Bryan Sumner
So many applications today require a large amount of system memory(RAM) to run these days. Let me explain how to simply upgrade yours. Upgrading is very affordable these days if your machine is few years old.
The first thing you need to do is to identify exactly what type in in your computer of mac. Please visit crucial.com and on the very main page, there is a small application you can run and check your system. It will tell you the type, speed, maximum amount your machine can handle, and how many slots you have available. After running the application on the website, it will give you a list of purchase options, just write down or print all of information from the system scan and shop elsewhere on the internet. You can surely find better pricing. It will save you a few dollars.
Ok, so you have shopped around, ordered your new memory, it has arrived, or you picked it up in the store and you are ready to install.
Now, you can add the new chips to the current setup if you have available slots and purchased identical or a very similar RAM upgrade. You can also remove what is currently in there and load it up with your new stuff.
IMPORTANT: POWER DOWN YOUR COMPUTER AND REMOVE POWER CABLE.
1. Open the case of your computer, look for one to four, 3 to 4 inch long, about an inch high, thin, green, chips standing on their edge. Usually located a bit off the center of the main board towards a corner. One way to match it up is to look at your new purchase and match it with what is inside the computer.
2. If removing memory, there is a little tab on each side of each stick attached to the board that swings down and away on each side. Use your thumb or finger to release it on each side of each chip and pull up easy to remove.
3. Now you want to put in your new hardware. Take note of the notch on the bottom of each piece, it is usually slightly off center and must be lined up correctly with the slot on the main board to install correctly. Very carefully line it up over the slot, then push down with evenly with both thumbs until the tab on the ends click and lock into place. You will see, hear, and feel this occur if done correctly. Follow the same procedure until all is installed.
4. Put your case back together. Plug it back in and turn on your computer, it will warn you system memory has changed. Hit the corresponding button that says “setup” to enter the BIOS, then save and exit out of the BIOS, then your system will restart.
So, there you go. The entire process should take no more than 15 minutes, you saved yourself some money, and now have some more power.
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Tags: Upgrade Memory
Posted in Hardware · June 16th, 2010 · Comments (0)
The Intel 8031 (or later 8051) is a very popular architecture that is used in many microcontrollers from different manufacturers. There are many optimizing 8051 compilers available. Some of them are free, while professional development packages can cost a significant amount of money. Anyway, even in the world of 32-bit microcontrollers the 8051 family is still popular.
The universal 8031 architecture sports a Harvard architecture, which contains two separate buses for both program and data. So, it has two distinctive memory spaces of 64K X 8 size for both program and data. It is based on an 8 bit central processing unit with an 8 bit Accumulator and another 8 bit B register as main processing blocks. Other portions of the architecture include few 8 bit and 16 bit registers and 8 bit memory locations.
Each 8031 device has some amount of data RAM built in the device for internal processing. This area is used for stack operations and temporary storage of data. This base architecture is supported with onchip peripheral functions like I/O ports, timers/counters, versatile serial communication port. So it is clear that this 8031 architecture was designed to cater many real time embedded needs. The following list gives the features of the 8031 architecture:
- Optimized 8 bit CPU for control applications.
- Extensive Boolean processing capabilities.
- 64K Program Memory address space.
- 64K Data Memory address space.
- 128 bytes of onchip Data Memory.
- 32 Bi-directional and individually addressable I/O lines.
- Two 16 bit timer/counters.
- Full Duplex UART.
- 6-source / 5-vector interrupt structure with priority levels.
- Onchip clock oscillator.
Now you may be wondering about the non mentioning of memory space meant for the program storage, the most important part of any embedded controller. Originally this 8031 architecture was introduced with onchip, ‘one time programmable’ version of Program Memory of size 4K X 8. Intel delivered all these microcontrollers (8051) with user’s program fused inside the device. The memory portion was mapped at the lower end of the Program Memory area. But, after getting devices, customers couldn’t change any thing in their program code, which was already made available inside during device fabrication.
So, very soon Intel introduced the 8031 devices (8751) with re-programmable type of Program Memory using built-in EPROM of size 4K X 8. Like a regular EPROM, this memory can be re-programmed many times. Later on Intel started manufacturing these 8031 devices without any onchip Program Memory. Now I go ahead giving more information on the important functional blocks of the 8031.
