Does this mean this is only because at launch only 512mb modules were available. . . Therefore presumably it would use the built in 128Mb and the additional 1024mb...wait using the calculator....1152Mb...wow...
You've got the right picture, robster. Apple's Developer Note for the 12-inch PowerBook actually stated that 1GB RAM chips might be available in the future, pushing the max RAM above 1GB.
This is a positive development. But it's still lame that Apple only solders 128MB onto the mobo. Overall, it would be much more useful if Apple would solder 256 or 512MB onto the mobo.
You've got the right picture, robster. Apple's Developer Note for the 12-inch PowerBook actually stated that 1GB RAM chips might be available in the future, pushing the max RAM above 1GB.
This is a positive development. But it's still lame that Apple only solders 128MB onto the mobo. Overall, it would be much more useful if Apple would solder 256 or 512MB onto the mobo.
Escher
I agree, and thanks for the positive comfirmation.
I'm just happy that I can get even more out of this 12" pb!
The only other things people want to see added I've seen is lit-up keyboard and DVI Out. Neither of which I happen to think are that important on a baby this size....Just more validation of my buying descision! woo-hoo
The link shows a screenshot of Apple System Profiler on what appears to be a 12" PB.
I have one and have always understood that the RAM limit is 640Mb
Does this mean this is only because at launch only 512mb modules were available.
Will it recognize AND USE 1024Mb?
Therefore presumably it would use the built in 128Mb and the additional 1024mb...wait using the calculator....1152Mb...wow...
Apple has under-reported the maximum RAM that can be used by their computers on a number of occasions, mainly because larger chips just weren't available at the time. Take the Wallstreet PowerBook for example. At the time, it had a maximum limit of 192 MB - a 64 MB low-profile SODIMM in the lower slot and a 128 MB high-profile SODIMM in the upper. At the time, nothing better was available. However, both slots will accept up to 256 MB of RAM, making the real limit 512 MB. Same goes with some early iBook models - the stated maximum is 320 MB but it's actually 576 MB because low profile 512 MB SODIMMs weren't available until after the iBook was released. Now, there's no guarantee they'll work (512 MB DIMMs don't work on the PowerMac G3, early PowerBook G3s, or early iMacs), but they might.
There have been reports of users stuffing 512MB modules into Rev. A-D (tray-loading) iMacs, for a total of 768MB max RAM. I believe someone over at the MacNN forums got one working as well. Not sure if they still sell them, but OWC used to sell 512MB SO-DIMMs for iMacs.
Yeah the max ram, in most machines, is only decided upon how much RAM you can actually fit in the machine. Now that larger dimms are out, you have a larger max RAM limit.
Would be quite cool to deck out a PM with 4 GB RAM just to see what it could do.
Unless they are playing some really funny games, you'll probably only get up to about 3GB of RAM into the Mac (at least, until the 970 comes along). 1GB of addressable space is usually required for PCI, FLASH, and internal memory areas of the processor.
Unless they are playing some really funny games, you'll probably only get up to about 3GB of RAM into the Mac (at least, until the 970 comes along). 1GB of addressable space is usually required for PCI, FLASH, and internal memory areas of the processor.
and this magic vortex of 1GB address space is just "not visible" now?
are you suggesting the current RAM is being underreported or addressed?
or perhaps the next 1GB DIMM you add will all drop into the void?
on all boards/chipsets? not logical.
pre-G3 might choke, but it sounds fishy to include everything.
I doubt you have a machine with 4GB of RAM, so why would RAM be being underreported? These devices are at the END of the 4GB address range (0xC0000000-0xFFFFFFFF), and RAM starts at the beginning. Until you got more than 3GB of RAM, there would be no overlap.
and this magic vortex of 1GB address space is just "not visible" now?
are you suggesting the current RAM is being underreported or addressed?
or perhaps the next 1GB DIMM you add will all drop into the void?
on all boards/chipsets? not logical.
pre-G3 might choke, but it sounds fishy to include everything.
Alright, here's an explaination of how things work at a lower level. Your PowerPC (non-970 ) has 32-bits of addressable space. This means it can access things from 0 to 4GB.
