John Conrod’s Original 1983 Radio Shack TRS-80 Model 4P
Our 1983 Radio Shack TRS-80 Model 4P Portable Computer. The Model 4 shipped with TRSDOS 6, an enhanced version of LDOS by Logical Systems. When the Model 4 booted into TRSDOS 6 the video display switched into 80×24 mode and the entire 64KB address space was mapped as RAM. The Model 4 was also capable of running all Model 3 software when a Model 3 operating system disk was detected and loaded during bootup with a 64×16 video mode and Model 3 ROMs mapped from address zero.
The Model 4 also had the ability to display 640×240 or 512×192 high-resolution monochrome graphics with an optional board. A “luggable” version known as the Model 4P (1983) was a self-contained unit with a case design similar to that of a portable sewing machine.