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Mark Pearl UNISA COS 2621 Computer Organization
Computer Arithmetic - Binary for Decimal Numbers
This may be of use to someone else doing this course… The Problem In the section on Computer Arithmetic it gives an example of converting -7.6875 to IEEE floating point format. I understand all the steps except for the first one, where it does the following... 7.6875 (base 10) = 111.1011 (base 2) I don't understand the conversion - I realize that 111 (base 2) = 7 (base 10), but how does the .6875 part relate to the .1011? Or am I totally off track with this? The Solution The fractional part of the ......

Posted On Wednesday, March 21, 2012 7:41 AM

Organizations & Architecture UNISA Studies – Chap 7
Learning Outcomes Name different device categories Discuss the functions and structure of I/.O modules Describe the principles of Programmed I/O Describe the principles of Interrupt-driven I/O Describe the principles of DMA Discuss the evolution characteristic of I/O channels Describe different types of I/O interface Explain the principles of point-to-point and multipoint configurations Discuss the way in which a FireWire serial bus functions Discuss the principles of InfiniBand architecture External ......

Posted On Saturday, March 17, 2012 12:28 PM

Organization & Architecture UNISA Studies – Chap 13
Learning Outcomes Explain the advantages of using a large number of registers Discuss the way in which compilers optimize register usage Discuss the evolution of CISC machines Describe the characteristics of RISC architecture Discuss the RISC vs. CISC controversy Describe the way in which RISC and CISC design principles can be combined Instruction Execution Characteristics To understand the the line of reasoning of RISC advocates, we need a brief overview of instruction execution characteristics. ......

Posted On Saturday, March 17, 2012 12:27 PM

Organization & Architecture UNISA Studies – Chap 6
Learning Outcomes Discuss the physical characteristics of magnetic disks Describe how data is organized and accessed on a magnetic disk Discuss the parameters that play a role in the performance of magnetic disks Describe different optical memory devices Magnetic Disk The way data is stored on and retried from magnetic disks Data is recorded on and later retrieved form the disk via a conducting coil named the head (in many systems there are two heads) The writ mechanism exploits the fact that electricity ......

Posted On Thursday, March 15, 2012 10:12 PM

Organization & Architecture UNISA Studies – Chap 5
Learning Outcomes Describe the operation of a memory cell Explain the difference between DRAM and SRAM Discuss the different types of ROM Explain the concepts of a hard failure and a soft error respectively Describe SDRAM organization Semiconductor Main Memory The two traditional forms of RAM used in computers are DRAM and SRAM DRAM (Dynamic RAM) Divided into two technologies… Dynamic Static Dynamic RAM is made with cells that store data as charge on capacitors. The presence or absence of charge ......

Posted On Thursday, March 15, 2012 2:49 PM

Organization & Architecture UNISA Studies – Chap 4
Learning Outcomes Explain the characteristics of memory systems Describe the memory hierarchy Discuss cache memory principles Discuss issues relevant to cache design Describe the cache organization of the Pentium Computer Memory Systems There are key characteristics of memory… Location – internal or external Capacity – expressed in terms of bytes Unit of Transfer – the number of bits read out of or written into memory at a time Access Method – sequential, direct, random or associative From a users ......

Posted On Thursday, March 15, 2012 9:34 AM

Organization & Architecture UNISA Studies - Chap 9
Learning Outcomes Explain how integers can be represented in a computer Use assembly language to perform arithmetic and logical operations on integers on a Pentium Use assembly language to perform bit manipulation operations on a Pentium Explain how floating point numbers are stored in a computer Show how a floating point number is stored in a computer using a given gloating point format calculate the value of a floating point number that is stored in a computer given the relevant floating point ......

Posted On Tuesday, March 13, 2012 6:14 AM

Organization & Architecture UNISA Studies - Chap 12
Learning Outcomes Describe the internal structure of the CPU in general Describe the register organization of the x86/Pentium Describe what an interrupt is and what happens when an interrupt occurs Describe what an exception is and what happens when an exception occurs Describe the instruction cycle for indirect addressing Discuss the basic principle of instruction pipelining Processor Organization A processor must be able to do the following… Fetch Instructions Interpret Instruction Fetch Data Process ......

