Tandy Pocket Computer

A Tandy Pocket Computer or TRS-80 Pocket Computer is one of a line of 1980s small pocket computers—calculator-sized programmable computing devices—sold by Tandy Corporation under the "Tandy" or "Radio Shack TRS-80" brands.

Computers in the line were actually rebadged Sharp and Casio devices with different model names. They were given designations from PC-1 to PC-8. The PC-1, PC-2, PC-3 and PC-8 are Sharp devices, while the PC-4, PC-5, PC-6 and PC-7 were designed by Casio.

Although not branded as such, the original TRS-80 Pocket Computer later became known as the PC-1, as subsequent models were labelled PC-2 through PC-8. Some were made by Sharp, and the rest by Casio (PC-4 through PC-7). The PC-2 had 4 colored ball point pens and could print or plot on plain paper. The others all used thermal paper, the PC-3 and PC-8 using the same printer, the PC-4, PC-5 and PC-6 using the same printer, and the PC-7 having no printer or cassette interface.

The Tandy/TRS-80 model names are listed with the corresponding original Sharp/Casio model number.

Pocket computers were an advancement over early programmable calculator designs. In addition to providing users with scientific math functions in a small portable package, the devices also understood a form of the BASIC programming language. They included a QWERTY keyboard, of either rubber capacitive or membrane type, to use for entering the names of scientific functions and programming commands, in addition to a traditional numeric keypad. (The exception was the PC-7, which had a rectangular and alphabetically ordered keyboard, like most scientific calculators.) On some models, the alphanumeric keypad had a different type, form factor, and location than the numeric keypad.

...
Wikipedia