Many early computers (limited to a 7-bit, 128-position character set) used a variant of ASCII with one of the less-frequently used characters replaced by the £. The UK national variant of ISO 646 was standardised as BS 4730 in 1985. This code was identical to ASCII except for two characters: x23 encoded instead of , while x7E encoded instead of . MSDOS on the IBM PC originally used a non-standard 8-bit character set Code page 437 in which the £ symbol was encoded as x9C; adoption of ISO character codes only came later with Microsoft Windows. The Atari ST also used position x9C. The HP Laserjet used position xBA for the £ symbol, while most other printers used x9C. The BBC Ceefax system which dated from 1976 encoded the £ as x23. The ZX Spectrum and the BBC Micro used x60 (grave). The Commodore 64 used x5C while the Oric used x5F . IBM's EBCDIC code page 037 uses xB1 for the £ while its code page 285 uses x5B. ICL's 1900-series mainframes used a six-bit (64-position character set) encoding for characters, loosely based on BS 4730, with the £ symbol represented as octal 23 (hex 13, dec 19).