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Low level Macivory interface

    Date: Wed, 14 Nov 90 10:21:28 GMT
    From: bwild%fzi.uka.de@RELAY.CS.NET (Bernd Wild)

    We have then put together a MacIvory board and a Transputer board
    into our MacII in order to make a shared memory communication
    between both boards. We have already succeeded in have them
    running simultaneously in peace, one under Genera 8.0.1 and the 
    other under Helios. The problem now is the coupling between
    both systems. While the transputer has an archaic 1-byte communication
    buffer/channel at a fixed memory address the Symbolics source code
    gives no indications about the implementation of low level 
    memory addressing of absolut NuBus addresses. We traced the function
    %MEMORY-READ and %MEMORY-WRITE but the essential sources are in
    a IPRIMITIVES.LISP file we don't have. 

%MEMORY-READ and %MEMORY-WRITE are hardware instructions of the Ivory
chip so having the IPRIMITIVES file wouldn't tell you much.  In any case
they are documented online.

    Is there anybody who knows something about writing/reading at/from an 
    absolut NuBus address

You can use this interim function until Symbolics provides NuBus support
in the sys:bus-read and sys:bus-write functions.  For example,

  (sys:%memory-read (sys:%make-nubus-slot-address #xC 0))

Be very careful using these functions, it's easy to crash your Macintosh and
I wouldn't be surprised if you could do actual damage to the hardware if there
are some devices on the NuBus that will damage themselves if you send them an
incorrect command or if you accidentally write all over the Macintosh operating

;;; -*- Mode: LISP; Syntax: Zetalisp; Package: SYSTEM-INTERNALS; Base: 8; Patch-File: T -*-
;;; Patch file for Private version 0.0
;;; Reason: Function SYS:%MAKE-NUBUS-ADDRESS:  Convert Nubus address to Ivory address.
;;; Function SYS:%MAKE-NUBUS-SLOT-ADDRESS:  Access superslot space.
;;; Written by Moon, 10/12/88 12:14:41


(NOTE-PRIVATE-PATCH "%make-nubus-address")


  "-*- Mode:LISP; Package:SYSTEM-INTERNALS; Base:8; Syntax: Zetalisp -*-")

    (OTHERWISE (ERROR "Only MacIvory systems have a NuBus")))
				   (%LOGLDB (BYTE 30. 2) ADDRESS))))