On Wed, 9 Oct 2002, Wagner Lipnharski wrote: *>Peter L. Peres wrote: *>> On Wed, 9 Oct 2002, Vasile Surducan wrote: *>> *>> *>On Tue, 8 Oct 2002, Mike Mansheim wrote: *>> *> *>> *>> I have a board that had a 16F876 and a 24LC01 eeprom on it. *>> Something *>> happened to the board that damaged both the processor *>> and the eeprom. *>> If the eeprom is moved to an otherwise good *>> board, SCL is low all the *>> time. Is there any way to recover the *>> data stored in this chip? *> *>> *> The same like used by the russians when they have copied the 8080 *>> a *>looong time ago: *>> *> use a very thin and delicate file and a good microscope... *>> *> then on a mathematics copy-book draw x and o as you see on the *>> *>microscope *>> *>> Must have magic microscopes them Russians, to see electrical charge in *>> EEPROM transistors buried under their access lines and transistors. *>> The files must have been excellent too. *>> *>> Peter *> *>Now lets try to be honest. Nobody in common sense will use a tunneling or *>deep probe microscope to duplicate a 8080... think about it... how *>difficult is to design a microprocessor? *> *>Think seriously about it. I am thinking. I was born in one of them 'behind the iron curtain' countries and it took me only a short time to think about this. Do not look for logic in what those people did at the time. Bright minds from up above told hem what to do and they did it. The fact that that certain social system is not famous for good management in general should ring a *loud* bell. They DID copy the 8080 and the Z80 and I think one of the 68xx Motorola chips. But I doubt they used microscopes and such. *>I am not defending or attacking no one, but in someway is ridiculous to *>think that someone who has ability to produce a wafer will have no ability *>to design the chip. It is the same as to think that someone is very expert *>in producing a car, engine and everything else, but dumb enough to not know *>how to design it. ;-) You should check out who exactly makes (physically) cars and other much higher tech implements. I am not saying that what you are saying does not make sense, it makes perfect sense. However major parts of the world do not. Producing wafers is very different from producing workable microprocessor systems and both are different from successfully marketing them in products or per se. The East had good technology and people in some areas but the management and planning glue that was supposed to make it work in the bigger picture was rotten. *>You can design a microcontroller in 30 minutes... wanna bet? No. I drew a micro that was to be implemented with TTL chips (4 bit) just for fun in 1986 or so. I never tried to build it, it would not have been a great micro (say a quarter of a 16C54 on 4 bits) and I doubt I could have sold it or made something out of it except sink tens of hours into it. *>You just need two EPROMS, a SRAM, an oscillator and few logic gates. *> *>You assemble the logic gates to do left/right shift, add, compare and *>simple logic packages. *>Connect the RAM to feed and to be fed by the logic gates. ... You don't really need this. All you need is a Mealy (or was it Moore - the one with the latch in the feedback) automaton with wide EPROM and that's your entire CPU minus the registers, which you would not use anyway, just use a SRAM and an address counter with provisions to load it from SRAM output. This kind of core can be used to run microcode or RISC style (one giant lookup table in the EPROM). For 8 bits the size is manageable, you can probably fit it in 1M of 8bit EPROM or EEPROM. 4bits is a joke to implement like this (16 operations on 4 x 4 bits plus a few more on single 4 bits would fit in a single 64k EEPROM). More than 8 bits causes table size explosion. It is interesting to simulate these designs using C on a larger computer (PC). Also you can reprogram new instructions on the fly if you allow the microcode EEPROM to be writable by the system. DDCF ? ;-) The real problems will begin when you will want to add interrupts. Because that's when your deterministic state machine will likely stop being deterministic unless you are very very very clever and careful about these things. Peter -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.