Direct-collapse black holes (DCBHs) are the leading candidates for the seeds of the first quasars, over 300 of which have now been found at z > 6, less than a billion years after the Big Bang. They form in massive, pristine cosmological halos at z ∼ 10 - 20 that reach virial temperatures of 104
K, triggering atomic cooling and catastrophic baryon collapse with infall rates of up to 1 M⊙
. Such rates are thought to build up supermassive primordial stars that can reach 3 × 105
before collapsing via the general relativistic instability. However, until now no one has ran these events long enough for the stars to collapse to DCBHs or modeled their evolution in the cosmological flows that create them. Here, I present cosmological simulations of direct collapse out to 3 Myr, ten times longer than studies to date sufficient to form quasar seeds. I also model the evolution of these stars with simulation accretion rates in an attempt to determine their masses at death and build up a rough initial mass spectrum for DCBHs. This simulation suite thus reproduces the mass of the first quasars at birth from first principles. I also present calculations of near infrared and radio signatures from DCBHs to determine if they could be detected by the next generation of telescopes such as the James Webb Space Telescope, the Square Kilometre Array and the Next-Generation Very Large Array.