Conference hydra::amiga_v1

    The B2000 designation refers to the motherboard design.  The B2000
    was designed in Westchester by Dave Haynie, whose name appears on
    the etch.
    
    The 'A'2000 motherboard was the first model designed in West Germany.
    Only a few machines made it here; mostly dealer demo models.
    
    I believe that the main difference is in the physical location of the
    top 512K of ram.  On the 'B'2000, it's on the motherboard, and will
    be accessible as CHIP ram for Fat Agnus.  The early machines (A)
    will suffer the same 512K CHIP ram fate as the A1000, since Agnus can't
    get to it.
    
    Here's something interesting... when I went to pick up my A2000
    ('A' as in Amiga, not motherboard rev) I insisted on getting the
    latest revision motherboard, which I understood to be 4.3.  I also
    wanted to install my 68010 chip.  Moe agreed to open the 2000 so
    that I could make the swap.
    
    The first machine that I opened had 'rev 4.1' etched on the
    motherboard, but had a small sticker that said 'rev 4.2' pasted
    onto the board.
    
    "Oh, no!" I said, "I want a rev 4.3 machine."  We opened a few more
    boxes, but they all had 4.1 etched on the board.
    
    The shipping invoice that was pasted to the boxes declared that
    the machines had left Westchester QC only a few weeks earlier, so
    I assumed that they were the latest models.  My machine has no label,
    only '4.1' etched on the board.
    
    So, I wonder if I have an older machine that sat on a boat for a
    few months?  Does your machine have 4.3 etched onto the board or
    just a sticker?
    
    Anyone know what changes/fixes were made between revs?  The machine
    is pretty robust, and seems 100% compatible with my 1000.
    
    Ed.
    
    
         
    

    By board has 4.3 etched next to the name of Haynie.
    
    I am still curious as to what those two connectors are adjacent
    to the power supply on the far right side of the mother board.
    
    BTW, did you notice the quotes from various songs printed on the
    circuit diagrams in the back of the User's Guide?
    
    Paul

    re: .0
    
    My A2000's clock also gains a few seconds a day, but I don't think
    Commodore has fixed the clock problem.  The watch on my wrist is
    accurate to within about 1 second a day, I don't see why the computer
    can't do as well.  I find myself resetting the Amiga's clock based
    on my watch every few days.
    
    (I set my watch to WWV, so I know it's accurate.)
    
    re: .2
    
    There is a tradition among hackers of including more-or-less relavent
    quotations in literary works.  I first encountered this in computer
    programs in the early 70s, but it's been done in books for a long
    time.  I'm not surprised to see it starting to turn up in circuit
    diagrams.
    
    In Don Knuth's recent errata list for Computers & Typesetting volume
    E, the only new correction was to one of the quotations.
        John Sauter

    There is a simple fix .. just adjust the potentiometer on the mother
    board ...

    
    	A man with a watch always knows what time it is.
    
    	A man with two watches is never sure.  ;')
    

    One of the problems I have with the 2000 is the extra hardware which
    I have no interest in - yet which I must pay for.
    
    I'm talking about the PC bus. Does the hardware for this raise the
    price of the 2000 significantly (I mean without buying the
    bridgeboard).
    
    What I want is an Amiga with the internal expansion that allows
    me to increase memory to the max, add peripherals such as MIDI,
    genlock, and framegrabber, and perhaps a few more.
    
    I take it that the 500 requires a costly expansion box to do this.
    
    
    
    				Gregg

    and some of the newer ibmpc clones have a cheap digital clock built
    into the front panel.  So you can have 3 clocks (the computer, clock,
    and your watch).
    
    the two connectors next to the power supply are the video expansion
    slots.  The "A2000" has one slot, the "B2000" has an additional
    one that the redesign folks thought was needed to bring out additional
    stuff needed for the US video market.
    
    My 2000 has a 4.2 sticker.  The clock is adjusted by a yellow pot
    near the 68000.
                  
    -dave

    re: .6
    
    the response from CBM was that, no, adding the pc bus didn't really
    increase the cost of the 2000.  It's just sockets, layout and etch.
    It isn't connected to anything until you buy a Bridgeboard.
    
    Price a 2000, price a 500, then use the difference to see if you
    can buy an expansion box for the 500 with all the expansion features
    built into the 2000.  Check for CPU slot, video slot, 200 watt power
    supply, internal mounting for a 3.5" and 5.25".  Then imagine what
    would happen if the power is on when a small child tries to separate
    the 500 from it's expansion box.
    
    -dave

    I look at it this way...
    
    In October '85 I paid $1295 for a 256K machine with no slots, and
    a 75 watt power supply.
    
    Today, you get a 1 meg machine with slots, a PC buss, a video slot,
    a coprocessor slot, a 200 watt supply, and a VT-like keyboard for
    $1600.  That's really not so bad.
    
    Ed.
    

    Yeah,
    
    	I paid top dollar for my A1000 a long time ago BUT it was
    great value even then. Now lucky people can get machines that are
    flexible, growable & more versatile for about the same price. The
    machines are maturing consistently & are price competitive even
    up here on the top of the world with high transport costs & a dollar
    equal .75 of yours.

        You may not want any sort of Blechh-compatability but its there
    for almost zilch dollars. I've seen a few cards such as an 8Mips
    Novix Forth Card that would be kind of fun to have. Pity I'd have
    to buy a bridgecard just to use this card. It will allow those with
    less money access to less-efficient but cheaper peripherals ect.
    and there are heaps of applications where dedicated hardware would
    just not appear for the machine without a Blechh-PC slug-buss, the volumes
    wouldnt be worth it.
    
    	Great I say, this is how technology should be. I wish Commodud
    had tried to keep the busses somewhat compatible but that's life.
    
