Difference between revisions of "PDP-1"

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The '''PDP-1''' was the first computer built by [[Digital Equipment Corporation]]; it was an 18-bit machine, built out of DEC's [[System Module|System Building Blocks]]. Around 55 were built.
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{{Infobox Machine
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| name = PDP-1
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| manufacturer = [[Digital Equipment Corporation]]
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| year first shipped = 1960
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| form factor = small computer
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| word size = 18 bits
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| physical address = 16 bits (64K words)
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| virtual address = 12 bits
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| logic type = micro-alloy diffused [[transistor]] [[System Module]]s
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| design type =
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<!-- | clock speed =  μsec (basic instructions) -->
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| memory speed = 5 μsec (read/write [[cycle time]])
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| successor = [[PDP-4]]
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| price = US$120K (4KW system)
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}}
  
{{stub}}
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The '''PDP-1''' was the first computer built by [[Digital Equipment Corporation]]. It was an 18-bit machine; a [[load-store architecture]], with a single [[accumulator]]. Around 50 were built.
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The basic PDP-1 included 4KW of [[core memory|core]] [[main memory]]; an optional Type 15 Memory Extension Control allowed (via [[bank switching]]) the addition of up to fifteen additional 4KW Type 12 Core Memory Modules, for a maximum total of 64KW.
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The later optional Type 10 Automatic Multiply and Divide added [[instruction]]s to perform multiplication and division at high speed in hardware (previously, they had been done in software [[subroutine]]s, albeit with support from specialized instructions).
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Standard peripherals included a [[paper tape]] reader and punch, and a [[terminal]]. Optional peripherals included [[graphics]] [[display]]s, a [[light pen]], [[line printer]], [[punched card]] reader and punch, and [[magnetic tape]] [[device controller|controller]] and [[magnetic tape drive|drives]]. <!-- Two different [[magnetic storage|magnetic]] [[drum]] [[secondary storage]] systems (xx) -->
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==Technical details==
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The instruction format consisted of a 5-bit basic operation code, a 1-bit indirect address bit, and a 12-bit memory address. If the indirect address bit was set in the indirect word, the indirection process repeated. <!-- The augmented instructions all share an operation code. In them, the address field is not used for an address; instead, each bit of the field can specify a separate operation, and generally more than one bit can be set at a time (except for most of the [[skip]] operations). --> The [[Program Counter]] is also 12 bits long.
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The PDP-1 used [[one's complement]] arithmetic.
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They were built out of DEC's [[System Module|System Building Blocks]]
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{{semi-stub}}
  
 
==Further reading==
 
==Further reading==
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==External links==
 
==External links==
  
* [http://www.bitsavers.org/pdf/dec/pdp1 PDP-1]
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* [http://www.bitsavers.org/pdf/dec/pdp1 PDP-1] - Original PDP-1 documents
 
* [https://www.computerhistory.org/pdp-1/_media/pdf/DEC.pdp_1.102664938.pdf PDP-1 and PDP-3 brochure]
 
* [https://www.computerhistory.org/pdp-1/_media/pdf/DEC.pdp_1.102664938.pdf PDP-1 and PDP-3 brochure]
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{{DEC}}
  
 
[[Category: DEC Systems]]
 
[[Category: DEC Systems]]

Revision as of 03:15, 15 May 2021


PDP-1
Manufacturer: Digital Equipment Corporation
Year First Shipped: 1960
Form Factor: small computer
Word Size: 18 bits
Logic Type: micro-alloy diffused transistor System Modules
Memory Speed: 5 μsec (read/write cycle time)
Physical Address Size: 16 bits (64K words)
Virtual Address Size: 12 bits
Successor(s): PDP-4
Price: US$120K (4KW system)


The PDP-1 was the first computer built by Digital Equipment Corporation. It was an 18-bit machine; a load-store architecture, with a single accumulator. Around 50 were built.

The basic PDP-1 included 4KW of core main memory; an optional Type 15 Memory Extension Control allowed (via bank switching) the addition of up to fifteen additional 4KW Type 12 Core Memory Modules, for a maximum total of 64KW.

The later optional Type 10 Automatic Multiply and Divide added instructions to perform multiplication and division at high speed in hardware (previously, they had been done in software subroutines, albeit with support from specialized instructions).

Standard peripherals included a paper tape reader and punch, and a terminal. Optional peripherals included graphics displays, a light pen, line printer, punched card reader and punch, and magnetic tape controller and drives.

Technical details

The instruction format consisted of a 5-bit basic operation code, a 1-bit indirect address bit, and a 12-bit memory address. If the indirect address bit was set in the indirect word, the indirection process repeated. The Program Counter is also 12 bits long.

The PDP-1 used one's complement arithmetic.

They were built out of DEC's System Building Blocks

Further reading

  • C. Gordon Bell, J. Craig Mudge, John. E. McNamara, "Computer Engineering: A DEC View of Hardware Systems Design" (Digital Press, Bedford, 1978) - Chapter 6 covers the PDP-1 and its background

External links

Template:DEC