Oki ML420 Maintenance Manual page 11

(2) Program ROM (external FLASH ROM)
The program to make the printer work is stored in FLASH ROM as external ROM.
FLASH ROM that can be installed is 64Mbit(16 x 4096k) or less. The access timing of
the outline to FLASH ROM is shown in the following.
(3) RAM
In RAM, the memory capacity built into SOC is 256K x 16bit (4Mbit).
(4) USB Controller
The USB Controller detects and controls the USB interfacee.
The USB controller is built into SOC. The figure below shows the outline circuit.
42113931TH Rev.1
SOC
A0~A21
D0~D15
A0~A21
CS-N
RD-N
WR-N
D0~D15
USB ON-N
SOC
USB ON-N
DP-P
DM-N
USB LEV-P
ROM
WR-N
RD-N
CS-N
+3.3V
USB Connector
D+
D-
VCC
0V
FG
0V
0V
Oki Data CONFIDENTIAL
11 /