RESERVED pins on the SE/30 PDS and PowerCache?????

[Trash80toHP_Mini]

DayStar Adapters definitely connect to pins reserved for Apple's use on the SE/30 PDS.

off buzzed his IIsi PowerCache TwinSlot Adapter for me and reported entirely unexpected GAL connections to PDSA1 and PDSA2:

 PowerCache 120 Shades of Pins.pdf

I just found a clear as day surface trace connection from GAL to PDSA1 on a single GAL DayStar Adapter for which I had high hopes. :-/

I figured I could start eliminating control signals from the list of suspects by tracing any direct connections from PDS slot to IIci slot on pics of the adapters I have on file. I started with the one TimHD sent me and was making some good progress and BAM! There it was  .  .  .  in red.





TimHD-OneChip-A-001.PDF

Little help please!

If anyone's familiar with the SE/30 or IIsi schematics, could you check to see if A1,A2 & B1 on the PDS are documented as being connected to something, anything? They have been reserved for Apple's use, but they must be doing something?

 

[Trash80toHP_Mini]

Let's narrow that down a bit.

SE/30 Engineering Release Schematic - Apple



Not helpful. :-/

The BOMARC schematic for the IIsi is a lot more helpful:



So PDSA2 is SELECT PDS? Why the heck would Apple document that one as reserved?

Gotta buy BOMARC's SE/30 schematic next.

edit: I found connections to PDSA1 a/o PDSA2 on pics of another pair of adapters that I haven't begun to tease apart. Looks like the cloning project has hit a major roadblock if it turns out that I can't treat that block of reserved pins as a black box.

 

[Trash80toHP_Mini]

Dug into the IIsi Schematic:



PDSA2 is tied to pin123 on MDU (Memory Decode Unit)

PDSA1 is tied to pins 120 and 69 on MDU and RBV (RAM Based Video) respectively



Need to see what goes on in the SE/30 Schematic, but it's looking like my theory that memory conflicts with Video Subsystems implemented as PseudoSlot $E in the SE/30 and IIsi are the problem. Implementation of NuBus or anything else at Memory Block blocked for Slot $E appears to be the root of all adaptation evil.

ISTR reading that IIci Vampire Video sucks memory mapped as Slot $B for its nefarious purposes because it has NuBus Slots $C-$E implemented. Dunno, couldn't find it this morning.

 

[Trash80toHP_Mini]

 

[Trash80toHP_Mini]

Well, that was a big help!  :   Not only is the BOMARC SE/30 schematic as silent as Apple's Engineering Release when it comes to "Reserved," it made me realize that their IIsi schematic is in error. They've got SEL PDS (NuBus) on pin A2 as opposed to C2 as documented in every Apple reference for the SE/30/IIsi PDS..

Dunno might turn out to be helpful. Since A2 and C2 appear flip-flopped, I can take another look at MDU in the IIsi  .  .  .

.  .  .  and start buzzing connections. :blink:

Playtime in BadGoldEagle's Pivot adapter thread was way more fun, too bad that's over and done from my end. :mellow: