Theory of Operation
3-42 2715 Spectrum Analyzer Service Manual
PEAKDIS_L. In the Normal Mode this bit selects one of the two acquisition
modes. Either the Max Peak, when low,or the Min/Max algorithm when high. In
the Enhance Mode this bit is used in conjunctionwith the ACQM0 bit of Mode
Control Register 2 to invoke Sample and Min Peak algorithms. SeeTable 3--3
below.
HLF/FLL_L. In the Normal Mode this bit selects one of two positions on the
CRT screen to normalizethe B, C--Save A display. When this bit is low, the
B,C--SaveA display will be normalized to the top of the CRT screen. Whenthis
bit is high, the B,C--SaveA display will be normalized to the middle of the
screen. In the EnhancedMode this bit is used in addition to the POS1 bit in
Mode Control Register 2. See Mode Control Register 2 below for more details.
ACQ_ON. This bit asynchronously enables/disables the storingof vertical data
into the waveform memory.When this bit is high, the vertical data will be stored
in waveform memory.When this bit is low, the vertical data will not be stored in
waveform memory.It is important to understand that the A/D converter is still
running and the vertical dataprocessing sections are still running. All that this
bit does is control the ability to store the vertical data after being processed.
RDZEN. This bit is not used in the Display Storage board.
DS_PROTECT. This bit is not used in the Display Storage board.
Mode Control Register 2. Mode Control R egister 2 is located in I/O space, at
location 0x0FA04. Mode Control Register 2 is a read/write register.
In order to write to this register,it must first be enabled by setting the MCREG2
bit (bit 7) of the Scroll Register high. Ifat any time the MCREG2 bit is cleared
(set low) Mode Control Regist er2 w ill be cleared and disabled.
Table3 -3: Mode Control Register 2
Bit
Number Mnemonic
Activity
Level Description
7Not used
6Not used
5Not used
4Not used
3Not used
2ENB2715 High Enables features available in 2715 instrument
1POS1 High MSB of B,C --Save A waveform position
0ACQM0 High LSB of acquisition mode control
ENB2715. This bit, when high, enables the Enhanced Mode of the board.