Wednesday, September 29, 2004

Should I buy a new Flash Memory now?


Good question. Based on recent ads, the prices of flash memory have tumbled significantly compared to few months ago. One of online merchant I visited (www.tigerdirect.com) even offers $9.99 for 256 Kingston CompactFlash memory (I guess it is 1x speed).

Depends on your need, the price range can go from US $9.99 up to couple hundreds of dollars for the top memory (such as 4 GB, 40x speed). The speed plays a big role in pricing. The access speed (read/write) factor is similar to CD drive (150 KB/sec is for 1x speed, 300 KB/sec is for 2x speed so on). The new high speed CF sometimes is called CF II.

One thing I still hate to see is there are too many variants and different standard of flash memory. There is CompactFlash I/II, there is Memory stick, MemoryStick Pro, MemoryStick Duo, SmartMedia, SmartDigital, MM and what else, I don't remember. Why don't these people just make one single standard then our life would be better, isn't?

For people who are eager to see and compare the prices, check www.shopping.com, www.dealtime.com, www.mysimon.com, www.techbargains.com, or www.ebay.com. There are many other online shopping comparation portals but I cannot list them all here. Just search them at google, you will see many of them. Comments from previous buyers on these sites are many times useful. The more buyers put comments, the more confidence (or inassurance) you may get. Just check them out!
Point-to-Point Protocol

Introduction


The Point-to-Point Protocol (PPP) originally emerged as an encapsulation protocol for transporting IP traffic over point-to-point links. PPP also established a standard for the assignment and management of IP addresses, asynchronous (start/stop) and bit-oriented synchronous encapsulation, network protocol multiplexing, link configuration, link quality testing, error detection, and option negotiation for such capabilities as network layer address negotiation and data-compression negotiation. PPP supports these functions by providing an extensible Link Control Protocol (LCP) and a family of Network Control Protocols (NCPs) to negotiate optional configuration parameters and facilities. In addition to IP, PPP supports other protocols, including Novell's Internetwork Packet Exchange (IPX) and DECnet.



PPP Components

PPP provides a method for transmitting datagrams over serial point-to-point links. PPP contains three main components:

General Operation

To establish communications over a point-to-point link, the originating PPP first sends LCP frames to configure and (optionally) test the data link. After the link has been established and optional facilities have been negotiated as needed by the LCP, the originating PPP sends NCP frames to choose and configure one or more network layer protocols. When each of the chosen network layer protocols has been configured, packets from each network layer protocol can be sent over the link. The link will remain configured for communications until explicit LCP or NCP frames close the link, or until some external event occurs (for example, an inactivity timer expires or a user intervenes).

Physical Layer Requirements

PPP is capable of operating across any DTE/DCE interface. Examples include EIA/TIA-232-C (formerly RS-232-C), EIA/TIA-422 (formerly RS-422), EIA/TIA-423 (formerly RS-423), and International Telecommunication Union Telecommunication Standardization Sector (ITU-T) (formerly CCITT) V.35. The only absolute requirement imposed by PPP is the provision of a duplex circuit, either dedicated or switched, that can operate in either an asynchronous or synchronous bit-serial mode, transparent to PPP link layer frames. PPP does not impose any restrictions regarding transmission rate other than those imposed by the particular DTE/DCE interface in use.

PPP Link Layer

PPP uses the principles, terminology, and frame structure of the International Organization for Standardization (ISO) HDLC procedures (ISO 3309-1979), as modified by ISO 3309:1984/PDAD1 "Addendum 1: Start/Stop Transmission." ISO 3309-1979 specifies the HDLC frame structure for use in synchronous environments. ISO 3309:1984/PDAD1 specifies proposed modifications to ISO 3309-1979 to allow its use in asynchronous environments. The PPP control procedures use the definitions and control field encodings standardized in ISO 4335-1979 and ISO 4335-1979/Addendum 1-1979. The PPP frame format appears in Figure 13-1.


The following descriptions summarize the PPP frame fields illustrated in Figure 13-1:

The LCP can negotiate modifications to the standard PPP frame structure. Modified frames, however, always will be clearly distinguishable from standard frames.

PPP Link-Control Protocol

The PPP LCP provides a method of establishing, configuring, maintaining, and terminating the point-to-point connection. LCP goes through four distinct phases.

First, link establishment and configuration negotiation occur. Before any network layer datagrams (for example, IP) can be exchanged, LCP first must open the connection and negotiate configuration parameters. This phase is complete when a configuration-acknowledgment frame has been both sent and received.

This is followed by link quality determination. LCP allows an optional link quality determination phase following the link-establishment and configuration-negotiation phase. In this phase, the link is tested to determine whether the link quality is sufficient to bring up network layer protocols. This phase is optional. LCP can delay transmission of network layer protocol information until this phase is complete.

At this point, network layer protocol configuration negotiation occurs. After LCP has finished the link quality determination phase, network layer protocols can be configured separately by the appropriate NCP and can be brought up and taken down at any time. If LCP closes the link, it informs the network layer protocols so that they can take appropriate action.

