Chess Challenger

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Sensory Chess Challenger, 1982, 6502 [1]

Chess Challenger, or Fidelity Chess Challenger,
was a series of dedicated chess computers produced and market by Fidelity Electronics. The Chess Challenger 1 was the first commercial chess computer of its kind in 1976, invented by Sidney Samole, with a program by Ron Nelson, developed for an Altair 8800 Microcomputer with an Intel 8080 CPU. Further versions of Nelson's program run on a more advanced Z80 CPU, great commercial success was the Chess Challenger 7 [2] in 1979. Ed English, an early game programmer affiliated with Fidelity Electronics in 1979/80, improved the alpha-beta implementation to double the playing speed [3].



Chess Challenger Prototype, 1976, 8080 [4] .

Sargon becomes Challenger

In 1980, when Dan and Kathe Spracklen started to collaborate with Samole, a 6502 Version of Chess Challenger was built for a Sargon III port. The 6502 was better suited for Sargon than Z80. Excerpt from their oral history how it went with Fidelity [5] :

So, that’s about the time we started looking at Fidelity again. We got in contact with Sid Samole, who was the President of the company, and he said, “Well, come out and see us and bring your- what you got out there and show it to us.” And so we got on a plane and flew out to Miami, and showed off our program to him. And they had their chief engineer, Ron Nelson, look at it, and they were impressed. And so they offered us a big contract, basically, to go to work for them, basically, fulltime. And we didn’t have to go to Miami. We could stay in San Diego.
They had the Chess Challenger 1, I think, out at the time, or 2, and they were looking for something better. Our program, that we brought with us, just shellacked their program. We had a little tournament there, in Miami, just a little, between us, on our- the one we brought with us. And they were impressed.
And we continued to sell both through, or Sargon, through Hayden. So Fidelity didn’t mind that. The said that’s cool. They didn’t see it as a competition with them. 

WMCCC 1980, MCC 1980

The immediate success was the lucky win of the 1st World Microcomputer Chess Championship, September 4 to 9, 1980, in London. Chess Challenger with a 6502 CPU, notably winning last three of five rounds against three of four other Sargon incarnations! While the ICGA tournament site states a Z80A CPU [6], Kevin O’Connell reported the World Microcomputer Chess Champion was equipped with a MOS Technology processor, despite newest Fidelity computers were shipped with Z80/Z80A [7]. As further confirmed by Fidelity Electronics' Vice President Myron Samole in an Personal Computing interview, the Champion Sensory Challenger, which also won the MCC 1980 at September 5 to 7 in San Jose, California had a program written around the 6502 chip [8].


German Chess Challenger brochure with Prof. Heinz Haber endorsement [9]
Chess Challenger Sensory Voice [10], a Z80 based Nelson Program as Micro Champ? [11]

WCCC 1980

The Chess Challenger which played the WCCC 1980 end of September in Linz and finished last was presumably an older Z80 based computer with a Nelson program [12]. Fidelity's flagship end of the 70s, with World Champion 1980 advertisement was the Chess Challenger Sensory Voice. The first 6502 based computer with a Spracklen program commercially available appeared in 1981 as Champion Sensory Chess Challenger [13] .

ACM 1980

The strong third place at the ACM 1980 in October was again a great success, only losing to Belle in the last round [14]. Description given from the ACM booklet with mentioned authors Dan and Kathe Spracklen, Ronald Nelson, Frank Duason [15]

This marks the first appearance in an ACM tournament for this popular machine. Chess Challenger is written in assembly language for a 6502 microprocessor. It has 20k bytes of memory and executes about 1,000,000 inst/sec. A book of about 1,000 moves is used. The program uses the alpha-beta algorithm with iterative deepening.

Name Confusion

Using the same name at almost the same time for programs with different authors and CPU architectures caused some confusion by potential customers, not to mention tournament organizers. Accordant to their product lineup and nomination, and caused by former tournament rules, permitting multiple, but different named entries from the same author, and commercial availability of participating computers, Fidelity Electronics somehow was "forced" to continue the naming obfuscation in further tournaments, where Fidelity computers with Spracklen programs participated as Fidelity X, Challenger-X, Elegance, Elite, Private Line, and Sensory.

Chess Challenger X

ACM 1986

In 1986, at the 17th ACM North American Computer Chess Championship, Fidelity showed up with a huge experimental, parallel machine, named Chess Challenger X. Authors were Ron Nelson, Dan Spracklen, Kathe Spracklen, and Danny Kopec as Book author. It had a Z80 controller, and 16 or more 68000 16-bit processors. The controller was written in C, the 16 or more Spracklen programs in assembler [16].

Chess Challenger X scored 50%, losing from Recom and Belle. Notably, in the same tournament, another Fidelity computer programmed by the Spracklens with a Kopec book took part, as Fidelity Experimental with a 68020 processor. It did not score better in that strong field and finally placed 10th.

