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Apple Macintosh Processor-Direct Slot (PDS)


Available on Apple Macintosh SE/30 & IIfx

Cards in the PDS are accessed at 20MHz. This speed should let developers create PDS cards without using expensive components while still providing access to the processor bus. There are two locations in the memory map for PDS cards. Developers should see the "Cards and Drivers Manual" for information on creating PDS cards. This manual is available from APDA.

The cache connector in the Macintosh IIci may look like the Macintosh IIfx PDS connector, but the pinouts are vastly different.

Pin Name Description
A1 res Reserved
A2 res Reserved
A3 /BUSLOCK Bus Clock
A4 /IRQ3 Interrupt Request 3
A5 /IPL2* 68030 IPL2
A6 /CIOUT* 68030 Cache inhibit out
A7 /STERM* Sync.cycle termination
A8 /DSACK1* 68030 Data ack 1
A9 SIZ1 transfer size bit 1
A10 /BGACK* 68030 bus grant ack
A11 FC2 68030 function code 2
A12 /RESET* System reset
A13 D0 Data bit 0
A14 D2 Data bit 2
A15 D5 Data bit 5
A16 D8 Data bit 8
A17 D10 Data bit 10
A18 D13 Data bit 13
A19 D16 Data bit 16
A20 D18 Data bit 18
A21 D21 Data bit 21
A22 D24 Data bit 24
A23 D26 Data bit 26
A24 D29 Data bit 29
A25 A31 address bit 31
A26 A29 address bit 29
A27 A26 address bit 26
A28 A23 address bit 23
A29 A21 address bit 21
A30 A18 address bit 18
A31 A15 address bit 15
A32 A13 address bit 13
A33 A10 address bit 10
A34 A7 address bit 7
A35 A5 address bit 5
A36 A2 address bit 2
A37 +5V +5 VDC
A39 GND Ground
A40 -12V -12 VDC
B1 res Reserved
B2 GND Ground
B3 /TM1A ?
B4 /IRQ2 Interrupt Request 2
B5 /IPL1* 68030 IPL1
B6 /DS* 68030 Data Strobe
B7 /CBACK* cache burst ack
B8 /DSACK0* 68030 Data ack 0
B9 SIZ0 Transfer Size bit 0
B10 /BG* 68030 bus grant
B11 FC1 68030 function code 1
B12 /BERR* Bus error
B13 +5V +5 VDC
B14 D3 Data bit 3
B15 D6 Data bit 6
B16 GND Ground
B17 D11 Data bit 11
B18 D14 Data bit 14
B19 +5V +5 VDC
B20 D19 Data bit 19
B21 D22 Data bit 22
B22 GND Ground
B23 D27 Data bit 27
B24 D30 Data bit 30
B25 +5V +5 VDC
B26 A28 address bit 28
B27 A25 address bit 25
B28 GND Ground
B29 A20 address bit 20
B30 A17 address bit 17
B31 +5V +5 VDC
B32 A12 address bit 12
B33 A9 address bit 9
B34 GND Ground
B35 A4 address bit 4
B36 A1 address bit 1
B37 +5V +5 VDC
B38 ECLK ?
B39 GND Ground
B40 -5V -5 VDC
C1 PWROFF Power Off?
C3 /TM0A ?
C4 /IRQ1 Interrupt Request 1
C5 /IPL0* 68030 IPL0
C6 /RMC* 68030 read modify cycle
C7 /CBREQ* 68030 cache burst req
C8 R/W* 68030 read write
C9 /AS* 68030 address strobe
C10 /BR* 68030 bus request
C11 FC0 68030 function code 0
C12 /HALT* 68030 Halt
C13 D1 Data bit 1
C14 D4 Data bit 4
C15 D7 Data bit 7
C16 D9 Data bit 9
C17 D12 Data bit 12
C18 D15 Data bit 15
C19 D17 Data bit 17
C20 D20 Data bit 20
C21 D23 Data bit 23
C22 D25 Data bit 25
C23 D28 Data bit 28
C24 D31 Data bit 31
C25 A30 address bit 30
C26 A27 address bit 27
C27 A24 address bit 24
C28 A22 address bit 22
C29 A19 address bit 19
C30 A16 address bit 16
C31 A14 address bit 14
C32 A11 address bit 11
C33 A8 address bit 8
C34 A6 address bit 6
C35 A3 address bit 3
C36 A0 address bit 0
C37 +5V +5 VDC
C38 C16M 16 MHz Clock
C39 GND Ground
C40 +12V +12 VDC

Below a table with differences found in the Apple Macintosh IIfx computers:

Pin Name Description
A1 GND* Ground
A3 res Reserved
A4 n.c. Not connected
A38 Reserved by Apple
B1 ECS Early cycle start
B2 n.c. Not connected
B3 /PDS.BG ?
B4 /IRQ15 ?
B38 n.c. Not connected
B39 /SLOT.E 68030 slot E replace in address map
C1 /PFW Shutdown bit
C2 n.c. Not connected
C3 /PDS.BR Bus request
C4 /IRQ6 ?
C38 CPUCLK* 20 MHz clock

Contributor: Joakim Ögren

Apple Tech Info Library 5744: Macintosh SE/30,IIfx: Processor-Direct Slot (PDS) Pinouts at Apple TIL homepage

Copyright © The Hardware Book Team 1996-2001.
May be copied and redistributed, partially or in whole, as appropriate.
Document last modified: 2001-06-07