Impact of Machine Architectures

1
Impact of Machine Architectures

• Juan Carlos Guzmán
• CS 6123 Theory Implementation of Programming
  Languages
• Southern Polytechnic State University

2
Machines
Von Neumann Machine

• Hardware computer that built out of wires,
  gates, circuit boards, etc.
• An elaboration of the Von Neumann Machine
• Software simulated computer that implemented in
  software, which runs on top of another computer

• Data
• Primitive Operations
• Sequence Control
• Data Access
• Storage Management
• Operating Environment

3
Why So Many Computers?

• It is economically feasible to produce in
  hardware (or firmware) only relatively simple
  computers
• More complex or abstract computers are built in
  software

4
A Six-Level Computer
Applications
Level 5
Application Level
Compilers, Editors, Navigators
Software
Level 4
Assembly Language Level
Assembler, Linker, Loader
Level 3
Operating System Machine Level
Operating System
Level 2
Instruction Set Architecture Level
Hardware
Microprogram or hardware
Level 1
Microarchitecture Level
Hardware
Level 0
Digital Logic Level
from Andrew S. Tanenbaum, Structured Computer
Organization, 4th Edition, Prentice Hall, 1999.
5
Virtual Computers

• How can we execute programs written in the
  high-level computer, given that all we have is
  the low-level computer?
• Compilation
• Translate instructions to the high-level computer
  to those of the low-level
• Simulation (interpretation)
• create a virtual machine

6
A Web Application
Input
Output
Web Application Computer (HTML web pages)
Web Virtual Computer (Navigator implemented in C
or Java)
C Virtual Computer (standard C libraries)
Operating System Virtual Computer (implemented in
machine Instructions)
Firmware Virtual Computer (implemented in
microcode)
Actual Hardware Computer
7
Binding

• Binding an association between an attribute and
  an entity
• Binding Time when does it happen?
• and, when can it happen?

8
Binding Time

• Static
• Language definition time
• Language implementation time
• Program writing time
• Compile time
• Link time
• Load time

• Dynamic
• Run time
• At the start of execution (program)
• On entry to a subprogram or block
• When the expression is evaluated
• When the data is accessed

9
Attributes

• Value (10)
• Value representation (10102)
• big-endian vs. little-endian
• Type (int)
• Storage (4 bytes)
• stack or global allocation
• Scope
• lexical or dynamic scope

10
Little- vs. Big-Endians

• Big-endian
• A computer architecture in which, within a given
  multi-byte numeric representation, the most
  significant byte has the lowest address (the word
  is stored big-end-first').
• Motorola and Sun processors
• Little-endian
• a computer architecture in which, within a given
  16- or 32-bit word, bytes at lower addresses have
  lower significance (the word is stored
  little-end-first').
• Intel processors

from The Jargon Dictionary - http//info.astrian.n
et/jargon
11
Static vs. Dynamic Scope

• Under lexical scope, sub1 will always reference
  the x defined in big
• Under dynamic scope, the x it references depends
  on the dynamic state of execution

• procedure big
• var x integer
• procedure sub1
• begin sub1
• ... x ...
• end sub1
• procedure sub2
• var x integer
• begin sub2
• ...
• sub1
• ...
• end sub2

begin big ... sub1 sub2
... end big