This functions a bit like the old string pool – in that each chunk of space has a length and the address of the next chunk of that type. In the new layout all the missing pieces are stored in the new “heap” area. Also, there was nowhere to store other permanent data which was neither strings nor code. The size of each chunk was fixed which meant that in practice it would either be too big or too small. While this was relatively easy to manage it did have some problems. In the original memory layout, each section (input buffer, dictionary, string pool and so on) got its own chunk of memory. Of course, while just removing some sections does make the picture simpler, it does not help much if the system needs them. The new, simplified, memory map is as shown at the right. The “old” memory map was roughly as shown at the left of this post. So it suddenly occurred to me that the existing memory is more complex and pre-defined than it need to be. The trouble is that it does not make much sense for these memory spaces to be fixed in size, especially for something like a text game which involves a lot of string manipulation. In order to handle multiple threads, processes, or users, I need a way for them to have their own memory spaces.
This is where the change to the memory map came in. However, I had been putting off deciding what to do about multi-user and multi-process aspects of the operating system, but the multi-user nature of a MUD is its heart, so if I want my system to be capable of this sort of thing, I need to at least have an idea how to make it work. I’ll write more about this another time.Īnyway, while I was enjoying myself I was also recalling the attempts I had made over the years at writing both single- and multi-user “text adventure” (a.k.a “interactive fiction”) games, some of which were based on technology quite like what I am building for CORNELIUS. I have been enjoying poking about in it and spotting the references to old sci-fi material such as The Hitch-Hikers Guide to the Galaxy, and the Traveller game. The prompt for the idea came initially from my discovery of Duncan Jauncey’s “Alternate Universe” MUD.
I had thought that the way I had laid out the memory was pretty much as simple as it could be for this application, but just yesterday it occurred to me that there could be a better way. Today I spent an hour ow two simplifying the memory map for my operating system and language CORNELIUS. It’s funny how ideas work their way out sometimes.
0 kommentar(er)
