page_title: ZX81 character set
section_title: Printable characters
hierarchical_section_title: ZX81 character set / Printable characters
caption_attribution_description: English: Screenshot of the output of the following simple ZX81 Sinclair Basic program which demonstrates the machine's character set for all code points; 0–255. 10 FOR C=0 TO 255 20 PRINT CHR$ C; 30 NEXT C Notes: The output includes tokenized BASIC keywords and non-printable characters such as 67–127 and 195 which appear as question marks (although some are used as control codes). Code point 11 is the double quote character (") when used in the video memory (called the display file). CHR$ 192 prints as the same character but that code point shows as two double quote characters ("") in BASIC listings and is used for including a single literal double quote character (") in a string without it being interpreted as a string delimiter.
context_page_description: The ZX81 character set is the character encoding used by the Sinclair Research ZX81 family of microcomputers including the Timex Sinclair 1000 and Timex Sinclair 1500. The encoding uses one byte per character for 256 code points. 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 predecessor ZX80.
context_section_description: The character set has 64 unique glyphs present at code points 0–63. With the most significant bit set the character is generated in inverse video; corresponding to code points 128–191. These 128 values are the only displayable ones allowed in the video memory (known as the display file). The remaining code points (64–127 and 192–255) are used as control characters such as 118 for newline, or uniquely to Sinclair BASIC for 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 and the at sign. The lack of an apostrophe led some software authors to use a comma instead.
  There are 11 block graphics characters, counting code point 0 which also doubles as space. Together with the 11 inverse video versions these 22 code points provide every combination of the character cell divided into 2×2 black-and-white block pixels for low-resolution 64×48 pixel graphics, or into 1×2 black, white or dithered gray wide block pixels for a 32×48 resolution. The 2×2 versions of these are also present in the Block Elements Unicode block.
  Code point 11 is the double-quote (") symbol when used in the display file. The BASIC function CHR$ 192 prints as the same character but is shown as "" in BASIC source listings; it is used for including the literal " character in a string without conflict with the " string delimiter.
caption: Screenshot of a ZX81 8K BASIC program that demonstrates all code points including BASIC keywords and nonprintable characters, rendered as question marks.
exif: {}