Testing old chess computers through emulation

In the days before everyone had computers, if you wanted to play chess, your only option was to play with another person. In the late 1970's Fidelity introduced a series of electronic computer chess games. These early models played poorly, but I knew people who bought them just to be able to play and practice whenever they wanted. I managed to borrow a few of these so that I could get a feel for how well they played.

Although the early machines did not play well, things started to improve in the 1980s. There was a golden age of dedicated chess computers that went from 1983 to about 1993.  In 1984, I purchased the Novag Super Constellation electronic chess game for what I think was $200, which was quite a bit of money in 1984. The U.S. Chess Federation had given it a rating of 2018, which is better than at least 90% of all adult tournament players. Any rating between 2000 and 2199 is considered to be the skill level of "Expert" and a higher rating of 2200 is considered to be "Master."

Although I am currently rated 2016, at the time I bought the Novag Super Constellation I was rated just a little over 1700. In a few months, I would reach a rating of 1800 which is considered to be "Class A." Nevertheless, what I remember about the Novag Super Constellation is that it played better than me, which is surprising since it only contains an 8-bit processor running at just 4 MHZ. That is not very fast compared to modern 64-bit processors with multiple cores running at gigahertz speeds.

Over time, I bought a couple of better chess-playing computers and I have fond memories of practicing with all of them. I sold all these machines when I got a desktop computer in the mid-'90s, but I kind of regret it because they all were fun to play with it.

This became an issue when I was researching these old chess-playing computers where I saw many online claims that these computers were not as good as the ratings that had been assigned to them. For example, I saw the claim that the Novag Super Constellation was only about 1750 strength, and two other computers that I owned rated 2100 and 2265 were also claimed to be weaker than their advertised ratings. None of these claims match my experience, since all of the computers played better than I did.

I was so curious about this that I wanted to get my hands on one of the old chess computers, assuming that one can be found, however unlikely, and see how it compares to my current chess ability. Fortunately, I found software that allows me to emulate dozens of old chess computers on my Windows PC.

In my first game against the emulated Novag Super Constellation on level 1, the lowest level, I was able to win by only the slimmest of margins. I tried the same thing on the Fidelity Designer 2100, a slightly better machine, and I lost. I have no doubt that the other computer I owned, the stronger Fidelity Designer 2265, would stomp me like it used to when I played it 30 years ago. I will confirm this eventually.

So I tested a variety of chess computers with a somewhat difficult chess problem..

Most serious chess players have seen this problem already and know the answer. However, if they were not familiar with it, the solution might be difficult for them to find in a real game. There is the more direct solution of 6. Nxe5 Bxd1 7. Bxf7+ Ke7 8. Nd5# (checkmate). However, for a computer to see the solution it also has to see 6... Nxe5 7. Qxh5 Nxc4 8. Qb5+ c6 9. Qxc4. There is also 7... Nf6 8. Qe2 Nxc4 9. Qxc4. Either way, that is 7 half-moves deep, which is pretty deep for ancient chess computers to look.

Based upon my testing, this is how long various chess computers take to solve this chess problem...

#	Model	Year	Processor	Speed	ROM	Time	Depth	Nodes/S
1.	Fidelity Chess Challenger 10	1978	Z80	4 MHZ	4K	Fails
2.	Fidelity Chess Challenger 7	1979	Z80	4 MHZ	4K	12 hours
3.	Novag Savant	1981	Z80	6 MHZ	24K	12:40m
4.	Novag Savant II	1982	Z80	6 MHZ	32K	12:33m
5.	Novag Constellation	1983	6502	2 MHZ	16K	6:46m
6.	Constellation 3.6 ROM set 1	1984	6502	3.6 MHZ	16K	3:30m*
7.	Constellation 3.6 ROM set 2	1986	6502	3.6 MHZ	16K	3:33m*	5 ply
8.	Novag Super Constellation	1984	6502	4 MHZ	56K	2:10m	5 ply
9.	Constellation Expert	1985	65C02	5 MHZ	64K	1:54m	5 ply
10.	Novag Forte A	1986	65C02	5 MHZ	64K	2:15m	5 ply	~1000
11.	Novag Forte B	1986	65C02	5 MHZ	64K	1:58m	5 ply	~1000
12.	Novag Super Forte	1987	65C02	5 MHZ	64K	1:13m	5 ply	~1350
13.	Novag Super Expert A	1987	65C02	5 MHZ	64K	1:00m	5 ply	~1100
14.	Novag Super Forte B	1989	65C02	5 MHZ	64K	30s	5 ply	~1400
15.	Novag Super Expert B	1989	65C02	5 MHZ	64K	19s	5 ply	~1375
16.	Novag Super Forte C	1990	65C02	5 MHZ	64K	11s	5 ply	~1500
17.	Novag Super Nova	1990	HD6301Y	4 MHZ	32K	10s	4 ply
18.	Novag Super Expert C	1990	65C02	5 MHZ	64K	6s	5 ply	~1050
19.	Novag Scorpio 68000	1990	68000	16 MHZ	98K	9s
20.	Novag Diablo 68000	1990	68000	16 MHZ	98K	9s
21.	Fidelity Excellence	1985	65C02	3 MHZ	16K	2:16m	5 ply
22.	Fidelity Excellence	1985	65C02	4 MHZ	16K	2:00m	5 ply
23.	Fidelity Designer Display 2000	1989	65C02	3 MHZ	32K	1:45m	5 ply	~81
24.	Fidelity Par Excellence	1986	65C02	5 MHZ	32K	1:22m	5 ply
25.	Fidelity Designer Display 2100	1988	65C02	6 MHZ	64K	54s	5 ply	~180
26.	Fidelity Designer Display 2265	1989	68000	16 MHZ	64K	5s	3 ply
27.	Fidelity Designer Display 2325	1991	68020	20 MHZ	64K	3s	4 ply
28.	Chessmaster NES	1990	6502	1.79 MHZ	48K	7:00m	5 ply
29.	Chessmaster Super Nintendo	1991	65816	3.58 MHZ	110K	4:43m	5 ply
30.	Chessmaster 2000 (DOS)	1986	?	?	NA	1:33m
31.	Chessmaster 3000 (DOS)	1991	?	?	NA	4s	4 ply
32.	Stockfish 14.1 2017-iMac	2022	i5	3.4 GHZ One Core	NA	<1s	<12 ply	~880,000

It is noteworthy that the Super Constellation solved the problem in roughly 2 minutes, which is within tournament time controls. I am disappointed in Chessmaster on the Super Nintendo because it failed to achieve this. It is running on a similar processor, and it is a port of Chessmaster 2000 written by Dave Kittinger, who also wrote the Super Constellation program!

* The second version of the Constellation 3.6 solves this problem on its top two tournament levels, but the first version moves too quickly to see the answer.  It can only solve the problem on its infinite level, even though it takes about the same amount of time to see the solution. The second ROM set is based upon the Novag Expert program.

Super Constellation game #1.