John Lawson said" John, I can't tell if this question has been answered since midnight, so I'll just recount my experience with Heathkit Analog Computer manuals. When you call the Heathkit Manual Replacement Service you need to have the model number of the kit you want a manual for. And the Heathkit Analog Computer, like some of their more complicated kits, is actually maded up of a number of different kits. Below I'll list the kits that I know of and a price if I have already purchased that assembly manual myself. ES-400 $25 Cabinet and Front Panel, 56 pages X ES-2 $25 Amplifier Power Supply, 24 pages X ES-50 $20 Reference Power Supply, 16 pages ES-100 $25 Initial Condition Power Supply, 12 pages X ES-151 $20 Relay Power Supply ES-201 $25 DC Amplifier, 16 pages ES-401 Voltage Regulator Transformer ES-405 Patch Cords, They don't have a manual for this. ES-447 Coefficient Potentiometer ES-450 Auxiliary Coefficient Potentiometer ES-505 Repetitive Oscillator ES-600 Function Generator, a stand alone accessary. I assume it is meant to generate functions like sine,cosine, and log. Again, the ones with prices I have. The ones without I have not checked on yet. And the ones with Xs, they had extra originals, so they sent me an original. They have lost their copy of the Operations Manual. I finally found a copy in Switerland. :) I know how you feel :) On a separate analog computer type note, I made a real exciting find a few weeks back. The S.F. Bay Area guys have already heard this. ======== Paste from old mail ============== Last week I was thumbing through "High-Speed Computing Devices", Engineering Research Associates, McGraw-Hill, 1950. This is the book that describes the state-of-the-art in 1950 and it discusses most of the one of a kind computers up until then. (It also has a large section on analog computers). Anyway, I was looking through the references section at the end of the the chapter on analog computers, when I noticed that Vannevar Bush had published most of his early articles in the Journal of the Franklin Institute. So I decided to see what would come up if I did a BookFinders.com search for the Journal of the Franklin Institute. I found: Bush, Vannevar "THE DIFFERENTIAL ANALYZER. A NEW MACHINE FOR SOLVING DIFFERENTIAL EQUATIONS." Contained in the Journal of the Franklin Institute, Volume 212, No. 4, October,1931, pp. 447-88. The complete Volume 212, octavo, attractively rebound full navy morocco. US$1500.00 Too expensive!!!! According to the references, the first article by Bush in this journal was in 1927 Volume 203. "Bush,V., F.D. Gage, and H.R. Stewart, A Continuous Integraph, Journal of the Franklin Institute, Vol.203, pp.63-84 (1927)" This is 2 years after he started work on the Integraph and 3 years before the Product Integraph is credited as being operational. So then I found on BookFinders: MCCLENAHAN, HOWARD: JOURNAL OF THE FRANKLIN INSTITUTE DEVOTED TO SCIENCE AND THE MECHANIC ARTS ; PHILADELPHIA: THE INSTITUTE, 1927. G, XLIB VOL. 203 USD25.00 I took the chance that this was not just a single issue. And it's not!! It arrived today, a hard bound copy of Volume 203 Jan-June 1927. And the article has 6 pictures and some diagrams. ======== End paste ============== (Vannevar Bush is considered the father of the electronic analog computer) --Doug =================================================== Doug Coward dcoward(a)pressstart.com (work) Sr Software Engineer mranalog(a)home.com (home) Press Start Inc. http://www.pressstart.com Sunnyvale,CA Visit the new Analog Computer Museum and History Center at http://www.best.com/~dcoward/analog ===================================================