From: andy@cbmvax.UUCP (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 <16531@amdahl.amdahl.com> kim@amdahl.amdahl.com (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 ... kim@amdahl.amdahl.com (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: keithe@tekgvs.TEK.COM (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 <2541@cbmvax.UUCP> andy@cbmvax.UUCP (Andy Finkel) writes: < <...the A500 ... doesn't have the tick " in the quoted section: this fakes out the news posting program an allows a "short" followup!] ============================================================================ From: daveh@cbmvax.UUCP (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 <16516@amdahl.amdahl.com>, kim@amdahl.amdahl.com (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: andy@cbmvax.UUCP (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 <361@tardis.cc.umich.edu> mike@ronin.cc.umich.edu (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: kim@amdahl.amdahl.com (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 <361@tardis.cc.umich.edu>, mike@ronin.cc.umich.edu (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: kim@amdahl.amdahl.com 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: kim@amdahl.amdahl.com (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 <2541@cbmvax.UUCP>, andy@cbmvax.UUCP (Andy Finkel) writes: > In article <16531@amdahl.amdahl.com> kim@amdahl.amdahl.com (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: kim@amdahl.amdahl.com 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: blgardne@esunix.UUCP (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 <17259@amdahl.amdahl.com>, kim@amdahl.amdahl.com (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: bryce@hoser.berkeley.edu (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 <552@esunix.UUCP> blgardne@esunix.UUCP (Blaine Gardner) writes: >in article <17259@amdahl.amdahl.com>, kim@amdahl.amdahl.com (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} . bryce@hoser.berkeley.EDU -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: grr@cbmvax.UUCP (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 <21572@ucbvax.BERKELEY.EDU> bryce@hoser.berkeley.edu (Bryce Nesbitt) writes: > In article <552@esunix.UUCP> blgardne@esunix.UUCP (Blaine Gardner) writes: > >in article <17259@amdahl.amdahl.com>, kim@amdahl.amdahl.com (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)