The 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. Although named after the TRS-80 line of computers, they were not compatible with it and did not use the Z-80 CPU. 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. History, lineage and nomenclature 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 four colored ball point pens and could print or plot on plain paper. The other print-capable models all used thermal paper, the PC-3 and PC-8 used one printer, while the PC-4, PC-5 and PC-6 used another. The PC-7 had no printer or cassette interface. Models The Tandy/TRS-80 model names are listed with the corresponding original Sharp or Casio model number. TRS-80 Pocket Computer "PC-1" – Sharp PC-1211 TRS-80 Pocket Computer PC-2 – Sharp PC-1500 Tandy/TRS-80 Pocket Computer PC-3 – Sharp PC-1251 TRS-80 Pocket Computer PC-4 – Casio PB-100 Tandy Pocket Computer PC-5 – Casio FX-780P Tandy Pocket Computer PC-6 – Casio FX-790P Tandy Pocket Computer PC-7 – Casio FX-5200P Tandy Pocket Computer PC-8 – Sharp PC-1246 Purpose 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. Design The models provided a short one-line dot-matrix LCD display, to show the current line of input text, or a segment of it containing the cursor. Character widths in these models varied from 12 characters in the PC-4 and PC-7 to 24