Vector Graphic Bitstreamer II, Руководство пользователя

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The 8itstreamer II has two independent parallel input/output channels,
called Parallel Channels A and 8. Each channel has its own 34-pin edge
connector. Vector Graphic supplies an optional 34-lina ribbon cable that
connects to this edge connector. The other end of this cable has no
connector on it, allowing you to configure it as desired. Many of the 34
lines are not used, as discussed below.
Each parallel channel has eight pins for output and eight pins for input.
Additional pins provide +5 VOC, +12 VOC, -12 VOC, and GND. Exact pin
assignments are given in Table 12 in Section 2.8. Input and output is
accomplished using IN and
OlJI'
machine language instructions wi thin sof twa re
prepared for specific applications. Output is latched on the board, so that
after an OUT instruction is executed, the eight bits of data remain
available to the external device until the computer changes it. Input is
NOT latched, so that software must be \vritten to sense in some way that data
is available and to input that data. There are no interrupt lines connected
to the parallel channels. Table 2 gives the specific machine language I/O
addresses assigned to each parallel channel.
We repeat a points made earlier:
as sources of interrupts, you cannot
A for normal parallel output. It is
register.
If you are using the 825ls on the board
use the output side of Parallel Channel
used instead as the interrupt
masking