=Paper= {{Paper |id=Vol-3398/p12 |storemode=property |title=Multi-Valued Logic Digital Circuits for Realizing a Complete Computer Architecture |pdfUrl=https://ceur-ws.org/Vol-3398/p12.pdf |volume=Vol-3398 |authors=Alessandro Simonetta,Maria Cristina Paoletti,Alessio Venticinque |dblpUrl=https://dblp.org/rec/conf/icyrime/SimonettaPV22 }} ==Multi-Valued Logic Digital Circuits for Realizing a Complete Computer Architecture== https://ceur-ws.org/Vol-3398/p12.pdf
Multi-Valued Logic Digital Circuits for Realizing a
Complete Computer Architecture
Alessandro Simonetta1 , Maria Cristina Paoletti1 and Alessio Venticinque2
1
    Department of Enterprise Engineering, University of Rome Tor Vergata, Rome, Italy
2
    Department of Electrical and Information Engineering, University of Naples Federico II, Napoli, Italy


                                           Abstract
                                           The objective of this paper is to lay the foundation for the construction of a computer architecture using entirely multivalue
                                           logic (MVL). To achieve this ambitious result, it is necessary to know how to design all the digital components that normally
                                           form the basis of a computerโ€™s operation. These are combinational circuits dedicated to mathematical computation and
                                           sequential circuits in charge of storing information. In the paper, a general methodology is proposed that can be used for
                                           the construction of digital circuits capable of working independently of the basis of representation of multivalue logic and
                                           the physical quantity used for encoding logical states.

                                           Keywords
                                           MVL, Multi-valued logic, CPU, Computer architecture, digital circuit, adder look ahead



1. Introduction
                                                                                                                                                     ๐‘
The subject of multivalue logic as a natural evolution of                                    ๐‘›โˆ‘๏ธโˆ’1       ๐‘โˆ’1
                                                                                                         โˆ๏ธ
representation in the binary system is a much debated           ๐‘“ (๐‘ฅ ๐‘œ , ๐‘ฅ 1 , ..., ๐‘ฅ๐‘โˆ’1 ) =       ๐‘˜ ๐‘– ยท     ๐‘†๐‘๐‘— (๐‘–)(๐‘ฅ๐‘— ) (2)
issue [1], [2]. Although various solutions, including tech-                                   ๐‘–=0        ๐‘—=0

nological ones, have been proposed, but at present there where:
is no calculator capable of operating in multivalued logic
[3], [4], [5]. However, with the arrival of memresistors [6]       โ€ข ๐‘˜๐‘– is the value taken at the i-th position in the
and a multiplicity of multi-state semiconductor compo-                combination, with ๐‘˜๐‘– โˆˆ T;
nents, the scenario is evolving and the theory developed           โ€ข ๐‘๐‘—(๐‘–) is the j-th digit of the number ๐‘–, represented
in [7] could find easy application. The theory we are                 in base ๐‘› with ๐‘— โˆˆ {0, ..., ๐‘ โˆ’ 1};
going to describe is based on the extension of Boolean             โ€ข ๐‘†๐‘๐‘— (๐‘–) is the value selector ๐‘๐‘— (๐‘–) applied to
algebra and the binary numbering system toward an                     operand ๐‘ฅ๐‘— with ๐‘— โˆˆ {0, ..., ๐‘ โˆ’ 1} e ๐‘– โˆˆ
๐‘›-valued (discrete) numbering system [8], [9]. In this                {0, ..., ๐‘›๐‘ โˆ’ 1};
paper we will start from the theoretical definition and
gradually go on to realize all the digital components that Thus, to express any MVL function ๐‘“ , p+2 basis function
characterize a traditional computer architecture.            are sufficient: ๐‘ selection, addition and multiplication
                                                             functions.

