EXPERIMENT #6 Simple Computer SLC-3.2 in SystemVerilog

6.1
ECE 385
EXPERIMENT #6
Simple Computer SLC-3.2 in SystemVerilog
I. OBJECTIVE
In this experiment, you will design a simple microprocessor using SystemVerilog. It will
be a subset of the LC-3 ISA, a 16-bit processor with 16-bit Program Counter (PC), 16-bit
instructions, and 16-bit registers. (For LC-3, see Patt and Patel (ECE 120 textbook).
II. INTRODUCTION
There are three main components to the design of a processor. The central processing unit
(CPU), the memory that stores instructions and data, and the input/output interface that
communicates with external devices. You will be provided with the interface between the CPU
and the memory (memory read and write functions). The computer will first fetch an instruction
from the memory, decode it to determine the type of the instruction, execute the instruction, and
then fetch again. See Figure 1.
The CPU will contain a PC, a Instruction Register (IR), a Memory Address Register
(MAR), a Memory Data Register (MDR), a Instruction Sequencer/Decoder, a status register
(nzp), a 8x16 general-purpose register file, and an Arithmetic Logic Unit (ALU). All registers
and instructions are 16-bits wide. The ALU will operate on 16-bit inputs. The Instruction
Sequencer/Decoder will be responsible for providing proper control signals to the other
components of the processor. It will contain a state machine that will provide the signals that will
control the sequence of operations (fetch decode execute fetch next) in the processor.
FETCH DECODE EXECUTE
Figure 1
6.2
The simple computer will perform various operations based on the opcodes. An opcode
specifies the operation to be performed. Specific opcodes and operations are shown in Table 1.
The 4-bit opcode is specified by IR[15:12]; the remaining twelve bits contain data relevant that
instruction.
In the table below, R(X) specifies a register in the register file, addressed by the three-bit
address X. SEXT(X) indicates the 2’s compliment sign extension of the operand X to 16 bits.
nzp is the status register mentioned above. It is a three-bit value that states whether the resulting
value loaded to the register file is negative, zero, or positive. This must be updated whenever an
instruction performs a write to the register file (except JSR). For all instructions, PC PC + 1 is
implicit, unless PC is stated to get some other value. In the table, right-hand-side “PC” indicates
the value of the PC register after it was incremented immediately following fetch.
Instruction Operation
ADD 0 R(DR)  R(SR1) + R(SR2)
ADDi 1 R(DR)  R(SR) + SEXT(imm5)
AND 0 R(DR)  R(SR1) AND R(SR2)
ANDi 1 R(DR)  R(SR) AND SEXT(imm5)
NOT R(DR)  NOT R(SR)
BR n z p
if ((nzp AND NZP) != 0)
 PC  PC + SEXT(PCoffset9)
JMP PC  R(BaseR)
JSR 1
R(7)  PC;
PC  PC + SEXT(PCoffset11)
LDR R(DR)  M[R(BaseR) + SEXT(offset6)]
STR M[R(BaseR) + SEXT(offset6)]  R(SR)
PAUSE ledVect12 LEDs  ledVect12; Wait on Continue
1100 000 BaseR 000000
DR
Instruction(15 downto 0)
1101
0111
1001
0110
0100
0000
0101
0101
0001
0001 SR2
imm5
SR1
SR
DR 00
DR
DR
SR BaseR
DR
SR
BaseR
SR
00 SR2
imm5
offset6
111111
offset6
PCoffset11
PCoffset9
DR SR1
Table 1: The SLC-3.2 ISA
The IR will provide the Instruction Sequencer/Decoder with the instruction to be
executed. The IR will also provide the datapath with any other necessary data. As mentioned
earlier, the Instruction Sequencer/Decoder will need to generate the control signals to execute the
instructions in proper order. The Instruction Sequencer/Decoder will also specify the operation to
6.3
the ALU (e.g. add, etc.). Note that each operation will take multiple cycles and the Instruction
Sequencer/Decoder will need to provide signals appropriately at each cycle.