When the operating system says "please fetch me the data at address 2GB (0x80000000 in hex notation), this address goes out on the processor bus. If there is a valid device there, data will be returned. If there is no device there, a bus error is generated to the computer.
If that address is in the range of your system memory (0 to however much RAM you have), the memory modules will respond, and return the requested data.
Now for the more difficult part: PCI. PCI has a memory (and I/O) area also, and is a seperate bus. There is a device called a "host bridge" that passes requests put out on the processor bus over to the PCI bus, and answers returned on the PCI bus back to the processor bus. This host bridge listens to a range of addresses on the processor bus for this, usually the last 1-2GB (or addressable space, not of RAM) depending on the system. This means that ANY request for data at those addresses will be handled by the host bridge, not your system RAM.
Similarly, there are other devices such as the FLASH memory (where the very lowest-level bootup code resides) that also listen to certain address ranges on the processor bus. Again, the amount of memory space this takes up is system dependent, but you can't have RAM at the same memory locations.
Until we get a 64-bit processor, the biggest address a PowerPC can request is 4GB. Since some of that is taken up by non-RAM devices (as mentioned above), you CAN'T have 4GB of RAM. There needs to be SOME space left for these devices.
That being said, the OS (with hardware support) could play some games, such as swapping banks of RAM in and out (all of your RAM isn't available at the same time), or some other method, to get more memory in. However, since there is little call for more than 1GB of RAM in the consumer market at this point, I'd be surprised if they had gone through the trouble (although they might have for the Xserve).
I've tried to make this as readable as possible, but it still might be confusing for someone who doesn't do it everyday like I do. If you want me to go into more detail on anything, let me know.
Until we get a 64-bit processor, the biggest address a PowerPC can request is 4GB. Since some of that is taken up by non-RAM devices (as mentioned above), you CAN'T have 4GB of RAM. There needs to be SOME space left for these devices.
That being said, the OS (with hardware support) could play some games, such as swapping banks of RAM in and out (all of your RAM isn't available at the same time), or some other method, to get more memory in.
Excellent description. I'm curious, what would happen if 4GB were put into a powermac? Is the non-RAM, remapped address space at the very top of the 32bit range? Basically, I'm wondering if this would leave a block of RAM unused, without causing memory addressing errors and crashing MacOS X?
Excellent description. I'm curious, what would happen if 4GB were put into a powermac? Is the non-RAM, remapped address space at the very top of the 32bit range? Basically, I'm wondering if this would leave a block of RAM unused, without causing memory addressing errors and crashing MacOS X?
First off, it turns out I was wrong. The 7455 actually has a 36-bit address bus, not a 32-bit (I just looked up the documentation). It looks like an OS on the PowerPC could play the same games that those on the newer Pentiums can (I believe they also have a 36-bit bus) to have larger amounts of memory. This would give you a total address space of 64GB, I believe. I'll have to dig into the Darwin code to see if they are using this extended addressing option (by default, only 32 bits are used), just because I am curious.
As for your original question, I'm not sure. I don't know if it would cause bus contention, or if only one device would respond (I usually work on boards with soldered-on RAM chips, and so far never over 1GB, so it hasn't been an issue ).
I'm still using the stock 256 config, and for Office/web it works fine, but As soon as 512 modules drop in price I will up my RAM to 640MB, which really ought to be enough to push me along nicely for the life of this machine.
Anyone know of 512MB sodimms for less than 250 Canadian?
When I get my digital camera this summer, no time to shop around/play with now, I'm gonna need a bit more RAM to make PS smoother.
If those GB modules drop, 512's should make a nice drop in the next 3-4 months.
Comments
The link shows a screenshot of Apple System Profiler on what appears to be a 12" PB.
I have one and have always understood that the RAM limit is 640Mb
Does this mean this is only because at launch only 512mb modules were available.
Will it recognize AND USE 1024Mb?
Therefore presumably it would use the built in 128Mb and the additional 1024mb...wait using the calculator....1152Mb...wow...
Originally posted by robster
Does this mean this is only because at launch only 512mb modules were available. . . Therefore presumably it would use the built in 128Mb and the additional 1024mb...wait using the calculator....1152Mb...wow...
