Wang 5536 - General Overview

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Since CPU bus-control logic is not available to supply data transfer timing
or to initiate refresh cycles during a DMA operation, separate DMA bus
timing must be provided by the OMA device. Some provision is required to
ensure that refreshes occur often enough to preserve memory content.
DMA requests are accepted from the. Data Link. The Data Link is given
priority to reduce delays in the Master. This priority schedule allows a
pending Disk Bus Request to be converted to a Data Link Transfer if the
Data Link Request is received before disk transfer actually begins.
Priority logic, then, effectively inhibits the unselected DMA device once
OMA transfers begin.
OMA Enables permit selected devices to place OMA addresses and data onto
th~ system bus. OMA Enables also ensure that only the selected device is
allowed to control the main memory write control lines.
2.3.2.4 Diagnostic PROM
Diagnostic PROM holds special instructions for CPU operation in the
maintenance mode, providing in-house service personnel with a broader range
o·f diagnostic capability. It is not used in the field.
2.4 TELECOMMUNICATIONS OPTION
2.4.1 GENERAL OVERVIEW
Telecommunications is supported on the 5536 workstation by utilizing the
Z80A microp~~cessor. The workstation has the ability to support a variety
of asynchr .ous and synchronous conununication protocols when loaded with
the appropriate microcode. A typical configuration is shown in Figure 2-9.
553~
WORKSTATION
ZBOA PROCESSER 1------1----1
KEYBOARD &
CRT MONITOR
COMM.
CHANNEL
MODEM
MASTER
Figure 2-9. 5536 Workstation with TC Configuration
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