All information on this page was taken from: http://www.cityfujisawa.ne.jp/~akitsura/connect/X68_ex.html

===== X68000 I/O Expansion Slot =====
|  |  **Side A**| | | |**Side B**  |  |
|  |  GND|**1**| |**51**|GND  | |
|  20MHz Clock|  20M|**2**| |**52**|10M  |10MHz Clock  |
|  |  GND|**3**| |**53**|10M  |10MHz Clock  |
|  Data Bus|  DB00|**4**| |**54**|E  |Enable  |
|  Data Bus|  DB01|**5**| |**55**|AB00  |Address Bus  |
|  Data Bus|  DB02|**6**| |**56**|AB01  |Address Bus  |
|  Data Bus|  DB03|**7**| |**57**|AB02  |Address Bus  |
|  Data Bus|  DB04|**8**| |**58**|AB03  |Address Bus  |
|  Data Bus|  DB05|**9**| |**59**|AB04  |Address Bus  |
|  Data Bus|  DB06|**10**| |**60**|AB05  |Address Bus  |
|  |  GND|**11**| |**61**|GND  | |
|  Data Bus|  DB07|**12**| |**62**|AB06  |Address Bus  |
|  Data Bus|  DB08|**13**| |**63**|AB07  |Address Bus  |
|  Data Bus|  DB09|**14**| |**64**|AB08  |Address Bus  |
|  Data Bus|  DB10|**15**| |**65**|AB09  |Address Bus  |
|  Data Bus|  DB11|**16**| |**66**|AB10  |Address Bus  |
|  Data Bus|  DB12|**17**| |**67**|AB11  |Address Bus  |
|  Data Bus|  DB13|**18**| |**68**|AB12  |Address Bus  |
|  Data Bus|  DB14|**19**| |**69**|AB13  |Address Bus  |
|  Data Bus|  DB15|**20**| |**70**|AB14  |Address Bus  |
|  |  GND|**21**| |**71**|GND  | |
|  +12V|  +12V|**22**| |**72**|AB15  |Address Bus  |
|  +12V|  +12V|**23**| |**73**|AB16  |Address Bus  |
|  CPU Function Code|  FC0|**24**| |**74**|AB17  |Address Bus  |
|  CPU Function Code|  FC1|**25**| |**75**|AB18  |Address Bus  |
|  CPU Function Code|  FC2|**26**| |**76**|AB19  |Address Bus  |
|  Address Bus Confirm|  AS|**27**| |**77**|AB20  |Address Bus  |
|  Lower Data Strobe|  LDS|**28**| |**78**|AB21  |Address Bus  |
|  Upper Data Strobe|  UDS|**29**| |**79**|AB22  |Address Bus  |
|  Transfer Direction|  R/W|**30**| |**80**|AB23  |Address Bus  |
|  |  GND|**31**| |**81**|GND  | |
|  -12V|  -12V|**32**| |**82**|HSYNC  |Horizontal Sync  |
|  -12V|  -12V|**33**| |**83**|VSYNC  |Vertical Sync  |
|  Address Bus Valid|  VMA|**34**| |**84**|DONE  |Transfer Complete (DMA)  |
|  Peripheral is addressed around 68000 family (???)|  EXVPA|**35**| |**85**|DTC  |Transfer Complete Device (DMA)  |
|  Data Transfer Acknowledge|  DTACK|**36**| |**86**|EXREQ  |External Request (DMA)  |
|  External Reset|  EXRESET|**37**| |**87**|EXACK  |External Authorization (DMA)  |
|  In: CPU Halt, Out: System Stop|  HALT|**38**| |**88**|EXPCL  |External Peripheral Control (DMA)  |
|  External Bus Error|  EXBERR|**39**| |**89**|EXOWN  |External OWN (DMA)  |
|  External Power On|  EXPW.ON|**40**| |**90**|EXNMI  |External NMI (DMA)  |
|  |  GND|**41**| |**91**|GND  | |
|  +5V|  Vcc2|**42**| |**92**|IRQ2-n  |Interrupt Request (n: slot 1 or 2)  |
|  +5V|  Vcc2|**43**| |**93**|IRQ4-n  |Interrupt Request (n: slot 1 or 2)  |
|  Memory Row/Column Switch Signal|  SELEN|**44**| |**94**|IACK2-n  |Interrupt Enable (n: slot 1 or 2)  |
|  Memory CAS Signal (Read)|  CASRDEN|**45**| |**95**|IACK4-n  |Interrupt Enable (n: slot 1 or 2)  |
|  Memory CAS Signal (Write Lower)|  CASWRL|**46**| |**96**|BRn  |Bus Request  |
|  Memory CAS Signal (Write Upper)|  CASWRU|**47**| |**97**|BGn  |Bus Grant  |
|  Main Memory Refresh Cycle|  INH2|**48**| |**98**|BGACK  |Bus Grant Acknowledge  |
|  +5V|  Vcc1|**49**| |**99**|Vcc1  |+5V  |
|  +5V|  Vcc1|**50**| |**100**|Vcc1  |+5V  |