17 Bit Software 3: The Continuation/17-Bit_The_Continuation_Disc.iso/amigan/amigan 19/2000_clock/2000_clock.txt

Text File | 1994-01-27 | 21KB | 492 lines

From: [e-mail] (Andy Finkel)
Subject: Re: The time (my watch has troubles) has come ...
Date: 19 Oct 87 21:10:04 GMT
Organization: Commodore Technology, West Chester, PA
Keywords: I should learn to RTFM


In article <[e-mail]> [e-mail] (Kim DeVaughn) writes:

> Yep ... the jumper was between pins 2 and 3 rather than the pictured default
> between pins 1 and 2!  So the timer chip had been getting popped at the
> vertical sync rate, rather than being locked to the line frequency.  No big
> deal, just swap the jumper.  Now the question is ... why would one want to
> drive the timer from the vertical sync, rather than from the line?  Maybe
> for use in areas with ill-controlled power?

This makes it compatible with the A500 which doesn't have the tick
coming from the power supply :-(  but must rely on the vertical
sync line for its timing, which we know is.........

                andy
--
andy finkel             {ihnp4|seismo|allegra}!cbmvax!andy
Commodore-Amiga, Inc.

"Interfere?  Of course we'll interfere.  Always do what you're best at,
 I always say."

Any expressed opinions are mine; but feel free to share.
I disclaim all responsibilities, all shapes, all sizes, all colors.

============================================================================

Date: Wed, 21 Oct 87 19:25:56 edt
From: ames!rutgers!cbmvax!daveh (Dave Haynie)
To: ames!amdahl!kim
Subject: Re: The time (my watch has troubles) has come ...


[e-mail] (Kim DeVaughn):
> Keywords: I should learn to RTFM

> Yep ... the jumper was between pins 2 and 3 rather than the pictured default
> between pins 1 and 2!  So the timer chip had been getting popped at the
> vertical sync rate, rather than being locked to the line frequency.  No big
> deal, just swap the jumper.  Now the question is ... why would one want to
> drive the timer from the vertical sync, rather than from the line?  Maybe
> for use in areas with ill-controlled power?

That, and for DC-only operation (the OS won't come up at all without this
clock ticking at at least some reasonable rate).  And for A500 compatibility;
the A500 doesn't have a line Tick, so they ALWAYS have the vertical sync
used instead.  I though about this fact, and figured that if there's a way,
someone will eventually write a program that depends on this fact.  So I
put in the jumper.  I really wish these could be more accessible, but after
seeing the board, you can probably understand the problems involved.


> And there was indeed a small trimmer cap near the Oki chip (just in front of
> the 86-pin coprocessor slot).  No markings to tell which way to go, but it's
> a 50-50 shot ... I tweaked it a hair CCW (is that the correct way to turn it
> to slow it down, Dave?)  We'll see ...

To tell you the truth, I'm not all that sure which way you want to twist it.
On the production line (in Taiwan) they have a watch calibration tool.  You
lay a probe next to the crystal, and tweak the trimmer until the green
light comes on.  They can specify the accuracy they'd like to get.  Not sure
what its set for, and with all that travelling, it's probably moved a bit
anyway.  At least the trimmer is easy to get to.


> BTW, it would be nice if the RTC were locked to the line freq. when the machine
> is plugged in (or at least is powered on), and switched to using the xtal
> oscillator only for battery backup, but I guess that'd be too expensive.

Also, various government groups get antsy when you tell them that the power
switch doesn't really turn off the power all the way.  I guess there's a way
around this, or my stereo, TV, and VCR remotes wouldn't work very well for
on and off functions.


> Anyway, if your clock(s) aren't keeping the right time, and particularly
> if the timer driven system clock is running about 0.3% slow, you now have
> a couple of things to check out.

And I've got to email to Taiwan and find out if perhaps they're shipping the
wrong jumper configuration, or if you're unit is just an accident (like maybe
the shunt plug fell off and was randomly put on wrong).

> /kim


> P.S.  FYI ... the Fat Agnus chip is called "FAT LADY" on the silk-screening,
>       and for some reason, Buster isn't named, though Gary, Paula, and Denise
>       are (this is on a rev 4.2 board).

