Conference hydra::amiga_v1

    Re .0:         

>   Specifically if, on my A500, I were to put 2 Mb into the A590 and then 
>   install an internal 1.5 Mb board would the result be 4 Mb total memory?
    
    I think so.  The internal memory would be "half fast", because it's
    controlled in common with the Chip RAM even though the custom chips
    (Fat Agnus, in particular) can't reach it all.  I've added 1MB to my
    A590 (and plans for another MB after I upgrade to the "Fatter Agnus")
    and I can find out what its address is.  If someone else has >512KB
    installed in the A500 expansion port, they could tell you where that
    memory appears.
    
    I have a general observation about memory expansion.  There is a
    decreasing return on each additional chunk you install.
    	Chunk	Total	Benefit
    	512KB	 1 MB	Amiga becomes usable for more than games
    	512KB	 1�MB	Multitasking of applications becomes possible
    	512KB	 2 MB	1 "Core hog" can run comfortably
    	 1 MB	 3 MB	"Core hogs" can coexist
    
    My "shot from the hip" prediction is that the M68000 will become the
    bottleneck once the system passes 3MB.  The fact that so much of that
    memory is "half fast" should only serve to exacerbate the problem.
    
    I don't think it is worthwhile to expand an A500 beyond its "natural
    limits" (1MB internal + 2MB in the A590).  You're already talking about
    a system that has the performance of a "mainframe" from the mid-1970s. 
    If one needs that much memory, one probably has other needs that aren't
    easily met by the A500.  Start saving for an A3000 (or a used A2000).

Re: .0, .1

Bill is definitivly right, when stating that over 3-4MB of RAM the 
68000 becomes the bottleneck. All that RAM eludes to start more and more
background "nicies", which in turn drags down you performance.

As far as autoconfiguring memory goes, the autoconfig space starts at
$200000 and the A590 will configure RAM from there on upwards to $400000.
If your internal expansion doesn't use these addresses AND the 64KB chunk
(at some higher address whose exact location escapes me in the moment) where
the controller part resides, you're in luck.

Regards,

<CB>

    Re: "start saving for a used A2000" now I admit to not knowing a
    lot, but I thought the only difference between an A500 and a 2000
    was things like the number of expansion slots, and if you (eg) change
    the A500 to one of these "A1500" thingies, you get all the
    functionality of a 2000???
    
    -Rog
    

    The A2000 also has a processor slot, which lets you replace the MC68000
    with a MC68020 or MC68030.
        John Sauter

    Re .3:
    
>   ... I thought the only difference between an A500 and a 2000 was things
>   like the number of expansion slots
    
    Yes and no.  As John observed in .4, the A2000 has a CPU expansion
    slot, which will allow for addition of a 68020 or 68030.  There's even
    the possibility of adding 32-bit fast RAM and a 32-bit disk controller
    to speed things up further.
    
    Similarly, the A2000 is blessed with a video slot, which enables use of
    a FlickerFixer and multi-sync monitor or some similar high-quality
    video configuration.
    
    Don't underestimate the A2000's expansion slots.  There are times when
    I'd really like to have even ONE for my A500.  Nor should you neglect
    the BridgeBoard, in its various incarnations.  MS-DOS isn't MY favorite
    environment either, but there are times when there are simply no
    alternatives.
    
    I *love* my A500, but it has its limits.  I think it would be wiser to
    upgrade to an A2000/A3000 than to add a lot of kludgy third-party
    expansions to the A500.  Try to PLAN your system's growth rather than
    getting into a mode where you respond to the CURRENT bottleneck without
    regard to what the NEXT one will be.

    I agree with -.1.  I now have an amiga 500 with 68020/68881/12Mhz, 3Mb
    of ram, and a couple of hard drives and I STILL am considering buying
    an A2000 just for the expansion slots.  I probably will upgrade memory
    to 5Mb.  I have a Supra memory and SCSI controller and just read where
    they are selling a new SCSI controller with memory upgradeable to
    *8Mb*.  If I can get two more meg without suffering configuration
    "hacks" I will be satisfied. :^}  <-we've all heard that before, eh?
    
    m

I agree with that 3-4 meg of ram is probably plenty; with 4 meg of fast and
.5 meg of chip, I ran out of chip fairly often, but usually had close to 2
meg of free fast ram. But that's only usually - if you like to do things like
run dpaint & a titling program & an animation program all at one time to
build large video presentations, 4 meg of fast can start looking awfully
small. I'm sure others can come up with similar situation.

Barry Shein has a principle regarding such, which is roughly that if you
can't zero all of your memory in < 1 second, then there's little point in
adding more memory.  With 7.14 MHz memory & a 16 bit wide bus, you can zero
a maximum of 14.28 meg of memory a second. Without an instruction cache,
that's going to be cut by at least 2/3rds; and you'll lose more because
of lossage in the memory system, so the figures is going to be under 5 Meg.
Of course, Barry was talking about demand paged systems, so those of us stuck
with real memory ("for real performance") can allocate some of that for
swap space.

I also agree about buying a used 2000 vs. a expanding a 500, especially if the
used 2000 is mine!

	<mike

    Don't know if anybody knows anything about the "A1500" expansion
    system you can buy in the UK... it separates the keyboard from the
    rest, and puts the latter in a big PC-type box. I thought I read
    in a review that you got more expansion capability this way than
    you did with an A2000, but maybe I misunderstood???
    
    -Rog
    

    You're correct Roger, the A1500 (from CheckMate Systems) can give you
    more expansion than an A2000 (except in one area).
    The A1500 can be configured to give a full A2000 CPU slot, a full A2000
    video slot (or a cut down version for Genlock only), and as many
    ZorroII slots as you can afford ;-)
    Where it can't compete with a real A2000 is in the Bridgeboard, for
    some reason this is NOT an option.
    
    					Alan T.

    
    	Are these slots on the A1500 BUFFERED And terminated...???
    
    

    You mean I could put a 50MHZ GVP '030/882 in the A2000 cpu slot
    in the A1500?
    
    md

    Yes ! (if you could afford it !!)

    I recall seeing a little blurp on USENET re: the A1500 but haven't seen
    any ads in the US magazines.  Is it only available in Europe and if so
    how much do you estimate it will cost in $US?
    
    m

    As far as I'm aware the A1500 is only available in the UK, I can give
    you the UK prices, but you'll have to use your imagination to translate
    them into a US$ selling price...
    
    	A1500 kit, (box for mother board, keyboard, cables - fit it
    		    yourself)		�200 + tax (15%)
    
    	Zorro II expansion box (2 zorro II slots in a stack-on-top box)
    					�100 + tax
    
    	Video slot - no price
    
    	CPU slot   - no price

    Can you give the address of the company (or persons) making the A1500?
    I would like to write them.
    
    md