HP 54750A, User Manual, Page: 430 / 478

How the Instrument W orks
System Architecture
The major mainframe hardware components
This section describes the major hardware components within the mainframe .
T rigger generator The trigger generator receives the trigger input and sends a signal to the
sequential delay generator whenever an edge meeting the trigger criteria is
received, when the trigger is enabled.
Sequential delay
generator
The sequential delay generator controls the time between when it receives a
trigger input from the trigger generator and when it sends a trigger output
to the pulse lter . These delay times increase sequentially with each trigger
event, allowing the trace to build up from left to right across the screen.
The delay values depend on the record length and timebase setting, and are
programmed into the sequencer memory by the system microprocessor .
A/D converter The A/D converter tracks the peak value of the analog pulse at its input and
converts it to a 12-bit digital word. These 12-bit words are put into a FIFO
memory which is then read and processed by the CPU .
CAL table The CAL table automatically adds the calibration factors to the sampled data.
The result is referred to as adjusted data, and it is sent to the system bus .
The CAL table increases the throughput of the analyzer because the CPU now
reads calibrated data, and does not have to explicitly correct it. This is faster
than using a software solution.
Microprocessors and
coprocessors
There are two 32-bit microprocessors , one 32-bit coprocessor , and one 16-bit
coprocessor in the mainframe .
Motorola 68020 A 32-bit microprocessor that controls the system hardware ,
and also acts as a trac controller on the system bus .
Motorola 68882 A 32-bit coprocessor that performs all of the oating point
math.
TMS34010 A 32-bit microprocessor that draws data on the display .
HP custom
graphics
coprocessor
A 16-bit coprocessor that controls the gray scale persistence
mode , and also writes blocks of data (like the markers and
display background) to the display .
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