The ZEBRA was a binary, two-address machine with a 33-bit word length. Storage was provided by a magnetic drum memory holding 8 K-words; accumulators were also implemented as recirculating drum tracks in a manner similar to that used in the Bendix G-15. Peripherals included paper tape reader and punch, and teleprinter.
The ZEBRA instruction word consists of a 13-bit drum address, a 5-bit register (or I/O) address, and a 15-bit operation field. Each bit of the operation field had a distinct meaning and could be used in nearly any combination, leading to many elegant tricks that today might be considered the domain of microprogramming.
Multiplication, division, square root, as well as all floating-point operations, were performed by subroutines, using the underlying serial computer ALU primitives add, subtract, shift right, shift left, and increment.
Programming aids included the Normal Code (assembler), trace utility, a floating point interpretive system, the Simple Code, the Matrix Interpretive Scheme, and an Algol compiler.
Since a magnetic drum does not support random access, some time is lost waiting for an instruction or piece of data become available. In a poorly-written program, the average wait time could be half the drum rotation speed, but there were ways to reduce this. A notable feature of the ZEBRA was a meter that measured how much of the machine's time was spent in non-wait states; this was called the "efficiency meter." When running the floating-point interpretive system, the efficiency meter tended to show around 50%, but if prospective customers were visiting, a more efficient program could be loaded for demonstration purposes!