:Template:RISC OS development graphical timeline
{{Graphical timeline
|link-to=RISC OS development graphical timeline
|title=RISC OS development
|align=right
|plot-colour=#bbeebb
|from=1986
|to=2025
|scale-increment=2
|width=9
|height=350
|height-unit=px
|disable-arrow-align=true
|bar1-text=a
|bar1-from=1987
|bar1-to=1999
|bar1-colour=#888888
|bar1-left=0
|bar1-right=0.2
|legend1=a Acorn Computers
|bar2-text=b
|bar2-from=1999
|bar2-to=2000
|bar2-colour=#999999
|bar2-left=0.2
|bar2-right=0.3
|legend2=b Element 14
|bar3-text=c
|bar3-from=1999
|bar3-to=2009.9
|bar3-colour=#aaaaaa
|bar3-left=0.3
|bar3-right=0.5
|legend3=c RISCOS Ltd
|bar4-text=d
|bar4-from=1999
|bar4-to=2003
|bar4-colour=#bbbbbb
|bar4-left=0.5
|bar4-right=0.6
|legend4=d Pace Micro Technology
|bar5-text=e
|bar5-from=2002
|bar5-to=2008
|bar5-colour=#cccccc
|bar5-left=0.6
|bar5-right=0.8
|legend5=e Castle Technology
|bar6-text=f
|bar6-from=2006
|bar6-to=2024.04
|bar6-colour=#dddddd
|bar6-left=0.8
|bar6-right=1.0
|legend6=f RISC OS Open Ltd.
|bar8-from=1998.9
|bar8-to=1999.1
|bar8-colour=red
|bar8-left=-0.05
|bar8-right=0.65
|bar9-from=2001.9
|bar9-to=2002.1
|bar9-colour=red
|bar9-left=0.55
|bar9-right=1.15
|note1=Acorn's demise
|note1-at=1999
|note1-nudge-left=7.2
|note1-nudge-down=0.8
|note1-remove-arrow=yes
|note2=Iyonix
|note2-at=2002
|note2-nudge-left=2.5
|note2-nudge-down=0.8
|note2-remove-arrow=yes
|note3=(Arthur) 1.2
(Acorn Archimedes{{!}}Archimedes)
|note3-at=1987
|note4=2.00
|note4-at=1989.3
|note4-nudge-down=0.2
|note5=2.01 (ARM3)
|note5-at=1990
|note5-nudge-up=0.05
|note6=3.00 (A5000)
|note6-at=1991
|note6-nudge-up=0.1
|note7=3.1
|note7-at=1992
|note7-nudge-up=0.15
|note8=3.5 (Risc PC)
|note8-at=1994
|note8-nudge-down=0.3
|note9=3.6 (Acorn A7000{{!}}A7000)
|note9-at=1995
|note9-nudge-down=0.2
|note10=3.7 (StrongARM)
|note10-at=1996
|note11=3.8 (Ursula)
|note11-at=1998
|note12=4.02
|note12-at=1999.5
|note12-nudge-down=0.2
|note13=4.03 (Kinetic)
|note13-at=2000.4
|note14=4.39
|note14-at=2004.4
|note15=6.0
|note15-at=2007
|note16=5.00 (Iyonix PC{{!}}Iyonix)
|note16-at=2002.7
|note17=6.20
|note17-at=2009.9
|note18=5.18
|note18-at=2011.2
|note19=5.20
|note19-at=2013.7
|note20=5.22
|note20-at=2015.4
|note21=5.24
|note21-at=2018.4
|note22=5.28
|note22-at=2020.10
|note23=5.30
|note23-at=2024.04
||caption=Time-scale of RISC OS releases and development
}}