Yea, you're right.  I never noticed that.  It may go back to the first Rev of
the board, which was layed out before there was a Buster chip.  The PCB guy
(Terry Fisher) may not have known the name of this magic new chip.  BTW, they
tell me that REV 4.2 means a REV 4.0 PCB with all the fixes (i.e. no goofy
1.5 turn ferrite beads to muck up the clarity of your video).

============================================================================

Date: Wed, 28 Oct 87 13:03:17 PST
From: kim (Kim DeVaughn)
To: ames!rutgers!cbmvax!daveh
Subject: Re: The time (my watch has troubles) has come ...


> > And there was indeed a small trimmer cap near the Oki chip (just in front of
> > the 86-pin coprocessor slot).  No markings to tell which way to go, but it's
> > a 50-50 shot ... I tweaked it a hair CCW (is that the correct way to turn it
> > to slow it down, Dave?)  We'll see ...
>
> To tell you the truth, I'm not all that sure which way you want to twist it.
> On the production line (in Taiwan) they have a watch calibration tool.  You
> lay a probe next to the crystal, and tweak the trimmer until the green
> light comes on.  They can specify the accuracy they'd like to get.  Not sure
> what its set for, and with all that travelling, it's probably moved a bit
> anyway.  At least the trimmer is easy to get to.

Thanks for the info!

As I said, I had a 50-50 shot, but just like ol' Ben Franklin, I blew it!
Turning the cap CCW makes it FASTER ... you go CW to slow things down.

I got pretty lucky, really ... after finding that CCW was the wrong
direction, I tweaked it a bit the other way.  I was out of town on
business for the week following, and found when I got back that I was
only 2 sec too slow.  I'll leave well enough alone and let it go at
that.  I figure that to be within a minute between times that we go
to/from daylight savings time is pretty good.  Hopefully, that won't
drift too much ...

Thanks again!

/kim

============================================================================

From: [e-mail] (Keith Ericson)
Subject: The time has come and genlock?
Date: 20 Oct 87 18:09:35 GMT
Organization: Tektronix, Inc., Beaverton, OR.
Keywords: I should learn to RTFM


In article <[e-mail]> [e-mail] (Andy Finkel) writes:
<
<...the A500 ... doesn't have the tick
<coming from the power supply :-(  but must rely on the vertical
<sync line for its timing, which we know is.........
<
<               andy

..........unless maybe one can get the GenLock goodie, lock onto a
local TV network affiliate and coat-tail along on their 3.57954545...
color burst signal, which is ultimately derived from NBS standard?

keith

[note the "<" instead of ">" in the quoted section: this fakes out
the news posting program an allows a "short" followup!]

============================================================================

From: [e-mail] (Dave Haynie)
Subject: Re: The time (my watch has troubles) has come ...
Date: 21 Oct 87 23:06:44 GMT
Organization: Commodore Technology, West Chester, PA


in article <[e-mail]>, [e-mail] (Kim DeVaughn) says:
> Keywords: I hope there are knobs in there
>
> [ There ain't no such thing as a free line. ]
>
> I've been burning-in my B2000, and have noticed that accuracy of both the
> normal internal clock (timer, really) and the battery-backed-up RTC are
> unacceptable.
>
> Can someone at CATS (Dave, George, Carolyn) please tell me if/where the
> trimmers are so I can get these clocks running right?  I'd prefer not to
> have to go thru the hassle of returning the machine to the dealer for just
> an adjustment.

OK, here goes.  The trimmer for the RTC is relatively easy to get at with just
the box top off.  You'll need a "tweaking tool", which usually looks like a
long piece of plastic with a thin metal tip (for those out there not familiar
with this sort of high-tech equipment....).  The trimmer is located just a
hair to the south of the Coprocessor slot.  It should be possible to adjust
this to be about as accurate as a digital watch, as the clock chip uses a
common watch battery.  They're supposed to be adjusted on the production line,
though it's certainly possible that some fall out in shipping and all.  There
will probably be a slight varience in the clock frequency depending on whether
or not the unit's powered on, I don't know how much this varience can amount
to.

