Hemp rope was used in the age of sailing ships , though the rope had to be protected by tarring , since hemp rope has a propensity for breaking from rot , as the capillary effect of the rope-woven fibers tended to hold liquid at the interior, while seeming dry from the outside.  Tarring was a labor-intensive process, and earned sailors the nickname " Jack Tar ". Hemp rope was phased out when Manila, which does not require tarring, became widely available. Manila is sometimes referred to as Manila hemp , but is not related to hemp; it is abacá , a species of banana .
The book of rules which we have described our human computer as using is of course a convenient fiction. Actual human computers really remember what they have got to do. If one wants to make a machine mimic the behaviour of the human computer in some complex operation one has to ask him how it is done, and then translate the answer into the form of an instruction table. Constructing instruction tables is usually described as "programming." To "programme a machine to carry out the operation A" means to put the appropriate instruction table into the machine so that it will do A.