Difference between revisions of "Intel 4004"

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[[Image:i4004.jpg|150px|thumb|right|i4004]]
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[[Image:i4004.jpg|150px|thumb|right|i4004, in later plastic packaging]]
  
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The '''Intel 4004''' [[microprocessor]] resulted when the Japanese company [http://en.wikipedia.org/wiki/Busicom Busicom] contracted [[Intel]] in 1969 to create a [[integrated circuit|chip]] set for a [[printer]]-calculator.
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The '''Intel 4004''' [[microprocessor]] was the first commercially available microprocessor (although not [[Intel]]'s first microprocessor design; work had started on what became the [[Intel 8008]] first). It was designed by [http://en.wikipedia.org/wiki/Federico_Faggin Federico Faggin], who in 1974 left Intel and started [[Zilog]]. (Interestingly, Fagin 'signed' his work; the chip contains an "F.F." in one corner.)
  
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Busicom eventually permitted Intel to use the chipset design for non-calculator applications (the year this happened was 1971, according to sources). The [[Central Processing Unit|processor]] chip was called the 4004 and sold for $200. This was the first commercially available microprocessor (although not Intel's first microprocessor design; work had started on what became the [[Intel 8008]] first).. It was designed by [http://en.wikipedia.org/wiki/Federico_Faggin Federico Faggin], who in 1974 left Intel and started [[Zilog]].
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==Details==
  
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The 4004 (see picture) came in a 16-pin [[Dual Inline Package|DIP]][1] and had some limitations when compared to later microprocessors. It could only [[execute]] code out of erasable [[Read-only memory|ROM]], [[Random Access Memory|RAM]] was only used for storing data, and this complicated the life of the [[programmer]] somewhat. The chip also needed a lot of support [[logic]].
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The 4004 came in a 16-pin [[Dual Inline Package|DIP]]<sup>[1]</sup> [[integrated circuit|chip]], and had limitations when compared to later microprocessors. It could only [[execute]] code out of [[Read-only memory|ROM]], [[Random Access Memory|RAM]] was only used for storing data, and this complicated the life of the [[programmer]] somewhat.  
  
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Data and [[address]] information were multiplexed on a 4-bit [[bus]]. The need to multiplex the buses was part of the constraints caused by using a 16-pin DIP (40-pin DIPs were already in use by competitors at the time), enforced by Intel's management. Multiplexing reduced the [[instruction]] execution speed that could have been achieved, for example.
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It seems to have limited support for off-chip RAM; the 16 4-bit-wide internal [[register]]s seem to be the primary locations for writing data; there is no 'store' [[instruction]]. But the SRC instruction seems to send an [[address]] out, for later used by the Wxx instructions. And the CM-RAM[0123] lines from the [[Central Processing Unit|processor]] chip are used to control "4002 RAM chips".
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Data and address information were multiplexed on a 4-bit [[bus]]. The need to multiplex the bus was part of the constraints caused by using a 16-pin DIP (40-pin DIPs were already in use by competitors at the time), enforced by Intel's management. Multiplexing reduced the instruction execution speed that could have been achieved, for example. The chip also needed a lot of support [[logic]].
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The 4004 was only the processor part of the chip set produced for the original client (Busicom; below). The original setup was known as 'The 4000 Family', AKA the 'Busicom Chip Set', AKA the 'MCS-4 Chip Set' and consisted of:
  
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The 4004 was only the processor part of the chip set produced for Busicom. The original setup was known as 'The 4000 Family', aka 'Busicom Chip Set', aka 'MCS-4 Chip Set' and consisted of:
 
 
* The processor (the 4004)
 
* The processor (the 4004)
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* 2048-bit ROM (read only memory) with a 4-bit programmable I/O port (the 4001)
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* 2048-bit ROM with a 4-bit programmable I/O port (the 4001)
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* 4-registers x 20 locations x 4-bit RAM (programmable memory) with a 4-bit output port (the 4002)
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* 320-bit RAM arranged in 4 'registers' containing 20 locations of 4-bit 'characters', with a 4-bit output port (the 4002)
 
* A shift register type memory with serial input and parallel output (the 4003)
 
* A shift register type memory with serial input and parallel output (the 4003)
  
 
<small>[1] Note: The BYTE article incorrectly states that the chip came in an ''18''-pin DIP.</small>
 
