On 21/10/2010, at 7:27 PM, Clark Martin wrote: > > On Oct 20, 2010, at 11:03 PM, Brian Christmas wrote: > >> >> >> As the cost of flash memory drops, it appears likely that an OS will be >> developed that uses flash as it's boot and running ram, but hard drives will >> continue to be used for 'bulk' storage for some time to come. > > Flash will become more common as a replacement for hard disks. But HDs will > still beat out Flash for the foreseeable future for large capacity storage, > it is going to take a while before some kind of solid state storage beats > rotating magnetic storage in $/byte. > > You don't need to develop an OS that uses flash, the are lots of Flash drives > now that are SATA drives and can be used just like a SATA HD. > > Flash isn't going to replace RAM, at least not for a long time. Flash isn't > anywhere near as fast as RAM. > > Clark Martin > Redwood City, CA, USA > Macintosh / Internet Consulting
G'day Clark Flash is a type of RAM, albeit a slow address form. It definitely won't replace fast access RAM. What I envisage is four tiers of memory. 1. Fast RAM for the immediate use of the processor, built on the processor. (existing) 2. Fast RAM for use of the processor, but separate from it. (existing) 3. Dedicated slower RAM (but cheap, as in Flash) for page swapping when required, built into the OS. This MIGHT also be used for instant startup memory. 4. Hard Drive and Flash storage for long term data storage and page swapping overflow. (existing) At the moment, Flash drives can be used by the OS for page swapping, provided the drive is not filled up by long term storage. Having two drives is confusing to the end user, and I believe that a dedicated page swapping source of Flash is required, invisible to the user. Some of the types of RAM mentioned below are also slow. Regards Santa Types of RAM The following are some common types of RAM: SRAM: Static random access memory uses multiple transistors, typically four to six, for each memory cell but doesn't have a capacitor in each cell. It is used primarily for cache. DRAM: Dynamic random access memory has memory cells with a paired transistor andcapacitor requiring constant refreshing. FPM DRAM: Fast page mode dynamic random access memory was the original form of DRAM. It waits through the entire process of locating a bit of data by column and row and then reading the bit before it starts on the next bit. Maximum transfer rate to L2 cache is approximately 176 MBps. EDO DRAM: Extended data-out dynamic random access memory does not wait for all of the processing of the first bit before continuing to the next one. As soon as the address of the first bit is located, EDO DRAM begins looking for the next bit. It is about five percent faster than FPM. Maximum transfer rate to L2 cache is approximately 264 MBps. SDRAM: Synchronous dynamic random access memory takes advantage of the burst mode concept to greatly improve performance. It does this by staying on the row containing the requested bit and moving rapidly through the columns, reading each bit as it goes. The idea is that most of the time the data needed by the CPU will be in sequence. SDRAM is about five percent faster than EDO RAM and is the most common form in desktops today. Maximum transfer rate to L2 cache is approximately 528 MBps. DDR SDRAM: Double data rate synchronous dynamic RAM is just like SDRAM except that is has higher bandwidth, meaning greater speed. Maximum transfer rate to L2 cache is approximately 1,064 MBps (for DDR SDRAM 133 MHZ). RDRAM: Rambus dynamic random access memory is a radical departure from the previous DRAM architecture. Designed by Rambus, RDRAM uses a Rambus in-line memory module (RIMM), which is similar in size and pin configuration to a standard DIMM. What makes RDRAM so different is its use of a special high-speed data bus called the Rambus channel. RDRAM memory chips work in parallel to achieve a data rate of 800 MHz, or 1,600 MBps. Since they operate at such high speeds, they generate much more heat than other types of chips. To help dissipate the excess heat Rambus chips are fitted with a heat spreader, which looks like a long thin wafer. Just like there are smaller versions of DIMMs, there are also SO-RIMMs, designed for notebook computers. Credit Card Memory: Credit card memory is a proprietary self-contained DRAM memory module that plugs into a special slot for use in notebook computers. PCMCIA Memory Card: Another self-contained DRAM module for notebooks, cards of this type are not proprietary and should work with any notebook computer whose system bus matches the memory card's configuration. CMOS RAM: CMOS RAM is a term for the small amount of memory used by your computer and some other devices to remember things like hard disk settings -- see Why does my computer need a battery? for details. This memory uses a small battery to provide it with the power it needs to maintain the memory contents. VRAM: VideoRAM, also known as multiport dynamic random access memory(MPDRAM), is a type of RAM used specifically for video adapters or 3-D accelerators. The "multiport" part comes from the fact that VRAM normally has two independent access ports instead of one, allowing the CPU and graphics processor to access the RAM simultaneously. VRAM is located on the graphics card and comes in a variety of formats, many of which are proprietary. The amount of VRAM is a determining factor in theresolution and color depth of the display. VRAM is also used to hold graphics-specific information such as 3-D geometry data and texture maps. True multiport VRAM tends to be expensive, so today, many graphics cards use SGRAM (synchronous graphics RAM) instead. Performance is nearly the same, but SGRAM is cheaper. >From Wikipedia... Intel Corporation saw the massive potential of the invention and introduced the first commercial NOR type flash chip in 1988.[4] NOR-based flash has long erase and write times, but provides full address and data buses, allowing random access to any memory location. And what, you ask, was the beginning of it all? And it is this...... Existence that multiplied itself For sheer delight of being And plunged with numberless trillions of forms So that it might find itself innumerably Sri Aurobindo -- You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/g3-5-list
