The Z1 for shure, but compared to the ENIAC, the Z3 had a comprehensive calculating speed. One problem is the different technologie used - ENIAC used a 10 digit fixed point decimal system, while Zuse already used binary floating point like todays computers. The ENIAC could do 14 fixed point multiplication per second, while the Z3 did (only) 0.3 floating point. Its the old thing of big money vs. no money - or government fund projects vs. private - for the ENIAC, upenn had (almost) unlimited government money, while Zuse didn't get any singe cent - so he had to use junk telephone relais instead of new one, and this also is the reason why he used a relais system istrad of tubes - he just couldn't aford it - It's the same in all ages - if you don't have to count every transistor, byte, megabyte (M$) you'll use everything available. (The ENIAC-on-a-chip project also took 174,569 transistors to rebuild the function :) Zuse: Pennsylvania ENIAC machine went all round the world - "18,000 tubes!". We could only shake our heads. What on earth were all the tubes for? Schreyer and I parted company after the War. At that time it was prohibited to develop electronic equipment in West Germany.< They had plans for a 2000 tubes computer around 1937, but didn't get the money, since the authorities belived that the war wouldn't need it, because the planned two year development would be to late ... Helmut Schreyer had build a small experimental machine for calculating 10 Digit numbers with something around 100 tubes, running in 1944. Not a complete comuter - more like a calculator. Gruss H. -- Ich denke, also bin ich, also gut HRK