I wonder how things that seem to have meant something, mean something else at other point of time...
When I posted, it just didn't come to my mind that simulating 12887 _with_ 8051 could mean to other person having an 8051 simulate 12887! (true indeed)
[I failed to "simulate" other persons' thinking in Real Time :D]

Anyways, I am building a college timer in which alarm data (or current time to setup RTC) is entered via a matrix keyboard interfaced to 8051. The DS12887 is connected as usual to 8051 as XRAM. 16*2 LCD is the O/P device for human interface. The uC keeps comparing the real time from RTC to the alarm(s) set inside the 8051, and whenever it finds a match it rings the bell, depending upon what day of the week it is, e.g. on Sunday or second Saturday it won't ring.

I wanted the system to be simulated a whole. But couldn't find something to model DS12887. So what I am doing now, for the time being, is to attach a memory 62256 as XRAM with higher byte of it hard-grounded so as to use only AD0-AD7 of 8051. The RTC's XDATA instructions are working perfectly well on it(62256), the only disadvantage being that the seconds etc. registers don't get automatically incremented inside 62256.

So, my final question is (or should have been): How to simulate DS12887? Does anyone know about some 'plugin' or so to simulate it in Proteus? I searched but found nothing.

Hope this was descriptive enough... :)
And I didn't say something that I didn't intend to.