CS 2150: 07-ibcm slide set

CS 2150 Roadmap

Data Representation				Program Representation
string int x[3] char x 0x9cd0f0ad 01101011		Objects Arrays Primitive types Addresses bits		Java code C++ code C code x86 code IBCM hexadecimal		High-level language Low-level language Assembly language Machine code

CPU registers
- 1 access per CPU cycle
- 3*10⁹ accesses per sec
- 1 Kb total storage
Cache
- SDRAM: 10 ns
- 10⁸ accesses per sec
- Multiple levels possible
- Higher levels are bigger and slower
- 1 Mb total storage

Main memory
- DRAM: 60 ns
- 2*10⁷ accesses per sec
- Limited by bus speeds
- 1 Gb total storage
Disk
- HDD speeds: 5 ms
- 200 accesses per sec
- 1 Tb total storage

4096 16-bit words
- Word
  - "chunk size" or addressable unit
- All initialized to zero initially
  - Unlike C/C++

Op	Name	HLL meaning	Description
3	load	`a := mem[addr]`	load accumulator from memory
4	store	`mem[addr] := a`	store accumulator into memory
5	add	`a := a + mem[addr]`	add memory to accumulator
6	sub	`a := a - mem[addr]`	subtract memory from accumulator
7	and	`a := a ∧ mem[addr]`	logical 'and' memory into accumulator
8	or	`a := a ∨ mem[addr]`	logical 'or' memory into accumulator
9	xor	`a := a ⊕ mem[addr]`	logical 'xor' memory into accumulator
A	not	`a := ~a`	logical complement of accumulator
B	nop	`/* */`	do nothing (no operation)
C	jmp	`goto addr`	jump to 'addr'
D	jmpe	`if a == 0 goto addr`	jump to 'addr' if accumulator equals zero
E	jmpl	`if a < 0 goto addr`	jump to 'addr' if accum. is less than zero
F	brl	`a := PC+1; goto addr`	jump (branch) to 'addr'; set accum. to the value of the PC just before the jump (i.e., to the address following the `brl`)

if (B == 0)
    S1;
else
    S2;

while(B >= 5)
    S;