from original Adobe PS 1.0.7 manuals:

• Macintosh SE, SE/30, II, IIx, IIci, IIcx with a minimum of 2 megabaytes of RAM

• System software 6.0.3

For Adobe PS 2.5:

• An Apple Macintosh II computer with a 68020 (or any later model) with a minimum 3 MB of RAM.

• System software 6.0.7

• 32-bit QuickDraw

Adobe recommends a Macintosh II with 68030 or 68040 processor, System 7 or higher and from 5 to 8 MB RAM.