Service manual

100 Theory of operation ENWW
Formatter hardware
The formatter system contains the following:
● CPU—Is a 266 Mhz RISC microprocessor.
● Read-only memory (ROM)—Stores the dot patterns of internal character sets (fonts) in
addition to storing microprocessor control programs.
● Random-access memory (RAM)—Stores printing and font information received from the
host system, and can also serve to temporarily store a full page of print-image data before
the data is sent to the print engine. Increasing the RAM will increase performance of graphic
intense printing operations but it will not increase the I/O buffer space or cause the printer to
print more pages per minute.
● Nonvolatile memory (NVRAM)—Stores information about the I/O and print environment
configuration. The printer keeps the contents of NVRAM when the power is turned off or
disconnected. (As in other HP LaserJet printers, downloaded fonts and macros are saved in
conventional RAM and are lost when power is turned off.)
● Interfaces
• Parallel interface—Receives incoming data through its IEEE1284 B interface connector.
The IEEE1284 B interface provides high-speed, two-way communication between the
printer and the host, letting the user change printer settings from the host computer.
• USB—Receives incoming data through its universal serial bus (USB) connector. The USB
interface provides high-speed, two-way communication between the printer and the host,
letting the user change printer settings computer.
• EIO—The PCI-based enhanced input/output (EIO) slots support a wide range of print
servers and other add-on devices. HP JetDirect EIO cards provide high-speed, two-way
communication for network printing over Ethernet, Ethernet and LocalTalk, Token Ring, or
Fast Ethernet networks.