Epson HX-20


The Epson HX-20 is considered to be the first real laptop computer or at least the first notebook sized portable computer that runs on internal batteries. It has the same size as a block of A4 printing paper and fits inside a briefcase. Despite the small size it has a full size keyboard and keys with a long travel distance. The downside, however, is that the display is crammed in-between the printer, microcassette drive and keyboard. This means that this computer is among those with the smallest display.

The computer was available in silver and beige color. In my opinion the silver version looks so much better and more hi-tech than the beige that looks cheaper and plastic-like.

The Tandy Model 100 used the same form factor as the HX-20 but with a much larger display.

The PX-8 was a later laptop from Epson that succeeded the HX-20. It incorporated a larger display with 8 lines with 80 columns. It kept the microcassette drive and a similar keyboard. OS was changed to CP/M-80.


A laptop computer with a built-in printer is not something you see everyday, unless you own a IBM ThinkPad 555BJ or a Canon Notejet. This computer also include a built-in microcassette drive. Those two features make this little notebook very unique and recognizable among others.



Form factorNotebook computer
ReleasedJuly 1982
CPU2x 614 kHz, 2x Hitachi 6301 CPUs
RAM16 kB
Storage32 kB ROM, built-in removable microcassette drive, interface for external cassette drive.
DisplayLCD 120×32 pixels, 20 characters x 4 lines
OSProprietary operating system with Epson Basic
Dimensions290 x 215 x 47 mm
Weight1,792 g (Incl. microcassette and paper roll)
I/O portsExpansion, Serial, RS-232C, barcode, cassette ext.,
PowerDC 6 V plug (center GND!), internal battery pack
Special featuresFirst notebook, Microcassette, built-in printer, smallest display,
ConditionCase is almost without scratches except for front right corner
Accessories Expansion module, carrying case, built-in microcassette
Serial ID041142
To doTest the printer and microcassette and some software


This computer was one of the first I bought on eBay. Once in a while they showed up on DBA but not with a price tag that I was willing to accept. The computer was sold as untested and came without the power supply.
After I had this computer for a while another HX-20, in beige, showed up on eBay at a reasonable price because it didn’t work and was in a cosmetic bad condition. The reason I wanted it was because it came with a plastic carrying case and also included the H20EU expansion module.

Restoration and modification

After some testing of both computers I found out that the mainboard in the silver version seemed to be dead while the mainboard in the beige version seemed to work ok. So I took the working mainboard and mounted it in the silver one. But kept the original ROM chips and mounted them in the working mainboard since I wanted to make sure that the system stayed English instead of the French beige computer.
I haven’t played a lot with it after the “brain transplantation” because it keeps going into something TRAP! error state that I’m not completely sure about. Maybe I just have to look into the manual and learn about how to use it and to test some software on it. This is also the reason why I can’t confirm if the microcassette or printer works.



One thought on “Epson HX-20

  1. Thanks for the links! That manual was very helpful. I’ve had one of these computers sitting in the corner of my office for the past 30 years. I can’t say when was the last time it was turned on. It had a custom CMOS in it from Miyano (a CNC machine manufacturer) as they sold it as an optional unit for their machines. I remember my father using it to edit/load/save programs to and from our Miyano machine.

    I just charged it back up and turned it on. Yep. I got the same TRAP! error. To fix this, shut the computer back off, press and release the reset button (in case CPU is stuck in a loop). Now turn on the computer and the moment you see “Initialize” press [Crtl] + [@] together at the same time. At this point it should now ask you for the date/time. Enter that, and then continue on to reinitialize the memory (aka a factory reset).

    I was then able to load one of my dad’s old programs off of a cassette I found and even print it out! Yes both the tape drive and the printer still worked (even the 30 year old ink!). Now I need to look at the tape drive motor. It’s noisy as sin, and I can’t get the display to darken (adjusting knob only makes it lighter). So I may pop this puppy apart and give it a good cleaning.

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