MicroMac Glossary for Technical Terms Page

Glossary

This page explains the terms that are used throughout the web site when explaining the features of the Macintosh models.

16-bit data path

The data path width, here 16-bits, refers to the number of bits that are transferred within the computer, for example between the CPU and the memory.
    The more bits are transferred simultaneously, the faster the computer works. Everything else being equal, a Macintosh with a 32-bit data path is faster than a Macintosh with a 16-bit data path.
    Mac models with a 16-bit data path, require that the memory upgrade with 30-pin 8-bit SIMMs is done in pairs.

32-bit data path

The data path width, here 32-bits, refers to the number of bits that are transferred within the computer, for example between the CPU and the memory.
    The more bits are transferred simultaneously, the faster the computer works. Everything else being equal, a Macintosh with a 32-bit data path is faster than a Macintosh with a 16-bit data path.
    Mac models with a 32-bit data path, require that the memory upgrade with 30-pin 8-bit SIMMs is done in sets of four.
    The term 32-bit data path is not to be confused with the term 32-bit addressing.

24-bit addressing

Early Macintosh models employ 24-bit addressing. These models use 24-bits to address the memory. The maximum achievable address space is 2²⁴ bytes, which is 16MB, which is too small for today's applications.

32-bit addressing



Later Macintosh models (starting from the IIci) employ 32-bit addressing. These models use 32-bits to address the memory. The maximum achievable address space is 2³² bytes, which is 4GB, 256 times the amount that is achievable with 24-bit addressing.

32-bit clean



Feature of all modern Macintosh models. Allows for 32-bit addressing. Some Mac Models (Mac II, IIcx, IIx and SE/30) provide enough SIMM sockets to address 128MB of memory, but they can only address 16MB, since the ROM is not 32-bit clean. This problem is fixed by the MODE32 extension, which makes the ROM of these Mac models "32-bit clean."

64-bit data path



The data path width, here 64-bits, refers to the number of bits that are transferred within the computer, for example between the CPU and the memory.
    The more bits are transferred simultaneously, the faster the computer works. Everything else being equal, a Macintosh with a 64-bit data path is faster than a Macintosh with a 16-bit data path or a 32-bit data path.
    Mac models with a 64bit data path, require that the memory upgrade with 72-pin 32-bit SIMMs is done in sets of two.
    A single 168-pin DIMM module implements a 64-bit data path.

Composite Memory Module

Apple defines a composite memory module as one that loads the data bus with more than one DRAM input load per bank. Both SIMM and DIMM can accommodate a maximum of two memory banks per module.
    Apple typically does not recommend the use of composite memory modules.

SIMM

Single In-line Memory Module, older standard for RAM, typically 30-pins or 72-pins for connection to logic board.

DIMM

Dual In-line Memory Module, modern standard for RAM, typically 168-pins, uses both sides of memory module for connection to logic board to achive more connections within the same space.

memory interleaving

Memory interleaving provides higher bandwidth (meaning faster speed) between the microprocessor and main memory. It also provides a significant performance boost, increasing the execution speed of programs.
    The memory interleaving is achieved by accessing data from two memory modules (DIMMs) within a very short time of each other. Memory interleaving supported only be a select number of high performance Macintosh models. It requires that the meory modules are installed in pairs.

parity

The parity bits of a memory module allow the Mac to check for memory errors. A Macintosh designed with a parity error checking (presently only Network Server 500 and 700) allerst the user about a memory error, but it does not correct the errror.

EDO memory

Extended Data Output memory are SIMMs or DIMMs that improve memory access time. This is done by extending the data output time of the present data while the circuitry on the logic board starts accessing the data.

10BaseT

Ethernet connection with oversized telephone connector (RJ45).
IEEE spec for running 10Mbps Ethernet using twisted pair cable. The maximum lenght of cable for a point-to-point connection is 100meters (=327 feet), and the maximum number of nodes is 1024.

10Base2

Ethernet connection with coaxial cable and BNC coax connector.
IEEE spec for running 10Mbps Ethernet using thin (Thinnet) coax cable. (75Ohm, RG58) A cable segment can be up to 185meters (606 feet) and can have a maximum of 30 nodes.

10Base5

IEEE spec for running 10Mbps Ethernet using thick (Thicknet) coax cable. (75Ohm, RG8) A cable segment can be up to 500meters (1640 feet) and can have a maximum of 100 nodes.

AUI

Attachment Unit Interface
Defined by ANSI 802.3. Physically is a DB15 connector.

The pinout can be viewed at the AUI Port Pin Assignments.

AAUI

Apple Attachment Unit Interface
Defined by Apple Computer. Physically a 14-pin connector.

The pinout can be viewed at the AAUI Port Pin Assignments.

