24-bit computing: Difference between revisions
imported>Sgroey m →Usage: ce |
|||
| Line 12: | Line 12: | ||
== Usage == | == Usage == | ||
The IBM [[System/360]], announced in 1964, was a popular computer system with 24-bit addressing and [[32-bit]] general registers and arithmetic. The early 1980s saw the first popular personal computers, including the [[IBM Personal Computer AT|IBM PC/AT]] with an [[Intel 80286]] processor using 24-bit addressing and [[16-bit computing|16-bit]] general registers and arithmetic, and the [[Apple Inc.|Apple]] [[Macintosh 128K]] with a [[Motorola 68000]] processor featuring 24-bit addressing and 32-bit registers. Some late-1980s Apple computers such as the [[Macintosh SE/30]] and [[Macintosh IIx]] retained some 24-bit code in their [[ROM image|ROMs]] despite being advertised as 32-bit computers. As a result, these computers require the installation of the [[MODE32]] memory manager to address more than 8Mb of RAM.<ref>{{Cite web |last=Staff |first=L. E. M. |date=1989-01-19 |title=Mac SE/30 |url=https://lowendmac.com/1989/mac-se30/ |access-date=2025-06-18 |website=Low End Mac |language=en-US}}</ref><ref>{{Cite web |last=Staff |first=L. E. M. |date=1988-09-19 |title=Mac IIx |url=https://lowendmac.com/1988/mac-iix/ |access-date=2025-06-18 |website=Low End Mac |language=en-US}}</ref> | The IBM [[System/360]], announced in 1964, was a popular computer system with 24-bit addressing and [[32-bit]] general registers and arithmetic. The early 1980s saw the first popular personal computers, including the [[IBM Personal Computer AT|IBM PC/AT]] with an [[Intel 80286]] processor using 24-bit addressing and [[16-bit computing|16-bit]] general registers and arithmetic, and the [[Apple Inc.|Apple]] [[Macintosh 128K]] with a [[Motorola 68000]] processor featuring 24-bit addressing and 32-bit registers. Some late-1980s Apple computers such as the [[Macintosh SE/30]] and [[Macintosh IIx]] retained some 24-bit code in their [[ROM image|ROMs]] despite being advertised as 32-bit computers. As a result, these computers require the installation of the [[MODE32]] memory manager to address more than 8Mb of RAM.<ref>{{Cite web |last=Staff |first=L. E. M. |date=1989-01-19 |title=Mac SE/30 |url=https://lowendmac.com/1989/mac-se30/ |access-date=2025-06-18 |website=Low End Mac |language=en-US}}</ref><ref>{{Cite web |last=Staff |first=L. E. M. |date=1988-09-19 |title=Mac IIx |url=https://lowendmac.com/1988/mac-iix/ |access-date=2025-06-18 |website=Low End Mac |language=en-US}}</ref> | ||
The [[ARM1]], supported 24-bit memory address, as it can access 16MiB memory. | |||
The [[eZ80]] is a microprocessor and microcontroller family, with 24-bit registers and therefore 24-bit linear addressing, that is [[binary-code compatibility|binary compatible]] with the [[8-bit|8]]/16-bit [[Z80]]. {{cn|date=September 2015}} | The [[eZ80]] is a microprocessor and microcontroller family, with 24-bit registers and therefore 24-bit linear addressing, that is [[binary-code compatibility|binary compatible]] with the [[8-bit|8]]/16-bit [[Z80]]. {{cn|date=September 2015}} | ||
Latest revision as of 03:43, 22 June 2025
Template:Short description Script error: No such module "redirect hatnote". Template:Refimprove Template:Computer architecture bit widths In computer architecture, 24-bit integers, memory addresses, or other data units are those that are 24 bits (3 octets) wide. Also, 24-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers, address buses, or data buses of that size.
Notable 24-bit machines include the CDC 924 – a 24-bit version of the CDC 1604, CDC lower 3000 series, SDS 930 and SDS 940, the ICT 1900 series, the Elliott 4100 series, and the Datacraft minicomputers/Harris H series.[1]
The term SWORD is sometimes used to describe a 24-bit data type with the S prefix referring to sesqui.Script error: No such module "Unsubst".
The range of unsigned integers that can be represented in 24 bits is 0 to 16,777,215 (Template:N-ary in hexadecimal). The range of signed integers that can be represented in 24 bits is −8,388,608 to 8,388,607.
Usage
The IBM System/360, announced in 1964, was a popular computer system with 24-bit addressing and 32-bit general registers and arithmetic. The early 1980s saw the first popular personal computers, including the IBM PC/AT with an Intel 80286 processor using 24-bit addressing and 16-bit general registers and arithmetic, and the Apple Macintosh 128K with a Motorola 68000 processor featuring 24-bit addressing and 32-bit registers. Some late-1980s Apple computers such as the Macintosh SE/30 and Macintosh IIx retained some 24-bit code in their ROMs despite being advertised as 32-bit computers. As a result, these computers require the installation of the MODE32 memory manager to address more than 8Mb of RAM.[2][3]
The ARM1, supported 24-bit memory address, as it can access 16MiB memory.
The eZ80 is a microprocessor and microcontroller family, with 24-bit registers and therefore 24-bit linear addressing, that is binary compatible with the 8/16-bit Z80. Script error: No such module "Unsubst".
The 65816 is a microprocessor and microcontroller family with 16-bit registers and 24-bit bank switched addressing. It is binary compatible with the 8-bit 6502.[4]
Several fixed-point digital signal processors have a 24-bit data bus, selected as the basic word length because it gave the system a reasonable precision for the processing audio (sound). In particular, the Motorola 56000 series has three parallel 24-bit data buses, one connected to each memory space: program memory, data memory X, and data memory Y.[5]
Engineering Research Associates (later merged into UNIVAC) designed a series of 24-bit drum memory machines including the Atlas, its commercial version the UNIVAC 1101, the ATHENA computer, the UNIVAC 1824 guidance computer, etc. Those designers selected a 24-bit word length because the Earth is roughly 40 million feet in diameter, and an intercontinental ballistic missile guidance computer needs to do the Earth-centered inertial navigation calculations to an accuracy of a few feet.[6]Script error: No such module "Unsubst".
OpenCL has a built-in intrinsic for multiplication (mul24()) with two 24-bit integers, returning a 32-bit result. It is typically much faster than a 32-bit multiplication.[7]
See also
- Catena, a term used for a 24-bit unit of data on the Bull Gamma 60 computer
References
<templatestyles src="Reflist/styles.css" />
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
- ↑ Script error: No such module "citation/CS1".
Script error: No such module "Check for unknown parameters".