Double-sided RAM
Encyclopedia
Double-sided RAM is a type of random-access memory
which has its chips divided into two sides (called "ranks"), only one of which can be seen at a time by the computer. Initially, these were created by essentially attaching two single-sided SIMM
cards to the same PCB
, but more modern chips use different wiring. Pins 33 and 45 on the board are used by double-sided memory, and can sometimes be an indicator as to whether a given module is single or double-sided. To use the second half of the storage available, the computer must switch to the second rank, and can no longer read or write to the first half until it switches back again. Single-sided RAM refers to a RAM expansion with a single "rank" of chips, which the computer can access all at once. The physical expansion card may have chips on both of its sides, or only on one side, but is considered to be single sided because the computer can "see" all of its memory at once.
Random-access memory
Random access memory is a form of computer data storage. Today, it takes the form of integrated circuits that allow stored data to be accessed in any order with a worst case performance of constant time. Strictly speaking, modern types of DRAM are therefore not random access, as data is read in...
which has its chips divided into two sides (called "ranks"), only one of which can be seen at a time by the computer. Initially, these were created by essentially attaching two single-sided SIMM
SIMM
A SIMM, or single in-line memory module, is a type of memory module containing random access memory used in computers from the early 1980s to the late 1990s. It differs from a dual in-line memory module , the most predominant form of memory module today, in that the contacts on a SIMM are redundant...
cards to the same PCB
Printed circuit board
A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a non-conductive substrate. It is also referred to as printed wiring board or etched wiring...
, but more modern chips use different wiring. Pins 33 and 45 on the board are used by double-sided memory, and can sometimes be an indicator as to whether a given module is single or double-sided. To use the second half of the storage available, the computer must switch to the second rank, and can no longer read or write to the first half until it switches back again. Single-sided RAM refers to a RAM expansion with a single "rank" of chips, which the computer can access all at once. The physical expansion card may have chips on both of its sides, or only on one side, but is considered to be single sided because the computer can "see" all of its memory at once.