If you are using Keil (and possibly other compilers) I think your problem is here:

xdata minutes _at_ 0x07FA;
xdata control _at_ 0x07F8;

Keil stores the lsb of 16 bit integer values at the higher address so you will be setting bit 6 of 0x7FB with control=0x40. Your read from minutes will suffer a similar problem.

Best to use unsigned char for these declarations.