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Macintosh SE/30 logicboard recreation (thread revival)

herd

Well-known member
I think I saw somewhere that you can take apart a 72-pin memory stick to build four 30-pin sticks. If they are equivalent, wouldn't it be pretty simple to print these new boards with two 72-pin sockets instead of eight 30-pin sockets? Would that be an improvement, or does that ruin the exercise somehow?
 

croissantking

Well-known member
I think I saw somewhere that you can take apart a 72-pin memory stick to build four 30-pin sticks. If they are equivalent, wouldn't it be pretty simple to print these new boards with two 72-pin sockets instead of eight 30-pin sockets? Would that be an improvement, or does that ruin the exercise somehow?
I think it’s been talked about. It’s an interesting idea especially with the difficulty in getting hold of 30-pin SIMM sockets. It would leave you with space on the motherboard to integrate something else…
 

Chopsticks

Well-known member
I think I saw somewhere that you can take apart a 72-pin memory stick to build four 30-pin sticks. If they are equivalent, wouldn't it be pretty simple to print these new boards with two 72-pin sockets instead of eight 30-pin sockets? Would that be an improvement, or does that ruin the exercise somehow?
I actually did that when I upgraded my se/30 to have 128mb of ram, for me it was way cheaper at the time to buy 72pin ram with the correct size memory IC's and make my own 16mb simms.

in terms of replaceing the se/30's 8 ram slot with 72pin simms, its certainly doable, however while I haven't looked at the differences its likely some addition logic (like a PAL/GAL etc) would be needed to deal with stuff like RAS/CAS etc..

and then as it would free up room on the logic board the next question is what to do with that unused space...

following from that the subject of the CPU and bus speed seems to get brought up.. i.e replacing the ASIC...
 
I Feel like I may be missing something obvious but I cannot find if anyone has posted a good source of 30 pin SIMM sockets, and for the 64 pin ROM socket. My donor board has some corrosion issues and would prefer to replace if possible.

Thanks much!
 

Jockelill

Well-known member
P
I Feel like I may be missing something obvious but I cannot find if anyone has posted a good source of 30 pin SIMM sockets, and for the 64 pin ROM socket. My donor board has some corrosion issues and would prefer to replace if possible.

Thanks much!
PE connectors seems to have:

I have not bought from them myself yet though, I tried to order, but they only do US shipping and seems to only accept US credit cards (mine bounced).
 

Chopsticks

Well-known member
I Feel like I may be missing something obvious but I cannot find if anyone has posted a good source of 30 pin SIMM sockets, and for the 64 pin ROM socket. My donor board has some corrosion issues and would prefer to replace if possible.

Thanks much!
if you hunt around you can still find 30pim sockets from time to time, but finding 64pin rom sockets its probably not even possible these days, last time i got some of those was around 4 years ago and while i bought about 5 of them, i kind of regret i didnt but like 10-20 of them.

i couple years ago i actually 95% finished a design for a rom socket that was 64pins on one side and 72pin on the opposite side with the idea of making a modern clone of SIMM programmer that uses a 72pin slot instead. the thought was that it would make it easier for people to build one and start messing around with hacking ROM's.

not sure if thats better then just putting a usb programmer right on the back of the simm or not (assuming it would fit clearance wise), but the unobtainium 64pin sockets sent me down that path before i got busy again with study
 
Well I am nearing the end of the build!

But I am getting the lovely horizontal lines no matter what RAM or ROM combination I use.

Any thoughts on the first component to suspect?
20230228_194501.jpg16776326624252099374747252250710.jpg
 
Well I am nearing the end of the build!

But I am getting the lovely horizontal lines no matter what RAM or ROM combination I use.

Any thoughts on the first component to suspect?
View attachment 53082View attachment 53083
I Have toned out the connections from bank A SIMMs to the Resistor Packs and then from the RPs to the UI/UJ2,3,4 and that is all good. So address muxes seem fine. Everything on this board is new components from mouser whenever possible.
No combination of RAM and ROM (inc rominator) changes the display
 

croissantking

Well-known member
I Have toned out the connections from bank A SIMMs to the Resistor Packs and then from the RPs to the UI/UJ2,3,4 and that is all good. So address muxes seem fine. Everything on this board is new components from mouser whenever possible.
No combination of RAM and ROM (inc rominator) changes the display
Do you get chimes of death?
 
No death chimes at the moment. No sounds happening at all.
I have also checked the lines through RP1 and UD1, those tone out good.
I have to work to tone out the ROM socket next, and obviously these chips were from a blown board so even the CPU could be bad.
 

robin-fo

Well-known member
Sadly I am scopeless. I may have to finally bite the bullet and order a scope.

You probably gonna need it 😔

I personally prefer USB scopes over standalone ones because they save desk space and are easier to configure. I have an entry level PicoScope which I like (but the Mac version of their software is quite unstable).

If you also want a logic analyser, go for Saleae! Their software is brilliant, I use it every day. There are also chinese clones which work ok.
 
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