| The Epson PX-4 is a portable CP/M-based computer introduced in 1985 as a follow-up to the PX-8. It used a Zilog Z80-compatible CPU (NEC μPD70008) running at 2.5 MHz and came with 64 KB of RAM. Like the PX-8, it ran CP/M and relied heavily on ROM-based software and modular storage options. The PX-4 featured a built-in LCD screen with an 80×8 character display (480×64 pixels), and a full QWERTY keyboard. Unlike the PX-8, the PX-4 had a more modular design, supporting interchangeable device bays. These bays could house different types of storage, such as microcassette drives or RAM disk modules. The system could also be expanded with ROM cartridges containing applications like WordStar or BASIC. Its lightweight, rugged design and optional battery operation made it attractive for field use in logistics, retail, and industrial settings. The PX-4 offered serial and parallel ports, barcode reader support, and docking options for more connectivity. Its flexibility and modular approach made it stand out among portable computers of its era. |
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