Programming
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.
Some bits made an instruction conditional on the accumulator state, as with the Zuse Z22 or Electrologica X1.
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!
Read more about this topic: ZEBRA (computer)
Famous quotes containing the word programming:
“If there is a price to pay for the privilege of spending the early years of child rearing in the driver’s seat, it is our reluctance, our inability, to tolerate being demoted to the backseat. Spurred by our success in programming our children during the preschool years, we may find it difficult to forgo in later states the level of control that once afforded us so much satisfaction.”
—Melinda M. Marshall (20th century)