My chess computers

A few steps backward...

1978, a high school friend of mine owned a Chess Challenger 10, and that was the first time I encountered a chess computer. A marvelous device coming from the US, very impressive but so costy, out of reach... At this time I also heard about its challenger Boris, but never approached one.

1979, last high school year before the general certificate of education, another mate with a wealthy family owns a brand new Apple II, a rather elitist computer at this time. He trusts it unbeatable at chess with its Sargon II program. I offer him to play a game against the highest level... Several hours thinking, are you saying? No problem, let's play one move per day; we meet at high school each and every day... and I beat the "monster". Once graduate, I get my first device: the
Fidelity Chess Challenger 7, offering a playing strength similar to the CC10 one at a much lower cost. I played so many games with this computer... I played some correspondence chess tounaments at this time and, despite its weak level, the CC7 helped me sort out some tacticals to check my strategy... A funny thing, with regards to current analysis power delivered by recent engines.

1980, I bought a secondhand TRS-80 model 1, basic level 2, featuring a Z80 processor with a 1.77Mhz clock (!). I upgrade it from 16K RAM to 48K thanks to an expansion interface, enabling as well to get rid of the tape recorder (equipped with a meter, an important feature at this time !) replaced by two 5.25" floppy drives. What about the resulting storage? 100Kb in the second drive, less in the first one as some space was used by the operating system (leaving roughly 80Kb for use on this drive, if I remember well). I successfully fit an overclocking kit on it, resulting in 50% speed-up, thus a 2.66Mhz Z80. The kit is smartly designed, when a drive access signal is triggered the clock gets back to normal speed - without this feature the drive read/writes would fail. A small manual switch provides ability to turn the speed-up off, a useful feature for instance when playing video games. Why do I describe all that stuff? Well, this will trigger the end of my CC7 and, for some time, of my interest with dedicated chess computers. I soon get various chess programs designed for the TRS-80, of course including the famous Sargon II, but Sfinks and MyChess as well, they outclass the CC7 despite its speed advantage (featuring a 4Mhz Z80, although I later was made aware its clock is actually more modestly set at 3.6Mhz). Proud of my successful TRS-80 overclocking, I tried a quartz substitution with the CC7. He never recovered this one...

1985, once fully graduate I have sold my TRS-80 back to get the funding for my first motorbike, I have completed my military service and I got taken on my first job since a few months. I miss chess computing, so I buy a
Fidelity Excellence. Once again a top quality/price balance, but this Spracklen's program (from Sargon III family) improved a lot and runs on a 3Mhz 6502 microprocessor, that is to say three times faster than the Apple II... a tough nut to crack. Too strong for me. I will play a lot less with the Excellence than with the CC7, loosing is not as fun as winning...

2010, I still own my Excellence, chess engines are able to play at astronomical level; nostalgia drives me on buying a second hand CC7, the one from my youthtime, about 30 years later. What a fun! I immediately remind its style, it is just like meeting an old mate again. I need to find opponents for it; costy chess computers from the eighties ot nineties are now offered as pre-owned for a few tens euros... And this is how one is going to find oneself owning a small collection of dedicated chess computers.

My 'occasional player level, class E & D' chess computers
My 'weak club player, class C level' chess computers
My 'average club player, class B level' chess computers
My 'strong club player, class A and over level' chess computers

Details about data provided:

Elo level: relative scale of computers strength, computed thru programs tournaments played at 15 seconds per move pace, thus 40 moves within 10 minutes. The Elo scale I manage (values are evolving continuously according to tournaments) is fixed to an 'anchor' I choosed, which is the Fidelity Electronics 3Mhz Excellence, according to several reasons:
- it is a device I own since more than thirty years,
- at the time it appeared, players and computers mixed tournaments existed, so Elo levels were quite well known (I am not talking about marketing claims from the constructors!)
As a personal conventional choice, I assigned the Excellence the 1780 Elo level, that is to say a good class B level. Assuming the Excellence wins or looses some points at the end of a tournament, I shift the whole Elo table with the required number of negative or positive points to get the anchor back to 1780.

CMhz: stands for '
Chess Mhz', this concept introduced by Eric Hallsworth in issue #34 of his 'Selective Search' magazine (June, July 1991) is useful for comparison purpose regarding our chess computers processors' power. Its reference value is 1 for a 6502 running at 1Mhz. Thus, an Apple II or a Commodore 64 are worth 1CMhz, and the 3Mhz Excellence is worth 3 on this processor power scale.

Rperf: stands for 'relative performance', uses the above concept of hardware power scaling to compute a pure software performance level. I use here again my Excellence 'anchor', to which I conventionally assign a 100% Rperf. So 100% is the chess playing skill of the Spracklen's program hosted by the Excellence. A 4Mhz Excellence (which I do not own) will show the same 100% Rperf. I compute the Rperf of a chess program as the ratio, displayed as a percentage, of the Elo measured for the considered program running on its own hardware, to the forecasted Elo the Excellence would achieve assuming same hardware power. I thus build a scaling which is agnostic from hardware, where a less developped program than the Excellence shows a less than 100% Rperf (for instance: Sargon II, 83%) and a more advanced one shows a Rperf higher than 100% (for instance: Elite Avant-Garde, 109%). The Par Excellence, successor of the Excellence and known to be quite stronger, benefits from its 5Mhz clock above all, as its 102% Rperf reveals a relatively low software enhancement, yet improved. The formula is, assuming a device with 'CMhz' power providing 'Elo' level:
Rperf = Elo / ( 1780 + Log10(CMhz/3) / Log10(2) * 60 ))
Explanation: 1780 is the established Elo level for the 'anchor' 3Mhz Excellence;
CMhz/3 is the CPU power ratio of the considered device to the Excellence (worth 3 CMhz), the ratio of base-10 log of previous value to base-10 log of 2 computes the number of times power is doubled from the Excellence to the considered device, and 60 is the (again conventionnally chosen) value of Elo gain for each computing power doubling.