On a reset, the Instruction Sequencer/Decoder should reset to the starting “halted” state,
and wait for Run to go high. The PC should be reset to zero upon a reset, where it should proceed
on incrementing itself when Run is pressed for fetching the instructions line by line. The first
three lines of instructions will be used to load the PC with the value on the slider switches, which
indicates the starting address of the instruction(s) of interest (in the form of test programs for the
demo), and the program should begin executing instructions starting at the PC. Your computer
must be able to return to the halted state any time a reset signal arrives.
Instruction Summary
ADD Adds the contents of SR1 and SR2, and stores the result to DR. Sets the status
register.
ADDi Add Immediate. Adds the contents of SR to the sign-extended value imm5, and
stores the result to DR. Sets the status register.
AND ANDs the contents of SR1 with SR2, and stores the result to DR. Sets the status
register.
ANDi And Immediate. ANDs the contents of SR with the sign-extended value imm5, and
stores the result to DR. Sets the status register.
NOT Negates SR and stores the result to DR. Sets the status register.
BR Branch. If any of the condition codes match the condition stored in the status
register, takes the branch; otherwise, continues execution. (An unconditional jump
can be specified by setting NZP to 111.) Branch location is determined by adding
the sign-extended PCoffset9 to the PC.
JMP Jump. Copies memory address from BaseR to PC.
JSR Jump to Subroutine. Stores current PC to R(7), adds sign-extended PCoffset11 to
PC.
LDR Load using Register offset addressing. Loads DR with memory contents pointed to
by (BaseR + SEXT(offset6)). Sets the status register.
STR Store using Register offset addressing. Stores the contents of SR at the memory
location pointed to by (BaseR + SEXT(offset6)).
PAUSE Pauses execution until Continue is asserted by the user. Execution should only
unpause if Continue is asserted during the current pause instruction; that is, when
multiple pause instructions are encountered, only one should be “cleared” per press
of Continue. While paused, ledVect12 is displayed on the board LEDs. See I/O
Specification section for usage notes.
Here are the operations in more detail:
Fetch:
MAR PC; MAR = memory address to read the instruction from
MDR M(MAR); MDR = Instruction read from memory (note that M(MAR) specifies
the data at address MAR in memory).
6.4
IR MDR; IR = Instruction to decode
PC (PC + 1)
Decode:
Instruction Sequencer/Decoder IR
Execute:
Perform the operation based on the signals from the Instruction Sequencer/Decoder and
write the result to the destination register or memory.
Fetch, Load, and Store Operations:
For Fetch, Load (LDR), and Store (STR) operations you will need to set the memory signals
(see Memory Interface below) appropriately for each state of the fetch/load/store sequence.
Also, notice that the RAM we use does not have an R signal indicating that a read/write
operation is ready. Instead, for any states reading from or writing to RAM, we stay at those
states for several clock cycles to ensure that a memory read/write operation is complete.
FETCH:
state1: MAR PC
state2: MDR M(MAR); -- assert Read Command on the RAM
state3: IR MDR;
 PC PC+1; -- "+1" inserts an incrementer/counter instead of an adder.
 Go to the next state.
LOAD:
state1: MAR (BaseR + SEXT(offset6)) from ALU
state2: MDR M(MAR); -- assert Read Command on the RAM
state3: R(DR) MDR;

STORE:
state1: MAR (BaseR + SEXT(offset6)) from ALU; MDR R(SR)
state2: M(MAR) MDR; -- assert Write Command on the RAM
Memory Interface
The DE2 board is equipped with one 2 MB (1Mx16) SRAM. You will need to provide a
memory address in MAR, data to be written in MDR (in the case of Store), and the Read and
Write signals. The interface for these memory chips is as follows:
Data Bidirectional 16-bit data bus.
ADDR 20-bit Address bus (in LC-3, the address space is only 16-bit wide, so the
addresses are zero-extended to 20 bits)
CE Chip Enable. When active, allows read/write operations. Active low.
UB Upper Byte enable. Allows read/write operations on I/O<15:8>. Active low.
LB Lower Byte enable. Allows read/write operations on I/O<7:0>. Active low.
6.5
OE Output Enable. When active, RAM chips will drive output on the selected
address. Active low.
WE Write Enable. When active, orders writes to selected address. Active low. Has
priority over OE.