Central Processing Unit
The CPU is the brain of the microcontrollers reading user’s programs and executing the expected task as per instructions stored there in. Its primary elements are an 8 bit Arithmetic Logic Unit (ALU), Accumulator (Acc), few more 8 bit registers, B register, Stack Pointer (SP), Program Status Word (PSW) and 16 bit registers, Program Counter (PC) and Data Pointer Register (DPTR). The ALU (Acc) performs arithmetic and logic functions on 8 bit input variables. Arithmetic operations include basic addition, subtraction, multiplication and division. Logical operations are AND, OR, xclusive OR as well as rotate, clear, complement and etc. Apart from all the above, ALU is responsible in conditional branching decisions, and provides a temporary place in data transfer operations within the device.
B register is mainly used in multiply and divide operations. During execution, B register either keeps one of the two inputs and then retains a portion of the result. For other instructions, it can be used as another general purpose register. Program Status Word keeps the current status of the ALU in different bits.
Stack Pointer (SP) is an 8 bit register. This pointer keeps track of memory space where the important register information are stored when the program flow gets into executing a subroutine. The stack portion may be placed in any where in the onchip RAM. But normally SP is initialized to 07H after a device reset and grows up from the location 08H. The Stack Pointer is automatically incremented or decremented for all PUSH or POP instructions and for all subroutine calls and returns. Program Counter (PC) is the 16 bit register giving address of next instruction to be executed during program execution and it always points to the Program Memory space.
Data Pointer (DPTR) is another 16 bit addressing register that can be used to fetch any 8 bit data from the data memory space. When it is not being used for this purpose, it can be used as two eight bit registers.
Input / Output Ports
The 8031’s I/O port structure is extremely versatile and flexible. The device has 32 I/O pins configured as four eight bit parallel ports (P0, P1, P2 and P3). Each pin can be used as an input or as an output under the software control. These I/O pins can be accessed directly by memory instructions during program execution to get required flexibility. These port lines can be operated in different modes and all the pins can be made to do many different tasks apart from their regular I/O function executions. Instructions, which access external memory, use port P0 as a multiplexed address/data bus. At the beginning of an external memory cycle, low order 8 bits of the address bus are output on P0. The same pins transfer data byte at the later stage of the instruction execution.
Also, any instruction that accesses external Program Memory will output the higher order byte on P2 during read cycle. Remaining ports, P1 and P3 are available for standard I/O functions. But all the 8 lines of P3 support special functions: Two external interrupt lines, two counter inputs, serial port’s two data lines and two timing control strobe lines are designed to use P3 port lines. When you don’t use these special functions, you can use corresponding port lines as a standard I/O. Even within a single port, I/O operations may be combined in many ways. Different pins can be configured as input or outputs independent of each other or the same pin can be used as an input or as output at different times. You can comfortably combine I/O operations and special operations for Port 3 lines.
Timers / Counters
8031 has two 16 bit Timers/Counters capable of working in different modes. Each consists of a ‘High’ byte and a ‘Low’ byte which can be accessed under software. There is a mode control register and a control register to configure these timers/counters in number of ways. These timers can be used to measure time intervals, determine pulse widths or initiate events with one microsecond resolution upto a maximum of 65 millisecond (corresponding to 65, 536 counts). Use software to get longer delays. Working as counter, they can accumulate occurrences of external events (from DC to 500KHz) with 16 bit precision.
Serial Port
Each 8031 microcontroller contains a high speed full duplex (means you can simultaneously use the same port for both transmitting and receiving purposes) serial port which is software configurable in 4 basic modes: 8 bit UART; 9 bit UART; Interprocessor Communications link or as shift register I/O expander.
For the standard serial communication facility, 8031 can be programmed for UART operations and can be connected with regular personal computers, teletype writers, modem at data rates between 122 bauds and 31 kilobauds. Getting this facility is made very simple using simple routines with option to select even or odd parity. You can also establish a kind of Interprocessor communication facility among many microcomputers in a distributed environment with automatic recognition of address/data. Apart from all above, you can also get super fast I/O lines using low cost simple TTL or CMOS shift registers.
There are many 8051 projects that use one of the microcontroller from this family. It is amazing that this 8-bit family is still popular today.
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Tags: 8051
Posted in Hardware · June 11th, 2010 · Comments (0)