2. Method                                                                                                         2.1. The selection functions
The proposed method use the teory in [10]. Assum- The selection functions ๐‘†๐‘– with ๐‘– โˆˆ {0, ..., ๐‘›โˆ’1}, that we
ing that we have a domain of discrete values T = can call Selectors too, are unary functions. We can define
{0, 1, .., ๐‘› โˆ’ 1}, we can easily show that any function ๐‘“ : as many selectors as there are symbols in the domain T.

                                                    ๐‘“ : T ร— ... ร— T โ†’ T                                (1)                                    ๐‘†๐‘– : T โ†’ B                                  (3)
can be expressed as a linear combination of the input              A selector is able to check whether the value of the
variables:                                                         operand matches a value in the set T:
                                                                                           {๏ธƒ
ICYRIME 2022: International Conference of Yearly Reports on Infor-                           1 ๐‘ ๐‘’ ๐‘ก = ๐‘–
matics, Mathematics, and Engineering. Catania, August 26-29, 2022                 ๐‘†๐‘– (๐‘ก) =                           (4)
" alessandro.simonetta@gmail.com (A. Simonetta);                                             0 ๐‘ ๐‘’ ๐‘ก ฬธ= ๐‘–
mariacristina.paoletti@gmail.com (M. C. Paoletti)
 0000-0003-2002-9815 (A. Simonetta); 0000-0001-6850-1184                                                                           with ๐‘–, ๐‘ก โˆˆ {0, ..., ๐‘› โˆ’ 1}. Using the selection functions,
(M. C. Paoletti); 0000-0003-3286-3137 (A. Venticinque)                                                                              any combination of the input variables can be identified.
                                       ยฉ 2022 Copyright for this paper by its authors. Use permitted under Creative Commons License
                                       Attribution 4.0 International (CC BY 4.0).                                                   For example, to check if all variables ๐‘ฅ0 , ..., ๐‘ฅ๐‘โˆ’1 have
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                                       CEUR Workshop Proceedings (CEUR-WS.org)




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the value ๐‘› โˆ’ 1 except ๐‘ฅ0 which must be equal to 1, we                      3. MVL digital circuits
can use the following function:
                                                                            In this section, we will see how it is possible to construct
                                                                            all the circuits that form the basis of a traditional com-
        ๐œ‘ = ๐‘†1 (๐‘ฅ0 ) ยท ๐‘†๐‘โˆ’1 (๐‘ฅ1 ) ยท ... ยท ๐‘†๐‘โˆ’1 (๐‘ฅ๐‘โˆ’1 )          (5)         puter architecture [11], [12]. Thus, we will start with
                                                                            combinational circuits, those in which the output is a
which returns the value 1 exclusively in the case where                     function of the inputs, and then we will consider the
the input variables meet the requirement:                                   smallest memory element, the D Latch. To accomplish
                                                                            this task we will use the same architectural choice made
          (๐‘ฅ0 , ..., ๐‘ฅ๐‘โˆ’1 ) = (1, ๐‘› โˆ’ 1, ..., ๐‘› โˆ’ 1)            (6)         in [10], and supported by studies in [13], thus a logic
                                                                            based on 4 values that coincides with the base-4 num-
2.2. Sum                                                                    bering system. The four logic values will be represented
                                                                            through the voltage levels as reported in table 1.
Let us consider the summation of equation 2, we observe
that only one term in the summation will be valued at ๐‘˜๐‘ค
corresponding to the coding in base ๐‘› of ๐‘ค. Indeed, all Table 1
the terms of the summation are null except the one corre- MVL levels
sponding to the combination identified by the selection                                               Interval
                                                                 Logic level                                             ๐‘‰๐‘–๐‘‘๐‘’๐‘Ž๐‘™
functions:                                                                                       ๐‘‰๐‘š๐‘–๐‘› โ‰ฅ     ๐‘‰๐‘š๐‘Ž๐‘ฅ <
                ๐‘“ (๐‘ฅ๐‘œ , ๐‘ฅ1 , ..., ๐‘ฅ๐‘โˆ’1 ) = ๐‘˜๐‘ค         (7)            ๐ฟ0                           0            1.25       0.625
                                                                                       ๐ฟ1          1.25        2.50       1.875
2.3. Multiplication                                                                    ๐ฟ2          2.50        3.75       3.125
                                                                                       ๐ฟ3          2.50        5.00       4.375
With reference to the generic term of the summation of
the equation 2, it can be expressed by a function ๐œ‘:                           We also studied the behavior of the proposed circuits
                                                                            by verifying the limits of the adopted components [14],
                  ๐œ‘ : T ร— B ร— ... ร— B โ†’ T                       (8)
                                                                            [15], [16]. In particular, the details for the configuration
that is equivalent to ๐œƒ:                                                    of the components are the following:

                        ๐œƒ :Tร—Bโ†’B                                (9)              โ€ข AND and OR logic gates:
                                                                                        โ€“ Td = 10n
thus:                                                                                   โ€“ Ref = 0.5
                                                                                        โ€“ Trise = 5n
 ๐‘ก ยท ๐‘0 ยท ๐‘1 ยท ... ยท ๐‘๐‘โˆ’1 = ๐‘ก ยท (๐‘0 ยท ๐‘1 ยท ... ยท ๐‘๐‘โˆ’1 ) = ๐‘ก ยท ๐‘ (10)
                                                                                        โ€“ Tfall = 5n
   Indeed, it is sufficient to make a function with two                                 โ€“ Vhigh = 5
operands: one MVL and the other binary. This function                            โ€ข inverted gates:
returns as output the value of the multivalue input (if
                                                                                        โ€“ Td = 5n
the binary value is unity) or zero in the other case:
                                                                                        โ€“ Ref = 0.5
                                                                                        โ€“ Trise = 5n
                          {๏ธƒ
                             0 ๐‘ ๐‘’ ๐‘ = 0
                ๐œƒ(๐‘, ๐‘ก) =                             (11)                              โ€“ Tfall = 5n
                             ๐‘ก ๐‘ ๐‘’ ๐‘ = 1
                                                                                        โ€“ Vhigh = 5
with ๐‘ก โˆˆ T and ๐‘ โˆˆ B.
Recalling that the logical conjunction operation returns
a result that is equivalent to multiplication between bits
                                                                            3.1. LTSpice
(the result is one if and only if all the operands are 1), we               The electronic circuits that we will describe, were de-
can conclude that it is possible to use the AND operator                    signed and validated using the product LTspiceยฎ XVII by
to compute the value ๐‘ in the binary domain. At this                        Analog Device Corporation [17], distributed on the devel-
point it is possible to use that bit to calculate the MVL                   operโ€™s website. This simulator has a graphical interface
function ๐œƒ(๐‘, ๐‘ก). Without loss of generality and with the                   to build the schematics and allows the user to test the
purpose of making the paper easier to read, we will use                     circuits. The tool also allows new features to be defined
the symbol normally used for multiplication to denote the                   and imported as elements in the various schemes. There-
function ๐œƒ conscious of the fact that it is multiplication                  fore, we chose to reuse the circuit diagrams proposed in
between values pertaining to different domains (B โІ T).                     [10] regarding the selectors, multiplexer and half-adder
                                                                            to design new ones.