ACM 1988

At the ACM 1988, the new experimental version of a 68030 based micro called Chess Challenger X showed a remarkable performance. Mentioned authors from the tournament report by Monty Newborn and Danny Kopec [17] were Dan and Kathe Spracklen as well as Ron Nelson. The 32-bit program, written in 68030 assembly language, drew Deep Thought and won versus Waycool, the current World Champion Cray Blitz, and HiTech. Chess Challenger X was likely the forerunner of the commercial available Fidelity Elite Avant Garde V9 [18] . One year later, at the WCCC 1989 in Edmonton, a similar machine, presumably with a further developed program, played under the name Fidelity X and finished sixth.

CC Clones

See also


1978 ...

1980 ...

2000 ...

Forum Posts

1998 ...

2000 ...

2010 ...

Re: Ron Nelson by Chessmaster Ireland, Hiarcs Forum, January 02, 2016
Re: Ron Nelson Chess Challenger 10 by ChessChallenger, Hiarcs Forum, January 24, 2016

External Links

Chess Challenger Voices

hosted by Tom Luif


Year Product Link(s) [19] [20] Author(s) Processor Tournaments
1977 Fidelity Chess Challenger 1
Fidelity Chess Challenger (CC1)
Fidelity Chess Challenger 1
Ron Nelson 8080
Fidelity Chess Challenger 3
Chess Challenger 3, CC1 vs CC3
Ron Nelson 8080, 2 MHz
1978 Fidelity Chess Challenger 10 Ron Nelson Z80, 4 MHz
1979 Fidelity Chess Challenger 7 Ron Nelson Z80
Fidelity Chess Challenger Voice Ron Nelson Z80, 4 MHz
1980 Fidelity Voice Sensory Chess Challenger Ron Nelson Z80, 4 MHz
Fidelity Decorator Challenger Ron Nelson Z80, 4 MHz
1981 Fidelity Chess Challenger Mini Sensory Ron Nelson 80C50, 6 MHz
Fidelity Champion Sensory Chess Challenger Dan and Kathe Spracklen 6502, 2 MHz WMCCC 1980, 1st
1982 Fidelity Super 9 Sensory Chess Challenger
Fidelity Super 9
Dan and Kathe Spracklen 6502, 2 MHz
Fidelity USCF Special Edition
Fidelity USCF Special Edition
Dan and Kathe Spracklen 6502, 2.5 MHz
1986 Chess Challenger X Dan and Kathe Spracklen
Ron Nelson, Danny Kopec
Z80, 16 x 68000 ACM 1986, 7th
1988 Chess Challenger X Dan and Kathe Spracklen
Ron Nelson
68030 ACM 1988, 2nd


  1. Sensory Chess Challenger, 1982 from The Computer History Museum
  2. Chess Challenger 7 from Wiki (German)
  3. Ed English | LinkedIn
  4. Chess Challenger Prototype from World Chess Hall of Fame and Sidney Samole Chess Museum, see Sidney Samole and Fidelity Electronics from
  5. Gardner Hendrie (2005). Oral History of Kathe and Dan Spracklen. pdf from The Computer History Museum
  6. 1st World Microcomputer Chess Championship - ICGA Tournaments
  7. Kevin O’Connell (1980). World Microcomputer Chess Championship. Personal Computer World, November 1980
  8. Harry Shershow (1981). The MyChess-CSC Confrontation at San Jose. Personal Computing, Vol. 5, No. 1, pp. 79-81
  9. Grand Master Voice 1980 Brochure | Flickr - Fotosharing by Chewbanta
  10. Fidelity Chess Challenger Voice from Wiki (German)
  11. Fidelity CC Sencory Voice was a Z80 based Nelson program, and not the 6502 based Spracklen program which won the WMCCC 1980
  12. Sargon immer noch Marktführer:: Mikros noch ohne Großmeister-Format, Computerwoche, November 28, 1980 (German)
  13. Fidelity CC Champion from Wiki (German)
  14. "Belle" wurde auch US-Champion 1980: Frecher Schachzwerg beweist Kaltblütigkeit, January 23, 1981, Computerwoche 3/1981 (German)
  15. The Eleventh ACM's North American Computer Chess Championship, pdf from The Computer History Museum
  16. The ACM's Seventeenth North American Computer Chess Championship and The Sixth World Microcomputer Chess Championship from The Computer History Museum, pdf
  17. Monty Newborn and Danny Kopec (1989). Results of The Nineteenth ACM North American Computer Chess Championship, in The Twentieth ACM North American Computer Chess Championship from The Computer History Museum, pdf
  18. Fidelity Elite Avant Garde V9 from Wiki (German)
  19. Fidelity from Wiki (German)
  20. Chess Computer UK by Mike Watters

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