Earlier than the appearance of smartphones, the head of ultra-portable computing was the PDA (Private Digital Assistant). A number of producers have produced fashions through the years and probably the most well-known is the PalmPilot vary, however all of them served the identical objective: placing computing energy within the person’s pocket. Some very latest fashions had the power to hook up with the web by way of WiFi or wired dongles, however most fashions lacked this connectivity. To recuperate your outdated PDA Psion on the web, Kian Ryan has constructed a “sidecar” RS232 terminal primarily based on Raspberry Pi.
Ryan’s machine is a Psion 5MX, which is a PDA launched in 1999. It has a full QWERTY keyboard, a decent 5.6-inch grayscale LCD show with 640 x 240 decision, a 36 MHz 32-bit Arm processor, 4 to 16 MB of RAM and might run for as much as 20 hours on a pair of AA batteries. However it could’t entry the web or networks in any respect – not less than not in the best way trendy units (and even computer systems of the time) do. The Psion 5MX does, nevertheless, comprise {hardware} for communication: an RS-232 serial port and infrared. The latter is extraordinarily gradual and actually solely appropriate for sharing small quantities of knowledge between close by units, however the RS-232 port is vital to this challenge.
Serial communication continues to be used at this time, and lots of trendy units assist the protocol. On this case, the Psion 5MX communicates with a Raspberry Pi Zero W by RS-232. To facilitate this, Ryan designed his personal RS-232 HAT and null modem for the Pi Zero. To make this “sidecar” self-contained, Ryan added WEDGE LiPo Pimoroni, Pimoroni LiPo Amigo Professional and a 2200mAh LiPo battery. He piled all of it up in a customized 3d printed pregnant to maintain issues so as.
The Raspberry Pi can function in headless mode and the Psion 5MX can entry its terminal by way of the RS-232 connection. There it could do something a person may do within the terminal if they’d a keyboard linked to the Raspberry Pi itself. However Ryan went a step additional and configured each for PPP (Level-to-Level Protocol). This enables the Psion 5MX to make use of the Raspberry Pi’s web connection by way of the RS-232 connection. All packets despatched by Psion will undergo RS-232 to the Raspberry Pi after which out to the broader Web, and packets acquired will observe the identical path in reverse.
In fact, the Psion 5MX has little or no software program that may make the most of the Web. However there are! Ryan was capable of set up the Opera internet browser on his Psion and used it to entry web sites – though most are safe today and never accessible to older {hardware}. Telnet, then again, nonetheless works advantageous.
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