Note that “Data” is declared as an inout port type. This means that it is a bidirectional
data bus. In general, any port that attempts to both read and write to a bus needs to be declared as
an inout type. A port can write to the bus through an output port. When not writing to the bus,
you should assign the output a high-impedance value (“ZZZZZZZZZZZZZZZZ”). Otherwise,
when reading from memory, both your circuit and the SRAM will try to drive the line at the
same time, with unpredictable results (possibly including damage to one or both chips). This part
has been provided to you in the given file named “tristate.sv”.
I/O Specifications
I/O for this CPU is memory-mapped. I/O devices are connected to the memory signals,
with a special buffer inserted on the memory data bus. When a memory access occurs at an I/O
device address, the I/O device detects this, and sends a signal to the buffer to deactivate the
memory, and instead use the I/O device’s data for the response. You will be provided with a
SystemVerilog entity that encapsulates this functionality into a single module for you to insert
between your processor and the external memory (this is part of what the mem2io module does)
(see figures 2 & 3)
Mem2IO
This manages all I/O with the DE2 physical I/O devices, namely, the switches and 7-
segment displays. See Table 2. Note that the two devices share the same memory address. This is
acceptable, because one of the devices (the switches) is purely input, while the other (the hex
displays) is purely output.
Physical I/O Device Type Memory Address “Memory Contents”
DE2 Board Hex Display Output 0xFFFF Hex Display Data
DE2 Board Switches Input 0xFFFF Switches(15:0)
Table 2: Physical I/O Device List
You will need to create a top-level port map file that includes your CPU, the Mem2IO
entity, and four HexDrivers. The CPU is a high level entity that contains the majority of your
modules, including the ISDU. The various memory control signal inputs and the memory address
input should be connected to the corresponding outputs from the CPU (which are also output
6.6
from your top-level entity to the actual memory). The memory data inout port from your CPU
should be connected to the Data_CPU inout port of the Mem2IO unit; the Data_Mem inout port
of the Mem2IO unit should be connected to an inout port on your top-level entity, which should
be assigned to the appropriate pin connected to physical memory. The four “HEX#” output
signals should be connected to HexDriver inputs. See the partial block diagrams in figures 2 & 3.
Figure 2: Conceptual Figure 3: Memory with Mem2IO unit
Picture of Memory
Usage of the Pause Instruction
The Pause instruction is to be used in conjunction with I/O. Pausing allows the user time
to set the switches before an input operation, and read the output after an output operation. The
top two bits of the ledVect12 field of the instruction indicate the related I/O operation as
indicated in Table 3. Note that these should be considered as masks, not as mutually exclusive
values. For example, a ledVect12[11:10] value of “11” would indicate that both new data is
being displayed on the hex displays and the program is asking for a new switch value. The
remaining ledVect12 bits should be used to output a unique identifier to communicate the
location in the program to keep track of the computer’s progress. NOTE: The ledVect12 vector
does not mean anything to the processor; their sole purpose is to be a visual cue that the user can
define (when programming) so that he/she can tell where the program is during execution. The
following table reflects the convention used in the test programs.
ledVect12(11:10) Mask Meaning (cue for the user only)
“01” Previous operation was a write to the hex display
“10” Next operation is a read from switches
Table 3: ledVect12(11:10) Masks for Pause Instruction
Control
Address
Data
Mem2IO
CPU Memory
Subsystem
CPU Physical
Memory
(off-chip)
HexDrivers
Switches
6.7
Your top-level circuit should have at least the following inputs and outputs:
Inputs
S – logic [15:0]
Clk, Reset, Run, Continue –logic
Outputs
LED – logic [11:0]
HEX0, HEX1, HEX2, HEX3, HEX4, HEX5, HEX6, HEX7 - logic [6:0]
CE, UB, LB, OE, WE –logic
ADDR – logic [19:0]
Bidirectional ports (inout)
Data - logic [15:0]
(You may expand this list as needed for simulation and debugging.)
