Transtech Transputer, User Manual

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The Host Interface
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Transputer Motherboard User Manual TMB M 711
space. Hence, the actual reads the transputer performs are reads
from the write port. Figure 90 illustrates this operation.
For communications from the transputer to the PC a similar process
occurs: the transputer writes to a block of memory in its external
memory space, this memory is folded by hardware to a single
location in the PC’s I/O space (the read port) which the PC reads with
a string read instruction.
Clearly the operation of the interface depends on synchronization
between the two processors. When the Intel processor writes to the
write port it cannot perform another write until the transputer has
performed a read operation. Similarly, when the transputer writes to
the read port, it cannot perform another write until the Intel processor
performs a read. This synchronization is achieved via the respective
processor’s wait line.
Intel processor
T2 transputer
PC’s I/O space
transputer memory map
read block
write port
write side
read side
memory interface
mapping
Figure 90. Inter processor communications (write)