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SD
Secure Digital (SD) is a flash (non-volatile) memory card format developed by Matsushita, SanDisk and Toshiba for use in portable devices, including digital cameras, handheld computers, PDAs and GPS units.

With a physical profile of 24 mm × 32 mm × 2.1 mm, the new card provided both an SDMI-compliant (Secure Digital Music Initiative), high-level of copyright protection and high-density memory capacity for the time.

SDHC
SDHC (Secure Digital High-Capacity) cards are flash memory cards with a minimum capacity of 4GB (gigabytes). SDHC cards provide removable memory for compatible digital devices including cameras, camcorders, PDAs, MP3 players and more. SDHC cards are designed for devices that are compatible with the SDHC 2.00 specification. Products designed exclusively to support previous SD specifications 1.0 and 1.1 will not be able to utilize SDHC cards.

The main feature provided by SDHC cards are: classifications of data transfer speed (DTS). The SDHC specification 2.00 calls for cards to be classified according to the minimal sustained DTS as follows:

Class 2: minimum sustained DTS of 2MB/sec.
Class 4: minimum sustained DTS of 4MB/sec.
Class 6: minimum sustained DTS of 6MB/sec.

SDMI
Secure Digital Music Initiative (SDMI) (pronounced "sodomy") was a forum formed in late 1998, comprised of more than 200 IT, consumer electronics, security technology, ISP and recording industry companies, ostensibly with the purpose of developing technology specifications that protected the playing, storing and distributing of digital music.

SDR
See SDRAM

SDRAM
Synchronous dynamic random access memory delivers bursts of data at high speeds using a synchronous interface. Its is actually SDR SDRAM (single data rate SDRAM) but is usually used to referred to as just "SDRAM."

Semiconductor
An element, such as silicon, that is intermediate in electrical conductivity between conductors and insulators, through which conduction takes place by means of holes and electrons.

Serial Presence Detect
An EEPROM on certain memory modules used to store and provide information to the system using the module.

SGRAM
Synchronous graphics RAM. A single port DRAM designed for graphics hardware that requires high-speed throughput such as 3-D rendering and full-motion video.

Shoot & Store
Shoot & Store cards are budget-priced flash memory cards introduced by SanDisk. The new range is aimed at new digital converts who want the convenience of leaving their flash cards with developers as well as those who don’t have the time or ability to download images to a computer. The cards, which are rewritable and function just like standard cards, are offered in capacities of 32 megabytes (MB), which holds up to 50 photos, and 64MB, which holds up to 100 photos, when used at a resolution setting of 1 megapixel.

Shrink
A reduction in die (chip) size. A reduction in the size of the circuit design resulting in smaller die sizes that increases the number of possible die per wafer.

SIM
Single inline module. Same as SIP except with a connector edge instead of leads.

SIMM
Single inline memory module. A high-density DRAM package alternative consisting of several components connected to a single printed circuit board.

Single Banked
A memory module with only one bank or row. See Bank.

Single-Rank
Defines a set of DRAM chips (on a module) comprising 8 byte wide (64 bits) data, or 9 bytes (72 bits) with ECC. All devices in a Rank are connected by a single Chip-Select. The actual memory size is not defined. Single-sided memory modules are always Single-Rank. Single-rank memory modules will allow a server to reach its maximum memory capacity and highest performance levels, whilst enabling support forthe latest server chipset and motherboard features.

SIP
Single inline package. A component or module that has one row of leads along one side.

SLC
A Single-Level Cell, SLC, memory card stores one bit in each cell, leading to faster transfer speeds, lower power consumption and higher cell endurance. The only disadvantage of Single-Level Cell is the manufacturing cost per MB. Based on that, the SLC flash technology is used in high-performance memory cards.

SLDRAM
Synchronous link dynamic random access memory. SLDRAM is a type of SDRAM that uses a multiplexed command bus allowing fewer pins to increase bandwidth and allow higher FSB speeds.

SODIMM
Small outline dual inline memory module. Smaller and thinner than standard DIMMs, SODIMMs are typically used in laptop computers.

SOJ
Small outline J-lead package. A rectangular package with leads sticking out of the side of the package. The leads are formed in a J-bend profile, bending underneath and towards the bottom of the package.

Solder
A solder is a fusible metal alloy (often of tin and lead, although lead-based solders were outlawed in many parts of the world in the 1980s), with a melting point or melting range below 450 °C (840 °F) and is melted to join metallic surfaces, especially in the fields of electronics and plumbing, in a process called soldering.

SORIMM
Small outline Rambus inline memory module. SORIMM's have a smaller profile that standard RIMM's and are used in laptop computers and systems that have strict size requirements.

SPD
Serial presence detect

Speed
The time it takes to put information into memory or get information out of memory. It is measured from the time that an address and proper control signals are given, until the information is stored or placed in the device's output(s). RAM speed is typically expressed in nanoseconds (lower is faster) for EDO and FPM, and in MHz (higher is faster) for SDR SDRAM, DDR, SDRAM, and RDRAM.

SRAM
See static random access memory

SSFDC
SmartMedia was initially named the Solid State Floppy Disk Card (SSFDC) and pitched as a successor to the floppy disk, albeit memory cards are nowadays associated with digital cameras, digital audio players, PDAs, and other devices. It was launched in the summer of 1995 to compete with MiniCard, CompactFlash, and PC card formats.

A SmartMedia card consists of a single NAND flash chip embedded in a thin plastic card (though some higher capacity cards contain multiple, linked chips). It was one of the smallest and the thinnest (0.76 mm) of the early memory cards, and managed to maintain a favorable cost ratio as compared to the others.

A SmartMedia card was used as storage for a portable device, in a form that could easily be removed for access by a PC.

Static Random Access Memory
An integrated circuit similar to a DRAM (dynamic random access memory) with the exception that the memory does not need to be refreshed. Unlike volatile memory (ie, DRAM), SRAM retains its contents even when the main current is turned off.

Synchronous Memory
Memory that has its signals synchronized with the system clock. SDRAM and DDR are examples of synchronous memory types.