SIMPLIFIED SAMPLE CPU BLOCK DIAGRAM
Notes: Arrows are shown for connections between components. There may be multiple
signals going from one block to the other even if there is only one connection shown between
the blocks. One arrow does not mean one signal/bus in all cases. Signal multiplexing has
been omitted (your diagram should show a mux in front of most registers). All registers will
also have Clk as an input. Note that this block diagram does not show the mem2io module
F
CPU
PC MAR
MDR
IR
Instruction
Sequencer/
Decode Unit
ALU RegFile
Memory
Subsystem
Run
Reset
Continue
A1
B1
A2
B2
nzp
HexDrivers
LEDs
6.8
that should serve as an interface between the CPU and the memory (it is implicit in the
memory subsystem block, this is just a reminder that you need to include it).
LC3 STATE DIAGRAM FROM APPENDIX C OF PATT AND PATEL
Notes: This is not the state diagram for the simplified LC3, it has some instructions that are
not required to be implemented in this lab. Please refer to the instruction summary for details
on which instructions are required to complete the lab.
6.9
III. PRE-LAB
A. Week 1:
Lab 6 is split up into two discrete tasks. In the first week, you will implement the FETCH
phase. You will have to understand the structure of the memory system, and how the memory
system interfaces with the CPU. You will also have to implement all the necessary CPU
entities and ISDU controls to be able to successfully fetch the instructions line by line from
the on-board memory to the CPU. Note that since you’ll not be doing DECODE and
EXECUTE during week 1, you don’t have to pass the fetched instructions into the ISDU. But
instead, you should display the content of the IR, which will be storing the fetched
instructions at the end of the FETCH phase.
You are provided with the following entities on the website Mem2IO, Test_Memory, ISDU,
and tristate. The use for Test_Memory is only to simulate your design, to replace the off chip
memory.
For the purpose of Week 1 demo, you should connect the HEX displays directly to the IR
rather than connecting them to the Mem2IO (in contrast, in week 2, you will specify a special
address in memory that you write to in order to show data on the HEX displays). To display
the content of the IR on the FPGA, there are extra pause states at the end of the FETCH
phase to be able to hold and see the content of the IR. Pressing the ‘continue’ button, your
ISDU should loop back to perform the FETCH phase all over again, instead of continuing
onto the DECODE phase.
You should not need to modify the given ISDU for week 1, a higher level LC3 entity is given
and you will have to implement all other component parts of the LC3 such as the program
counter, register file, and data bus.
Week 1 Demo Point Breakdown:
1 point: Simulate the correct value of MAR = PC and PC = PC +1;
1 point: Simulate the correct value of MDR = M(MAR) and IR = MDR;
1 points: Correct operation on the FPGA: Displaying correct value of IR on HEX4-7 in state
PauseIR1.
6.10
B. Week 2:
For the second week, you will need to implement the DECODE and the EXECUTE phase.
You will first extend the provided skeleton ISDU to include all the necessary state
transitions and the necessary inputs/outputs in each of the states.
You will need to learn and understand the specification of the LC3 and its state diagram to
figure out how to assign the various control signals in each state to produce the desired
operations. At this point, you will have to take out the pause states which you have inserted
after the FETCH phase during week 1, for the ISDU to continue onto the DECODE and the
EXECUTE phase instead.
Week 2 Demo Point Breakdown:
1 point: Basic I/O Test 1
1 point: Basic I/O Test 2
1 point: Self Modifying Code Test
1 point: XOR Test
1 point: Multiplication Test
1 point: Sort Test
1 point: Correct “Act Once” Behavior
IV. LAB
Follow the Lab 6 demo information on the course website. Follow the Week 2 Test
Programs Documentation in the Lab 6 information page on the course website to demonstrate
the 5 tests.