As for the internal system clock, that is based on the 60Hz tick from your
line voltage.  Or SHOULD be.  Because in fact, the B2000 can be internally
jumpered to count time off the vertical sync line, just as the A500 does.
This is all controlled by J300, which is (you guessed it) hidden under
the power supply.  It's the jumper just a bit to the North of the Paula
chip, if you do happen to open your machine up and look inside.  These are
supposed to be shipped in the line Tick position, which means the shunt
plug is to the left.  If this is installed properly, the only other thing
that could affect your timing here is lousy line frequency regulation in
your area.


> Though it should not matter, I have a 68010 in the machine (you *don't* have
> any s/w timing loops in there, do you?)

I've got one too, and as far as I know, my clocks stay pretty accurate.


> Why aren't these locked to the line frequency, which has very good long-term
> accuracy, though may suffer from short-term stability?

The OS clock is, or should be, but that only works when the machine is on.  The
RTC can't be, or it would lose its time base if the power went out or you
moved the machine.

> /kim
--
Dave Haynie     Commodore-Amiga    Usenet: {ihnp4|caip|rutgers}!cbmvax!daveh
   "The B2000 Guy"              PLINK : D-DAVE H             BIX   : hazy
    "Computers are what happen when you give up sleeping" - Iggy the Cat

============================================================================

From: [e-mail] (Andy Finkel)
Subject: Re: Problems with the Real Time Clock on my Amiga 2000
Date: 27 Oct 87 15:48:09 GMT
Organization: Commodore Technology, West Chester, PA


In article <[e-mail]> [e-mail] (Michael Nowak) writes:
>I recently traded my Amiga 1000 for an Amiga 2000 and I've noticed a real
>problem with my Real Time Clock:  I set it by using date and setclock but
>when I reload it in the startup-sequence (about every day), it seems to gain
>about 10 minutes!

The RTC is adjustable.  C912 (on the main board) can be used as a slow/fast
control to tune the clock to greater accuracy.

--
andy finkel             {ihnp4|seismo|allegra}!cbmvax!andy
Commodore-Amiga, Inc.

"Interfere?  Of course we'll interfere.  Always do what you're best at,
 I always say."

Any expressed opinions are mine; but feel free to share.
I disclaim all responsibilities, all shapes, all sizes, all colors.

============================================================================

From: [e-mail] (Kim DeVaughn)
Subject: Re: Problems with the Real Time Clock on my Amiga 2000
Date: 30 Oct 87 01:41:06 GMT
Organization: Amdahl Corporation,  Sunnyvale, CA 94086
Summary: "The time has come", the walrus said, "to talk of many things ..."


In article <[e-mail]>, [e-mail] (Michael Nowak) writes:
> I recently traded my Amiga 1000 for an Amiga 2000 and I've noticed a real
> problem with my Real Time Clock:  I set it by using date and setclock but
> when I reload it in the startup-sequence (about every day), it seems to gain
> about 10 minutes!  I'm delaer doesn't know what to make of it.  Is this
> a hardware problem or what?  Has anyone else encountered this?

Surely have!  Sounds like your machine and mine were "tuned" by the same
person over there in Taiwan.

It's easy to fix though ... there is a small trimmer capacitor just about
directly to the front of the 86-pin coprocessor slot, very near to the
Oki clock/calendar chip, that you can adjust.  On my machine, it was a
bright yellow color.

Anyway, you'll need a VERY narrow-bladed screwdriver, preferably one with
a plastic shank.  You should be able to find something suitable at Radio
Shack, etc (ask to see their selection of alignment tools).

To adjust it to run SLOWER, you want to tweak the adjusting screw (down
in the middle of the capacitor) a LITTLE bit in the CLOCKWISE direction.
I suggest trying a sixteenth of a turn, and then checking to see how much
that improves things over (say) a 24-hour period.  Then just tweak away
until you've zeroed in on the accuracy you want (or the limit of your
patience, whichever occurs first :-) )!