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3.2. Combinational Circuits

Table 2
MVL true table: adding single MVL digits

       ๐ด๐‘–    ๐ต๐‘–     ๐ถ๐‘–     ๐‘†๐‘–    ๐ถ๐‘–+1      ๐‘”๐‘–      ๐‘๐‘–
       0     0        0     0     0        0         0
       0     0        1     1     0        0         0
       0     1        0     1     0        0         0
       0     1        1     2     0        0         0
       0     2        0     2     0        0         0
       0     2        1     3     0        0         0
       0     3        0     3     0        0         0
       0     3        1     0     1        0         1
       1     0        0     1     0        0         0          Figure 1: Look-ahead full adder single digit detail
       1     0        1     2     0        0         0
       1     1        0     2     0        0         0
       1     1        1     3     0        0         0
       1     2        0     3     0        0         0
       1     2        1     0     1        0         1
       1     3        0     0     1        1         0
       1     3        1     1     1        1         0
       2     0        0     2     0        0         0
       2     0        1     3     0        0         0
       2     1        0     3     0        0         0
       2     1        1     0     1        0         1
       2     2        0     0     1        1         0
       2     2        1     1     1        1         0
       2     3        0     1     1        1         0
       2     3        1     2     1        1         0
       3     0        0     3     0        0         0
       3     0        1     0     1        0         1
       3     1        0     0     1        1         0
       3     1        1     1     1        1         0
       3     2        0     1     1        1         0
       3     2        1     2     1        1         0
       3     3        0     2     1        1         0
       3     3        1     3     1        1         0
       with ๐ด๐‘– , ๐ต๐‘– , ๐‘†๐‘– โˆˆ T and ๐ถ๐‘– , ๐ถ๐‘–+1 , ๐‘”๐‘– , ๐‘๐‘– โˆˆ B

MVL look-ahead adder In this section we will study
the behavior of the circuit MVL look-ahead adder of 4-          Figure 2: Look-ahead full adder blocks scheme
digit base-4 words. In [7] a half-adder consisting of two
inputs and two outputs in base 4 has already been pre-
sented, and starting from this circuit the authors design       as indicated in table 3.
a full-adder in [10]. The most obvious problem with this
circuit is the response time, which depends on the prop-
                                                                Table 3
agation delay of the carryover in the various half-adders.      Adding two MVL words of ๐‘ž length
The time grows as the number of digits of operands and
thus half-adders used to construct the adder increases                         ๐ถ๐‘ž     ๐ถ๐‘žโˆ’1      ...   ๐ถ0
                                                                                      ๐ด๐‘žโˆ’1      ...   ๐ด0    +
[18], [19]. Indeed, in a look-ahead adder the carryover
                                                                                      ๐ต๐‘žโˆ’1      ...   ๐ต0    =
is not affected by the delay of circuit elements placed
in cascade.      Consider two MVL words of length ๐‘ž:                            ๐‘†๐‘ž    ๐‘†๐‘žโˆ’1      ...   ๐‘†0
๐ด = {๐ด๐‘žโˆ’1 , ..., ๐ด0 } and ๐ต = {๐ต๐‘žโˆ’1 , ..., ๐ต0 }, if the
calculated carryovers are ๐ถ = {๐ถ๐‘ž , ..., ๐ถ1 } and ๐ถ0 is            If by the variables ๐‘๐‘– and ๐‘”๐‘– we denote the generated
the potential carryover of a previous least significant         and propagated carryover, respectively, we can build the
word, we can calculate the sum word ๐‘† = {๐‘†๐‘ž , ..., ๐‘†0 }         truth table (table 2) related to the sum of two generic



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Figure 3: Look-ahead adder with 4 MVL digits



