From the Gadgetmans shelves:
The Casio PB-100

This calculator lookalike have the pretencious words 'Personal Computer' on the front. I wonder why...

What it is, is a calculator with a good oldfashioned Basic language built in.
A few details:

• Memory: 544Bytes available for programs.
• Storage: On audio cassettes using an optional cassette adapter.
• Can have up to 10 programs in memory (P0 - P9)
• Screen: One row of 12 characters (each a 5 by 7dot matrix) and a few small words above the characters
• Expandability: A slot for a 'options pack' next to the batteries inside the unit.
• Batteries: 2 flat button type cells. (Probably CR2032 type. CR2025 is a tad to thin)
• Basic commands are stored as single bytes thereby saving memory...
• Expansion port: There's a 12pin connector along the top edge of the unit. The same type of connector can also be found on the bak side of the cassette adapter. This means that there might be other accessories for it too... (The printer. )

• To replace the batteries, you have to unscrew the two screws and remove the backside.
• The batteries are connected in series, so removing one will erase the memory... (Luckily, the batteries seems to last a while :-)