To get the improved client-server performance out of the machines, IBM has re-written the microcode (licensed internal code) extensively to change the machine’s program and process models: in conventional AS/400s, running processes tend to stick around for a long time, so task switching is more important than swift task creation and destruction; in the client-server environment the requirements are reversed – when a client requests a piece of data it is important that the server process is created swiftly, while task-switching on the other hand hardly comes into the equation; at the same time, the hardware inside the Server Models 100, 135 and 140 boxes bears little relation to the others in the same 9402 and 9404 ranges, Soltis says. Instead the company has plundered the technology found in the larger AS/400 models to optimise performance, so, for example, BiCMOS cache technology is lurking in there somewhere, along with high-speed input-output processors and to cap it all, the Model 140 is actually a dual processor – the first time that the company has crammed more than one CPU into a 9404 chassis. Soltis says that low-end multiprocessors are the shape of things to come and that we should expect other n-way processors in the low-end AS/400 models in the future.