Pin Assignment Table
Port Name Location Comments
Clk PIN_Y2 50 MHz Clock from the on-board oscillators
Run PIN_R24 On-Board Push Button (KEY3)
Continue PIN_N21 On-Board Push Button (KEY2)
Reset PIN_M23 On-Board Push Button (KEY0)
S[0] PIN_AB28 On-board slider switch (SW0)
S[1] PIN_AC28 On-board slider switch (SW1)
S[2] PIN_AC27 On-board slider switch (SW2)
S[3] PIN_AD27 On-board slider switch (SW3)
S[4] PIN_AB27 On-board slider switch (SW4)
S[5] PIN_AC26 On-board slider switch (SW5)
S[6] PIN_AD26 On-board slider switch (SW6)
S[7] PIN_AB26 On-board slider switch (SW7)
S[8] PIN_AC25 On-board slider switch (SW8)
S[9] PIN_AB25 On-board slider switch (SW9)
S[10] PIN_AC24 On-board slider switch (SW10)
S[11] PIN_AB24 On-board slider switch (SW11)
6.11
S[12] PIN_AB23 On-board slider switch (SW12)
S[13] PIN_AA24 On-board slider switch (SW13)
S[14] PIN_AA23 On-board slider switch (SW14)
S[15] PIN_AA22 On-board slider switch (SW15)
LED[0] PIN_G19 On-Board LED (LEDR0)
LED[1] PIN_F19 On-Board LED (LEDR1)
LED[2] PIN_E19 On-Board LED (LEDR2)
LED[3] PIN_F21 On-Board LED (LEDR3)
LED[4] PIN_F18 On-Board LED (LEDR4)
LED[5] PIN_E18 On-Board LED (LEDR5)
LED[6] PIN_J19 On-Board LED (LEDR6)
LED[7] PIN_H19 On-Board LED (LEDR7)
LED[8] PIN_J17 On-Board LED (LEDR8)
LED[9] PIN_G17 On-Board LED (LEDR9)
LED[10] PIN_J15 On-Board LED (LEDR10)
LED[11] PIN_H16 On-Board LED (LEDR11)
HEX0[0] PIN_G18 On-Board seven-segment display segment (HEX0[0])
HEX0[1] PIN_F22 On-Board seven-segment display segment (HEX0[1])
HEX0[2] PIN_E17 On-Board seven-segment display segment (HEX0[2])
HEX0[3] PIN_L26 On-Board seven-segment display segment (HEX0[3])
HEX0[4] PIN_L25 On-Board seven-segment display segment (HEX0[4])
HEX0[5] PIN_J22 On-Board seven-segment display segment (HEX0[5])
HEX0[6] PIN_H22 On-Board seven-segment display segment (HEX0[6])
HEX1[0] PIN_M24 On-Board seven-segment display segment (HEX1[0])
HEX1[1] PIN_Y22 On-Board seven-segment display segment (HEX1[1])
HEX1[2] PIN_W21 On-Board seven-segment display segment (HEX1[2])
HEX1[3] PIN_W22 On-Board seven-segment display segment (HEX1[3])
HEX1[4] PIN_W25 On-Board seven-segment display segment (HEX1[4])
HEX1[5] PIN_U23 On-Board seven-segment display segment (HEX1[5])
HEX1[6] PIN_U24 On-Board seven-segment display segment (HEX1[6])
HEX2[0] PIN_AA25 On-Board seven-segment display segment (HEX2[0])
HEX2[1] PIN_AA26 On-Board seven-segment display segment (HEX2[1])
HEX2[2] PIN_Y25 On-Board seven-segment display segment (HEX2[2])
HEX2[3] PIN_W26 On-Board seven-segment display segment (HEX2[3])
HEX2[4] PIN_Y26 On-Board seven-segment display segment (HEX2[4])
HEX2[5] PIN_W27 On-Board seven-segment display segment (HEX2[5])
HEX2[6] PIN_W28 On-Board seven-segment display segment (HEX2[6])
HEX3[0] PIN_V21 On-Board seven-segment display segment (HEX3[0])
HEX3[1] PIN_U21 On-Board seven-segment display segment (HEX3[1])
HEX3[2] PIN_AB20 On-Board seven-segment display segment (HEX3[2])
HEX3[3] PIN_AA21 On-Board seven-segment display segment (HEX3[3])
HEX3[4] PIN_AD24 On-Board seven-segment display segment (HEX3[4])
HEX3[5] PIN_AF23 On-Board seven-segment display segment (HEX3[5])
HEX3[6] PIN_Y19 On-Board seven-segment display segment (HEX3[6])
HEX4[0] PIN_AB19 On-Board seven-segment display segment (HEX4[0])
HEX4[1] PIN_AA19 On-Board seven-segment display segment (HEX4[1])
HEX4[2] PIN_AG21 On-Board seven-segment display segment (HEX4[2])
HEX4[3] PIN_AH21 On-Board seven-segment display segment (HEX4[3])
HEX4[4] PIN_AE19 On-Board seven-segment display segment (HEX4[4])
