datapoint 2200 in 1970

A compter terminal manufactured in 1969.

An ARMA model contains parts for an AR and MA model so is ARMA(p,q). An ARIMA model is extended as it includes the extra part for differncing. If a dataset exhibits long term variation (i.e. trend-cycle componenet) the ACF graph will show a straight line edge and will not quickly drop to zero. In this case it is useful to difference the data. This simply takes each datapoint and calculates the change from the previous datapoint. The ARIMA model is ARIMA(p,d,q) where p is the order of the AR part, d is the number of times differncing has been carried out and q is the order of the MA part. The extension allows the model to deal with long term variation better so improves the uesfulness of this modelling technique

The Abacus, around 1000 B.C. Of course, if you mean personal computer, it started with the IBM mainframes in the 1950s, and branched off for a while, finally creating the first personal computer, the DATAPOINT 2200, in 1970, and the MITS Altair 8800, in 1975, then the Apple ][ in 1977, finally with the invention of the IBM 5150 in 1981, the first modern PC. The IBM 5100, the first commercially available portable computer, appeared in September 1975, and was based on the SCAMP prototype.

Sources: Wiki and Yahoo

rofl and 2008