Epson C117001-N Service Manual - Page 58

from the Parallel Interface, Mimml, 0per8thg, Ffinchl&e - dfx + driver

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DFX-5000+ Servics Mimml 0per8thg Ffinchl&e Figure 2-19 shows the data flow for data input via the parallel interface. Although various circuits perform data processing, the control core is the CPU and all operations are executed via the CPU. In this circuit, the gate array IC (IC7) provides the interface between the external heat computer and the CPU, and all data processing is performed by read/write operations to MMIO (Memory Mapped Input/Output). Data from the host computer is latched by repeating steps 1 through 3 below. 1. Upon receiving the STROBE signal, IC7 latches the data into ports DIOO - 7and sets the BUSY signal to HIGH. 2. The CPU reads the latched data from the MMIO pcx% checks whether the data is a print command (CR code), and stores it in the input data buffer if it is not. 3. After checking the data, the CPU makes IC7 clear the BUSY signal and output the ACKNLG signal, via the MMIO accesses. When either a CR code is received or the input data buffer becomes full, the CPU sets the BUSY signal to HIGH and executes printing. E05A87 (IC7) CPU (ICI) PS-RAM (IC3) a, .:$ STROBE 1 2 Input Data 40 o Buffer DATA DATA 0 CR command ? DATA Buffer Full. ,.. Yes -: + e Yes ')o BUSY or IACK L .......... m w '*A +r-, I 'u(lCl) I d4 Command Analyzer el- AHribute T Printer Mechanism Driver o8 + Character Generator I Down Load ""; Image Buffer I I ?1 I Figure 2-19. D8tti flow from the Parallel Interface 4. The CP[J reads the data from the input data buftkr, analyzes eacii byte to determine whether it is a character or a coremand, and converts it to print data. The print data consists of l-byte character codes and 2-byte attributes. Character data is stored as character codes and commands or character types are stored as attributes. Rev. A 2-19

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DFX-5000+
Servics
Mimml
0per8thg
Ffinchl&e
a
,
.:
$
Figure 2-19 shows the data flow for data input via the parallel interface. Although various circuits
perform data processing, the control core
is
the CPU and all operations are executed via the CPU.
In this circuit, the gate array
IC
(IC7)
provides the interface between the external heat computer
and the CPU, and all data processing is performed by read/write operations to
MMIO
(Memory
Mapped Input/Output).
Data from the host computer is latched by
repeating
steps 1 through
3
below.
1. Upon receiving the STROBE signal,
IC7
latches the data into ports
DIOO
- 7and sets the BUSY
signal to HIGH.
2. The CPU reads the latched data from the
MMIO
pcx%
checks whether the data is a print
command (CR code), and stores it in the input data buffer if it is not.
3. After checking the data, the CPU makes
IC7
clear the BUSY signal and output the
ACKNLG
signal, via the
MMIO
accesses. When either a CR code is received or the input data buffer
becomes full, the CPU sets the BUSY signal to HIGH and executes printing.
E05A87
(IC7)
STROBE
40
1
CPU
(ICI)
PS-RAM
(IC3)
o
2
Input
Data
Buffer
.
.
-:
+
e
‘)
o
0
. . . . . . . . . . . . . . . . .
DATA
.:
DATA
CR command ?
DATA
Buffer Full.
,..
Yes
Yes
BUSY or
IACK
m
+r-,
..+---------
. . . . . . . . . . . . . .
L
w
‘*A
I
‘u(lCl)
I
d
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
4
Command
Analyzer
el-
AHribute
T
Printer Mechanism
Driver
o
8
+
Character Generator
Image Buffer
. . . . . . . . . . . . . . . .
I
I
Down Load
““;
I
I
?1
Figure 2-19.
D8tti
flow
from the Parallel Interface
4.
The
CP[J
reads the data from the input data
buftkr,
analyzes
eacii
byte to determine whether it
is a character or a coremand, and converts it to print data. The print data consists of l-byte
character codes and 2-byte attributes. Character data is stored as character codes and
commands or character types are stored as attributes.
Rev.
A
2-19