"High-Speed Computing Devices" is a report on the state of computing machines in the US that was published in 1950. I have first edition copy but it is also available on the Internet Archive. http://www.archive.org/details/HighSpeedComputingDevices My favorite part is "Table 10-1, Large-Scale Digital Computing-Machine Projects in the United States." It lists all nine operational machines with eleven more under construction. (Pages 214 and 215, the DJVU file is offset 14 pages so this starts on page 228.) The description of the ENIAC starts on page 194. The book describes the computing circuitry in detail. You can build your own accumulator with a handful of vacuum tubes. Michael Holley