Finally, link termination occurs. LCP can terminate the link at any time. This usually is done at the request of a user but can happen because of a physical event, such as the loss of carrier or the expiration of an idle-period timer.

Three classes of LCP frames exist. Link-establishment frames are used to establish and configure a link. Link-termination frames are used to terminate a link, and link-maintenance frames are used to manage and debug a link.

These frames are used to accomplish the work of each of the LCP phases.

Summary

The Point-to-Point Protocol (PPP) originally emerged as an encapsulation protocol for transporting IP traffic over point-to-point links. PPP also established a standard for assigning and managing IP addresses, asynchronous and bit-oriented synchronous encapsulation, network protocol multiplexing, link configuration, link quality testing, error detection, and option negotiation for added networking capabilities.

PPP provides a method for transmitting datagrams over serial point-to-point links, which include the following three components:

  • A method for encapsulating datagrams over serial links
  • An extensible LCP to establish, configure, and test the connection
  • A family of NCPs for establishing and configuring different network layer protocols

PPP is capable of operating across any DTE/DCE interface. PPP does not impose any restriction regarding transmission rate other than those imposed by the particular DTE/DCE interface in use.

Six fields make up the PPP frame. The PPP LCP provides a method of establishing, configuring, maintaining, and terminating the point-to-point connection.

Review Questions

Q—What are the main components of PPP?

A—Encapsulation of datagrams, LCP, and NCP.

Q—What is the only absolute physical layer requirement imposed by PPP?

A—The provision of a duplex circuit, either dedicated or switched, that can operate in either an asynchronous or synchronous bit-serial mode, transparent to PPP link layer frames.

Q—How many fields make up the PPP frame, and what are they?

A—Six: Flag, Address, Control, Protocol, Data, and Frame Check Sequence.

Q—How many phases does the PPP LCP go through, and what are they?

A—Four: Link establishment, link quality determination, network layer protocol configuration negotiation, and link termination.

Ubuntu Linux - Another Distro

another Linux distro coming. It is Ubuntu (unfamiliar with the name? me either, but sounds like an african language). Well, it is based on an african language but I forgot exactly what it means (something about "peace").

Anyway, not like other distros that use KDE, this distro comes with GNOME as its default desktop GUI. I have not tried GNOME desktop for a while, so I cannot comment about the latest GNOME.

For more detail, check this out: http://www.ubuntulinux.org/

Saturday, September 25, 2004

STI cell processor
Next generation processors


According to this website STI Cell Processor, a very sophisticated and advanced microprocessor is being jointly designed by 3 giant companies of microelectronics: Sony, Toshiba and IBM. The processor will be used for 21th century applications such as multimedia in living room, game console and other applications that may require broadband access.

The interesting thing from this story is that the broadband access will be more widely used in households not only for entertainment equipments, but also appliances such as smart microwave, smart refrigerator, or smart HVAC (Heat, Ventilation and Air Conditioning). This string of applications will definitely require a powerful microprocessor, not only for general computation as on PCs today but also for many real-time processes in embedded systems.

Many impressing nanoelectronic technology breakthroughs and inventions will be implemented on to this microprocessor. Among other things are SOI (Silicon on Insulator); 65-nm EUV (Extreme Ultra Violet) lithography; Cell architecture (similar to how human brain works); low-k (low dielectric) which means more silicon components (transistors, diodes, etc.) can be packed into a small die; copper wire.

This $400-million project will definitely change the way we think about a "PC" as the processor is considered as "supercomputer-on-a-chip". According to the site, the processor will even be more powerful than IBM's Big Blue supercomputer, one of the fastest computer in this universe. Not only because the processor will do Tera Floating Operation Per Seconds (Tera-FLOPS), but also because it will have about 20 "mini-cores" which work independently but in coherent and can be grouped all together programmably through software.

Another interesting part is that Sony will use this processor for its next generation game console, PS3. If we look at how amazing the NVidia 6800 Ultra performs but yet with much lower FLOPS compared to this Cell processor, you can imagine how good it can be with this "Tera FLOPS" Cell processor.

Utilizing massive data bandwidth and vast floating point capabilities, coupled with a parallel processing architecture, the Cell processor based development environment is expected to deliver quantum-leap innovation to entertainment applications. Cell-based workstations will be designed to expand the platform for creating digital content across future movie and video game entertainment industries.

Many applications, especially in multimedia and gaming, will be very boosted in performance by this chip. Video rendering processes which now might take hours, even days, can be done in minutes or even seconds. Ultra clear super surround sound, hyper-realistic 3D animation and other unimaginable possibilities and capabilities with current processors will be easily achieved by computers using these chips.

I believe the era of "WinTel" will soon dim, and new era of computing will shine. One thing I want to underline is that I believe the first operating system to support this chip is Linux. Believe me!

Tuesday, September 21, 2004

Confusing DRAM nomenclatures

Just figured out the different term for different kind of DRAM as listed in the following table:



















StandardSpeed/ClockName
DDR266 MHzPC2100
DDR333 MHzPC2700
DDR2400 MHzPC3200
DDR2533 MHzPC4200
DDR2675 MHzPC5400