A “luggable” version known as the Model 4P is a self-contained unit with a case design similar to that of a portable sewing machine. It had all the features of the desktop Model 4 except for the ability to add two outboard floppy disk drives and the interface for cassette tape storage (audio sent to the cassette port in Model III mode are sent to the internal speaker). It was sold only with the two internal single-sided 180KB drives.
The 4P’s CPU board lacked the Model III ROM chips containing the Model III Microsoft BASIC interpreter. Instead the computer was furnished with a floppy disk labelled “Model III/A”. This was called the “Model III ROM Image” disk. If the operator wanted to boot a Model III DOS, he inserted this disk into the boot drive after powering up. Once it was loaded, he replaced the ROM Image disk with his Model III DOS boot disk and pressed reset. From then on the computer would behave exactly like a Model III.
| Manufacturer | Tandy / Radio Shack | CPU | Zilog Z80 @ 4 MHz |
| Year Introduced | 1983 | RAM | 64KB |
| Introductory Price | $1,799 | Storage | 5.25" floppy disks (178KB, internal x 2) |