Apple II
Technical Notes
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                                                  Developer Technical Support


Apple II Miscellaneous
#6:    IWM Port Description

Revised by:    Glenn A. Baxter                                  November 1988
Written by:    Cameron Birse                                    February 1986

This Technical Note documents the IWM port pin assignments on various 
machines.
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Apple IIGS Disk Port Pin Assignments

            Signal Name    Disk Port Pins (DB-19)
            Phase 0                11
            Phase 1                12
            Phase 2                13
            Phase 3                14
            /WReq                  15
            Dr1                    17
            Rd                     18
            Wr                     19
            Wrt Prot               10
            Dr2                     9
            HeadSel                16
            Gnd                 1,2,3
            3.5Disk                 4
            -12v                    5
            +5v                     6
            +12v                  7,8

Apple IIe UniDisk 3.5 Controller Disk Port Pin Assignments

            Signal Name    Disk Port Pins (DB-19)
            Phase 0                11
            Phase 1                12
            Phase 2                13
            Phase 3                14
            /WrtReqII              15
            /HstEnbl               17
            Rd                     18
            Wr                     19
            Wrt Prot               10
            No Connection        9,16
            Gnd               1,2,3,4
            -12v                    5
            +5v                     6
            +12v                  7,8

Apple IIc Disk Port Pin Assignments

            Signal Name    Disk Port Pins (DB-19)
            Phase 0                11
            Phase 1                12
            Phase 2                13
            Phase 3                14
            /WrtReq                15
            /Enbl 2                17
            Rd                     18
            Wr                     19
            Wrt Prot               10
            No Connection          16
            Gnd               1,2,3,4
            -12v                    5
            +5v                     6
            +12v                  7,8
            External Interrupt      9

            Note:    On the Apple IIc Plus, 
            the disk port pins are driven 
            by a custom ASIC instead of by 
            the IWM chip.

Macintosh Disk Port Pin Assignments

            Signal Name    Disk Port Pins (DB-19)
            Phase 0                11
            Phase 1                12
            Phase 2                13
            Phase 3                14
            /WrtReq                15
            /Enbl 2                17
            Rd                     18
            Wr                     19
            PWM                    10
            HdSel                  16
            GND               1,2,3,4
            -12v                    5
            +5v                     6
            +12v                  7,8

