Specifications

Memory Guide Early Macintosh - 1
Macintosh Plus
The Macintosh Plus has no
soldered DRAM, but comes
with four 256K DRAM SIMMs
installed. You can expand the
memory to a total of 4 MB by
installing DRAM SIMMs.
Remember to install the
highest density SIMM in Bank
A first.
Note: When 1 MB SIMMs
are installed, the 256K
resistor (R8 or R9) must be
clipped or removed to enable
recognition of the higher
density SIMMs.
Memory Information
DRAM Speed 150 ns
SIMM Type 30-pin
Soldered DRAM None
Number of SIMM Slots 4
Supported Sizes in MB 256K, 1
Maximum DRAM 4 MB
Virtual Memory No
Soldered VRAM None
Number of VRAM Slots None
Note: Clip one lead of the resistor and move
the resistor out of the way so it can be
reinstalled if necessary.
DRAM Configurations
1 MB • Install four 256K SIMMs.
• Leave resistor R8.
• Remove resistor R9.
2.5 MB • Install two 1MB SIMMs
(Bank A).
• Install two 256K SIMMs
(Bank B).
• Remove resistor R8.
• Remove resistor R9.
4 MB • Install four 1MB SIMMs.
• Remove resistor R8.
• Remove resistor R9.