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OS_Out may also be used to write screen driver codes by writing them in a series of OS_Out sequences, eg. 1, '2', '+', 'B' to switch on bold typeface.
Related calls
GN_Nln, send newline (CR/LF) to standard output
GN_Soe, write string at extended address to standard output
GN_Sop, write string to standard output, local memory
OS_Bout, write null-terminated string block at (B)HL to standard output
OS_Pout, write embedded null-terminated string at caller (PC) to standard output