Apple LaserWriter 12/640 PS - Manual (Page 319)

319 Technical Information
You can optionally install the Windows PPD files for these Apple LaserWriter
printers:
m LaserWriter Select 360
m LaserWriter Pro 600
m LaserWriter Pro 630
m LaserWriter Color 12/600 PS
m LaserWriter 16/600 PS
m LaserWriter 12/640 PS
RAM upgrade specifications
To increase the printer’s RAM, purchase SIMMs with the following
specifications:
SIMM dimensions
m Length: 107.95 mm +/- 0.20 mm (4.25 in. +/- .008)
m Height: 25.53 mm (1.005 in.) maximum
SIMM sizes and speeds
Size Configuration Speed Connector type
4 MB SIMM 1 M X 32 bit (one 4 MB bank) 70 ns or less 72-pin
8 MB SIMM 2 M X 32 bit (two 4 MB banks) 70 ns or less 72-pin
16 MB SIMM* 4 M X 32 bit (one 16 MB bank) 70 ns or less 72-pin
32 MB SIMM* 8 M X 32 bit (two 16 MB banks) 70 ns or less 72-pin
* Must have a 2 KB row (11 bit x 11 bit) refresh configuration. 16 MB SIMMs with a 4 KB row (10 bit X 12 bit) refresh
configuration are not compatible with the printer.