Counterfeit 7400 logic?

On Tue, Jul 16, 2013 at 12:19 PM, Alexandre Souza <alexandre.tabajara at gmail.com> wrote: I don't have it in front of me, but it _might_ be a TPT-100 "Handy Tester". I can't find any data on it online (it's 20 years old) but it's similar to the Instek GUT-6600A (except that the TPT-100 can test +5V DIP DRAMs from 64Kx1 through 1Mx4). There's an older PIC microcontroller inside that reads the 5-6 buttons and displays results on a 16x1 textual LCD. You insert the chip, either navigate up/down through the list of supported part numbers or press "TEST" to start at the bottom and work up the list until there's a functional match. Great for identifying common parts with obliterated numbers or OEM part numbers. It's not perfect, but you can easily tell a 7400 from a 7474. Long ago, I rigged up a DIP cable to a TC-16 test clip so I could test all the ICs in simple (no interconnects) DEC M-series modules. The power requirement of all 4-6 chips per board didn't crush the tester, and I just had to reposition the clip, press "test", look for "OK", then repeat. We got it years ago because we had a 5150 (or compatible) PC that we used with a $20K 68000 tracer/debugger that wouldn't boot, and it was the least expensive instrument to test the DRAMs one chip at a time (we identified 2 bad DRAMs and one bad mux and had those parts inches away on the test bench). I use it almost every month. -ethan