Accelerator Cards and Original Device CPUs

badferday

badferday

Tinkerer
Jan 26, 2024
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If I wanted to slim down a group of boards, and the highest point is a socketed accelerator, could I delete the OG CPU on the board?

I'm wondering if, once the accelerator is connected, the original CPU is totally ignored by the system. Orrrr.... maybe OG CPU is needed for very early boot stuff.

Anyone tried this out?
 
B

bakkus

Moderator
Staff member
Mar 18, 2022
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The way CPU accelerators _generally_ work on Macs is that the original CPU (along with the ROM) does the first startup of everything, including launching the OS. Then a system extension takes over and punts the processing over to the accelerator. Removing the original CPU will render the system unbootable.

Note that it very much depends on your exact system and your exact accelerator, but described over are the most common ones.
 
Anden Selmani

Anden Selmani

New Tinkerer
Sep 28, 2022
19
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3
Albania
I am thinking that your question is too vague!

Depending on if you are using PDS-slot type or CPU-socket type!

On the SE30 main-board you would removing the old CPU to install a socket-upgrade! New CPU completely replaces the old one!
 
badferday

badferday

Tinkerer
Jan 26, 2024
174
42
28
Anden Selmani said:
I am thinking that your question is too vague!

Depending on if you are using PDS-slot type or CPU-socket type!

On the SE30 main-board you would removing the old CPU to install a socket-upgrade! New CPU completely replaces the old one!
Click to expand...
Hi Anden.

I'm asking about socketed types.

Thanks!
 
Bolle

Bolle

Tinkerer
Nov 1, 2021
46
74
18
badferday said:
I'm asking about socketed types.
Click to expand...
Still depends on the machine and upgrade type, they're not all the same.
On the one shown above it's obvious as the original CPU comes out for the upgrade to drop in.
Some machines that use adapters that go into the CPU socket and present a IIci style slot for an accelerator move the logicboard over to the adapter in a passthrough socket and they still rely on the original CPU to be in place.

A lot of the upgrades for 68000 based Macs do need the original CPU to work as well. The Performer for example won't work without a 68000 in place even if you use the CPU socket interface instead of the PDS.
 
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