Samsung MSYS 5150 Service Manual page 52

Circuit Description
DRAM CONTROLLER
As KS32C6100 has DRAM contro l l e r, DRAM can be
connected with external memory.
The control mode of DRAM contro l l e r c a n a c c e s s
EARLY WRITE, NORMAL READ, PAGE MODE, and
BYTE/HALF, and supports EDO DRAM as well as
normal DRAM.
DRAM READ/WRITE signals use /DWE signal to
control system buses. It supports CAS BEFORE RAS
for DRAM REFRESH. Connected with common
/CAS(0-3), /RAS(1:0), it consists of 2 banks and each
may be connected with up to 2M - 8M halfword , t h e
default setting of this system is 8MB.
The field of DRAM is in figure 5 - 1 ( E n t i re S t ructure o f
Main Circ ui t fo r E ac h Key Sig nal ), related timing
diagram is in figure 5 - 4 .
RTC (REAL TIME CLOCK)
RTC circuit maintains current time information, and it
operates in both primary power mode and battery
back-up mode. As RTC does not in MFP contro l l e r,
RTC IC is needed separately. T h i s c i rc u i t ( RTC-4513)
r eceives clock sourc e f rom an internal 32.768 kHz
crystal, and divides it into hours, minutes, seconds,
year, month, and day. RTC_EN, DATA and CLK
contro l t h e RTC IC. RTC_EN is CHIP SELECT signal,
D ATA i s b i d i rectional signal and used to select mode,
write addre s s , read/write data. CLK reads or output
d a t a i n r i s i n g e d g e .
5-4
PARALLEL PORT INTERFA C E
KS32C6100 has parallel port interface enabling
parallel interface with PC. This part connected with
the computer through the centronics connector makes
possible parallel interface with the computer. I t
generates control signal and consists of /ERROR, PE,
BUSY, /ACK, SLCT, /INIT, /SLCTIN, /AUTOFD,
and /STB.
Data is transmitted according to the standard of IEEE
P1284 (http://www.fapo.com/ieee 1284.html). The
controller supports compatibility mode which is the
traditional way to transmit print data, nibble mode
(4bit data) to upload data to the computer, a n d ECP
(Extended Capabilities Port: 8bit data transmission)
duplex high-speed transmission with the computer.
Compatibility mode, called as Centronics mode, is
p rotocol which used to transmit data from PC to
p r i n t e r. ECP mode is protocol which supports rapid
b i d i rectional communication with input/output
device such as printer, s c a n n e r. ECP mode supports 2
c y c l e s f o r b i d i rectional communication: Data cycle
and Command cycle. Command cycle is formed run-
length count and channel addressing. RLE (Run
Length Encoding) mode can compress data, and be
used to transmit raster image to printer or scanner.
This system uses RLE method for high-speed
transmission. It enables data to be printed, uploaded,
and downloaded. It also monitors system.
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