Path: utzoo!utgpu!watmath!clyde!att!pacbell!ames!mailrus!cornell!uw-beaver!ubc-cs!van-bc!root
From: lphillips@lpami.van-bc.UUCP (Larry Phillips)
Newsgroups: comp.sys.amiga.tech
Subject: Re: 32-bit LUCAS memory board
Message-ID: <1985@van-bc.UUCP>
Date: 29 Nov 88 14:40:14 GMT
Sender: root@van-bc.UUCP
Lines: 41

In <1988Nov23.104910.15213@gpu.utcs.toronto.edu>,
	 anakin@gpu.utcs.toronto.edu (Anakin Research) writes:
> 	I would like to move the kickstart area into this 32-bit wide path.
> I must admit that I haven't given this enough thought and any ideas on how 
> this would be accomplished would be appreciated. I can prevent assertion of
> *AS (Address Strobe) in the kickstart range and simply have ROMS on the LUCAS 
> memory board. This seems to me constitute a copywrite infringement. Anyone 
> understands the legalese of this and who could hopefully suggest an honest 
> workaround, please advise me.

  This reminds me of a little trick I used when I built my first computer.
I had a bootstrap ROM (16 bytes.. whoopeee), and 1K of RAM. When the
'load/run' switch was in the 'load' position, the boot ROM was at location 0,
and the ram was at $1000. When in the 'run' position, the ROM and RAM
switched locations.  The boot ROM accepted keystrokes on the hex keypad
when the ROM was active, and placed them sequentially (2 strokes, one byte)
into RAM.  I would then press the 'reset' switch, toggle 'load/run' to
'run', and let the reset switch go, and the program I entered would run.

  The 'load/run' switch simply toggled address line 12, being attached to
one leg of an exclusive OR gate, line 12 to the other leg.

  So...  what about a PAL latch or a flip-flop that controls one address
line such that we can transfer the contents of KS ROM to a chunk of RAM
well out of the way of any currently used locations.  We then write to the
PAL or flip-flop location to toggle it.  The toggling would (a) change the
address of the newly written KS to the proper location, (b) write protect
it, and (c) 'steer' any accesses to the 32 bit KS.

Just a thought.

-larry

--
"Intelligent CPU?  I thought you said Intel CPU!" 
        -Anonymous IBM designer-
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|   //   Larry Phillips                                          |
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