Posted On Friday, March 9, 2012 6:52 AM

Organization & Architecture UNISA Studies - Chap 11
Learning Outcomes Identify the addressing mode used in a given instruction Give examples of instructions in which specific Pentium addressing modes are used Discuss the advantages and disadvantages of different instruction formats Addressing Addressing mode used in an instruction indicates the way in which the operand is accessed. The most common addressing modes include Immediate Direct Indirect Register Register Indirect Displacement Stack General Note Typically we have two operands in binary operations ......

Posted On Saturday, March 3, 2012 2:59 PM

NASM – writing to the console
If you are new to NASM like me – you might find the following code snippets useful just to get started… (this is targeted to the Windows environment, it may be different in Linux) Printing the number 6 character to the console… the value in the ah register changes to 02h and you mov the message to dl org 0x100 bits 16 jmp main displayCharacter: mov ah,2h int 21h ret main: mov dl,36h call displayCharacter int 20h Printing a string to the console…. the value in the ah register changes to 09h and you ......

Posted On Thursday, March 1, 2012 7:23 AM

Organization & Architecture UNISA Studies – Chap 3
Computer Components Virtually all contemporary computer designs are based on concepts developed by John von Neumen, which includes the following three concepts… Data and instructions are stored in a single read-write memory The contents of this memory are addressable by location, without regard to the type of data contained there Execution occurs in a sequential fashion (unless explicitly modified) from one instruction to the next Keep in mind that software and hardware are typically interchangeable ......

Posted On Wednesday, February 8, 2012 5:41 AM

Organization & Architecture UNISA Studies – Chap 1
Organization & Architecture Computer architecture – those attributes of a system visible to a programmer or, put another way, those attributes that have a direct impact on the logical execution of a program. Computer organization – the operational units and their interconnections that realize the architectural specifications Examples of computer architectural attributes include… Instruction set The number of bits used to represent various data types I/O mechanisms and techniques for addressing ......

Posted On Saturday, January 28, 2012 1:37 PM

Organization & Architecture UNISA Studies – Chap 2
Designing for Performance The basic building blocks for todays computers are virtually the same as those of the early IAS computers. The focus has been on optimizing and increasing speeds while keeping the same architecture. Processors Increasing speed with processors uses several techniques including… Branch prediction – a processor looks ahead in the instruction code fetched from memory and predicts which branches or groups of instructions are likely to be processed next. Data flow analysis – the ......

Posted On Saturday, February 4, 2012 11:59 AM

More NASM
So, in the coming days I am going to go through some more NASM examples. Today I am going to blog about some more basics of NASM. All of these items can be found in more detail at http://www.nasm.us/doc/nasm... Pseudo-instructions Assembly language has machine instructions and pseudo instructions. Pseudo-instructions contain commands to the assembler itself. Some examples in NASM include… DB, DW, DD, DQ and DT (allocate storage space and initialise the space to specified values) REB, RESW, ......

Posted On Wednesday, April 13, 2011 7:56 PM

The DOS DEBUG Environment
Today I thought I would go back in time and have a look at the DEBUG command that has been available since the beginning of dawn in DOS, MS-DOS and Microsoft Windows. up to today I always knew it was there, but had no clue on how to use it so for those that are interested this might be a great geek party trick to pull out when you want the awe of the younger generation and want to show them what “real” programming is about. But wait, you will have to do it relatively quickly as it seems like DEBUG ......

Posted On Tuesday, February 15, 2011 8:49 AM

Getting Started with NASM
Today I got to play with NASM. This is an assembler and disassembler that can be used to write 16-bit, 32-bit & 64-bit programs. Let me say upfront that the last time I looked at assembly code at any depth was when I was studying Computer Science in Pietermaritzburg – ten years ago – and we never ever got to touch any real assembly code so a lot of what I am looking at today is very new to me. The first thing I did was download NASM compiler. This turned out to be a bit more complicated than ......

Posted On Saturday, February 12, 2011 4:39 PM

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