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PDP-8 Frequently Asked Questions (posted every other month)
Section - What different PDP-8 models were made?

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The total sales figure for the PDP-8 family is estimated at over 300,000
machines.  Over 7000 of these were sold prior to 1970, and 30,000 were
sold by 1976.  During the PDP-8 production run, a number of models were
made, as listed in the following table.  Of these, the PDP-8/E is generally
considered to be the definitive machine.  If the PDP-8 is considered to
be the Model T of the computer industry, perhaps the PDP-8/E should be
considered to be the industry's Model A.


    PDP-5	63-67	 116		Transistor
    PDP-8	65-69 	1450	$18,500	Transistor
    LINC-8	66-69	 142	$38,500	Transistor
    PDP-8/S	66-70	1024	$10,000	Transistor	Very slow
    PDP-8/I	68-71 	3698	$12,800	TTL
    PDP-8/L	68-71 	3902	 $8,500	TTL		Scaled down 8/I
    PDP-12	69-73?	3500?	$27,900	TTL		Followup to LINC-8
    PDP-8/E	70-78	>10K?	 $6,500	TTL MSI	Omnibus
    PDP-8/F	72-78?	>10K?	<$5K	TTL MSI Omnibus	Based on 8/E CPU
    PDP-8/M	72-78?	>10K?	<$5K	TTL MSI Omnibus	OEM version of 8/F
    PDP-8/A	75-84?	>10K?	 $1,317	TTL LSI Omnibus	New CPU or 8/E CPU
    VT78	78-80		 $7,995	Intersil 6100	Workstation
    DECmate I	80-84			Harris 6120	Workstation
    DECmate II	82-86		 $1,435	Harris 6120	Workstation
    DECmate III	84-90		 $2,695	Harris 6120	Workstation
    DECmate III+85-90			Harris 6120	Workstation

Additional information is available in part two of this FAQ, where all
known models of the PDP-8, along with variants, alternate marketing
names, and other peculiarities are given.

The last years of the PDP-8 family were dominated by the PDP-8 compatible
microprocessor based VT78 and DECmate workstations.  The Intersil 6100,
also known as the CMOS-8 chip, was developed in 1976; GE later acquired
Intersil.  DEC also used the followup Harris 6120 microprocessors
(Introduced 1981) in many peripheral controllers for the PDP-11 and
PDP-15 as well as in the DECmate series of systems.  While all of the
earlier PDP-8 systems were open architecture systems, the DECmates had
closed architectures with an integrated console terminals and limited
peripheral options.  It is interesting to note that the Harris 6120 was
a 10Mhz chip and some chips could be clocked at 15Mhz; furthermore, the
6120 was essentially based on gate array technology.

The following PDP-8 compatible or semi-compatible machines were made and
sold by others; very little is known about many of these:


	TPA1001		 69	Hungarian, KFKI product, transistorized.
	TPA1001/i	 71	Hungarian, KFKI, IC version of 1001.
	TPA/i		 71	Hungarian, KFKI, renamed TPA1001/i
	TPA/l		 7? 	Hungarian, KFKI, enhanced TPA/i.
	TPAl/128H	 7? 	Hungarian, KFKI, TPA/l with 128K memory.
	TPA/s		 7?	Hungarian, KFKI, based on Intersil CPU chip.
	TPA Quadro	 8?	Hungarian, KFKI, comparable to a DECmate.
        Electronica-100  ?	Russian, discrete transistor technology.
        Electronica-100I ?	Russian, probably a PDP-8/I clone.
	Electrotechnica-100I ?	Yugoslavian, PDP-8/I?  Possibly same as above.
	Saratov-2	 ?	Russian, built like a PDP-8/M but bulkier.
	SPEAR u-LINC 100 ?	SPEAR, Inc, Waltham Mass (a LINC clone!)
	SPEAR u-LINC 300 ?	SPEAR, Inc, Waltham Mass (a LINC clone!)
	DCC-112		 70	Digital Computer Controls, PDP-8/L clone.
	DCC-112H	 71	Digital Computer Controls
	MPS-1		 74	Fabritek, PDP-8/L clone
	MP-12		 74	(is this just different numbering of above?)
	6100 Sampler	 76?	Intersil, their IM6100 promotional kit
	Intercept I	 7?	Intersil, based on IM6100
	Intercept Jr	 7?	Intersil, based on IM6100
	TLF MINI-12      77     Based on IM6100, in an elegant package.
	PCM-12		 7?	Pacific CyberMetrix, based on Intercept bus
	PCM-12A		 77	Pacific CyberMetrix, fixed to clock at 4MHz
	SBC-8		 84-88	CESI, Based on IM6120? SCSI bus

More information on the Hungarian TPA series, built by KFKI (the Central
Research Institute for Physics), was provided by Varga Akos Endre,; information on and photos of these machines are
currently available from:

The original machine in this series, the TPA1001, was built from the
description in DEC's Small Computer Handbook.  Only after the series was
in production, when a machine was exhibited in Ljubljana, Yugoslavia, was
full DEC compatability demonstrated, when a DEC user booted the TPA machine
from a DEC paper tape.  By the end of the TPA production run, around 900
PDP-8 compatable machines had been built.  Given the Soviet era central
planning for the computer industries in eastern europe, it is quite possible
that the Electrotechnica and Electronica models listed above may have been
TPA machines packaged for use in the USSR and other Soviet Block countries.

It is amusing to note that the name TPA is very similar in origin to the name
PDP used by DEC!  There was a decree that computer development in Hungary was
to cease, with all computers to be purchased from the USSR.  In response, the
people at KFKI ceased developing computers and began developing "Stored Program
Analyzers" or, the acronym for which is TPA in Hungarian.

The CESI (Computer Extension Systems, Inc.) machine had 128K words of local
RAM on each processor card and allowed up to 4 processor cards per OMNIBUS,
along with 128K words of global shared memory.  3 AMD 2901 bit-slice
processor chips were used to build the 12-bit ALU and data paths, controlled
by an 80-bit microword.

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Top Document: PDP-8 Frequently Asked Questions (posted every other month)
Previous Document: What character sets does the PDP-8 support?
Next Document: What about the LINC/8 and PDP-12?

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Last Update March 27 2014 @ 02:11 PM