A chemistry analyzer is disclosed that can include a unitary base with vertical and horizontal supports for constraining subassemblies. The subassemblies include at least a reagent/sample carousel subassembly, a transfer arm subassembly, and a reaction carousel subassembly. A centralized hydraulic system can also be provided behind a user access panel. The analyzer can use machine-readable test specifications coupled with its reagent vessels to define tests that include operations that employ the reagents. The analyzer can also display to the operator a pictorial representation that includes graphical elements that convey levels of usage for the storage vessels, and access icons that are each associated with a color and each lead to a set of screens for different types of operations for the analyzer.