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Chapter 7 1972- 1977

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					 Chapter 7
1972- 1977

The Personal
 Computer
               1
      Paul Ceruzzi

“The development of personal
computing followed a
trajectory that is difficult to
explain as rational.”


                              2
        Mark Twain
“Very few things happen at
 the right time, and the rest
 do not happen at all. The
 conscientious historian will
 correct these defects”


                                3
 Stewart Brand- Stanford
“Ready or not, computers
are coming to the people.
That’s good news, maybe
the best since psychedelics.”
            Rolling Stone Magazine
            December 7, 1972
            “Spacewar: Fanatic Life &
            Symbolic Death Among
            Computer Bums”
                                        4
       TOPS-10 & PDP-10
• PDP-10  large           • Though mainframe,
  mainframe                  “it was personal”
   – Spacewar & Time-
     sharing @ Stanford
   – Good operating
     system + disk
• 1972  TOPS (@ MIT)
   – Timesharing
     operating system
   – Description Pg. 209
   – Sounds like… DOS            First PDP-10
                                                5
         TOPS-10 (cont.)
• PIP - Peripheral Interchange System
  –Moved files to and from I/O devices
• TECO - Text editor & corrector
  –Text editing from a terminal
• DDT - Dynamic Debugging Tool
  –From terminal
• Simple and elegant: user “in control”
                                         6
       Early Time Sharing
• Scientific Data Systems (SDS)
  – SDS-940 – did well in market
  – Berkeley, ARPA
  – Bought by Xerox
• Xerox PARC
  – MAXC-Multiple Access Xerox Computer
    • A PDP-10 clone

• Tymshare, CA
  – One of the few companies that leased time
    and survived
                                             7
  – Bought by McDonnell- Douglas
   Personal Computing
• Chuck House, Hewlett Packard
 RE: Calculators
 “One could charitably say we
  invented nothing: we simply
  took all the ideas that were out
  there and figured out how to
  implement them cost
  effectively”
                                     8
 Personal Computing (cont.)
• Gordon Bell            • Would personal
  “The semiconductor       computing arrive
    density has really     top-down or
    been the driving       bottom-up?
    force, and as you
    reach different
    density levels,
    different machines
    pop out of that in
    time.”
                                              9
Personal Computing (cont.)
• 1st mainframes operated as
  personal computers
• LINC; MIT & Lincoln Labs
 –1962, DEC
 –Late 1960’s – 1,200 in use
   • Personal tool for researcher
 –LINC + PDP-8 for $43,000

                                    10
           Calculators
• Chip density made electronic
  calculators feasible & affordable
• Early ones: +,-,*,/, square root
   –Too big to carry, very expensive
• 1964-Wang 300-undercut price
• HP-9100A- $5,000
• Olivetti- Programma 101- $3,500
• Still used discrete circuits, tubes,
  cards (magnetic)
• 1970’s – began to use ICs            11
    Calculators of 1970’s
• IC’s; $400+; size of paperback
• 1971- Bowmar Brain - $250
   –1st real public notice
• Prices dropped
   –1972- $150
   –1973- $100
   –1976- $50
• HP35 - $400- scientific, engineering   12
     Calculator Trends
• Became “throw-away” items
• HP & TI survived
 –HP – engineering & scientific
 –TI – cut prices
• HP-65 – programmable
 –Marketing - “personal computer”


                                    13
    Impact of Calculators
• Long production run
  – Allowed companies to amortize high
    design costs
• Unleashed personal creativity of
  masses
  – Hacker culture but professionals
  – Users groups, etc. for support
• Chips were too specialized for
  general purpose computing              14
People
• Hackers
 –Did impact industry
 –Serious Users had money
 –Altair Kit
• User Groups
 –Homebrew Computer Club-Stanford
 –Tech Model Railroad Club
                               15
 Moore’s Law

