Theory of Operation
TDS 310, TDS 320 & TDS 350 Service Manual 3Ć9
Display System A1Ă 7
A display controller IC processes text and waveforms. The display system
sends the text and waveform information to the monitor assembly as a video
signal. The display system also generates vertical (VSYNC) and horizontal
(HSYNC) sync signals for the monitor assembly.
The display circuit's primary function is writing waveforms into waveform
planes. The circuitry provides Vector,Dot, Vector Accumulate, Dot
Accumulate, XY,and YT display modes.
The display system provides text, graticule, and waveform bit planes. All
information displayed is first written to a plane. Planes are stored in
dedicated DRAMS along with the vector lists. The information is sent at
regular refresh intervals as an analog video signal.
The waveform display circuit takes a list of sample points, translates them
into intensities for the bit map, writes those intensities to the bit map in the
proper location, and interrupts the CPU when it is done.
Vector Lists Ċ Fourvector lists available from two DRAMs U706 and U707
(TDS 320 SN B029999 and below) or U706 (TDS 310 and TDS 350 and
TDS 320 SN B030100 and above) store waveform sample data. Before
starting a normal display mode, the CPU writes data to a vector list.
Rasterizers Ċ The display controller (U701) provides tworasterizers. Their
primary function is to draw" vectors between sample points. The display
controller also performs the top and bottom clip display functions on
waveforms.
Video Timing Ċ Q701-Q704 and associated circuitryconvert digital video
signals from the display controller into an analog video signal, with two
levels controlled by and from the daculator.
The display controller also creates monitor timing (31.25 Hz) and
(60 Hz). U703, U708D, and U705 generate AUX HSYNC, and AUX
VSYNC and AUX VIDEO for the Option 14 VGA Video output connector
(TDS 310, TDS 320, and TDS 350 SN B030100 and above).
The A2 Option Board has GPIB, RSĆ232, and Centronics interfaces for
external control and hard copy operations. The A3 board has VGA Video
output and printer power interfaces (TDS 310, TDS 320,and TDS 350
SN B030100 and above).
Refer to schematic A2Ă 1. Signals travel from the processor board through
the J1 connector to the U2 address decoder.U2 uses lines A15, A16, and
A18 to break incoming addresses to either the RSĆ232, Centronics, GPIB or
option ROM.
A2/A3 Option Board(Option 14Instruments Only)