as file downloads. There is also SCRIPT software which saves your fingers. It is limited in terminal emulation capability, but fine for Cix and BBS use.. Widget have announced at VT100 emulator, and a first version is available in the files list here, but wil work only til the end of March 1994. It has a wider availity to connect to VT100 machines like Unix main and incorporates an imbedded keypad rather neatly. It wouldn't always handle the incoming stream from my works computer, giving "buffer overflow" but I have messaged them about that. Batteries ========= Everyone agrees that use of the serial port cuts battery life, one said it finnished off a two-week-old set in hald an hour. Most recommend use of a mains adapter. But I have to say my experience is that the Psion even with serial link active is much better on batteries than other handhelds. If you use scripts and do your business quickly it isn't a big problem.