<small>[1] Note: The BYTE article incorrectly states that the chip came in an ''18''-pin DIP.</small>
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===Width===
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The 4004 is often considered a '4-bit' chip, but the discussion is complicated; made even more confusing that there is no universally accepted standard for what sets a machine's 'width'; and indeed, for most suggested benchmarks, one can find a machine which violates it:
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* [[address space]] ([[KA10]]; 18 bits - 36 bit machine)
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* instruction size ([[Motorola M68000 family]]; 16 bits - 32 bit machine)
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* [[bus]] width ([[Motorola MC68000]]; 16 bits - 32 bit machine)
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* [[arithmetic logic unit|ALU]] width ([[LSI-11]]; 8 bits - 16 bit machine)
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On a number of these metrics, the 4004 is actually ''sort of'' an 8-bit machine:
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* Instructions are all multiples of 8 bits long
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* Instruction addresses (in some [[jump]]s, etc) are 8 bits long (although there is one in which they are 12 bits)
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* Immediate data is sometimes 8 bits wide
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* Register pairs, the target of 'load immediate' instructions, are 8 bits wide
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* Some data is 8 bits wide (in the FIN instruction, the data goes to a register pair, so 8 bits wide)
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On the other hand:
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* The [[accumulator]] is only 4 bits wide
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* The ALU (and thus all data handling in arithmetic instructions) is only 4 bits wide
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* Some data is 4 bits wide (it's not clear if in the LDM instruction, the 'DDDD' bits are immediate data, or the address of the data [probably immediate]; either way, it goes to the accumulator, so only 4 bits wide)
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So, it's truly a mix.
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==History==
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The 4004 resulted when the Japanese company [http://en.wikipedia.org/wiki/Busicom Busicom] contracted [[Intel]] in 1969 to create a chip set for a [[printer]]-calculator.
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Busicom eventually permitted Intel to use the chipset design for non-calculator applications (the year this happened was 1971, according to sources). The processor chip was eventually called the 4004 and sold for $200.
  
 
==External links==
 
==External links==
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[[Category: Intel Microprocessors]]
 
[[Category: Intel Microprocessors]]
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[[Category: 4-bit Computers]]
 
[[Category: 8-bit Computers]]
 
[[Category: 8-bit Computers]]

Revision as of 21:13, 12 July 2023

i4004, in later plastic packaging

The Intel 4004 microprocessor was the first commercially available microprocessor (although not Intel's first microprocessor design; work had started on what became the Intel 8008 first). It was designed by Federico Faggin, who in 1974 left Intel and started Zilog. (Interestingly, Fagin 'signed' his work; the chip contains an "F.F." in one corner.)

Details

The 4004 came in a 16-pin DIP[1] chip, and had limitations when compared to later microprocessors. It could only execute code out of ROM, RAM was only used for storing data, and this complicated the life of the programmer somewhat.

It seems to have limited support for off-chip RAM; the 16 4-bit-wide internal registers seem to be the primary locations for writing data; there is no 'store' instruction. But the SRC instruction seems to send an address out, for later used by the Wxx instructions. And the CM-RAM[0123] lines from the processor chip are used to control "4002 RAM chips".

Data and address information were multiplexed on a 4-bit bus. The need to multiplex the bus was part of the constraints caused by using a 16-pin DIP (40-pin DIPs were already in use by competitors at the time), enforced by Intel's management. Multiplexing reduced the instruction execution speed that could have been achieved, for example. The chip also needed a lot of support logic.

The 4004 was only the processor part of the chip set produced for the original client (Busicom; below). The original setup was known as 'The 4000 Family', AKA the 'Busicom Chip Set', AKA the 'MCS-4 Chip Set' and consisted of:

  • The processor (the 4004)
  • 2048-bit ROM with a 4-bit programmable I/O port (the 4001)
  • 320-bit RAM arranged in 4 'registers' containing 20 locations of 4-bit 'characters', with a 4-bit output port (the 4002)
  • A shift register type memory with serial input and parallel output (the 4003)

[1] Note: The BYTE article incorrectly states that the chip came in an 18-pin DIP.

Width

The 4004 is often considered a '4-bit' chip, but the discussion is complicated; made even more confusing that there is no universally accepted standard for what sets a machine's 'width'; and indeed, for most suggested benchmarks, one can find a machine which violates it:

On a number of these metrics, the 4004 is actually sort of an 8-bit machine:

  • Instructions are all multiples of 8 bits long
  • Instruction addresses (in some jumps, etc) are 8 bits long (although there is one in which they are 12 bits)
  • Immediate data is sometimes 8 bits wide
  • Register pairs, the target of 'load immediate' instructions, are 8 bits wide
  • Some data is 8 bits wide (in the FIN instruction, the data goes to a register pair, so 8 bits wide)

On the other hand:

  • The accumulator is only 4 bits wide
  • The ALU (and thus all data handling in arithmetic instructions) is only 4 bits wide
  • Some data is 4 bits wide (it's not clear if in the LDM instruction, the 'DDDD' bits are immediate data, or the address of the data [probably immediate]; either way, it goes to the accumulator, so only 4 bits wide)

So, it's truly a mix.

History

The 4004 resulted when the Japanese company Busicom contracted Intel in 1969 to create a chip set for a printer-calculator.

Busicom eventually permitted Intel to use the chipset design for non-calculator applications (the year this happened was 1971, according to sources). The processor chip was eventually called the 4004 and sold for $200.

External links

Retrieved from "https://gunkies.org/w/index.php?title=Intel_4004&oldid=30473"