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CHAPTER 3
THE 2920 SIGNAL PROCESSOR
3.0 THE 2920 SIG NAL PROCESSOR
This chapter will discuss the 2920 device operation func-
tional elements and operating conventions.
3.1 Device Operation
3.1.1 Overview of the 2920
Figure 3-1 shows a block diagram of the 2920. The 2920
is divided into three major sections: a program storage
area implemented with EPROM, the arithmetic unit
with data memory and the analog
110
section.
The EPROM section of the 2920 includes an instruction
clock generator and program sequence counter. Signals
from the clock generator and EPROM control the other
two sections.
The arithmetic section includes a 40 word by 25-bit ran-
dom access memory (RAM) with two ports, and an
arithmetic and logic unit (ALU). One of the two input
ports to the AL U is passed through a scaler (barrel
shifter). The arithmetic section executes commands
from EPROM, thereby performing digital simulation of
analog functions in real-time.
The analog section performs analog to digital (AID)
and digital to analog
(01
A) conversions upon com-
mands from the EPROM section. The analog section
includes:
• an input multiplexer (4 inputs),
• an input sample-and-hold circuit,
• a digital to analog converter
(01 A),
• a comparator, and
• an output mUltiplexer with 8 output sample-and-
hold circuits.
A special register called the DAR (for digital/analog
register), acts as an interface between the digital and
analog sections.
VSP------------~--------------------------------------------,
PROGRAM STORAGE
(EPROM)
1----------
RST/EOP
RUN/PROG--------·L __
~~--------------~'9:2~X~24~--~----~~----~~
SIGIN ( 0 ) - - - - - - - - - - ,
SIGIN ( 1 ) - - - - - - - 1
SIGIN
(2)-------,
SIGIN ( 3 ) - - - - - - 1
X2
CCLK _----X-'_/C_LK-I
CLOCK LOGIC
&
PROGRAM
COUNTER
'EXTERNAL COMPONENTS
1
VREF
Figure 3-1. 2920 Block Diagram
3-1
1 - - - - - -
SIGOUT
(0)
1--------
SIGOUT (,)
1-------
SIGOUT (2)
DMUX
1--------
SIGOUT
(3)
&
s&H's
1--------_
SIGOUT
(4)
1 - - - - - -
SIGOUT
(5)
1--------
SIGOUT
(6)
I - - - - - - S I G O U T
(7)
M2
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