Conference hydra::amiga_v1

    these would be the 2090a's that have displayed problems when used
    for graphics with overscan mode.ask for 2091a disk controller.looks
    like CBM wants to clear out the 2090a's.I plan on getting a GVP
    for my hard drive controller.By the By a 2000hd without the drive
    is a 2000.
    							bill

    re: .0 - That does sound like a nice deal.  The 2090a does experience
    a performance decrease when used with hi-res/overscan screens, but for
    most people that isn't a problem.
    
    I did stop by System Eyes last weekend.  I don't recall their A2000HD
    price, but they did say that they removed the 2090a, and replaced it
    with the GVP Hardcard/Quantum setup.  What do they do with the 2090's?
    
    From memory, the A2500/20 was priced at $3200
                     A2500/30               $3700
                     A2630/2Meg             $1800  < this is appealing
    
    I thought the hardware prices were reasonable, but that the software
    was high. (Software prices similar to the Memory Location.)  I did 
    think that the selection was quite good.
    
    ~Steve (bought myself a Christmas present - a 'fatter' Agnus)

    I stop again last night ad it is the 2090A controller. They also
    dropped the price of the 2000 to $1299 without the drive because they
    have sold so many drives separately they are looking to unload the
    straight 2000.
    
    Bill

    re .2: It should be noted that System Eyes sells all their software
    for 10% off the list(marked price),and 15% off for store club members.
    They(System Eyes) could have taken advantage of this buyout deal
    but felt they could better serve their customer's with the GVP card
    until the 2091a's were made available.However they did have some people
    approach them trying to trade these controllers toward the GVP
    controllers.When it comes to hardware I learned a long time ago
    that you have to look around,and to the future if you want to protect
    your investment.I bit the bullet and bought the 8meg card,while
    The 2meg looked inticing,now I am going to do the same for my hard
    drive purchase.I look at my hardware purchases as an investment,and
    as such feel that one should buy what works best,and is supported
    fully.
    							bill

    Please enlighten me on the issue of 2090a vs 2091a.  Is this issue
    just the disk controller?  I have been looking at the Amiga 2000HD
    with 40MB of hard disk for $2400.  If I were to buy the 2000 for
    $1300 per Note 3245.3 and add a third party disk and controller,
    does the glich described in Note 3245.1 become a non-issue?  If
    so, what is a reasonable price for a 40MB disk and controller?
    
    I have just begun to look at the Amiga, so I am not familiar with
    the model number and the architecture.  So if these questions are
    a bit basic I apologize.
    
    Please advise.
    
    Chuck
    

    The 2090 or 2090a do not exhibit the slowdown with ST-506 drives
    because they are slow enough to let the other chips (68000, agnes ...)
    steal cycles, but using SCSI drives and while DISPLAYING a hi-res 16
    color screen, they are slower than floppies, I was told that ALL
    controllers that are true DMA suffer the same fate, so look before you
    leap.
    
    Jean
    

    	re: -.1 Could you try that again in English?  The 2090 or 2090a
    do not exhibit the slowdown with ST-506 drives because they(which?)
    are already slow enough to let the other chips (. . .) steal
    cycles(from where?), but using SCSI drives(always?) and while
    DISPLAYING a hi-res 16 color screen(always?), they are slower than
    floppies(hard to accept), . . .  I'm not a real techie and have
    just enough of a grasp on some of this stuff to nod at the right
    places and not make too much of a fool of myself. The only point
    you made that sounds wrong rather than just in need of more detail
    is the speed comparison to a floppy. I've never known a hard disk
    to be nearly as slow as a floppy drive under any circumstances.

    Displayin a hi-rez 16 color screen takes a lot of bandwidth, which
    leaves little time for other things to happen, like transferring data
    from disk controller to memory.  If the controller is DMA (Direct
    Memory Access), it accesses memory without processor intervention so in
    effect it "steals" access time from the 68000 and the other chips that
    access memory directly.  Now each one of those devices has a priority
    of access to memory, obviously (to keep the picture from going away)
    the display chips have the highest priority, and the one that can wait
    the longest is the 68000, in between are the ones that are linked to
    mechanical devices like rotating disks.  Now ST-506 drives are slower
    than SCSI drives so they are able to assemble their words in the
    controller and transfer them in time, with SCSI drives the words come
    by too fast and sometimes the disk has to make a few revolutions to
    transfer the whole file and this takes time, a lot of time.  I have
    timed my 2090a for a hi-rez transfer (16 color) while displaying
    another hi-rez picture and it took close to 2 MINUTES, the drive light
    was solid on this whole time, if however I push the hi-rez screen in
    the back, it works fine (a few seconds).  
    
