Project 4: RAM battery backup

• By the end of lab time on Mon, April 24th
• Build the battery backup circuit on page 4 of the handout
• demonstrate that it works by:
  • writing a program that displays (on the LEDs) the value in RAM location 100 (memory location 2100H), then sets that value to 95H
  • now disconnect the power supply
  • move to another power supply
  • run your program again -- the output should be 95H
  • disconnect both the battery backup and the power supply, and run your program again -- the output should be something other than 95H
• writing a program:
  • create an assembly program in a file in directory \331 on the PC in the lab. The extension should be .ASM (in this description, we use "FILE.ASM" as the example)
  • assemble the program by typing (in directory \331) PROGW FILE
  • connect your microcomputer to the COM port of the PC and run TERMPHON. F2 will ask you for the name of the program to download (in this example, FILE)
  • you should now be able to use the PC keyboard to test your program (F1 exits). Check with the TA if you need assistance.