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BJC-2000
BJC-2000
Nibble mode
In nibble mode, the printer transfers data twice to the host computer in 4-bit units.
The data is transferred with the PtrClk signal and HostBusy signal handshakes.
After the printer confirms that the HostBusy signal is Low, it prepares 8-bit data,
lowers the PtrClk signal and outputs the lower 4-bits along the control signal line.
After the PtrClk signal is Low, the host computer receives the data and raises the
HostBusy signal. Next, after the printer confirms that the HostBusy signal is Low for
a second time, it outputs the upper 4-bits along the control signal line. If there is no
data to be sent to the host computer after the HostBusy signal is High, the DataAvail
signal becomes High and the printer stands by for the next data transfer.
1284 Active
Ack Data Req
Data (1 to 8)
Host Busy
Host Clk
Ptr Clk
Ptr Busy
Data Avail
0000 0000
Printer Busy Status
Xflag
Figure 2-11 Timing Chart (Nibble Mode)
Bit2
Unknown
Bit3
Ptr
Host
Bit0
With data
Nibble mode
Bit1
Support
TP
2-19
Part 2: Product Specifications
Bit6
Bit7
Bit4
Bit5
TP
TP
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