h6. [[OS SWI Calls]] h6(. » [[OS_Byte]] h6((. » OS_Byte 217 h2. OS_Byte 217 h5. (SWI &06) |_<^{width:4em}. Entry | | |<^. R0|<^. 217 (&D9) | |<^. R1|<^. EOR value | |<^. R2|<^. AND value | |_<^{width:4em}. Exit|_<^. | |<^. R0|<^. Preserved | |<^. R1|<^. Previous count | |<^. R2|<^. Corrupted | h4. Use The purpose of this call is to read or write the count of lines displayed since the last halt when in [[VDU 14|paged mode]] (VDU 14). h4. Notes This call reads or sets the count of lines displayed since the last page halt when in. Usually this call is used to set the count to 0, before requesting user input – [[OS_ReadLine]] makes this call automatically. h4. See also * [[OS_Byte]] * [[OS_ReadLine]] * [[VDU 14]]