SAP R/1 (1972-1980)
is 1-tier architecture. In which all 3 layers [Presentation + Application + Database] are installed in one systems/server.
( One Server scenario where Presentation + Application + Database all 3 layers in One Server)
Originally release in 1972, when SAP developed its Financial Accounting System called RF and later Material Management System called RM/1 and eventually bare the name R/1. and its based on DOS operating system in its initial stage. The R/1 era was established on a One Server scenario (1972 - 1980). It is in 1980 that SAP developed its RV module (ie: Sales and Distribution or SD module). So, by 1980, FI, MM, SD was in place within R/1.
SAP R/2 (1981-1990)
is 2-tier architecture. In which all 3 layers [Presentation + Application + Database] are installed in two separate systems/server.
( Server One – Presentation , Server Two – Application + Database)
This is the R/2 Era from 1981 - 1990. Initially 1981 expanded to the PP (Production Planning and Execution) module. Late 1980s, SAP started developed into Industrial Solution, first which is Billing system for the Utilities Industry.
SAP R/3 (1991-2000)
is 3-tier architecture. In which all 3 layers [Presentation + Application +Database] are installed in three separate systems/server.
(server One -Presentation, server Two – Application, Server Three – Database)
The R/3 Era from 1991- 2000, with the advent and popularity of Client-Server Architecture, SAP moved on to demonstrate this from R/2 to the release of R/3. Also late 1990s, starts to realize parts of its solution through mysap.com with the internet scenarios as well as new screen interfaces.
Beyond 2000 until today was a very confusing period to me, R/3 took a name change to something like Enterprise 4.7 but very soon took on another name as ECC (Enterprise Centric Component). It is likely that they like the market to think of it as a a Backend Solution. Many other software since then took precedence in Development such as BW, APO, CRM, SRM, SEM, Portal, Mobile ... etc.
There was the version ECC5.0 and then now for some years the version ECC6.0. Since last year,there were a lot of speculation of the upcoming ECC7.0 perhaps powered with Hana capabilities. Many students asked me if I was looking forward to it, I had no answer to them nor myself.
But deep down, I still prefer R/3, I personally like to see more processes build to the Core-Backend solution of R/3 and not some fancy front-end which I have seen come and go. I still very much believe that many companies do not need advanced solutions such as APO, CRM, SRM (I think). There are many improvements can that still can be done to the basic processes in R/3 which the company may not see profitability and "marketability" in developing which I think are so basic and fundamental.
Since my first exposure to MRP systems in the 1980s in the University, then working in the factory as a Production Planner using an MRPII system; and from 1990s until today has been such a long time, a very very long time indeed working with the SAP MRP system. I am not sure I will have anymore enthusiasm or excitement on "new" challenges from SAP.
I am an OLD FROG,