Apple ColorLaserWriter 12/600PS - Manual (Page 170)

You can purchase additional RAM for the printer in units of 1, 4, and 16 MB
SIMMs. You can also purchase RAM expansion kits from many electronics
and computer outlets. For information about the RAM specifications required
to expand your printer’s memory, see Appendix A.
IMPORTANT The RAM used in the Color LaserWriter 12/600 PS is not the
same type of RAM used in earlier LaserWriter II printers. The two are not
interchangeable.
Installing RAM
The printer’s controller board has two slots, marked J10 and J11, for installing
additional memory. RAM is provided on SIMMs (Single Inline Memory
Modules) that you insert into the slots.
Your printer comes with 8 MB of RAM soldered on the main board and 4
MB inserted into slot J10.
You must have at least 12 MB of RAM in the printer, and you can increase
the total to as much as 40 MB. For example, to increase the memory size
to 16 MB, install a single 4 MB SIMM in slot J11. To increase the memory
size to 24 or 40 MB, install one or two 16 MB SIMMs in slots J10 and J11
(16 + 8 = 24; 16 + 16 + 8 = 40).
WARNING Refrain from handling the memory until you have put on
a grounding wrist strap. Handling the memory without wearing a
grounding strap may allow static electricity to be discharged into
the memory and damage it. If you don’t have a grounding wrist strap, be
sure to purchase one from a computer dealer.
145 Installing Options