# Mark Pearl

## March 2012 Entries

##### Writing multiple lines of text to the console in nasm
In it’s simplest form… the following asm code should work org 0x100 bits 16 jmp main message: db 'example text ', 0xa,'and some more text', 0xa, 'and another line','\$' main: mov dx,message mov ah,09h int 21h int 20h Points to look out for… 0xa is a newline operand… ‘\$’ signifies the end of the text Everything else should look pretty standard… ......
##### 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 ......
##### 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 ......
##### 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. ......
##### 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 ......
##### 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 | Comments (0) |

##### 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 | Comments (0) |

##### Samsung Omnia 7 – enable GSM Modem mode

For anyone out there that has a Samsung and wants to enable GSM modem tethering. Here are the steps….

Dial ##634# and press call

This will add a diagnosis mode to the phone.

Change Tethering Settings

In diagnosis mode dial *#7284# and it will prompt you for the tethered option.

That’s it!

Posted On Tuesday, March 13, 2012 2:36 PM | Comments (0) |

##### 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 | Comments (0) |

##### Using gVIM to program NASM (a noobs insights)
I’m new to vim and to nasm… several months ago I put up a post on how I had discovered a tutorial on VIM and was going to give it a second try – my first attempt failing dismally. At the time my second attempt fell through after about two weeks – I was just to comfortable with Windows and the concept of not having everything menu based was too daunting for me. So when a few weeks ago I decided to give vim a third chance, it was pretty much a “last chance” - if I didn’t see any light at the end of ......

Posted On Saturday, March 10, 2012 8:10 AM | Comments (1) |

##### 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 | Comments (0) |

##### 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 | Comments (0) |

##### 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 | Comments (0) |