MVL digits. The values of ๐‘๐‘– and ๐‘”๐‘– are given by the       a switch driven by a binary signal, can send the value
relation 12 for a cirucite in which the signals are in basecorresponding to ๐ฟ1 to the second half-adder. The adder
n.                                                         circuit will use two half-adders to calculate ๐‘†๐‘– = ๐ถ๐‘– +
                 {๏ธƒ                                        ๐ด๐‘– + ๐ต๐‘– ; the variable ๐‘”๐‘– will be calculated from the first
                   0 ๐‘–๐‘“ ๐ด๐‘– + ๐ต๐‘– โ‰ค ๐‘› โˆ’ 1                    half-adder while ๐‘๐‘– will be calculated using the selection
           ๐‘”๐‘– =                                         (12)
                   1 ๐‘–๐‘“ ๐ด๐‘– + ๐ต๐‘– > ๐‘› โˆ’ 1                    function to understand whether ๐ด๐‘– + ๐ต๐‘– = ๐‘› โˆ’ 1 (figure
                 {๏ธƒ                                        1). This component will be replicated for each couple of
                    0 ๐‘–๐‘“ ๐ด๐‘– + ๐ต๐‘– = ๐‘› โˆ’ 1                   input in order to build a look-ahead adder as in figure
           ๐‘๐‘– =                                         (13)
                                                           2. In figure 3 a look-ahead adder circuit with 4 MVL
                    1 ๐‘–๐‘“ ๐ด๐‘– + ๐ต๐‘– ฬธ= ๐‘› โˆ’ 1
                                                           digits is made. This circuit can be used to perform MLV
In the same way, in the case of the MVL, we can determine word sum with lengths multiple of 4: for example, we can
in advance the values of the carryovers ๐ถ  โˆ‘๏ธ€๐‘–+1 from
                                                   โˆ๏ธ€ the add up 8 MVL digits by cascading two circuits (figure 4).
variables ๐‘”๐‘– and ๐‘๐‘– . Using the symbols        and , for The behavior of the circuit is verified through a concrete
logical disjunction (OR) and logical conjunction (AND), example: suppose we add the value ๐ด = 310200023
respectively, we can write the equation 14.                with ๐ต = 33212131 and that the carryover ๐ถ0 will be 0.
                                                           The expected result is the number S=130232220 as can
                         ๐‘–        ๐‘–โˆ’1      ๐‘–
                       โˆ๏ธ         โˆ‘๏ธ      โˆ๏ธ               be easily seen from the calculation shown in the table 4.
     ๐ถ๐‘–+1 = ๐‘”๐‘– + ๐ถ0        ๐‘๐‘— +       ๐‘”๐‘˜       ๐‘๐‘—     (14)
                       ๐‘—=0       ๐‘˜=0     ๐‘—=๐‘˜+1
                                                                    Decoder A decoder is a combinational circuit with ๐‘Ÿ
However, the values of the carryovers (๐ถ๐‘–+1 ), determined           inputs and ๐‘›๐‘Ÿ outputs. It returns as output the decoded
in such a way, are in the binary domain, instead we need            form of a coded word given as input.
the value corresponding to the logical level ๐ฟ1 of the table        Starting with the most basic decoder, which decodes a
1. Then a transduction element is needed that, through              single digit in the four possible values, we will construct



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Alessandro Simonetta et al. CEUR Workshop Proceedings                                                                     78โ€“89




Figure 4: Look-ahead adder with 8 MVL digits



Table 4                                                               Table 5
An example of two words sum of 8 MVL digits                           MVL True Table
        1    1                       1    1                                         ๐ผ๐‘     ๐‘†0    ๐‘†1    ๐‘†2     ๐‘†3
             3    1    0    2   0    0    2    3   +
             3    3    2    1   2    1    3    1   =                                 ๐ฟ0    ๐ฟ1    ๐ฟ0    ๐ฟ0     ๐ฟ0
                                                                                     ๐ฟ1    ๐ฟ0    ๐ฟ1    ๐ฟ0     ๐ฟ0
        1    3    0    2    3   2    2    2    0                                     ๐ฟ2    ๐ฟ0    ๐ฟ0    ๐ฟ1     ๐ฟ0
                                                                                     ๐ฟ3    ๐ฟ0    ๐ฟ0    ๐ฟ0     ๐ฟ1

the decoder that decodes two-digit words. Making a
single-digit decoder is a simple task because it is sufficient        Since we have two one-value decoders, it is possible to
to use the selection functions by applying them to the                construct a decoder with ๐‘Ÿ = 2 and 42 = 16 outputs (fig-
same input (figure 5).                                                ure 6) using an AND gates array that realizes all possible
                                                                      combinations of pairs relative to the outputs of the two
                                                                      decoders. The figure 6 shows the circuit with the compo-
                                                                      nents X2 and X3 representing single-digit decoders. In
                                                                      this case, if the input is the number 134 (๐ผ๐‘1 = ๐ฟ1 and
                                                                      ๐ผ๐‘0 = ๐ฟ3 ) the only enabled digit in output would be
                                                                      ๐‘‚7 (logic level ๐ฟ1 ) .
Figure 5: MVL Decoder 1x4

