In the late 1980s and early 90s, I worked for Extech. The company sold the Psion Organiser and we were desinging printers and modems for it. Psion later came out with the Series 3 and then 3a. I had a 3a. Psion the hinges off the Casio. It was even programmable through a Basic-like language called OPL.
Psion did a magnificent job designing the cases, though my hinge did break after a few years. I found another one and used that for acuple of years, then bought an HP PDA. I still have it but don't use it. The WiFi was terrible.
Casio didn't abandon this field until recently. Back in the '90s I was an enthusiastic owner and programmer of the Casio PV palm-sized PDA (here my web page about it, never touched since, I guess, ten years or so!) and I remember the excitement when they published the SDK for this NEC-Renesas SoC-based device. It wasn't an ARM CPU yet at that time, but the SoC brand experience (about releasing the SDK) later convinced me to purchase another Renesas-ARM tablet, which I enjoyed hacking the Kernal and Android AOSP as well: here my group. It's a real shame Renesas isn't in the game anymore...
This article brought back some of my childhood memories. My dad had one of these with a colour LCD. It was so futuristic. I played with it for a while to understand all the functions and helped my dad punch in all the contacts and taught him how to use it. In hindsight, maybe he was just trying to have quality time with me :)
It even had a screen saver like function that showed a cruise ship sailing by with a dolphin in the background. It was the most impressive thing I had seen.
The battery comment also reminded me how I used to carefully follow the instructions when I was changing them for him :)
I had a similar one but not a Casio, some name starting with 'K' (Kaice or something I think). I never got to use it. After all how many phone numbers would a 12 year old need in the 90s ?
Impressive! I did something similar with a PCMCIA SRAM card and my Toshhiba T1000. Acting as a hard disk, I loaded up WordStar, VP Planner spreadsheet, and Procomm for logging in to the work. It had a 10 MHz 8086, and had snappy performance. The battery lasted 2-21/2 hours, too. Finally, I even had a reasonable text to speech program that PWMed the speaker which produced good quality, understandable speech! These days, the splash screen for some apps is bigger than systems of some years ago that did real work. I did play around win an HP95, but only to put VI on it...