HEX4[5] PIN_AF19 On-Board seven-segment display segment (HEX4[5])
HEX4[6] PIN_AE18 On-Board seven-segment display segment (HEX4[6])
HEX5[0] PIN_AD18 On-Board seven-segment display segment (HEX5[0])
HEX5[1] PIN_AC18 On-Board seven-segment display segment (HEX5[1])
6.12
HEX5[2] PIN_AB18 On-Board seven-segment display segment (HEX5[2])
HEX5[3] PIN_AH19 On-Board seven-segment display segment (HEX5[3])
HEX5[4] PIN_AG19 On-Board seven-segment display segment (HEX5[4])
HEX5[5] PIN_AF18 On-Board seven-segment display segment (HEX5[5])
HEX5[6] PIN_AH18 On-Board seven-segment display segment (HEX5[6])
HEX6[0] PIN_AA17 On-Board seven-segment display segment (HEX6[0])
HEX6[1] PIN_AB16 On-Board seven-segment display segment (HEX6[1])
HEX6[2] PIN_AA16 On-Board seven-segment display segment (HEX6[2])
HEX6[3] PIN_AB17 On-Board seven-segment display segment (HEX6[3])
HEX6[4] PIN_AB15 On-Board seven-segment display segment (HEX6[4])
HEX6[5] PIN_AA15 On-Board seven-segment display segment (HEX6[5])
HEX6[6] PIN_AC17 On-Board seven-segment display segment (HEX6[6])
HEX7[0] PIN_AD17 On-Board seven-segment display segment (HEX7[0])
HEX7[1] PIN_AE17 On-Board seven-segment display segment (HEX7[1])
HEX7[2] PIN_AG17 On-Board seven-segment display segment (HEX7[2])
HEX7[3] PIN_AH17 On-Board seven-segment display segment (HEX7[3])
HEX7[4] PIN_AF17 On-Board seven-segment display segment (HEX7[4])
HEX7[5] PIN_AG18 On-Board seven-segment display segment (HEX7[5])
HEX7[6] PIN_AA14 On-Board seven-segment display segment (HEX7[6])
CE PIN_AF8 Chip Enable for SRAM – active low
UB PIN_AC4 Upper Byte enable for SRAM– active low
LB PIN_AD4 Lower Byte enable for SRAM – active low
OE PIN_AD5 Output Enable for SRAM – active low
WE PIN_AE8 Write Enable for SRAM – active low
Data[0] PIN_AH3 Bidirectional Data Bus for SRAM - bit 0
Data[1] PIN_AF4 Bidirectional Data Bus for SRAM - bit 1
Data[2] PIN_AG4 Bidirectional Data Bus for SRAM - bit 2
Data[3] PIN_AH4 Bidirectional Data Bus for SRAM - bit 3
Data[4] PIN_AF6 Bidirectional Data Bus for SRAM - bit 4
Data[5] PIN_AG6 Bidirectional Data Bus for SRAM - bit 5
Data[6] PIN_AH6 Bidirectional Data Bus for SRAM - bit 6
Data[7] PIN_AF7 Bidirectional Data Bus for SRAM - bit 7
Data[8] PIN_AD1 Bidirectional Data Bus for SRAM - bit 8
Data[9] PIN_AD2 Bidirectional Data Bus for SRAM - bit 9
Data[10] PIN_AE2 Bidirectional Data Bus for SRAM - bit 10
Data[11] PIN_AE1 Bidirectional Data Bus for SRAM - bit 11
Data[12] PIN_AE3 Bidirectional Data Bus for SRAM - bit 12
Data[13] PIN_AE4 Bidirectional Data Bus for SRAM - bit 13
Data[14] PIN_AF3 Bidirectional Data Bus for SRAM - bit 14
Data[15] PIN_AG3 Bidirectional Data Bus for SRAM - bit 15
ADDR[0] PIN_AB7 SRAM address bit 0
ADDR[1] PIN_AD7 SRAM address bit 1
ADDR[2] PIN_AE7 SRAM address bit 2
ADDR[3] PIN_AC7 SRAM address bit 3
ADDR[4] PIN_AB6 SRAM address bit 4
ADDR[5] PIN_AE6 SRAM address bit 5
ADDR[6] PIN_AB5 SRAM address bit 6
ADDR[7] PIN_AC5 SRAM address bit 7
ADDR[8] PIN_AF5 SRAM address bit 8
ADDR[9] PIN_T7 SRAM address bit 9
ADDR[10] PIN_AF2 SRAM address bit 10
ADDR[11] PIN_AD3 SRAM address bit 11
ADDR[12] PIN_AB4 SRAM address bit 12
6.13
ADDR[13] PIN_AC3 SRAM address bit 13
ADDR[14] PIN_AA4 SRAM address bit 14
ADDR[15] PIN_AB11 SRAM address bit 15
ADDR[16] PIN_AC11 SRAM address bit 16
ADDR[17] PIN_AB9 SRAM address bit 17
ADDR[18] PIN_AB8 SRAM address bit 18
ADDR[19] PIN_T8 SRAM address bit 19
V. POST-LAB
1.) Refer to the Design Resources and Statistics in IQT.17-19 and complete the following
design statistics table.
