Oki OKICOLOR 8 Maintenance Manual page 15

(1) CPU
The CPU is a 64-bit RISC architecture processor (provided by NEC). It inputs a frequency
of 50MHz and runs at 200MHz. It transfers data to and from memory at 50MHz.
(2) MASK ROM
The Mask ROM block consists of four 16Mbit (1M x 16bits) chips and its total size is 8M bytes.
The chips are mounted on the PCE-PCB by means of IC sockets and store programs and
character fonts.
(3) DRAM
The DRAM block consists of eight 16Mbit (1M x 16bits) chips and its total size is 16M bytes.
The chips are mounted on the PCE-PCB and can be expanded up to 144M bytes by adding
the 32M byte SIMMs to the SIMM slots on the PCE-PCB.
(4) EEPROM
The EEPROM block consists of 16K-bit chips mounted on a board by means of IC sockets
and stores the following:
- Menu data
- Counter values
- Adjustment values
(5) Flash ROM
The Flash ROM block consists of four 4M bit (256K x 16bits) chips and its total size is 2M
bytes. The chips are mounted on the PCE-PCB and are used for storing fonts, macro and
demo pages.
(6) Memory control LSI
This block mainly consists of memory control, CPU control, compression and decompres-
sion, and video interface functions.
(7) Interface control LSI
This block mainly consists of PU interface control, operator panel interface control, EEPROM
control, parallel interface control, and HSP control functions.
(8) Host interface
This printer has the following interfaces to the host.
• Centronics bidirectional parallel interface
• Network interface (Option)
The single effective interface or the automatic interface select mode can be selected using
the menu. If the busy state of the printer continues for a long time period, the buffer near-full
control releases the busy status at constant intervals even if the host side is busy so as not
to cause interface time-out at the host side.
(a) Centronics bidirectional parallel interface
This is an interface conforming to IEEE-1284 and provides either unidirectional and
bidirectional communications according to each of the following communication modes.
• Compatibility mode
Unidirectional communications from the host to the printer.
• Nibble mode
This mode transfers 4-bit wide data from the printer to the host. In this mode, each
bit of 1-byte data is transmits in the form of two nibbles using ERROR, BUSY, FAULT,
and SELECT signal leads. This mode can provide bidirectional operation in
combination with the compatibility mode.
41057610TH Rev. 1
14 /