    Hope this makes sense, (if it doesn't, what do you expect at this
    time of the day!)
    
    Jean (going to bed now)
     

    
    The Microbotics Hardframe does not suffer any slowdown while stressing
    the chip bandwidth.  The problem with the 2090 is a design flaw
    involving the overflow of some FIFOs somewhere.  There is a very nice
    long test of DMA controllers on COMP.SYS.AMIGA where the Hardframe &
    2090 were compared.  The Hardframe won, mainly because MB sidestepped
    the problem that bit Commodore.
    
    Ed.
    

    The reasons when and why the 2090(a) suffers in transfer speed where
    pretty well descriped in the last few replies. In short, the 64
    byte FIFO on the 2090(a) want's to be DMA'ed into it's target location
    in the Amiga memory in one piece, which under certain internal DMA
    situtations like hi-res/4 bitplane screens upfront is nearly
    impossible. So it tries again and again...
    The speed penalty is also quite visible with ST-506 drives, I can
    assure you that. But with SCSI drives it becomes a nightmare.
    
    Both the Microbotics HardFrame and the now available A2091 (there's
    no such thing as an A2091a) from Commodore don't expirience this
    problem, however heavy internal DMA will of course have it's effects
    on their transfer rates, too.
    These two controllers and the Supra 2000 (and the A2090(a) ) are the 
    only _real_ DMA controllers for the Amiga I'm aware of.
    
    Neither GVP nor CLtd. Kronos feature DMA.
    
    I would go for the A2091 or the MB HardFrame, if you can afford
    them...
    
    Regards,
    
    <CB>

    Re .5:
    
>                             -< what is 2090a? >-
    
    First an answer to your question.  The A2090a autoboots (with V1.3 of
    the Amiga ROMs) whereas the A2090 didn't.  The A2091 replaces both and
    solves a problem that causes a performance degradation for some users.
    
>   Please enlighten me on the issue of 2090a vs 2091a.  Is this issue
>   just the disk controller?
    
    My understanding (based on reading a BUNCH of sometimes-contradictory
    articles on Amiga hard disk controllers) is that the severe performance
    degradation exhibited by the A2090/A2090a controllers during deep
    overscan (lots of bit planes of many bits each) was cured in the A2091
    (and A590) controller.  A lot of people (especially the promoters of
    non-DMA controllers) blamed DMA *itself* for the degradation, when in
    fact the problem was the A2090's implementation thereof.
    
    Consider your anticipated usage of the A2000.  If you're going to be
    stressing the memory bandwidth by displaying lots of bit planes with
    overscanning to get more than 640x400 pixels each, you'll need a hard
    disk controller that can keep up with you.  In such a case you should
    hold out for the A2091 or the HardFrame.  Non-DMA controllers can also
    be seriously impacted due to the fact that the 68000 must fetch data
    bytes from them to place into memory, at an additional cost to memory
    bandwidth.
    
    If you're like most of us, you won't notice the problem.  OmniTek has
    A2000HD systems at a VERY ATTRACTIVE price (much less than the $2400
    you've been quoted) these days, with the A2090a and a 40MB drive built
    in.  Starting with an A2000 for $1300 and adding a controller and drive
    is attractive too, though you'll have the problem of going through the
    Amiga DOS learning curve at the same time you're trying to install the
    hard drive (the A2000HD's drive comes pre-formatted and loaded with
    Amiga software and extras).

    I went to Omnitek in Tewksbury this weekend to see what they are
    offering.  As Bill Kumpel has already noted, they have some
    aggressively priced pac.  I must admit, however, that I am leary
    of the 2090A controller issue.  I have been studying ads for GVP
    and Supra Hardcards.  I was thinking of buying Omnitek's Amiga 2000
    for $1300 and ordering the 40MB Supra Hardcard with the Wordsync
    controller.  This set up seems to cost only about $100 more than
    the Amiga 2000HD.  This does not seem to be too high a premium to
    pay if it avoids the risk of the "overscan problems" described in
    some of these notes.  Tell me, will the Supra hardcard setup avoid
    this problem?  Have any of you Amiga veterans had any experience
    with this drive and controller?
    
    Please advise,
    Chuck