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Copyright ©1996, 97, 98, 99 MicroMac Technology	This page was last modified on March 16, 1999

Glossary This page explains the terms that are used throughout the web site when explaining the features of the Macintosh models.
16-bit data path		The data path width, here 16-bits, refers to the number of bits that are transferred within the computer, for example between the CPU and the memory. The more bits are transferred simultaneously, the faster the computer works. Everything else being equal, a Macintosh with a 32-bit data path is faster than a Macintosh with a 16-bit data path. Mac models with a 16-bit data path, require that the memory upgrade with 30-pin 8-bit SIMMs is done in pairs.
32-bit data path		The data path width, here 32-bits, refers to the number of bits that are transferred within the computer, for example between the CPU and the memory. The more bits are transferred simultaneously, the faster the computer works. Everything else being equal, a Macintosh with a 32-bit data path is faster than a Macintosh with a 16-bit data path. Mac models with a 32-bit data path, require that the memory upgrade with 30-pin 8-bit SIMMs is done in sets of four. The term 32-bit data path is not to be confused with the term 32-bit addressing.
24-bit addressing		Early Macintosh models employ 24-bit addressing. These models use 24-bits to address the memory. The maximum achievable address space is 2²⁴ bytes, which is 16MB, which is too small for today's applications.
32-bit addressing		Later Macintosh models (starting from the IIci) employ 32-bit addressing. These models use 32-bits to address the memory. The maximum achievable address space is 2³² bytes, which is 4GB, 256 times the amount that is achievable with 24-bit addressing.
32-bit clean		Feature of all modern Macintosh models. Allows for 32-bit addressing. Some Mac Models (Mac II, IIcx, IIx and SE/30) provide enough SIMM sockets to address 128MB of memory, but they can only address 16MB, since the ROM is not 32-bit clean. This problem is fixed by the MODE32 extension, which makes the ROM of these Mac models "32-bit clean."
64-bit data path		The data path width, here 64-bits, refers to the number of bits that are transferred within the computer, for example between the CPU and the memory. The more bits are transferred simultaneously, the faster the computer works. Everything else being equal, a Macintosh with a 64-bit data path is faster than a Macintosh with a 16-bit data path or a 32-bit data path. Mac models with a 64bit data path, require that the memory upgrade with 72-pin 32-bit SIMMs is done in sets of two. A single 168-pin DIMM module implements a 64-bit data path.
Composite Memory Module		Apple defines a composite memory module as one that loads the data bus with more than one DRAM input load per bank. Both SIMM and DIMM can accommodate a maximum of two memory banks per module. Apple typically does not recommend the use of composite memory modules.
SIMM		Single In-line Memory Module, older standard for RAM, typically 30-pins or 72-pins for connection to logic board.
DIMM		Dual In-line Memory Module, modern standard for RAM, typically 168-pins, uses both sides of memory module for connection to logic board to achive more connections within the same space.
memory interleaving		Memory interleaving provides higher bandwidth (meaning faster speed) between the microprocessor and main memory. It also provides a significant performance boost, increasing the execution speed of programs. The memory interleaving is achieved by accessing data from two memory modules (DIMMs) within a very short time of each other. Memory interleaving supported only be a select number of high performance Macintosh models. It requires that the meory modules are installed in pairs.
parity		The parity bits of a memory module allow the Mac to check for memory errors. A Macintosh designed with a parity error checking (presently only Network Server 500 and 700) allerst the user about a memory error, but it does not correct the errror.
EDO memory		Extended Data Output memory are SIMMs or DIMMs that improve memory access time. This is done by extending the data output time of the present data while the circuitry on the logic board starts accessing the data.

10BaseT		Ethernet connection with oversized telephone connector (RJ45). IEEE spec for running 10Mbps Ethernet using twisted pair cable. The maximum lenght of cable for a point-to-point connection is 100meters (=327 feet), and the maximum number of nodes is 1024.
10Base2		Ethernet connection with coaxial cable and BNC coax connector. IEEE spec for running 10Mbps Ethernet using thin (Thinnet) coax cable. (75Ohm, RG58) A cable segment can be up to 185meters (606 feet) and can have a maximum of 30 nodes.
10Base5		IEEE spec for running 10Mbps Ethernet using thick (Thicknet) coax cable. (75Ohm, RG8) A cable segment can be up to 500meters (1640 feet) and can have a maximum of 100 nodes.
AUI		Attachment Unit Interface Defined by ANSI 802.3. Physically is a DB15 connector. The pinout can be viewed at the AUI Port Pin Assignments.
AAUI		Apple Attachment Unit Interface Defined by Apple Computer. Physically a 14-pin connector. The pinout can be viewed at the AAUI Port Pin Assignments.