  The $Roman$ microlensing program can detect and fully characterize black
holes (BHs) that are in orbit with about 30 million solar-type and evolved
stars with periods up to the mission lifetime $P<T=5$ yr, and semi-major axes
$a>0.2$au, i.e., $P> 10$ d $(M/M_\odot)^{-1/2}$, where $M$ is the BH mass. For
BH companions of about 150 million later (fainter) main-sequence stars, the
threshold of detection is $a>0.2$ au $\times 10^{(H_{\rm Vega}-18.5)/5}$. The
present $Roman$ scheduling creates a "blind spot" near periods of $P=3.5$ yr
due to a 2.3-year gap in the data. It also compromises the characterization of
BHs in eccentric orbits with periods $P>3$ yr and peribothra within a year of
the mission midpoint. I show that one can greatly ameliorate these issues by
making a small adjustment to the $Roman$ observing schedule. The present
schedule aims to optimize proper-motion measurements, but the adjustment
proposed here would degrade these by only 4%-9%. For many cases of $P>90$ d
BHs, there will be discrete and/or continuous degeneracies. For G-dwarf and
evolved sources, it will be straightforward to resolve these by radial-velocity
(RV) follow-up observations, but such observations will be more taxing for
fainter sources. Many BH-binaries in orbits of 5 yr $<P<10$ yr will be reliably
identified as such from the $Roman$ data, but will lack precise orbits.
Nevertheless, the full orbital solutions can be recovered by combining $Roman$
astrometry with RV followup observations. BH binaries with periods 10 yr $<P<$
95 yr $(M/10 M_\odot)^{1/4}$ can be detected from their astrometric
acceleration, but massive multi-fiber RV monitoring would be needed to
distinguish them from the astrophysical background due to stellar binaries.
