a464@mindlink.UUCP (Bruce Dawson) (02/21/90)
The maximum memory that a 68000 based Amiga can have is 10 Megs total.
That's pretty good, considering that the absolute maximum that a 68000 can
address is 16 Megs.
An '030 based Amiga can, in theory, have 4090 Megs of memory, depending on
whether Commodore has reserved any of that top 4080 Meg memory map. However,
that depends on your '030 board. The A2630 has space for 4 Megs, and a
connector for extra 32-bit ram when cards become available. I don't know what
the equivalent possilibities are for other boards.
Regardless, you should ditch your 16-bit memory board. If you're going to
spend $2,000+ on an '030 board, you don't want it slowing down to 68000 speed.
But that's exactly what it will do (usually a bit faster than a 68000, but
sometimes actually slower) if you leave that 16-bit memory in. So, unless you
want to be paying $600 (assumed amount you could get for selling the 16-bit
memory board) for the privilege of having a slower computer, get rid of it.
If you set things up to make sure that the 4 Megs of 16 bit RAM is not
used for anything except a disk-cache, then you might get some speed increase
out of it, but not necessarily, since a 1 Meg 32-bit cache might be faster than
a 1 Meg 32-bit and 4 Meg 16-bit cache.
Plus, the 32 bit RAM, for the 2630 anyway, is not expensive. I sold my
2-meg board, bought two Megs of ram for my 2630 and came out ahead!
.Bruce Dawson.
P.S. Don't forget to get a fat agnus as well, to get rid of that .5 Meg
of slow fast memory.schur@venera.isi.edu (Sean Schur) (02/21/90)
My question is this: As I understand it, the maximum memory you can have on an Amiga 2000 is 9 MB (8 MB Fast:1 MB Chip). Is this absolute? I ask this because I have a 2058 memory expansion card populated with 4 MB of 16 bit Fast Ram. Now I am interested in getting an '030 accelerator card (still deciding on brand). But as I understand it, things will run faster if I have 32 bit chips to run with the accelerator. So, if I keep my 2058, can I only add 4 MB of 32 bit Ram? Should I dump my 2058 and get 8 MB of 32 bit chips (ouch, that would be expensive :-) ). I also have a 80 MB Quantum hard drive attached to a Hardframe 2000. I have also heard that you can attach your hard drive directly to an accelerator card. Will things run slower if I keep it hooked to my Hardframe. Should I dump that also and have everything run from an accelerator card? Any suggestions and help would be appreciated. Thanks in advance. \ / \ \ / / Sean Schur \ \ / / \ \/ / USENET: schur@isi.edu \ /a\mpyr/ Compuserve: 70731,1102 \/ \ / ideo Plink: OSS259 \/
a464@mindlink.UUCP (Bruce Dawson) (02/22/90)
> peter writes: > > Msg-ID: <9786@cbmvax.commodore.com> > Posted: 22 Feb 90 17:13:19 GMT > > Org. : Commodore, West Chester, PA > Person: Peter Cherna > > Note that the system is set up so that memory allocation uses 32-bit memory > before it moves on to the slower 16-bit memory, and that's why is doesn't > "hurt" to have 16-bit memory around. > True, the system is set up so that 32-bit memory shows up first in the memory list. But, that unfortunately doesn't mean that your 16-bit memory will only get used if you run out of 32-bit memory. Recoverable ramdisks, for instance, tend to allocate memory from the end of the memory list. Ensuring that that 16-bit memory only gets used in dire situations can be complicated. If you do need more than 5-megs, then yeah, keeping your sixteen bit memory is OK, just because it's currently the only option. My main warning goes out to those who have 5-megs of memory, 2 megs of which is 16-bit memory. You will make money and have a way better system if you sell your 16-bit board and buy 2-megs of the appropriate chips for your 2630. I know. I did it. Trust me. .Bruce Dawson.
peter@cbmvax.commodore.com (Peter Cherna) (02/23/90)
In article <1179@mindlink.UUCP> a464@mindlink.UUCP (Bruce Dawson) writes: > > An '030 based Amiga can, in theory, have 4090 Megs of memory, depending on >whether Commodore has reserved any of that top 4080 Meg memory map. However, >that depends on your '030 board. The A2630 has space for 4 Megs, and a >connector for extra 32-bit ram when cards become available. I don't know what >the equivalent possilibities are for other boards. > > Regardless, you should ditch your 16-bit memory board. If you're going to >spend $2,000+ on an '030 board, you don't want it slowing down to 68000 speed. >But that's exactly what it will do (usually a bit faster than a 68000, but >sometimes actually slower) if you leave that 16-bit memory in. So, unless you >want to be paying $600 (assumed amount you could get for selling the 16-bit >memory board) for the privilege of having a slower computer, get rid of it. Perhaps that should be made a bit clearer: 32-bit memory is way better than the equivalent amount of 16-bit memory. But the 16-bit memory is better in all ways than no memory at all. In other words, you should look at adding 32-bit memory if you like, but you don't have to pull out your 2058 unless you think you now have "too much" memory. It is preferable that your computer slow down to access the 16-bit memory than have a program exit with an error or guru because the system is out of memory. Note that the system is set up so that memory allocation uses 32-bit memory before it moves on to the slower 16-bit memory, and that's why is doesn't "hurt" to have 16-bit memory around. >.Bruce Dawson. > > P.S. Don't forget to get a fat agnus as well, to get rid of that .5 Meg >of slow fast memory. Here the system isn't set up properly for best ordering on memory allocation. Under 1.3, run FastMemFirst to fix that. So that .5 meg isn't slowing down your system if you've run FastMemFirst, but if you could use the chip memory you may as well get a Super Agnus. Peter -- Peter Cherna, Software Engineer, Commodore-Amiga, Inc. {uunet|rutgers}!cbmvax!peter peter@cbmvax.cbm.commodore.com My opinions do not necessarily represent the opinions of my employer.
new@udel.edu (Darren New) (02/23/90)
In article <9786@cbmvax.commodore.com> peter@cbmvax.cbm.commodore.com (Peter Cherna) writes: >Note that the system is set up so that memory allocation uses 32-bit memory >before it moves on to the slower 16-bit memory, and that's why is doesn't >"hurt" to have 16-bit memory around. But note also: If you have 16-bit memory then Avail() calls will access the 16-bit memory. I was doing an AvailMem() on every memory allocation and it was almost as slow on a 68020 as it was on a 68000. Eventually, I just modified it to allocate a chunk of memory, then allocate until it ran out, then free the chunk of memory. I suggest that if you are programming on a 68000, you do this too. -- Darren