You've got the right picture, robster. Apple's Developer Note for the 12-inch PowerBook actually stated that 1GB RAM chips might be available in the future, pushing the max RAM above 1GB.
This is a positive development. But it's still lame that Apple only solders 128MB onto the mobo. Overall, it would be much more useful if Apple would solder 256 or 512MB onto the mobo.
Escher
Originally posted by Escher
You've got the right picture, robster. Apple's Developer Note for the 12-inch PowerBook actually stated that 1GB RAM chips might be available in the future, pushing the max RAM above 1GB.
This is a positive development. But it's still lame that Apple only solders 128MB onto the mobo. Overall, it would be much more useful if Apple would solder 256 or 512MB onto the mobo.
Escher
I agree, and thanks for the positive comfirmation.
I'm just happy that I can get even more out of this 12" pb!
The only other things people want to see added I've seen is lit-up keyboard and DVI Out. Neither of which I happen to think are that important on a baby this size....Just more validation of my buying descision! woo-hoo
Originally posted by mrmister
"the calculator appplication has come with all of apples OSes since 1986!"
Yes, but the one from Jaguar does currency conversions, which was the point of the poster.
yep, it was. thank you, mrmister for watchin' my back.
Originally posted by robster
I'm confused...
The link shows a screenshot of Apple System Profiler on what appears to be a 12" PB.
I have one and have always understood that the RAM limit is 640Mb
Does this mean this is only because at launch only 512mb modules were available.
Will it recognize AND USE 1024Mb?
Therefore presumably it would use the built in 128Mb and the additional 1024mb...wait using the calculator....1152Mb...wow...
Apple has under-reported the maximum RAM that can be used by their computers on a number of occasions, mainly because larger chips just weren't available at the time. Take the Wallstreet PowerBook for example. At the time, it had a maximum limit of 192 MB - a 64 MB low-profile SODIMM in the lower slot and a 128 MB high-profile SODIMM in the upper. At the time, nothing better was available. However, both slots will accept up to 256 MB of RAM, making the real limit 512 MB. Same goes with some early iBook models - the stated maximum is 320 MB but it's actually 576 MB because low profile 512 MB SODIMMs weren't available until after the iBook was released. Now, there's no guarantee they'll work (512 MB DIMMs don't work on the PowerMac G3, early PowerBook G3s, or early iMacs), but they might.
Originally posted by mrmister
You can actually get 1GB into slot loading iMacs.
i think he meant tray loading.. Rev A-D were the old ones... spaRt typod...
My bad.
Originally posted by DaveLee
Did you note how much they were?
Would be quite cool to deck out a PM with 4 GB RAM just to see what it could do.
Unless they are playing some really funny games, you'll probably only get up to about 3GB of RAM into the Mac (at least, until the 970 comes along). 1GB of addressable space is usually required for PCI, FLASH, and internal memory areas of the processor.
Originally posted by John Whitney
Unless they are playing some really funny games, you'll probably only get up to about 3GB of RAM into the Mac (at least, until the 970 comes along). 1GB of addressable space is usually required for PCI, FLASH, and internal memory areas of the processor.
and this magic vortex of 1GB address space is just "not visible" now?
are you suggesting the current RAM is being underreported or addressed?
or perhaps the next 1GB DIMM you add will all drop into the void?
on all boards/chipsets? not logical.
pre-G3 might choke, but it sounds fishy to include everything.
Originally posted by curiousuburb
and this magic vortex of 1GB address space is just "not visible" now?
are you suggesting the current RAM is being underreported or addressed?
or perhaps the next 1GB DIMM you add will all drop into the void?
on all boards/chipsets? not logical.
pre-G3 might choke, but it sounds fishy to include everything.
[edit] Explained in better detail below
Originally posted by John Whitney
I doubt you have a machine with 4GB of RAM, so why would RAM be being underreported? These devices are at the END of the 4GB address range (0xC0000000-0xFFFFFFFF), and RAM starts at the beginning. Until you got more than 3GB of RAM, there would be no overlap.