LUT
DSP
Memory (BRAM)
Flip-Flop
Frequency
Static Power
Dynamic Power
Total Power
Document any problems you encountered and your solutions to them, and a short conclusion.
Before you leave from your lab session submit your latest project code including the .sv files to
your TA on his/her USB drive. TAs are under no obligation to accept late code, code that doesn’t
compile (unless you got 0 demo points) or code files that are intermixed with other project files.
2.) Answer at least the following questions in the lab report
• What is MEM2IO used for, i.e. what is its main function?
• What is the difference between BR and JMP instructions?
• What is the purpose of the R signal in Patt and Patel? How do we compensate for the lack
of the signal in our design? What implications does this have for synchronization?
VI. REPORT
6.14
You do NOT need to write a report after week 1. Instead you will write one report for the
entirety of Lab 6. Write a report, you may follow the provided outline below, or make sure
your own report outline includes at least the items enumerated below.
1. Introduction
a. Summarize the basic functionality of the SLC-3 processor
2. Written Description and Diagrams of SLC-3
a. Summary of Operation
b. Describe in words how the SLC-3 performs its functions. In particular, you should
describe the Fetch-Decode-Execute cycle as well as the various instructions the
processor can perform.
c. Block Diagram of slc3.sv
d. This diagram should represent the placement of all your modules in the slc3.sv.
Please only include the slc3.sv diagram and not the RTL view of every module (this
can go into the individual module descriptions).
e. Written Description of all .sv modules
i. A guide on how to do this was shown in the Lab 5 report outline.
f. Description of the operation of the ISDU (Instruction Sequence Decoder Unit)
i. Named ISDU.sv, this is the control unit for the SLC-3. Describe in words how
the ISDU controls the various components of the SLC-3 based on the current
instruction.
ii. If you prefer to, you can lump this section into the module description section
under ISDU.sv.
g. State Diagram of ISDU
i. This should represent all states present in the ISDU and their transitions. The
diagram from Patt & Patel Appendix C can be used as a starting point but
would need to be modified to be representative of the ECE385
implementation of the LC-3. You will lose points if you just copy the
diagram.
3. Simulations of SLC-3 Instructions
a. Simulate the completion of 3 instructions from the following groups:
ADD/ADDi/AND/ANDi/NOT; BR/JMP/JSR; LDR/STR. For example, consecutively
simulating ADD, BR and then LDR would be an acceptable simulation. You must
annotate this diagram (for instance, label where instructions begin, where the answer
is stored, etc.)
6.15
b. Simulation using TestBench_Week2.sv. Annotation is required.
4. Post-Lab Questions
a. Fill out the Design Resources and Statistics table from Post-Lab question one
b. Answer all the post-lab questions. As usual, they may be in their own section or
dispersed into the appropriate sections in the rest of the report.
5. Conclusion
a. Discuss functionality of your design. If parts of your design didn’t work, discuss what
could be done to fix it
b. Was there anything ambiguous, incorrect, or unnecessarily difficult in the lab manual
or given materials which can be improved for next semester? You can also specify
what we did right, so it doesn’t get changed.