Simple GAL Programmer

  
This GAL programmer is controlled via a parallel port, so that any exclusive interface is not requires for the programmer. It is easy to use on the notebook PCs. When program a PIC, a socket converter is needed. After assembly is finished, check if the wiring is correct and then power on. If all right, adjust VR1 to Vcc is 5.25 volts, and VR2 to Vpp is 15.0 volts. PGALCHK.COM is a function check program which checks if programmer works completely or not. The checker program can manipulate each socket pin voltage. Timer test is complete if finished in ten seconds. If not stabled (other pins changed, etc..), I think it is due to ground bounce. Long cable increases this effect. This programmer reducing ground bounce by add C/R to BUSY line. But longer cable can occures any errors. In this case, change to shorter cable or increase resister value R1.
Simple GAL Programmer - schematic

Control programs are DOS based applcations that running on the IBM AT compatibles and NEC PC9800 series. I recommend to run them on the true DOS. But it seems that stable running on the Windows (in DOS window), I think that because it has a timer on the programmer for get control timings. Run pgal.com with a JEDEC file, then a message that request to put a GAL device will displayed. Put a GAL on the socket and type any key, start to program. When the programming was finished with successful, remove the GAL from socket. A 20-pin GAL is put on the socket with adjust GND pin. RIght list shows the devices that confirmed to program. Run pgal.com with /R switch and dislpays a GAL type selection menu. Select a required device, display a message that request to put a GAL. Put a GAL on the socket and then type any key, starts to reading, output fuse data and terminates program. Fuse map is output to console, so that please redirect to a file. Erasing a GAL PGAL /E To erase a GAL, run pgal.com with /E switch. But GAL is erased before program so that this command is not used normaly. Read and Write PIC PICW84.COM is a control program for program to the PIC. Its usage is same as GAL programming. Hex-file format must be INHX8, and it must includes a configuration word.




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