Whether marked Quadra 630 DOS Compatible, LC 630 DOS Compatible, or Performa 631 or 640, these models have 4 MB of RAM soldered to the motherboard, two 72-pin SIMM sockets for memory expansion up to 52 MB, and usually a DOS Compatibility card as well.

The Quadra model is a bit more powerful with its full 68040 CPU, while the LC and Performa models use the 68LC040 version of the CPU, which has not FPU (Floating Point Unit).

With the edge connector facing away from you, you will see a SIMM socket near the left edge of the motherboard, running from the front of the computer to the rear. It is typically filled with a 4 MB SIMM from the factory. This can be filled with a 1 MB, 2 MB, 4 MB, 8 MB, 16 MB, or 32 MB SIMM. The SIMM must be 80ns or faster.

The second SIMM socket only supports single-sided modules to a maximum of 16 MB.

Some 64 MB SIMMs are compatible with the 630’s left SIMM socket. See the pickle’s Low-End Mac FAQ for clarification on which 64 MB SIMMs are compatible and which are not. With a compatible SIMM, you can have 68 MB in your 630.

To add memory, simply put the new SIMM in the SIMM socket.

LC 630 DOS Compatible page from Apple Memory Guide.

DOS Compatibility Card

The DOS Compatibility Card is unique to these Quadra, LC, and Performa models. It has no built-in RAM and a single 72-pin SIMM socket. It can use memory on the computer’s motherboard if memory is not installed on the DOS Compatibility Card.

The DOS Card supports 4 MB, 8 MB, 16 MB, and 32 MB 72-pin SIMMs that are 80ns or faster. The card also has 512 KB of built-in VRAM for PC video.

Keywords: #quadra630 #maclc630 #performa640

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