                                                            Encoder The encoder is a combinational circuit too,
                           {๏ธƒ                               that receives as input ๐‘›๐‘Ÿ MVL digits and returns as output
                           ๐ฟ1 ๐‘–๐‘“ ๐ผ๐‘ = ๐‘–                     ๐‘Ÿ MVL digits. It performs the opposite function to the
            ๐‘†๐‘– (๐ผ๐‘ ) =                                 (15)
                           ๐ฟ0 ๐‘–๐‘“ ๐ผ๐‘ ฬธ= ๐‘–                    decoder: it receives a decoded representation as input
                                                            and provides the corresponding encoding as output. The
Based on the value of the input IN, it will select the cor- figure 14 shows an encoder with 16 inputs and 2 outputs.
responding output (level ๐ฟ1 ), while all other outputs will Each ๐ผ๐‘๐‘– input passes through a ๐‘†๐‘– switch that detects
be zero (level ๐ฟ0 ), according to what reported in table 5. the ๐ฟ1 level at the input (equation 16).



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Figure 6: MVL Decoder 2x16



                      {๏ธƒ                                            the corresponding switch by propagating the IN signal
                        ๐ฟ1 ๐‘–๐‘“ ๐ผ๐‘๐‘– = ๐ฟ1                              to the output ๐‘‚๐‘ˆ ๐‘‡3 .
          ๐‘†1 (๐ผ๐‘๐‘– ) =                                   (16)
                        ๐ฟ0 ๐‘œ๐‘กโ„Ž๐‘’๐‘Ÿ๐‘ค๐‘–๐‘ ๐‘’
                                                                    Shifter In this section we will look exclusively at
   To make the circuit simpler, we grouped the selector             parallel-type shifters, which are normally used to per-
switch outputs that would determine the same value on               form mathematical operations (e.g. multiplication and
the output signals ๐‘‚๐‘ˆ ๐‘‡ 1 and ๐‘‚๐‘ˆ ๐‘‡ 2. Note that the                 division by base). In general, having a summation and a
output of each enabled switch causes its closure, which             shifter makes it possible to perform multiplication and
brings the output level value. For example, if ๐ผ๐‘ 7 = ๐ฟ1            division operations for general numbers as long as they
the output of selector ๐‘†๐ธ๐ฟ8 enables the OR gates that               are expressed in terms of the base [20]. An example
determine ๐‘‚๐‘ˆ ๐‘‡ 1 = ๐ฟ1 and ๐‘‚๐‘ˆ ๐‘‡ 0 = ๐ฟ3 .                             of multiplication between 17 and a generic number ๐‘ฅ,
                                                                    with ๐‘ฅ โˆˆ N, performed through the use of shifting and
Demultiplexer The demultiplexer (or simply demux)                   addition, is given in the equation 18.
is a circuit typically used to restore multiplexing pro-
duced by a multiplexer in communications. Its treatment                     17 ยท ๐‘ฅ = (41 + 40 ) ยท ๐‘ฅ = 41 ยท ๐‘ฅ + 40 ยท ๐‘ฅ    (18)
in MVL can be found in [10]. It consists of ๐‘›๐‘Ÿ data inputs,
๐‘Ÿ selection signals and an output. It takes a value equal              Right Shifter The shifter right moves the digits to
to the input line corresponding to the decoding of the              the right by as many positions as specified in a dedicated
data word. The figure 8 shows the simplest MVL demux                line. For integers this corresponds to performing a divi-
with 4 data lines and selection input SEL of data lines.            sion of the number with respect to the base. Since these
To make the circuit, we used a selector block (module               are components that can be used in series to perform op-
X2) that contains the 4 basic selectors. The output of the          erations on multiple digits, we must provide for receiving
block determines which signal ๐‘‚๐‘ˆ ๐‘‡๐‘– of the circuit will             and sending these digits to adjacent modules (figure 9).
end up in the ๐ผ๐‘ input. The equation 17 describe the                In the following examples, we will use 4-digit words, and
behavior of the output.                                             the lines of communication with adjacent modules will
                       {๏ธƒ                                           be 3. Indeed, the variable ๐‘†๐ธ๐ฟ indicating the number of
                         ๐ผ๐‘ ๐‘–๐‘“ ๐‘†๐‘– = ๐ฟ1                              digits to be moved can take 4 values (including zero).
             ๐‘‚๐‘ˆ ๐‘‡๐‘– =                                   (17)
                         ๐ฟ0 ๐‘œ๐‘กโ„Ž๐‘’๐‘Ÿ๐‘ค๐‘–๐‘ ๐‘’
                                                        Right Rotate Shifter In this section we wanted to
  For example, if ๐‘†๐ธ๐ฟ = ๐ฟ3 there will be ๐‘†3 = ๐ฟ1 .
                                                      show the simplicity of implementation of a 4-digit word
The output signal from the selectors block ๐‘‹2 enables
                                                      rotation shifter. A selection input ๐‘†๐ธ๐ฟ determines the
                                                      number of shifts in the word (figure 11).