• 1964- Gordon Moore
 –Fairchild  formed INTEL
 –Since 1958, number of circuits on
  a single integrated circuit have
  doubled each year
 –Predicted: by mid-1970’s would
  have single chip equivalent to
  1950’s mainframe                    16
  Computer on a chip???
• Late 1960’s; TTL & MOS (metal
  oxide semiconductor)
  –More density
• TI, Intel, and others
  –Generally believed “computer on a
   chip” was feasible, but market too
   low to be profitable
• 1971 - Silicon chip
  –TI, Intel
                                    17
Invention of Microprocessor
• Intel - Focus on memory, not
  logic chips
• Busicom, Japan, Calculator Co.
 – Wanted set of custom logic chips for
   line of specialized calculators
• Ted Hoff- assigned
 – Inspired by PDP-8
 – Design few general purpose chips &
   tailor with software                   18
       Hoff’s Logic Chip
• All components of general-purpose
  computer
• Patent Diagram Pg. 219
• Critical feature: subroutine call
   –Used stack for multiple calls
• Slow; but plenty fast for calculator
• Complexity in the software in memory
   –Recall Maurice Wilkes
                                    19
   Intel’s Microprocessor
• Negotiated lower price to Busicon for
  rights to sell chips to non-calculator
  customers
• 1971- set of 4 chips
  – “A micro-programmable computer on a
    chip”
  – 4004:registers & control function
  – ROM (EPROM)
  – RAM
  – Chip for output
                                          20
  Intel 4004-8008-8080
• 4004; 1971
  – Worked with groups of 4 bits
  – Much question over patents (2)
• 8008; 1972
  – For Computer Terminal Corp (later Data
    Point), San Antonio – for terminals
    • Chose another chip
  – Worked with 8-bit byte
• Others now offering processor chips
                                         21
        Intel (cont.)
• 8080; 1974
 –More memory
   •near compatibility of mini
 –Less support chips
 –$360 (?Why?)
 –Compatible with 8008
 –Instruction set, memory range
  similar to minicomputers        22
Intel’s Early Chips




Intel’s 4004, 8008, 8080 Chips



                                 23
    Early 1974 Climate
• Semiconductor engineers 
  powerful microprocessors +
  larger memories
• Time-sharing users

* Did not see the convergence
 coming
                                24
        MICRAL-1973
• 1st micro-processor-based
  computer sold commercially
• Thi Truong- France
• Based on 8008
• < $2,000; 2000 sold
• Replaced mini’s for control
  systems
• Never expanded market
                                25
 Intel Development System
• Kit: RAM, ROM, + control on a
  circuit board
 –Tutorial
 – $200 or free
• Industrial customers developed
  applications & burned on ROM -
  Embedded Controller
                                   26
    Intel System (cont.)
• Intellec 4 & 8
  –$10,000
  –Develop software- PL/M
  –Were PC’s, but not recognized
  –Not available to public
  –“public wouldn’t want to do
   programming”
                                   27
  Hobbyists Get Involved
• There were hobbyists who were
  willing to micro-program
• After WWII- Electronics hobbies grew
  – Expertise and war surplus
• Electronics magazines
  – QST; Popular Electronics,
    Radio- Electronics
  – Typically included a project
                                     28
Kenbak-1

• Scientific American
  –Sept. 1971
  –For private use & schools
• Small & medium scale IC’s
• No Microprocessor
• Very limited capabilities    29
         Scelbi - 8H
•March 1974 -
 QST
•Intel 8008
 –1st microprocessor
  sold to public
• Kits as low as
  $440
                       30
               Mark -8
• Radio- Electronics
   – July 1974
• Intel 8008
• Had to order $5.00 booklet
   – Sold thousands
• Mark-8 Users Group, Denver
   – Stored programs on audio cassette
• Set of circuit boards - $47
• 8008- $120
                                         31
     TV-Typewriter
•Radio- Electronics
  –September 1973
• Allowed display of
  alphanumeric characters on
  ordinary TV
• ASCII based
• First “Screen”               32
 1974- Personal Computing
• January: HP- 65 Programmable
  Calculator
• Summer: Intel 8080
• July: Radio- Electronics, Mark 8
• December: Jan. issue of Popular
  Electronics
• Altair- $400
                                     33
                Altair
• Edward Roberts – Designer
   – “Invented Personal Computer”
   – Small hobby shop, Albuquerque
• 1st Personal Computer- “minicomputer
  kit”
• 8080 Micro-processor; IC’s; TTL
• Why Success??
   – Promoted & designed as minicomputer
   – Powerful as commercial mini
                                       34
       Altair 8800 (cont’d)
• Modeled after D.G.
  Nova
• IC memory
• 1/10 cost of mini- $400
• Cost of 8080; Not
  $360 but $75
  – Faster than Scelbi & Mark 8


