Oscillator; Housekeeper Ic - Tektronix 11A52 Service Manual

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Table 2-3 lists miscellaneous pins on the 8052.
Bit# Desc
Reset I
XTLl I
XTL2
0
PSEN
0
ALE
0
Oscillator
TABLE2-3
Miscellaneous Pins
Theory of Operation
ort bits are set hi h on reset
Address latch enable
Microprocessor U700 contains circuitry to drive a 12 MHz ceramic resonator (Y640). All oscillator circuitry is
inside U700 except the 30 pF capacitor etched into the circuit board runs to Y640.
Housekeeper IC (U600)
U600 is a multi-function integrated circuit that provides a serial communication path to the oscilloscope, a
channel switch sequencer, control circuits for an ACVS system with up to 16 analog outputs, and multiplexed
output drivers for setting the gain and bandwidth control bits for both plug-in channels.
In table 2-4, I =Input, 0 = Output, BI = Bi-directional.
Signal
Pin
WR(L)
23
INT
22
cs
21
PSEN(L)
20
ALE 18
RD(L)
24
ADO 17
ADl 16
AD2 15
11A52 Extended Service Manual
Desc
I
0
I
I
I
I
Bi
Bi
Bi
TABLE2-4
U600 Signals
Usage
Writes data into U600.
Interrupt to processor (communication from
oscillosco e)
The PSEN signal when low, allows CPU execution of
instructions stored in RAM (U801)
The RD (read strobe) signal when low, allows the
reading of data stored in RAM by the CPU. The RD
input also causes the U600 to send the data specified by
the last address it captured with ALE from its AD7-
ADO ins, onto those same AD7-ADO ins.
Address in
2-11