David Given wrote: > So's the insides. We know so much more about operating systems now. RISC > OS is a mess. It's grown organically with not enough oversight for too > long. For example, there's about half a platform abstraction layer, but > most code talks to hardware directly. Yes, as I said, it was great for home computers. RISC OS was released 1989 when many computers had less than 1 MB RAM. The hardware of a computer model was more or less always the same and people did not change the hardware, except maybe to put additional RAM or a hard disk drive. But the other components, such as graphic chip, CPU, controllers etc. were not replaced. In these good old days it was an advantage to access directly to the hardware. It was faster and you did not need memory for any layers. When I was a child, I programmed small programs and games for the Commodore 64, just for fun. It was normal to peek and poke directly to the hardware addresses, you even had to do that because you had only 64 KB RAM and a part of it was reserved for the graphic chip (VIC 2) and the BASIC language (that was a part of the OS). A layer between your program and the hardware was something that would cost too much memory. You simply could not afford it. But nowadays we need layers and drivers because hardware components are very flexible and people replace them. And RAM is cheap! :-) I still think that direct access to hardware may be in some cases useful. In case of the Raspberry Pi you have a fix, specified hardware (you can not replace the CPU or GPU, even not the RAM) and programers may gain speed benefits if they access directly to the hardware. Furthermore, the Raspberry Pi is meant to be a computer for educational purposes and the kids could learn about hardware programming, too. But a direct access to the hardware should be only an alternative that a programmer could choose in some situations, but not the general method of programming normal applications. A modern OS should have layers. Clean and, as you said, it needs oversight. :-) I really love the Kits in Haiku. They are so easy to understand. :-) Best wishes, Miroslav Stimac -- Empfehlen Sie GMX DSL Ihren Freunden und Bekannten und wir belohnen Sie mit bis zu 50,- Euro! https://freundschaftswerbung.gmx.de