OK, Steve Hardy, you are right in many (almost all) aspects! PIC HELP FORM ------------- 1) Background . Description of application : A test square wave in RA0 (just to see if anything works) . PIC Device number: Its a 16J probe, 16C64 used! 2) Hardware config including . Power supply - Voltage confirmed (oscilloscope, multimeter) Re: checked! - Connected to _all_ power pins e.g. '74 has two GND and +5 pins - Bypass cap . Oscillator type - Clock speed? Re:4MHz (oscillator configured as XT) - Confirmed set configuration bits. Re:Check - Confirmed clock signal on OSCOUT. Re: There is none - Confirmed frequency (oscilloscpe, freq meter) Re: There is none (Oscilloscope used: Philips PM3355 60MHz 250MS /s) . MCLR pin - Method of control e.g. tie to +5, external brownout protection. Re: Used the Configuration of PIC16C64 sheets . I/O pins - Connections in circuit - give description or ascii diagram. Re:Not connected! Direct entry to oscilloscope - Mode (in, out, I/O, analogue, comparator, used by peripheral) Re: All peripheral disabled . Other considerations e.g. - Electrically noisy environment Re: Normal - Temp range Re: Normal 3) Software . What is the code supposed to do? A square wave in RA0 (~2Mhz) . Reset path - Setting of option register (reset value 0ffh) - Setting I/O port directions and initial values (bcf trisa,0 - RA0 as output) - Analogue input configuration (Its a 16C64! 16C74A configured as digital I/O) - Peripheral configuration (default) . Using interrupts? No . Code lowest and highest address (looking for page boundary overflows) 0h to 35h . Use of peripheral functions - Timers - NO - SPI - NO - UART - xx - ADC - xx - Capture/compare/PWM - NO . Using watchdog timer? Disabled . Using power-down (sleep) modes? NO . Add assembler listing fragments if appropriate. Note that a balance has to be made between excessive bandwidth from list server and ability to see all the code. You should be prepared to send a complete listing if requested. Re: I did sent it. I send now the list from Program Memory Window: 0000 2830 goto Main 0001 3FFF addlw 0xff 0002 3FFF addlw 0xff 0003 3FFF addlw 0xff 0004 3FFF addlw 0xff 0005 3FFF addlw 0xff 0006 3FFF addlw 0xff 0007 3FFF addlw 0xff 0008 3FFF addlw 0xff 0009 3FFF addlw 0xff 000A 3FFF addlw 0xff 000B 3FFF addlw 0xff 000C 3FFF addlw 0xff 000D 3FFF addlw 0xff 000E 3FFF addlw 0xff 000F 3FFF addlw 0xff 0010 3FFF addlw 0xff 0011 3FFF addlw 0xff 0012 3FFF addlw 0xff 0013 3FFF addlw 0xff 0014 3FFF addlw 0xff 0015 3FFF addlw 0xff 0016 3FFF addlw 0xff 0017 3FFF addlw 0xff 0018 3FFF addlw 0xff 0019 3FFF addlw 0xff 001A 3FFF addlw 0xff 001B 3FFF addlw 0xff 001C 3FFF addlw 0xff 001D 3FFF addlw 0xff 001E 3FFF addlw 0xff 001F 3FFF addlw 0xff 0020 3FFF addlw 0xff 0021 3FFF addlw 0xff 0022 3FFF addlw 0xff 0023 3FFF addlw 0xff 0024 3FFF addlw 0xff 0025 3FFF addlw 0xff 0026 3FFF addlw 0xff 0027 3FFF addlw 0xff 0028 3FFF addlw 0xff 0029 3FFF addlw 0xff 002A 3FFF addlw 0xff 002B 3FFF addlw 0xff 002C 3FFF addlw 0xff 002D 3FFF addlw 0xff 002E 3FFF addlw 0xff 002F 3FFF addlw 0xff 0030 1683 Main bsf 0x3,0x5 0031 1005 bcf 0x5,0x0 0032 1283 bcf 0x3,0x5 0033 1405 MaiLoo bsf 0x5,0x0 0034 1005 bcf 0x5,0x0 0035 2833 goto MaiLoop 0036 3FFF addlw 0xff . Add listing of interrupt routine. Since interrupt handlers can have drastic and unexpected effects, it is well worthwhile to include at least this part of the code. Re:Don't use NB: Assembler list output is more useful than source code since it allows confirmation that macros have expanded correctly etc. In many cases you will solve your own problem by looking through the listing. 4) Development environment . PC operating system (DOS, WIN31, WIN95 etc.) - WIN95 . MPLAB, Clearview PDE etc. and version numbers - MPLAB 2.20 Feb./96 . Programmer hardware - PICMASTER with PICMASTER CE 5) Testing procedure - detail results. . Use MPSIM? If not, give reason as to why use of MPSIM etc. was not helpful e.g. too difficult to make real-time stimulus. Re:No. I verify the Register File Memory . Use in-circuit-emulator? Re:YES . Use programmed chip in target circuit? . Was test-point code added e.g. toggling a spare port pin at certain points in code. If so, what did this indicate? Re:I am tryed to do that as a test! Doesn't work! 6) Any other relevant information. Re:The code works with a UV version of the 16C64 7) Go over your email to make sure that it is not ambiguous or misleading. Correct the typos, spelling and grammar to the best of your ability. Re: I'm very sorry for the grammer and spelling! Not natural language!