Host Interface - Samsung SCX-5312F Service Manual

CIRCUIT DESCRIPTION

3-4 HOST INTERFACE:

Referred to IEEE 1284 standard.
3-4-1. HOST INTERFACE
PARALLEL PORT INTERFACE PART KS32C61200 has the Parallel Port Interface Part that enables Parallel Interface with
PC. This part is connected to PC through Centronics connector. It generates major control signals that are used to actuate
parallel communication. It is comprised of/ERROR, PE, BUSY, /ACK, SLCT, /INIT, /SLCTIN, /AUTOFD and /STB. This part
and the PC data transmission method
(http://www.fapo.com/ieee1284.html). In other words, it supports both compatibility mode (basic print data transmitting
method), the nibble mode (4bit data; supports data uploading to PC) and ECP (enhanced capabilities port: 8bits data - high
speed two-way data transmission with PC). Compatibility mode is generally referred to as the Centronics mode and this is
the protocol used by most PC to transmit data to the printer. ECP mode is an improved protocol for the communication
between PC and peripherals such as printer and scanner, and it provides high speed two-way data communication. ECP
mode provides two cycles in the two-way data transmission; data cycle and command cycle. The command cycle has two
formats; Run-Length Count and Channel Addressing. RLE (Run-Length Count) has high compression rate (64x) and it
allows real-time data compression that it is useful for the printer and scanner that need to transmit large raster image that has
a series of same data. Channel Addressing was designed to address multiple devices with single structure. For example,
like this system, when the fax/printer/scanner have one structure, the parallel port can be used for other purposes while the
printer image is being processed.This system uses RLE for high speed data transmission. PC control signals and data
send/receive tasks such as PC data printing, high speed uploading of scanned data to PC, upload/download of the fax data
to send or receive and monitoring the system control signal and overall system from PC are all processed through this part.
PPD( 7: 0)
BUSY
nSTROBE
nACK
Repair Manual
3-22
support the method
DATA
<Compatibility Hardware Handshaking Timing>
- This Document can not be used without Samsung's authorization -
specified in IEEE P1283 Parallel Port Standard
Samsung Electronics