On: Sat, 21 Sep 2002 16:46:35 -0500 Jeff Walther <[EMAIL PROTECTED]> Copied:
>At 12:58 -0700 09/21/2002, Bolton Peck wrote: >>So my question is, how is the memory mapped in Mac OS and within the >>machine? That is, does the Mac OS get put in the lowest available >>address, and does that correspond to motherboard RAM? And then: Jeff Walther Wrote >I don't know whether the motherboard RAM is at the high addresses or >the low. However, it appears that the Mac OS mostly loads starting >at the lower addresses, but there's also some stuff that seems to go >at the highest addresses. So it's not as simple as we would like it >to be. Another nice list member sent me a memory utility several >months ago that made this apparent. Of course, my leaky wetware >memory doesn't remember the name of the kind list member nor >the >name of the utility. Hi Bolton and Jeff, I may have been the one that sent "Memory Mapper" to Jeff and a few others when we were going around about Memory allocation. "Memory Mapper" shows where, in memory, various componants of the system and applications are located. The locations are given on a vertical map starting at zero at the bottom and going to whatever maximum ram is installed, however there is nothing that I have been able to find that relates the logical addresses as given by "Memory Mapper" and the motherboard numbering of the Ram sticks. Hence Jeff"s "Ram Sandwich ram test. Even if a memory tester told us the address of the a failed location we can't relate that address to specific chip. Unless we had a failed stick and lots of time to play. Since an S900 will boot with only Motherboard ram at least in that case we know where the system has to be. And whatever slot the next stick is put in defines the next bit of ram and so on. But add another stick and we don't know which one is next. The Algorithm for assigning ram addresses to populated slots is not known to me. Mem Mapper shows that System memory is in four spaces: 1. Lo Memory Globals at the bottom of the Heap start at address zero ( These are System parameters that never change, A Global usually refers to variables that are used in many places in a program). 2. A part of the System Heap adjacent to the Lo Memory Globals. This part of the system heap has room to grow , as things change more memory can be aquired as needed. 3. At the very high memory is the rest of the system heap and below that and adjacent is: 4. more Globals which have some room to grow downward. (A small amount on my machine. YSMV.) As I write this, Eudora is all that is running that is large enough to show on the graph and moving to lower numbered memory it comes next. 5. Below Eudora is another very small amount of globals, or possibly Extensions. I loaded iCab and it went in adjacent to the Globals below Eudora. So the extensions/control panels must be above the blank space above Eudora so that they can grow down into the blank space as info is put into various CP's. All new Apps will load into the next lowest memory address blocks depending on how much you have allocated to them individually. Most of the above is what I have gleaned from various sources, my programming experience is vary sparse and limited so a lot of what I have so blythly stated is actually conjecture. Version Tracker has "Memory Mapper" v 1.5, it may still to be a free download. Enjoy, Ernie -- SuperMacs is sponsored by <http://lowendmac.com/> and... Small Dog Electronics http://www.smalldog.com | Refurbished Drives | Service & Replacement Parts [EMAIL PROTECTED] | & CDRWs on Sale! | Support Low End Mac <http://lowendmac.com/lists/support.html> SuperMacs list info: <http://lowendmac.com/supermacs/list.shtml> --> AOL users, remove "mailto:"; Send list messages to: <mailto:[EMAIL PROTECTED]> To unsubscribe, email: <mailto:[EMAIL PROTECTED]> For digest mode, email: <mailto:[EMAIL PROTECTED]> Subscription questions: <mailto:[EMAIL PROTECTED]> Archive: <http://www.mail-archive.com/supermacs%40mail.maclaunch.com/> Using a Mac? Free email & more at Applelinks! http://www.applelinks.com
