ANSI C
The ANSI C PRNG is a linear congruential PRNG which returns an integer in the range 0 to RAND_MAX-1 inclusive, where RAND_MAX is at least 32767. One complaint PRNG is of the form:

Xn = (1103515245 * Xn-1 + 12345) mod RAND_MAX

Assume that when you seed this, the seed = X0

Microsoft C
This is the PRNG in the MS C library version 4.0. It returns an integer in the range 0 to 32767 inclusive.

TEMP = (214013 * Xn-1 + 2531011) mod 2147483648
Xn = INT(TEMP / 65536)