[edit] Explained better below
Originally posted by curiousuburb
and this magic vortex of 1GB address space is just "not visible" now?
are you suggesting the current RAM is being underreported or addressed?
or perhaps the next 1GB DIMM you add will all drop into the void?
on all boards/chipsets? not logical.
pre-G3 might choke, but it sounds fishy to include everything.
Alright, here's an explaination of how things work at a lower level. Your PowerPC (non-970
When the operating system says "please fetch me the data at address 2GB (0x80000000 in hex notation), this address goes out on the processor bus. If there is a valid device there, data will be returned. If there is no device there, a bus error is generated to the computer.
If that address is in the range of your system memory (0 to however much RAM you have), the memory modules will respond, and return the requested data.
Now for the more difficult part: PCI. PCI has a memory (and I/O) area also, and is a seperate bus. There is a device called a "host bridge" that passes requests put out on the processor bus over to the PCI bus, and answers returned on the PCI bus back to the processor bus. This host bridge listens to a range of addresses on the processor bus for this, usually the last 1-2GB (or addressable space, not of RAM) depending on the system. This means that ANY request for data at those addresses will be handled by the host bridge, not your system RAM.
Similarly, there are other devices such as the FLASH memory (where the very lowest-level bootup code resides) that also listen to certain address ranges on the processor bus. Again, the amount of memory space this takes up is system dependent, but you can't have RAM at the same memory locations.
Until we get a 64-bit processor, the biggest address a PowerPC can request is 4GB. Since some of that is taken up by non-RAM devices (as mentioned above), you CAN'T have 4GB of RAM. There needs to be SOME space left for these devices.
That being said, the OS (with hardware support) could play some games, such as swapping banks of RAM in and out (all of your RAM isn't available at the same time), or some other method, to get more memory in. However, since there is little call for more than 1GB of RAM in the consumer market at this point, I'd be surprised if they had gone through the trouble (although they might have for the Xserve).
I've tried to make this as readable as possible, but it still might be confusing for someone who doesn't do it everyday like I do. If you want me to go into more detail on anything, let me know.
Originally posted by John Whitney
Until we get a 64-bit processor, the biggest address a PowerPC can request is 4GB. Since some of that is taken up by non-RAM devices (as mentioned above), you CAN'T have 4GB of RAM. There needs to be SOME space left for these devices.
That being said, the OS (with hardware support) could play some games, such as swapping banks of RAM in and out (all of your RAM isn't available at the same time), or some other method, to get more memory in.
Excellent description. I'm curious, what would happen if 4GB were put into a powermac? Is the non-RAM, remapped address space at the very top of the 32bit range? Basically, I'm wondering if this would leave a block of RAM unused, without causing memory addressing errors and crashing MacOS X?
Originally posted by dfiler
Excellent description. I'm curious, what would happen if 4GB were put into a powermac? Is the non-RAM, remapped address space at the very top of the 32bit range? Basically, I'm wondering if this would leave a block of RAM unused, without causing memory addressing errors and crashing MacOS X?
First off, it turns out I was wrong. The 7455 actually has a 36-bit address bus, not a 32-bit (I just looked up the documentation). It looks like an OS on the PowerPC could play the same games that those on the newer Pentiums can (I believe they also have a 36-bit bus) to have larger amounts of memory. This would give you a total address space of 64GB, I believe. I'll have to dig into the Darwin code to see if they are using this extended addressing option (by default, only 32 bits are used), just because I am curious.
As for your original question, I'm not sure. I don't know if it would cause bus contention, or if only one device would respond (I usually work on boards with soldered-on RAM chips, and so far never over 1GB, so it hasn't been an issue
Originally posted by dfiler
So what's a person with as much tech knowledge as you doing in the burgh? CMU?
Working for a small startup called TimeSys, porting our Linux kernel to (generally) various embedded PowerPC boards.
Anyone know of 512MB sodimms for less than 250 Canadian?
When I get my digital camera this summer, no time to shop around/play with now, I'm gonna need a bit more RAM to make PS smoother.
If those GB modules drop, 512's should make a nice drop in the next 3-4 months.