BTW, if you should also find that your machine LOOSES time BETWEEN "setclock"
operations, your J300 jumper (near one of the 8520 chips, under the power
supply) is probably in the wrong position.  It *should* be set to jumper pins
1 and 2 together, which will cause the timer to be locked to the line
frequency.  Mine had pins 2 and 3 jumpered, which causes the timer to be
locked to the vertical sync rate.

/kim


--
UUCP:  [e-mail]
  or:  {sun,decwrl,hplabs,pyramid,ihnp4,uunet,oliveb,cbosgd,ames}!amdahl!kim
DDD:   408-746-8462
USPS:  Amdahl Corp.  M/S 249,  1250 E. Arques Av,  Sunnyvale, CA 94086
CIS:   76535,25

============================================================================

From: [e-mail] (Kim DeVaughn)
Subject: Re: The time (my watch has troubles) has come ...
Date: 30 Oct 87 02:07:11 GMT
Organization: Amdahl Corporation,  Sunnyvale, CA 94086
Summary: everything's a tradeoff (sigh)
Keywords: I should learn to RTFM


In article <[e-mail]>, [e-mail] (Andy Finkel) writes:
> In article <[e-mail]> [e-mail] (I) wrote:
>
> >Yep ... the jumper was between pins 2 and 3 rather than the pictured default
> >between pins 1 and 2!  So the timer chip had been getting popped at the
> >vertical sync rate, rather than being locked to the line frequency.  No big
> >deal, just swap the jumper.  Now the question is ... why would one want to
> >drive the timer from the vertical sync, rather than from the line?  Maybe
> >for use in areas with ill-controlled power?
>
> This makes it compatible with the A500 which doesn't have the tick
> coming from the power supply :-(  but must rely on the vertical
> sync line for its timing, which we know is.........

Strange that it (the 500) doesn't pick off the line frequency ... doesn't
seem like much of a cost savings not to.

An "interesting" side effect of changing the jumper from the video sync to
the line tick, is that my floppy now *grinds* noticibly LOUDER (gak!)
Everything is nice and tight, mounting wise, so it must be due to the
slight difference in timer interrupt rates (resonance ?)  Sounds pretty
fishy, but I don't have a better explanation ...

Last night, I installed a 2nd 3.5" floppy, and *it* is REALLY quiet ...
literally, quiet as a whisper.  It's the exact same Matsushita drive
(model, assembly level, etc.) as df0: but *much* quieter than df0: was
even before I changed the timer jumper!  Oh well ...

/kim


--
UUCP:  [e-mail]
  or:  {sun,decwrl,hplabs,pyramid,ihnp4,uunet,oliveb,cbosgd,ames}!amdahl!kim
DDD:   408-746-8462
USPS:  Amdahl Corp.  M/S 249,  1250 E. Arques Av,  Sunnyvale, CA 94086
CIS:   76535,25

============================================================================

From: [e-mail] (Blaine Gardner)
Subject: Re: Problems with the Real Time Clock on my Amiga 2000
Date: 31 Oct 87 17:05:53 GMT
Organization: Evans & Sutherland Computer Corporation


In article <[e-mail]>, [e-mail] (Kim DeVaughn) says:
<
< It's easy to fix though ... there is a small trimmer capacitor just about
< directly to the front of the 86-pin coprocessor slot, very near to the
< Oki clock/calendar chip, that you can adjust.  On my machine, it was a
< bright yellow color.

< To adjust it to run SLOWER, you want to tweak the adjusting screw (down
< in the middle of the capacitor) a LITTLE bit in the CLOCKWISE direction.
< I suggest trying a sixteenth of a turn, and then checking to see how much
< that improves things over (say) a 24-hour period.  Then just tweak away
< until you've zeroed in on the accuracy you want (or the limit of your

There has GOT to be a better way! George, Dave, anybody, if I've got an
oscilloscope (and an A2000 of course :-) where do I look, and for what
signal? I assume you're dividing a higher clock down to 60 Hz?
--
Blaine Gardner @ Evans & Sutherland    540 Arapeen Drive, SLC, Utah 84108
UUCP Address:   {ihnp4,ucbvax,decvax,allegra}!decwrl!esunix!blgardne
                {ihnp4,seismo}!utah-cs!esunix!blgardne
"I don't see no points on your ears boy, but you sound like a Vulcan!"