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Figure 7: Encoder 16x2




Figure 8: MVL Demux 4x1




Figure 9: Collegamento in cascata di piรน shifter right




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Alessandro Simonetta et al. CEUR Workshop Proceedings                                                                   78โ€“89




Figure 10: Right Shifter



                                                                   3.3. Sequential Circuits
                                                                   A digital circuit is said to be sequential if the output de-
                                                                   pends on the inputs applied and the state of the circuit. In
                                                                   contrast, in combinational circuits the output is uniquely
                                                                   determined by the values of the inputs. Thus, a sequen-
                                                                   tial circuit has the ability to store information through
                                                                   feedback in the circuits that allows the informative con-
                                                                   tent calculated in the past to be brought back into the
                                                                   input due to the non-instantaneous propagation times
                                                                   in the semiconductors. We will then realize the D latch
                                                                   circuit in MVL logic.
Figure 11: Right Rotate Shifter
                                                                   D Latch The schema of the D latch is shown in figure
                                                                   13, and it consists of two cascaded multiplexers in which
   Left Shifter Similar to what we described for the               the output of the first one determines the selection of the
right shifter, the left shifter moves the input signals to         input of the second one. The data signal ๐ท lands in all
the left. For integers it corresponds to a multiplication          data inputs of the first mux except the input ๐ผ๐‘0 . Indeed,
by the base. The figure 12 shows the circuit with 7 data           in ๐ผ๐‘0 comes the output data of the second mux. A clock
inputs and a selection signal ๐‘†๐ธ๐ฟ. In this case, each              signal ๐ถ๐ฟ๐พ, which intermittently takes on the values ๐ฟ0
module can expect the arrival of three digits from the             and ๐ฟ1 , allows selection between the new data present
one located to its left. Meanwhile, the module under               in ๐ท (๐‘†๐ธ๐ฟ โ‰ฅ ๐ฟ1 ) and the one previously calculated
consideration can shift three values of its base word to           (๐‘†๐ธ๐ฟ = ๐ฟ0 ).
the left.                                                             To verify the operation of the D latch, we used an
 In this case if ๐‘†๐ธ๐ฟ = 0, the most significant outputs             articulated data signal (table 6) so as to check that the
are set to ๐ฟ0 , enabling the input ๐ผ๐‘0 of the first three          circuit had the desired behavior.
multiplexers on the left of the figure (๐‘‹8,๐‘‹10, ๐‘‹9). The
outputs ๐‘‚๐‘ˆ ๐‘‡6 , ๐‘‚๐‘ˆ ๐‘‡5 and ๐‘‚๐‘ˆ ๐‘‡4 are set to level zero. In
this case the inputs ๐ผ๐‘1 ,๐ผ๐‘2 ,๐ผ๐‘3 do not compete with             4. Limits and Future Works
the outputs. As the value of the signal ๐‘†๐ธ๐ฟ increases,
                                                                   New circuits in multivalue logic may be a step toward
the inputs will be shifted to the left until ๐ผ๐‘3 moves from
                                                                   addressing the computational problems of certain appli-
the output ๐‘‚๐‘ˆ ๐‘‡3 to ๐‘‚๐‘ˆ ๐‘‡6 (๐‘†๐ธ๐ฟ = 3) and three new
                                                                   cations such as artificial intelligence and blockchain. The
signals will be present on ๐‘‚๐‘ˆ ๐‘‡0 , ๐‘‚๐‘ˆ ๐‘‡1 and ๐‘‚๐‘ˆ ๐‘‡3 .
                                                                   amount of time, energy, and resources to deliver certain
                                                                   services is increasing more and more, and traditional cir-
                                                                   cuits seem unresponsive to current needs [21],[22], [23].
                                                                   We presented several theoretical solutions, and many of




