Page Comparison

IN:
     A = reason code:
     SR_SUS ($01)   Save user screen
	 SR_RUS ($02)   Restore user screen
     SR_WPD ($03)   Write parameter data (mailbox)
     SR_RPD ($04)   Read parameter data (mailbox)
     SR_FUS ($05)   Free user screen
     SR_CRM ($06)   Remove card (not implemented)
     SR_CIN ($07)   Insert card (not implemented)
     SR_PWT ($08)   Page wait
     SR_RND ($09)   Occasionally a random number
     SR_SRS ($0A)   Set random seed

     BC, DE, HL, IX = arguments
OUT, if call successful:
     Fc = 0
     returned values depend on A(in)

OUT, if call failed:
     Fc = 1
     A = error code:
          RC_UNK ($03), unknown request
          RC_BAD ($04), bad arguments
          RC_HAND ($08), bad handle
          RC_ROOM ($07), no room
          RC_ESC ($01), with SR_PWT
          RC_SUSP ($69), with SR_PWT
          RC_DRAW ($66), with SR_PWT
          RC_QUIT ($67), with SR_PWT