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Thread: NuBus Slot ID Assignment Encoding . . . maybe?


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Permlink Replies: 1 - Pages: 1 - Last Post: Dec 17, 2016 5:35 PM Last Post By: Trash80toHP_Mini Threads: [ Previous | Next ]
Trash80toHP_Mini

Posts: 45
Registered: 10/19/12
NuBus Slot ID Assignment Encoding . . . maybe?
Posted: Dec 7, 2016 7:36 AM
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Info from DCaDftMF3e p.54: Card slot identification signals

Identification signals 3 through 0 (/ID3-/ID0) are binary encoded to specify the physical location of each slot. The highest numbered slot ($F) has the four signals wired low. The lowest numbered slot ($0) has all ID signals high.

< snip >

. . . each of the 16 possible NuBus card slots has an address . . .
____________________________________________________________________

I think I've noodled it out, here's the table:

https://imagizer.imageshack.us/v2/569x743q90/922/x3o45Y.jpg

This would confirm my guess that "NuBus Slot $D encoding could be a single bit Delta value for /ID0 on pin C26."

Looks like I just need to make sure the top slot of the Gemini Card IDs as the IIsi's native $9 (instead of the Duo's $C) and then just pull /ID1 low on pin A26 to morph the lower slot into the IIsi's $B slot assignment. Same for the /30! :D

Does this look right? I always wondered why the Mac's IDs jumped from $0 to $9, it never made sense before.


edit: just thought I may have it backwards. Would the normal states for signals usually be high and pulled low or where "wired low" is pulled pulled high for encoding?

Message was edited by: Trash80toHP_Mini

Trash80toHP_Mini

Posts: 45
Registered: 10/19/12
Re: NuBus Slot ID Assignment Encoding . . . maybe?
Posted: Dec 17, 2016 5:33 PM   in response to: Trash80toHP_Mini in response to: Trash80toHP_Mini
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Well, I think I finally have this one licked. Check from this pos ton for final updates: NuBus Slot ID Assignment Encoding . . . maybe?

I've got enough to go on to move ahead with take two of my long back burnered project: TWO SLOT IIsi Nubus Card hack . . . (SE/30 hacks)

We shall see . . . 8-)

Message was edited by: Trash80toHP_Mini

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