possible). As an example of a POKE-driven support chip control scheme, the following POKE command is directed at a specific register of the Commodore 64's built-in VIC-II graphics chip, which will make the screen border turn black: POKE 53280, 0 A similar example from the Atari 8-bit family tells the ANTIC display driver to turn all text upside-down: POKE 755, 4 The difference between machines, and the importance and utility of the hard-wired memory locations, meant that "memory maps" of various machines were important documents. An example is Mapping the Atari, which starts at location zero and mapped out the entire 64 kB memory of the Atari 8-bit systems location by location. PEEK and POKE in other BASICs North Star Computers, a vendor from the early 1980s, offered their own dialect of BASIC with their NSDOS operating system. Concerned about possible legal issues, they renamed the commands EXAM and FILL. There were also BASIC dialects that used the reserved words MEMW and MEMR instead. BBC BASIC, used on the BBC Micro and other Acorn Computers machines, did not feature the keywords PEEK and POKE but used the question mark symbol (?), known as query in BBC BASIC, for both operations, as a function and command. For example: > DIM W% 4 : REM reserve 4 bytes of memory, pointed to by integer variable W% > ?W% = 42 : REM store constant 42; equivalent of 'POKE W%, 42' > PRINT ?W% : REM print the byte pointed to by W%; equivalent of 'PRINT PEEK(W%)' 42 32-bit values could be POKEd and PEEKed using the exclamation mark symbol (!), known as pling, with the least significant byte first (little-endian). In addition, the address could be offset by specifying either query or pling after the address and following it with the offset: > !W% = &12345678 : REM ampersand (&) specifies hexadecimal > PRINT ~?W%, ~W%?3 : REM tilde (~) prints in hexadecimal 78 12 Strings of text could be PEEKed and POKEd in a similar way using the Dollar sign ($). The end of the string is marked with the Carriage return character (&0D in ASCII); when read back, this terminating character is not returned. Offsets cannot be used with the dollar sign. > DIM S% 20 : REM reserve 20 bytes of memory pointed to by S% > $S% = "MINCE PIES" : REM store string 'MINCE PIES', terminated by