== Introduction ==
<b>RSX</b> (<b>R</b>esident <b>S</b>ystem e<b>X</b>tensions) were a way to extend the command set of Locomotive BASIC, e.g. for accessing external peripherals like disk drives, light pens, speech synthesizers and so on.
RSX commands can be distinguished from normal commands by the preceeding preceding pipe symbol "'''| '''" (Also also called "RSX bar", "RSX pipe" or "RSX slash").
Some of the best known RSX commands are the ones provided by AMSDOS, as they were present on all CPC664, CPC6128, 6128plus CPC6128+ and CPC464 with DDI-1:
<b>'''|A'''<br /b><br>
Makes drive A: the current work drive
<b>'''|B'''<br /b><br>
Makes drive B: the current work drive
<b>'''|CPM'''<br /b><br>
Starts CP/M (or other systems) from a system disk
<b>'''|DISC'''<br /b><br>
Switches back to disk drive use after |TAPE
<b>'''|TAPE'''<br /b><br>
Makes the CPC use the tape recorder for file access
RSX command extensions can be implemented through ROMs (like AMSDOS or other disk operating systems) or by programs.
== Reference documentation ==
Reference documentation to write a RSX (assembly-level calls to register one, etc) is supplied in [[Soft968: CPC 464/664/6128 Firmware]] section 10.
[[Category:Stub]] [[Category:Disc Operating_System]]
[[Category:Programming]]
[[Category:BASIC| ]]
[[Category:Operating System| ]]
[[Category:Software]]
[[Category:Programming software| ]]
[[Category:Expansion ROM| ]]
[[Category:RSX| ]]