This information is edited from a repost of an acig.org forum post by mrdetonator:
http://www.secretprojects.co.uk/forum/index.php/topic,25.msg59.html#msg59
The fire control system/radar system ensures:
1. target acquisition in all-aspect at any weather condition, day/night
2. identification friend or foe
3. tracking of single target in head-on/pursuit, measuring range and angular position
4. all-aspect engagements of air targets at altitudes =>1.5 km with the R-23R and rear-aspect engagement with the R-23T,R-3S,R-13M,R-60. (Hc <>= Hs)
5. rear-aspect engagements of targets flying at low altitudes using the R-23T,R-3S,R-13M,R-60. (Hc > Hs)
6. rear-aspect engagements of small/big targets flying at low altitudes using the R-23R, R-23T,R-3S,R-13M,R-60. (Hc < Hs)
7. rear-aspect engagements of maneuvering targets using asynchronous aiming methods and gun weapons.
8. detection and engagements of low-speed targets
9. giving command signals to fire, end of intercept,......when manual/automatic(ARL-SM) flight controls.
10. giving command signals for ready/launch of R-23R,R-23T,R-3S,R-13M,R-60.
11. providing STT mode for the R-23R.
12. giving the range information to the ASP HUD-sight when gun firing at air targets.
13. giving the range information to the ASP HUD-sight when gun firing at ground targets and bombing.
(Hs- altitude of the Mig-23, Hc- target altitude)