This manual (Chapter 10) describes a 'ROM Cartrudge II' that is provided as
a plug-in option in the HX-20. The ROM Cartridge II supplies from 8k to 32k
bytes of data. Data in the externam ROM memory unit is in the forrm of a
read-only ROM file. Data are read from the external ROM memory unit via
i/oports using an addressing counter and a shift register....
port info follows.....
-----Original Message-----
From: Tony Duell <ard(a)p850ug1.demon.co.uk>
[HX20]
The microcassette drive was actually removable.
I don't know if Epson
ever released anything else that could plug into that space besides the
The hardware manual mentions (and gives a schematic for) an EPROM
cartridge that will fit up there. I've never tried to build one, but it
looks possible.
-tony