============================================================================

From: [e-mail] (Bryce Nesbitt)
Subject: Re: Problems with the Real Time Clock on my Amiga 2000
Date: 3 Nov 87 06:31:25 GMT
Organization: University of California at Berkeley


In article <[e-mail]> [e-mail] (Blaine Gardner) writes:
>in article <[e-mail]>, [e-mail] (Kim DeVaughn) says:
>
>< It's easy to fix though ... there is a small trimmer capacitor just about
>< directly to the front of the 86-pin coprocessor slot, very near to the
>< Oki clock/calendar chip, that you can adjust.  On my machine, it was a
>< bright yellow color.
>
>There has GOT to be a better way! George, Dave, anybody, if I've got an
>oscilloscope (and an A2000 of course :-) where do I look, and for what
>signal?

Anybody here:

Pin 1 of the OKI MSM6242B can be used for calibration.  Hook a scope
to it (better yet, a frequency counter).
You will probably see something close to:

1/64th second
1 second
1 minute
1 hour
-or-
something strange (in the neighborhood)

It will probably be near 1/64th.  Adjust until it is exact.  (Beware
that temperature affects crystals).

If it is *not* at 1/64th of a second, register $E needs to be set
to zero.  This falls in the category of "magic" unless you have
the docs for the chip or perhaphs the A500/A2000 tech. ref.


BTW: I got an answer from comp.sources.amiga.  Perhaphs there is
life after all!

|\ /|  . Ack! (NAK, SOH, EOT)
{o O} . [e-mail] -or- ucbvax!hoser!bryce
 (")
  U     "You can count how many seeds are in an Apple, but not how
         many Apples are in a seed." -Ken Kesey

============================================================================

From: [e-mail] (George Robbins)
Subject: Re: Problems with the Real Time Clock on my Amiga 2000
Date: 7 Nov 87 07:30:56 GMT
Organization: Commodore Technology, West Chester, PA


In article <[e-mail]> [e-mail] (Bryce Nesbitt) writes:
> In article <[e-mail]> [e-mail] (Blaine Gardner) writes:
> >in article <[e-mail]>, [e-mail] (Kim DeVaughn) says:
> >
> >< It's easy to fix though ... there is a small trimmer capacitor just about
> >< directly to the front of the 86-pin coprocessor slot, very near to the
> >< Oki clock/calendar chip, that you can adjust.  On my machine, it was a
> >< bright yellow color.
> >
> >There has GOT to be a better way! George, Dave, anybody, if I've got an
> >oscilloscope (and an A2000 of course :-) where do I look, and for what
> >signal?
>
> Anybody here:
>
> Pin 1 of the OKI MSM6242B can be used for calibration.  Hook a scope
> to it (better yet, a frequency counter).
> You will probably see something close to:
>
> 1/64th second > 1 second > 1 minute > 1 hour > -or-
> something strange (in the neighborhood)
>
> It will probably be near 1/64th.  Adjust until it is exact.  (Beware
> that temperature affects crystals).
> If it is *not* at 1/64th of a second, register $E needs to be set
> to zero.  This falls in the category of "magic" unless you have
> the docs for the chip or perhaphs the A500/A2000 tech. ref.

Unless you have access to an accurate frequency counter, this menthod isn't
going to be any better than the twiddle until it seems about right method.
Think about error percentages, scope resolution and seconds/day...

If you do have access to good test equipment, then set up test mode much
as Bryce describes, then use a frequency counter in "period" mode to get
that 64 Hz, or 1 Hz test signal just on.

Perhaps someone can come up with some clever trick, whereby you jumper the
test pin on the clock chip over to the parallel port, then via software
compare the battery clock frequency to the line frequency?

--
George Robbins - now working for,       uucp: {ihnp4|rutgers|allegra}!cbmvax!grr
but no way officially representing      arpa: out to lunch...
Commodore, Engineering Department       fone: 215-431-9255 (only by moonlite)