The Epson PX-4 (HC-40 or HX-40) is a portable
CP/M
CP/M, originally standing for Control Program/Monitor and later Control Program for Microcomputers, is a mass-market operating system created in 1974 for Intel 8080/Intel 8085, 85-based microcomputers by Gary Kildall of Digital Research, Dig ...
based computer introduced in 1985. The screen was 40×8 characters physical, but 80×25 or 40×50 virtual, making it almost compatible with the
Epson PX-8 Geneva. It could be operated from a Nickel-Cadium battery pack (Epson RB 105), 4xAA batteries, or a 6V 600mA DC power supply.
It was targeted as successor of the
Epson HX-20
The HX-20 (also known as the HC-20) was an early laptop computer released by Epson, Seiko Epson in July 1982. It was the first Notebook (laptop), notebook-sized portable computer, occupying roughly the footprint of an A4 paper, A4 notebook while ...
portable, which was very popular with field engineers.
Another feature of the PX-4 was its high modularity. Inheriting the ROM capsules from the
Epson PX-8 Geneva, it added a cartridge bay (similar but incompatible with the
Epson HX-20
The HX-20 (also known as the HC-20) was an early laptop computer released by Epson, Seiko Epson in July 1982. It was the first Notebook (laptop), notebook-sized portable computer, occupying roughly the footprint of an A4 paper, A4 notebook while ...
), for which Epson offered several printers, micro-cassette drive, modem, EPROM writer, DMM (Digital Multimeter Module), RAM and ROM cartridges.
[PX-4 OPERATING MANUAL] Third parties could make custom cartridges. The modem, EPROM writer and DMM needed user programs. The system allowed for BIOS extensions (User BIOS). Other features were the Serial ''and'' RS232 port, barcode reader interface like with the
Epson PX-8 Geneva. New were a cassette port and
parallel printer port.
The keyboard was also easily replaceable, allowing country specific layouts but also custom layouts, like the 'item keyboard' turning the PX-4 into a cash register. This trend was taken further by the
Epson PX-16 for which even 'item keyboards' with touch screens were available.
Internal RAM was 64K, of which a part could be reserved as RAM disk. An External RAM disk could be attached, creating a 120K RAM disk, leaving internal RAM as user BIOS and workspace.
The PX-4+ was an improved version which had the External RAM disk integrated (HX-45 in the US, HC-45 in Japan).
References
;Literature
* ''PX-4 / HX-40 Operating System Reference Manual'', EPSON, 1985. Y20699101600
* ''PX-4 DISK UTILITIES OPERATING MANUAL'', EPSON, 1984. H8592003-0 / Y322990003
* ''PX-4 BASIC REFERENCE MANUAL'',EPSON, 1985. Y200599100601
* ''PX-4 OPERATING MANUAL'' EPSON 1985. H8592005-1 / Y205991005
External links
PX-4 info, documentation and software
PX-4
Computer-related introductions in 1985
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