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Alessandro Simonetta et al. CEUR Workshop Proceedings                                                            78โ€“89




Figure 12: Left Shifter




Figure 13: D Latch with MVL MUX 4+1




                                                               Figure 15: Testing D Latch: inputs




Figure 14: Testing D Latch



them are aligned with new technological solutions [24],
[25], such as mem-resistors [26] or programmable resis-
tor arrays in complex layers [27]. These last components
were developed by Massachusetts Institute of Technology
(MIT) to create neural networks to support a new area          Figure 16: Testing D Latch: outputs
of artificial intelligence called analog deep learning.
The lack of integration of models developed with such
technologies is one of the limitations that must be over-      employ bases that are powers of two; future efforts will
come to make the use of this logic effective.                  focus on this type of logic.
The first step in achieving the target of usability of such    The proposed work has two important advantages over
logic within circuits is their integrability within current    what has been produced in the literature on MVL sys-
systems in digital logic. To this end, it is desirable to      tems:




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Alessandro Simonetta et al. CEUR Workshop Proceedings                                                            78โ€“89



Table 6                                                     The paper shows circuits that adopt the same represen-
Test Input Signals                                          tation system as traditional binary digital ones, but im-
                                                            plement them using MVL signals (values). Among the
                        Time    Volts
                                                            strengths of the presented solution, there is the scalabil-
                        0u      0.625                       ity. Indeed, the presented approach is independent of the
                        30u     0.625                       base used and thus of the number of levels.
                        31u     4.375                       However, the gap with hardware technologies and tech-
                        60u     4.375                       niques to support MVL, such as storing MVL values, is far
                        61u     1.875
                                                            from being closed. The previously mentioned inorganic
                        90u     1.875
                        91u     4.375                       material, which makes the resistor extremely energy ef-
                        120u    4.375                       ficient, is an example solution that could accelerate the
                        121u    1.875                       industrialization of such circuits.
                        150u    1.875                       One challenge for the further use of multi-valued logic
                        151u    3.125                       in circuit design is the creation of an effective computer-
                        180u    3.125                       aided design package. At present, many multi-core ar-
                        181u    0.625                       chitectures have been developed and implemented, but
                        210u    0.625                       although parallel computing resulting from multi-core
                        211u    4.375                       architectures is a solution to increase the performance
                        240u    4.375
                                                            of a computer [32, 33, 34], with it arise various issues
                        241u    0.625
                        270u    0.625
                                                            related to the competition and collaboration of cores, es-
                                                            pecially when the latter are used in the neural networks
                                                            applications to the solution of different types of problems
                                                            [35, 36, 37, 38]. We can think of the problem of inaccu-
     โ€ข The system we proposed has the ability to work
                                                            rate interrupts or information sharing in caches. Such
        independently of the adopted base. Obviously,
                                                            issues are absent in a single computer operating with a
        the choice of this value must be fixed through the
                                                            computing model close to that of a human.
        trade-off between expressive power and the inter-
        nal complexity of the circuits to be made. Just as
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