                                  35
 Altair (Cont.)
Open Bus
• Replaced cable after
  1st model lost
• Circuit boards + 2
  cards
                         • Also, company
• Many slots
                           couldn’t keep up with
• Released specs so        orders
  others made cards
                         • Several years to
• But, opened door for     peripherals/
  clones                   applications
                                             36
          1975-1977
• Burst of Creative Energy
• User groups, newsletters,
  magazines, clubs, conventions,
  retail stores
• Cassette storage; Kansas City
  Standard (from user group)
• Lack of peripherals, storage held
  back the development            37
                  BASIC
• No OS nor programming languages for P.C.
  (also held back)
• Current BASICs not acceptable
   – Versions; try to fit to small computers
• Altair announcement
   – Bill Gates / Paul Allen decided to write
     BASIC for Altair
   – Better - available in June 1975
      •Use ONLY 4K of memory
      •New version soon
                                            38
         BASIC Cont.
• Cost with Altair memory boards
  –$60 for 4K; $75 for 8K
  –$150 for extended (needed
   storage)
• $500 for other 8080 systems
• USR – convert to machine language
• Other extensions – Peek, Poke
                                   39
  Development of BASIC
• Gates @ HARVARD; no 8080
  system
• With Monte Davidoff
• Wrote PDP-10 using 8080
  specification
• 1975- Paul Allen demonstrated
  in Albuquerque to Roberts and
  Yates
• Altair began to advertise       40
 Open Letter to Hobbyists
• Bill Gates
• Problems with illegal copies of BASIC
• “The value of the computer time we
  have used exceeds $40,000.”
• If not paid there will be no incentive
  to develop future software, putting
  personal computing at risk
• Microsoft moved from N.M. to
  Bellevue, WA                           41
Floppy DISK
• David Noble, IBM
  – For 370 initial control program
  – Didn’t expand to other uses
• Gary Kildall- consultant to Intel
  developing languages
  – Noted floppy
  – Wrote a small program to manage
    information to & from floppy
• Fast; Random access; read and write
                                      42
“Small” Operating Systems
• DEC tape still heavily used on
  PDP’s
• Late 1960’s- DEC OS/8 for PDP-8
 –Showed small machines could have
  capabilities of mainframes
• RT-11 for PDP-11- 1974
 –Managed data on disks

                                 43
  CP/M - Computer Program
         for Micros.
• Gary Kildall (PL/M for 8080 @ IBM)
• CP/M (Control Program for Micros) - $100
  – To control disk drives
  – Similar to DEC commands
  – $800 with floppy drive & controller
• Final piece of puzzle for PC
• Formed Digital Research
  –Product CP/M                           44
       Micros. (cont.)
• IMSAI- Altair clone
   –Wanted CP/M license
   –Redesigned CP/M so small
    portion customized for IMSAI
   –Specialized Part BIOS
     •BASIC Input/ Output System
     •This Standardized system sw
                                45
               1977
• All parts in place for pc revolution
• Altair + add-ons
• Basic + SW for money
• 8 inch floppy + CP/M
• Ports for peripherals
• Lots of publications & groups

                                     46
 Chapter 7
1972 - 1977

The Personal
 Computer
               47

				
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