  Disks of two sizes and weights in alternating sequence are confined to a long
and narrow channel. The axis of the channel is horizontal and its plane
vertical. The channel is closed off by pistons that freeze jammed microstates
out of loose disk configurations subject to moderate pressure, gravity, and
random agitations. Disk sizes and channel width are such that under jamming no
disk remains loose and all disks touch one wall. We present exact results for
the characterization of jammed macrostates including volume and entropy. The
rigorous analysis divides the disk sequences of jammed microstates into
overlapping tiles from which we construct a small number of species of
statistically interacting particles. Jammed macrostates depend on dimensionless
control parameters inferred from ratios between measures of expansion work
against the pistons, gravitational potential energy, and intensity of random
agitations. These control parameters enter the configurational statistics via
the activation energies prior to jamming of the particles. The range of disk
weights naturally divides into regimes where qualitatively different features
come into play. We sketch a path toward generalizations that include random
sequences under a modified jamming protocol.
