Epson HX-20 User Manual

Chapter 5

When you use BASIC or almost any application program, you will
interact with the HX-20 by typing on the keyboard, and it will

respond by displaying text and graphics on the screen. This is made

possible by the  screen editor.  Because the screen editor is central to

almost all HX-20 applications, you can do little with the HX-20

until you learn how to use it.

Since the screen editor is so important, this chapter will show you

how to use it in a “hands-on” fashion.

The LCD screen can display four lines of text, with twenty

characters per line. That won’t let you display a lot of information.

That’s where the screen editor comes in. By using the screen

editor, the HX-20 can display information on a very large  virtual

screen. The virtual screen doesn’t have a physical existence, like the

LCD screen, but is rather an imaginary  screen. You can think of it as
lying just behind the LCD screen.

The dimensions of the virtual screen can vary according to the

program you run, but in most cases the virtual screen will be eight

lines high and forty characters wide-twice as high and twice as

wide as the LCD screen itself. The LCD screen is merely a  window

onto this virtual screen. By pressing appropriate keys, you may

move this window up, down, left, and right, thus bringing into view

any desired portion of the virtual screen.

This means that you won’t be limited by the size of the LCD

screen, but can interact with the HX-20  as if it had a much bigger

How can a small window allow you to view the text on a large

virtual screen? To understand how this works, tear page 37 out of
this book, and use scissors to cut out the white box on that page.