What is the purpose of the resistor between the Vcc and discharge pins in the astable 555 timer?
If you look at the 555 internal schematic as shown on the TI datasheet, you will see that the Discharge pin is only connected to the collector of a transistor - that transistor can pull the Discharge pin Low, but there is nothing in the chip to pull that pin high, or to provide and charging current to the capacitor.  R1 pulls that pin high, and provides the charging current for the capacitor.