ABS and airbags became optional in 1987 for the 944 series. Neither were ever offered for the 924S.
The 87 944 Turbo had airbags standard with ABS being a rarely equipped option.
The 88 944S got airbags as standard. The 88 944 Turbo S had standard ABS in addition to the airbags.
In 1989 both the 944 turbo (S) and the 944 S2 had airbags and ABS standard.
US safety laws mandated cars built 4/89 and later to have airbags or other safety devices. At this point the 89 944 was given standard airbags for its final months of production.
AFAIK ABS was never standard on the 944 (base) or 944S.