Jump to content

Macintosh SE/30 Schematics (modernization effort)


Recommended Posts

10 hours ago, trag said:

Even with identical pairs, it would be the equivalent of "composite" SIMMs.   A little messy logically.

That's one reason why a pair of 64MB SIMMs, one per bank have replaced pairs of 32MB SIMMS for each bank in my related project. Combining a pair of 32MB or a quartet of 16MB SIMMs to fill a single 72pin slot was a thing, that's for yet another research project. Those boards really don't seem all that logically messy  .  .  .  but what do I know. ::)

Link to post
Share on other sites
  • Replies 150
  • Created
  • Last Reply

Top Posters In This Topic

7 hours ago, Trash80toHP_Mini said:

That's one reason why a pair of 64MB SIMMs, one per bank have replaced pairs of 32MB SIMMS for each bank in my related project. Combining a pair of 32MB or a quartet of 16MB SIMMs to fill a single 72pin slot was a thing, that's for yet another research project. Those boards really don't seem all that logically messy  .  .  .  but what do I know. ::)

One 128 meg SIMM would give you two banks of 64 megs, with less fuss.

Link to post
Share on other sites

It would be very cool to have a replacement board for battery bombed systems. I just decided to give up on one today after days of debug. In all cases I've seen the custom ASICs look to be salvageable.  Populating a replacement board would be much faster than going down the rabbit hole of trace repair. 

Link to post
Share on other sites
On 5/15/2020 at 3:36 PM, elemenoh said:

What do these asterisks (or are they bullets?) on the sheet labels mean? Inversion?

 

Screen Shot 2020-05-15 at 1.23.01 PM.png

 

I didn't see this answered earlier, I apologize if I'm blind. Asterisks like that usually mean "active low". (IE, the line is pulled to zero to activate the named function. This is usually the case for chip selects. Not universally so, but usually, because TTL process chips in particular tend to float to "1" if they're left disconnected so it's the slightly safer choice.) Another common convention is to put a /slash in front of the name.

Link to post
Share on other sites
  • 68kMLA Supporter

Another thing I'd love to see on a new board, is a separate crystal for the FPU. On the main system, I believe a lot of things are hanging on the same crystal oscillator, thus the FPU can't easily be replaced with a faster one with its own crystal to run asynchronous, which I believe should be possible if it is given its own. Would it add a lot of performance? No, but, it's the benchmark bragging rights you get, and parts and space wise I don't think a crystal, its caps and the traces should take up much space at all.

Link to post
Share on other sites
  • 68kMLA Supporter

Thank you very much for creating this schematic. I will be using it extensively over the next few days to troubleshoot a sound issue on my SE/30! The Apple schematic was readable, but working through the blur of it added an extra layer to the cognitive challenge of buzzing traces.

Link to post
Share on other sites
  • 2 weeks later...
  • 68kMLA Supporter

@Trash80toHP_MiniThere should be a single file version in the folder called "Macintosh SE/30 Schematic Redraw of 050-0253-01 May-25-2020.pdf"

 

https://drive.google.com/drive/folders/1a29ekZRdQKhGU77sb_dueorzq3sbFU0k?usp=sharing

 

Please let me know if you don't see it there.

Edited by elemenoh
Link to post
Share on other sites

Yep, saw that one and it too is fab. I was thinking about a side to side scrolling single page with connections continuous across what are now discrete pages with tagged connections. That's what I did on paper using prints of the IIsi schematic. I could trace my way across the folded map, following traces from section to section from one end to the other.

 

If you can't do it easily in your PCB package, I can probably do it from your PDF pages in Illustrator, or someone else might pick up the gauntlet?

Link to post
Share on other sites
On 5/25/2020 at 6:13 PM, Trash80toHP_Mini said:

Haven't looked at 128MB as my target machines are IIsi and Quadra 950 which have discrete 64MB banks along with the SE/30's pair of such banks. IIRC, the last I looked I could get a pair of 64MB SIMMs for less than a single 128MB SIMM, has that changed?

The last time I bought SIMMs, I bought half a dozen 128 meg SIMMs for around $10 apiece. Two were used in a Cobalt Raq, and four are waiting for when I recap a Quadra 800 motherboard so I can have a system with 520 megs.

 

The price difference should be negligible, but I was thinking that requiring less SIMM sockets should reduce complexity and cost, no?

Link to post
Share on other sites

Dunno, but I think it might be a bit more power efficient to use the 128MB variety? I lost PMs in progress twice to @trag about this stuff. I think I'm just going to start a parallel thread about the move to 72-pin in a relatively stock SE/30replacement board. I have a single, angled 72-pin Socket. I think more headroom might be necessary for the SE/30 case than the straight up variety might require?

 

Not to rain on your parade, but IIRC no Quadra could address more than 256MB? But maybe they can! Given original "supported" configs at time of release and the introduction of higher capacity modules using higher density RAM ICs, you never know until you try. [:D]

Link to post
Share on other sites

The paths open up in AI9, but the nice type devolves into simple paths. This is doable, below is only a screen shot. Components and connectors on yours are missing, bitmap overlays? line weights and colors are easily fixed. Which pages line up in what order to left and right of this page?

 

Screenshot_of_AI_Schematic.thumb.jpg.cf1dba2d46a1d342ed71d8d606ade36a.jpg

 

Screen Shot 2020-05-21 at 4.09.39 PM.png

 

Three layers showing control signals on one layer with data and address buses on the other two for viewing individually might be helpful?

Link to post
Share on other sites

@elemenoh I just took a good look at these sheets, this is fantastic work. Now you've done the hard work of reading those fuzzy old schematics and people have had a chance to review them, a move to a working schematic in KiCad or similar is so much easier. And from there a PCB. I wonder if Apple would shut it down? There are lots of re-done Amiga PCBs around but Commodore is long gone.

Link to post
Share on other sites
  • 68kMLA Supporter
On 7/12/2020 at 4:58 PM, aeberbach said:

 I wonder if Apple would shut it down? There are lots of re-done Amiga PCBs around but Commodore is long gone.

I really doubt that they care about these machines at all, much less go after someone recreating the PCBs.  It's been done for the Apple II machines, so I doubt they would start now!  No worries!

Link to post
Share on other sites

Wow, really nice work @elemenoh, this is just what I was hoping to see happen sometime.

 

Definitely I'd like to see these schematics make their way into a better information repository than Google Drive, like the 68kMLA wiki, etc.  I'd offer that probably the best way to go about maintaining/improving the schematics would be to put them in a GitHub repo or anything more proper of a revision control system than Google Drive.

 

Sounds like @Bolle may have started on laying out the footprints as a first step in creating the printed circuit board layout.  Even without complete PCB traces, this would allow for the creation of an "interactive BOM" which can be helpful for guiding a recap operation, for example.

 

For sure, it would be interesting to see this go further and include other Macintosh models too.  As I'm also familiar with KiCad, I'd also be willing to chip in to the PCB design.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...

×
×
  • Create New...