ZX80 character set

It has no relationship with previously established ones like ASCII or EBCDIC, but it is related though not identical to the character set of the successor ZX81.

With the most significant bit set the character is generated in inverse video; corresponding to code points 128–191.

The remaining code points (64–127 and 192–255) are used as control characters or Sinclair BASIC keywords, while some are unused.

The small effective range of only 64 unique glyphs precludes support for Latin lower case letters, and many symbols used widely in computing such as the exclamation point or the at sign.

There are also changes to the control characters and code point 1 is no longer an unprintable string terminator.

Screenshot of a ZX80 4K BASIC program that demonstrates all code points including BASIC keywords and nonprintable characters, the latter rendered as question marks except `CHR$(1)` rendered as a null string. Therefore the top line covers the 33 code points 0–32, the following 5 lines cover 32 each, and the last lines with keywords cover yet fewer.