The Mac LC/Performa 580 shipped with 4 MB soldered on the motherboard and two 72-pin SIMM sockets for memory expansion – twice as many as the LC 550 and 575 – for up to 52 MB total system memory, the most possible in any 500-series Mac. Like other 500-series Macs, it has a slide-out motherboard.
With the ports on the motherboard facing you, you will see two SIMM socket near the left edge. The leftmost SIMM socket can accept single-sided or double-sided SIMMs of 1 MB, 2 MB, 4 MB, 8 MB, 16 MB, or 32 MB. The other socket can only accept single-sided SIMMs, which come in 1 MB, 4 MB, and 16 MB sizes. The 72-pin SIMMs must be 80ns or faster.
Some Configuration Options
With six capacity options for the left SIMM slot and three for the right one, there are numerous upgrade options.

Mac LC 580 page from Apple Memory Guide.
- 1 MB in either slot, 5 MB total
- 2 MB in left slot or two 1 MB SIMMs, 6 MB total
- 2 MB in left, 1 MB in right, 7 MB total
- 4 MB in left, 8 MB total
- 4 MB in left, 1 MB in right, 9 MB total
- 2 MB in left, 4 MB in right, 10 MB total
- 8 MB in left or 4 MB in left and 4 MB in right, 12 MB total
- 8 MB in left, 1 MB in right, 13 MB total
- 8 MB in left, 4 MB in right, 16 MB total
- 16 MB in left, 20 MB total
- 16 MB in left and 1 MB in right or 1 MB in left and 16 MB in right, 21 MB total
- 16 MB in left and 4 MB in right or 4 MB in left and 16 MB in left, 24 MB total
- 8 MB in left, 16 MB in right, 28 MB total
- 32 MB in left or 16 MB in left and 16 MB in right, 36 MB total
- 32 MB in left, 1 MB in right, 37 MB total
- 32 MB in left, 4 MB in right, 40 MB total
- 32 MB in left, 16 MB in right, 52 MB total
Keywords: #maclc580 #performa580
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