    This machine has a few of the features that made the Blechh-PC and
    the Apple-II so successful:1. An open box with LOTS OF SLOTS, 2.
    An open box with LOTS OF SLOTS & 3. An open box with LOTS OF SLOTS
    (With none of the drawbacks i.e rediculous OS imposed memory
    limitations & maps, slug peripherals (UNLESS YOU CHOOSE THEM)) 

        Let the user decide how best to configure their machine, 80286, 68020
    SCSI, ST506 ....... Its all possible with a graphics, sound engine
    thrown in if you want to take the viewpoint the other way. No one
    complains that we still accomodate UNIBUS devices on current VAXEN
    so think of this as Commodud supporting Slug-bus to ease customers
    into changing to better technology.

    See Ya,
    John
    

    Has anyone tried using a PC hard disk on a 2000?  Would this be
    accessible from the 68000 side assuming a bridgecard is installed?
    If so, what would the performance be like?  I would guess from  
    discussions elsewhere that due to little, if any, shared memory,
    the performance would not be good.  However, you can get PC hardcards
    pretty cheap.
    
    dan

Re: Battery Backed Up Clock

The problem with the battery backed up clock wasn't due to any hardware
problem.  The clock has an adjustable tick rate controlled by a little
trimmer capacitor next to the processor slot.

As a matter of fact, last Sunday I wrote a little program to allow me
to calibrate the battery backed up clock against the 60 hertz CIA chip
timer in the Amiga.  Before adjustment, my clock gained 2 minutes a day.
After calibration, it has lost 6 seconds in 4 days.

If anyone expresses interest, I'll try and write up some documentation
and upload the program.


Re: Video Connector

The B2000's additional video connector was added when the Commodore folks
suddenly thought, "Gee, if we provide a second video slot that brings
all 12 bits of digital RGB out, someone might be able to make a deinterlacer
that provides support for all 4096 colors."  So, the B2000 has two video
slots.  One slot is there to accept a genlock card, and was also in the
A2000.  The other new slot is the slot that the FlickerFixer fits in.

As it turns out, the FlickerFixer was designed and prototyped for an
Amiga 1000.  However, since all the digital RGB information wasn't
available, it imposed a limitation on the displayable colors.  I talked
to the FlickerFixer's developer, and he had plans to do a version
for the 500/1000 that would not be able to handle as many colors as
the 2000 version, but would be far cheaper.  (The 500/1000 version
required far less memory for its internal video buffers, hence the
lower cost.)


Re: A2000 versus B2000

The B2000 has the following features not found in the A2000:

	Second video slot for deinterlacers
	Monochrome video output jack
	Improved processor slot--You do not need to pull the 68000
	   from its socket when you install a 68020 accelerator board.
	One megabyte on the motherboard.
	The Fat Agnus chip.

One the other hand, the A2000:

	Had only 512K on the motherboard, but came standard with a
	memory card plugged into the processor slot.  This memory
	card came standard with 512K installed, so the base machine
	did come with one meg of memory.  The memory card had empty
	sockets for either another .5 or 1.5 meg of memory.  This
	allowed anyone a cheap memory upgrade by plugging in more
	chips and setting a jumper.

	Had the original "skinny" Agnus chip used in the Amiga 1000.

The Byte preview of the Amiga 2000 last spring was based on the A2000.


Re: Motherboard Revisions

I think I saw a posting of the difference between the 4.3 and 4.2
motherboards.  It was pretty ho hum. I remember the difference between
a 4.1 and 4.2 board was that the 4.1 had a small daughter board to
fix a problem with the Buster support chip.  The 4.2 boards where
produced after Buster was fixed, and thus the daughter board was
unnecessary.

The following is a comp.sys.amiga message on the difference between the
4.2 and 4.3 motherboards.  Summary: 4.3 fixes a problem that occurs if
you have the 4.3 version of Gary and a Commodore 68020 card. Ho hum.

------------------------------------------------------------

> Which brings up a point that I've been wondering about ... just what are
> the changes from the rev 4.2 to the rev 4.3 boards?
 
The main difference is that the Rev 4.3 board has a 470 Ohm pullup on the /VPA
in, whereas the Rev 4.2 only have a 4.7K pullup on the /VPA line.  This is
only an issue if you have the MOS version of the Gary chip (started some time
after R4.3 went into production) AND you're using a 68020 accelerator board
like the A2620 (hint: you're not using an A2620 yet).
 
> Any chance of posting a "revision history" list?  (Dave ?)
 
If get a chance I can look and see if there are any other changes to write
about, but most of them are similar little tweaks.  
 
People get so panicky over little things like ".2" vs. ".3" that they're not
supposed to even know about.  Now I know why I never used this numbering 
scheme before.  Next time we go back to coding it, like most other vendors
do.
 
> /kim
-- 
Dave Haynie  "The B2000 Guy"     Commodore-Amiga  "The Crew That Never Rests"
   {ihnp4|uunet|rutgers}!cbmvax!daveh      PLINK: D-DAVE H     BIX: hazy
		"I can't relax, 'cause I'm a Boinger!"

    re: .11--I haven't tried it, but the BridgeBoard documentation
    describes making a PC disk available to AmigaDOS.  If I remember
    correctly you need to partition the disk: one part for MS-DOS and
    the other for AmigaDOS.
    
    re: .12--Yes, please upload your calibration program.  I recently
    ordered a screwdriver small enough to tweak that pot, and I was
    afraid that I would have to adjust it by trial and error.
    You might also consider contributing the program to Fred Fish.
        John Sauter

re: .12

yes please!  my clock hasn't been bad enough to do anything with yet, but is bad
enough to annoy.  I, like Mr. Sauter, was not thrilled with the thought of
adjusting the clock by trial and error.

	Paul