The following procedure will guide you to success.
For those of you in need of quick gratification,
you will be able to apply power at the earliest possible time
to see something happening, and verify that the microprocessor is working.
It's probably a good idea to check each step off as you go.
Part 1 - Layout and Processor Verification
74Ls240 - install into project
74Ls240 - pin 10 to GND
74Ls240 - pin 1 to GND
74Ls240 - pin 19 to GND
74Ls240 - pin 20 to +5V
Install R1 thru R6 close to the location for the LEDs.
Connect one end of R1-A, R2-A, R3-A, R4-A, R5-A, & R6-A to +5V
Install LED1 thru LED6 with + (longer end) next to R1 thru R6
LED1 + to R1-B
LED2 + to R2-B
LED3 + to R3-B
LED4 + to R4-B
LED5 + to R5-B
LED6 + to R6-B
LED5 - to 74LS240 pin 16 (clock indicator)
Install 87C750 Microprocessor (or a matching socket)
87C750 pin 12 to GND
87C750 pin 24 to VCC
Install Xtal. Connect leads to 87C750 pins 10 and 11
Install C1. Connect negative end to 87C750 pin 9
Connect C1 positive end to +5V
Install R7 8.2K. Connect one end to 87C750 pin 9
Connect free end of R7 to GND.
74LS240 pin 4 to 87C750 Pin 4
74LS240 pin 18 to 87C750 Pin 8
Check all the above steps at this time.
Apply Power to the circuit. LED 5 should flash at a rate of about 6 times per second