Yet another computer museum
The Epson PX-4 cartridges


One of the most apparent features of the PX-4 was the cartridge bay. Apart from developing several cartridges themselves, Epson also provided full documentation on the cartridge interface, so third parties could make cartridges too. Below is an overview of the cartridges developed by Epson.

ROM
H403A
Epson Px-4 ROM cartridge The ROM cartridge is fully supported by the PX-4 OS and maps the ROMs default as J: and K:. The ROM types supported are the same as for the internal ROM drives (B: and C:), 8kByte, 16kByte and 32kByte.
RAM Epson Px-4 RAM cartridge The RAM cartridge is fully supported by the PX-4 OS and maps the RAM as disk I:. The standard Epson RAM cartridge contains only 16 kByte, but 32 kByte and 64 kByte are supported too. The third party cartridge shown here contains 128 kByte and probably needs a user-BIOS driver to work properly. Without driver, it is 32kByte in size.
Microcassette
H404A
Epson Px-4 Microcassette Drive The microcassette drive is fully supported by the PX-4 OS and maps to drive H:.
Printer
H409A
Epson Px-4 Cartridge Printer The Cartridge Printer is fully supported by the PX-4 OS. The width is 60 dots or 40 characters. A character is printed as 6 x 8 dots. The ribbon cartridge is ERC-09 B.
Modem Epson Px-4 Modem cartridge The modem cartridge is not supported by the PX-4 OS, so needs special software to function. It can dial and auto anwser and communicate up to 300 bps (Bell 103). The internal PX-4 RS-232 port is used for data transfer.
In the Operating System Reference Manual is a Modem Sample Program that demonstrates the cartridge. As I have no modem cartridge, I cannot test this.
Digital Multimeter Cartridge
H407A
Epson Px-4 DMM cartridge The DMM cartridge is not supported by the PX-4 OS, but needs special software to function. The ranges are:
  • DCV: auto, 300mV, 3V, 30V, 300V, 500V
  • ACV: auto, 3V, 30V, 300V, 350V
  • Ohm: auto, 300ohm, 3kohm, 30kohm, 300kohm, 3000kohm
  • Low power ohm: auto, 3kohm, 30kohm, 300kohm, 3000kohm
The DMM is powered by its own two AAA-type batteries.
PROM WRITER
H413A
Epson Px-4 PROM WRITER cartridge The PROM Writer cartridge is not supported by the PX-4 OS, but needs special software. An example is the ROMWRITE capsule ROM. A description of the software is available. The PROM Writer supports 2764, 27128 and 27256 type EPROMs.
Another package in ROM is PROM WRITE 2, which is an integrated image creator and programmer.

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Latest update: 2018-05-20

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