Editing Apple LaserWriter Plus (section)

== System Architecture ==

=== Processor and Memory ===
The LaserWriter Plus used identical processing hardware to the original LaserWriter:

'''Central Processing Unit:'''
* '''CPU:''' Motorola MC68000
* '''Clock speed:''' 12 MHz crystal (operating at 11.16 MHz)
* '''Data bus:''' 16-bit
* '''Address bus:''' 24-bit (16 MB addressable)
* '''Wait states:''' 1 wait state on memory access (performance limitation)

'''Memory Configuration:'''
* '''ROM:''' 1 MB mask ROM (doubled from original)
* '''RAM:''' 1.5 MB total DRAM
** 512 KB workspace RAM for PostScript interpreter
** 1 MB frame buffer for page rasterization

* '''RAM type:''' 150ns DRAM chips
* '''Memory expansion:''' None (fixed configuration)

=== Controller Board Design ===
The LaserWriter Plus maintained the streamlined PAL-based architecture:

* '''Logic implementation:''' Monolithic Memories medium-scale integration PALs
* '''Address decoding:''' PAL-based memory management
* '''Timing control:''' PAL-generated signals for DRAM refresh and video timing
* '''Bus interface:''' Direct 68000 bus connection to memory and I/O
* '''ROM addressing:''' Extended addressing for 1 MB ROM space

=== PostScript Interpreter ===
The LaserWriter Plus featured the same PostScript implementation with expanded font resources:

'''PostScript Implementation:'''
* '''Version:''' PostScript Level 1
* '''Licensor:''' Adobe Systems
* '''Language features:''' Complete programming language with stack-based execution
* '''Graphics capabilities:''' Vector graphics, Bézier curves, arbitrary transformations
* '''Font handling:''' Type 1 outline fonts with hinting
* '''Font cache:''' Dynamic allocation in RAM

'''Interpreter Performance:'''
* '''Rasterization:''' Real-time interpretation during printing
* '''Complex pages:''' Could require several minutes for full rasterization
* '''Memory management:''' Dynamic allocation for fonts and graphics