I sell a hand held CNC Gcoder that might be helpful to you.
CncGcoder HD: Software: Light Tool Supply
# Eliminate Costly "DNC" Systems by Tranfering "G" Code From CNC Control to PC via PDA
# You can use the CncGcoder® HD to make quick program edits right in front of your CNC. The built-in CNC style keyboard makes it easy to change speeds, feeds, or even program numbers on the shop floor. You can make your changes and send the new program to the cnc in seconds. (only files less than 30,000 characters can be edited in the CncGcoder)
# The unit is liquid, dust and shock resistant. It will withstand a splash of oil or a few chips. It will even tolerate the occasional dents and dings common in any shop.
# Never have difficulty finding the right program again. File management has been simplified. The G-Code programs can be saved with descriptive manes as PC formatted files. These files can be organized into any number of folders or directories.
# The unit also has an integrated SD slot for limitless memory capabilities. Use an SD memory card to store and organize all of your G-Code programs, or use different cards for different machines.
# The CncGcoder HD is equipped with a large capacity rechargeable battery for hours of continuous use between charges.
# Never need to worry about available memory on your CNC again. Store your G-Code programs on your PC and then use your CncGcoder HD to transfer the programs to your CNC when needed. (up to 1 MB per transfer is supported)
# By displaying the program on the unit's screen, you can be sure it is correct the first time. No time is wasted running to and from the computer to check what is being transferred. You can walk up to the machine and start communications.
YouTube - CncGcoder HDx