• Computer system basics: digital vs. analog?
• If digital, then which base to choose?
• If binary, all information is encoded in bits.
• What are the encoding  algorithms and why?  Focus on numeric values

• Two strategies for encoding data, ie. rep(x):
  1. Mathematical formula requires the decimal-to-binary function d2b() for non-negative values
  2. Strategic assignment of arbitrary values
• ALL ENCODINGS are dramatically influenced by the "operations" on the encoded data.
• Sign Magnitude, 1's complement, 2's complement

• Practice conversions of base 10 integers to base 2, 16, and 8 (and vice versa). Note - we are starting off with "non-negative integers". You need to get fast at the conversions, particularly between base2 and base16.
• Build a table given nbits, and multiple signed integer strategies; compare the differences between the columns, as to which values are represented by the same encoding.
• Specifying the max and min values, for n-bits
• Design algorithms to convert from the binary encoding of a signed integer back to it's decimal value.

• Announcements, Career Fair, Linux, FAQ, Mystery Question...
• Motivation for Floating Point  Data Type
• "the lowest level":  The current "device" is a Transistor

• Review the ALU and multiplexor
• Gated-D Latch: Controlling the R-S Latch
• A simple 4bit stored value
• Storage in the CPU: Registers, a temporary storage for your programs
• Memory

• Multi-byte addresses
• Multi-byte ordering between a CPU and a register:  "endianness"
• Alignment: What are the preferred addresses of a multi-byte quantity (in order to have the best performance)

• Storage Elements, including the Master Slave
• Memory
• Finite State Machine

• Review FSM and Master-Slave  Flip-flop
• MicroArchitecture for the LC3
• "Von Neumann" model (aka Eckert/Mauchly...)
• CPU <--> Memory Interface (MAR, MDR)
  
• Instruction Cycle
  

• Instruction Cycle: fetch, decode, execute...
• Exploring the LC-3 datapath for the ADD instruction

• General Questions on HW3
• Exam Topics
• Memory Hierarchy: motivation and concept of "Locality of Reference". (See Handout#15: Supplement on Memory Hierarchy and ROM/RAM)
• Patt/Patel problem 4.10 for the ADD instruction only. (Add another row to the table with the label: Register File (R0-R7). For each phase of the ADD instruction, identify the register that is written and mark the corresponding cell in the table.

• Last minute questions on the exam
• Continuing with ISA taxonomy

• You are the compiler, generating the code for the Example on Handout #22: i.e you will finish writing the assembly language for (LC-3 Program 1 worksheet)
• Discuss the Assembler Directives, Pseudo instructions, and questions on the instructions that we have covered so far.
• Discuss simple algorithms for subtract,  decrement, etc.
• If time: quick look at the LC-3 Assembler and Simulator

• Review LC-3 Assembly Language
• implementing HLL conditionals: example IF-ELSE
  
• implementing HLL iteration: example WHILE
• Requires two types of instructions:  conditional branch instructions (BRn, BRnz, ...) and unconditional branch (such BRnzp or BR )
  

• Everyone wrote the LC-3 code for an if-(then)-else statement:
  
• how to initalize a register to zero or non-zero
• Thinking about "arrays and memory layout"

• Memory Layout in Java
• Programming with arrays (sequential access)

• Hmwk5 Question 1:  Assemble a small program (for Pass1)
• Structures: 
  
• Working with non-zero offsets; 
  
• structures that include an array or object
• arrays of structures
• Use real-world ISAs for multi-byte quantitites
• Notes on the above topics.
  

• MQ4: Backus & looking at a Fortran example of do-while and if statement, and Bachus' focus on creating a compiler that could efficiently generate the assembly lang.  Also, Dijkstra's story on Recursion
• Review JSR and JMP <register>  (RET is a pseudo instruction for JMP R7)
  

• Reviewing where to store the "function state": in registers (if possible);  in memory at a static location, such as the Fortran strategy;  and the (3rd) strategy is dynamic location of memory  by storing the state on the run-time stack.  
• Sidebar:  When local variables are included with the run-time stack, then memory for local variables are allocated ONLY when the function is called.
• Introduction to the Run-time stack and the concept of a "stack-frame" aka "activation record".

• Concepts such as passing arguments by value or by address
• Saving Registers - who saves them and why?  caller? or callee?
• Two Common Strategies of Compiler Templates for Function Calls: 
•  Using Registers when possible
• CS310 Complete Stack Frame

• Work with the Compiler Template for Function Calls:  using a stack frame that includes args, return value, and local variables (along with other state): we're calling it the Complete Stack Frame.

LC3 initial Addr Modes:
 P/P5.3
focus on various "addressing modes"  for loads and stores.

PC relative
P/P 5.4: focus on BR/JSR

register indirect JMP, JSRR...

• PC-relative:  assembly time vs run-time
• What if the PC-relative offset field isn't sufficient?  How can we work around it?
  
• Do addressing modes impact you?  Try writing code using the indirect register addressing mode?   the indexed addressing mode?
• Here's the link to current RISC ISAs and Embedded ISAs, then click on Online Appendix C.  Browse pages 2&3, Read pages 4&5 about their addressing modes.  Have fun exploring a specific RISC ISA if you have an interest.

Memory Indirect Addressing Modes: LDI/STI

• Review the Function Call template focusing on Registers
• Practice with Supplement #17: ISA Operand Taxonomy
• Each ISA has 0..3 explicit operands (the others are implicit) and either memory or register operands.
• ***Accumulator ISA (1 explicit operand for ADD)
• ***"Stack Operand" ISA (0 explicit operands for ADD)
• Three explicit operands for ADD: e.g. the LOAD-STORE ISA (with 3 register operands), and CISC ISA's such as the VAX who would have any combination of memory and register operands.
• ***"Two explicit Operands" for ADD: e.g. the Intel ISA with at most one memory operand.
• For any instruction: encode it (given the necessary facts); what is the size of the instruction; how many memory accesses were needed to fetch and execute the instruction.
• Practice with the usage of LEA and LD to distinguish between them.
• Sample Exam2 Problems

• Interrupt Hardware, focusing on the interrupt phase and the RTI:  Good practice in 10.2.3
• Interrupt Software:  Good practice to read Pg7 of the Interrupt Supplement, and Slides for Hdt52.