Canon multipass c3000 Service Manual (en)

Download
b-2) Data transfer from the facsimile to the host computer in Nibble mode
Data is transferred by the following steps.
The host computer sets HostBusy to low to indicate that it is ready to receive data (①). 
The facsimile sets the low-order nibble of the byte (0 to 3 bits) to four lines: nDataAvail,
Xflag, AckDataReq, and PtrBusy.  (These lines are the reverse channel data lines.)(②).
The facsimile sets PtrClk to low (③), and the host computer receives data (0 to 3 bits). 
The host computer sets HostBusy to high to notify the facsimile that the computer has
received data (④).
The facsimile sets PtrClk to high to end the data (0 to 3 bits) transfer (⑤). 
The host computer sets HostBusy to low to receive the data (4 to 7 bits) (⑥). 
4 to 7 bits data transfer is carried out as same as 0 to 3 bits transfer and 1 bite  transfer
completes (②' ~ ④'). 
If the next byte can be transferred, the facsimile sets nDataAvail to low (⑦), and PtrClk to
High to responds to host’s receipt (⑤').
Some types of host computers use a mode other than the Bi-Centronics
interface Nibble mode as default.  In this case, the host computer must be
set to Nibble mode.  Check the host computer specifications and change the
print mode if necessary.  The Nibble mode is specified in the IEEE-P1284
standard, but it may be called differently STD, Uni-Direction, Compatible,
AT, etc. For some computers.
Chapter 2: Technical Reference
2-13
Data bit 2
Data bit 3
Data bit 0
Data bit 1
Data bit 7
Data bit 4
Data bit 5
1
2
3
4
5
6
2
3
4
7
5
AckDataReq
(PError)
HostBusy
(nAutoFd)
PtrBusy
(Busy)
PtrClk
(nAck)
nDataAvail
(nFault)
Xflag
(Select)
P
H
P
P
P
P
Data Transfer Phase
Data bit 6
P : Peripheral (Facsimile)
H : Host
'
'
'
'
Figure 2-6 Nibble Mode Facsimile to Host Data Transfer
NOTE