Printronix P9212 - Communicating with the Host Computer

2–28
Principles of Operation
68EC030
CPU
68EC030 BUS
16 Bit Port
25 Bit Address
FPU
68882
27256
Boot ROM
32K Byte
8 Bit Port
LMI 030 Board
DRAM
4 Banks of
1M/4M Byte
32 Bit Port
DRAM
Controller
Row/Col Address
RAS CAS WE OE*
84C31
Data
Buffers
74F245
LMI Board
* RAS = Row Address Strobe
CAS = Column Address Strobe
WE = Write Enable
OE = Output Enable
Figure 2–17. Hardware Implementation of the LMI 030 Board
Communicating with the Host Computer
The Z8S180 processor runs both the parallel and serial interfaces.
Host Parallel Input Parallel inputs are nine bits wide, but the Z8S180 direct
memory access (DMA) used to make the transfer is only eight bits. The