I had a problem once - I got a design for a sine wave generator using an 8-bit shift register that has inverted feedback - ie it fills up with 1's then fills up with 0's. You dimension the resistors off the outputs so that at each point the resistors divide the 1's and 0's to the right voltage at that point on the sine wave. Only problem was, I wanted a 10-bit shift register. So had to redimension all the resistors. I worked out a program to do it on my 33E. It involved quadratic equations but with RPL and the stack they are easy. I was sorting thru some old articles the other day and came across my original hand written notes on this. The program only just fitted into memory (think it was max 50 steps?) but it worked just fine.
Like David I have a Zimbabwean accent. My favourite story was back in 1992 I phoned someone in California to mail me some data (no email, web sites and fax wasn't really clear). I gave my name and address and finished off with "Ontario, Canada". The voice on the other side countered with
"well, that explains the accent"!
@"...dating from the mid-1050s"
Goodness - I didn't know they'd been going THAT long... ;-)
Typos aside, another good story illustrating the quality of the old HP stuff. Sorry, I'm not clear, which one did you sell, the HP or the 465? I have fond memories of the 465...the first scope I ever used...as a radio tech in the Rhodesian police. Our comms were 40 MHz AM, so you could look at the TX output directly on a sniffer port of our dummy load. Damn good scopes, Tektronix is a close second to HP in my opinion, but they only really made scopes in those days, unlike HP who made pretty much everything.
Oh, goodness, too many HP test equipment stories to tell but here is just one. I am now retired and I have a number of old'ish HP test equipment around. A couple of months ago, I pulled an HP-120B oscilloscope off the shelf where it had been languishing for 20+ years.
I had a two fold objective: get it working so I could use it to fix my Tektronix 465 o'scope and then to be able to sell it. The HP120B is a (mostly) vacuum tube beast dating from the mid-1050s. I put it on the bench and used a variac to bring it up over a 12 hour period. I rotated the controls and spritzed them with suitable cleaner. As the variac reached 90V, the old HP120 started to come to life and, after more than 20 years, it was soon working much it did '..back in the day..' After using it to find my problem, I then sold it to another electronics guy down south. Fantastic but not totally unexpected. They build them good!
Re the calculators: When I was in Jr. High, I wanted an HP-35. In High school, I wanted the 45, and when it came out, the 55. When I was a freshman in college, I actually bought a 29C from an ad in Scientific American. I really loved that calculator, but I had difficulty (several failed attempts) replacing the battery, and eventually sold it to a collector on eBay for about 50% more than I paid for it in the first place.
Today I have a 48G on my desk. Unlike the 29C, which I knew backwards and forwards, I can only use about 10% of the capabilities of this amazing machine. I just wish the build quality matched the 29C...
Anyone who has an interest in HP calculators might enjoy a trip to www.hpmuseum.org. There's even sections on slide rules and the Curta "pepper grinder".
I have several pieces of late 60's through end of 1970's HP equipment. I call them "infinitely repairable" instruments because they generally used discrete transistors, or at most complex, very basic op amps and TTL chips. I guarantee you this fact alone accounts for their longevity and reliability.
Any problem I have ever found in these instruments concerns the silver coloured electrolytic capacitors they used, which short. Sprague was the manufacturer in most cases.
And David, there is likely nothing wrong with your 8640B except a blown fuse on the generator output. A picofuse most likely, they fused the output on many instruments to protect the output stage.
I attribute my engineering degree to the HP-35. While everyone else was pushing their slide rules around, I managed to find an extra 20 minutes in the exam. I still have it and some of the books that described the algorithms to resolve complex (not imaginary) calculations.
When they released the HP35S about 3 years ago, I just had to buy one. It is much closer to the HP61 because of the programmability and key functionality. Sort of resembles the 35 as much as the new Mini car resembles the old one.
I must say though, after my recent acquisitions of HP printers and scanners I don't think the HP quality is still there. See my thoughts here
Blog Doing Math in FPGAs Tom Burke 15 comments For a recent project, I explored doing "real" (that is, non-integer) math on a Spartan 3 FPGA. FPGAs, by their nature, do integer math. That is, there's no floating-point ...