davidy@sumax.UUCP (David L. Yee) (11/03/90)
(Apologies if this has already been discussed- I missed a few days worth of posts, and you know how the traffic is......:^) I am in need of some help and or information. I just recieved my GVP Series II hardcard with on-board memory exapansion. This is the new one with DMA access. Anyway, it refused to operate with the memory installed and the memory configuration jumpers set appropriately. If I disabled the RAM jumpers, or removed the RAM entirely, the card booted and runs fine. Needless to say, I was a little perturbed, so I called up GVP today (11-2-90, 1:30 PST) and asked to see what was up. A person named Gary took my call. What he told we was this: I have a rev 4.3 motherboard. Gary said that Commodore made a number of 4.3 motherboards without a certain resistor. This resistor is a 470 ohm, 1/4 watt resistor that (I believe) he said was supposed to be connected to the DTACK line of the 68000 (My memory on the DTACK portion is a little hazy, the rest is not.) Anyway, here is approximately where it should go: ________ | | | | | | | | | | || | | R || | | || <-resistor pack |MC68000 | || | | || || R= location of missing resistor | | || || | | ||<-resistor pack | | || || | | || || | | || || | | || | | || ---------- Front of A2000 I hope this is adequate to describe where the missing resistor is supposed to go, because he was trying to describe its location and where it should be soldered over the telephone, which was NOT easy. :^) GVP claimed that they had been in touch with Commodore, and that earlier this Monday they had concluded that this was why the Series II RAM's were failing. He said that this was Commodore's fault, and that it was a random occurance as to which rev 4.3 boards were missing this resistor. Now, I tried checked up on this by calling a local Commodore service center (Butler's Computers in Federal Way, WA) and they said no way. They had not heard anything about such a problem, and they were very effusive in their praise for Commodore and its support/information supplied for the service centers. I was certainly not going to try soldering on a resistor with no electronics assembly experience and with over-the phone directions. So, the $25,000 question is: *****Is their really such a problem with the rev 4.3 motherboards? I hope someone from Commodore can help out here, because I don't know who to call or email to to find out the scoop from Commodore's side. I do not want to unfairly malign Commodore if GVP is trying to pass the buck. (GVP was very courteous and helpful, though.) If anyone can provide enlightement or suggestions, it would be enormously appreciated. I hope this will help out anybody else who may be suffering from GVP II/RAM combos. Please email replies if possible, I cannot always keep up with the tremendous flow of posts on the amiga forums. Thanks in advance, ----DLY----- David L. Yee email to: davidy@sumax.seattleu.edu BTW: The guy at GVP that was supposed to have discovered the 4.3 problem with Commodore was named Robert. Sorry, I didn't get his last name, I should have.
davidy@sumax.UUCP (David L. Yee) (11/04/90)
In article <1484@sumax.UUCP> davidy@sumax.UUCP (David L. Yee) writes: > > (Apologies if this has already been discussed- I missed a few days > worth of posts, and you know how the traffic is......:^) > > I am in need of some help and or information. I just recieved >my GVP Series II hardcard with on-board memory exapansion. This is the new one >with DMA access. Anyway, it refused to operate with the memory installed and >the memory configuration jumpers set appropriately. If I disabled the RAM >jumpers, or removed the RAM entirely, the card booted and runs fine. > I have a rev 4.3 motherboard. Gary said that Commodore made a > number of 4.3 motherboards without a certain resistor. This > resistor is a 470 ohm, 1/4 watt resistor that (I believe) he said > was supposed to be connected to the DTACK line of the 68000 (My > memory on the DTACK portion is a little hazy, the rest is not.) > Anyway, here is approximately where it should go: Well, no word from Commodore, but some desperate experimentation may be of some interest. By axing the FastMemFirst command from startup-sequence , the A2000 booted! 3 Megs (well, 2.8 anyway) now mine to command! But-------- It didn't work out. Big graphics applications died, like Photon Paint, Digi-Paint 3, and PageSetter II. They either gurued right off the start or died later on. The GVP supplied ramtest showed mucho bad RAM, yet, avail and mergemem showed all the RAM there. Running FastMemFirst at any time kills off the system. So, if you are desperate, you might try removing the FastMemFirst command. If it works for you, please let me know via email. A follow up call to GVP Monday, to try and pin this down and see what they think of this little anomaly. Thanks All, ----DLY---- David L. Yee email to: davidy@sumax.seattleu.edu
daveh@cbmvax.commodore.com (Dave Haynie) (11/08/90)
In article <1484@sumax.UUCP> davidy@sumax.UUCP (David L. Yee) writes: > I have a rev 4.3 motherboard. Gary said that Commodore made a > number of 4.3 motherboards without a certain resistor. This > resistor is a 470 ohm, 1/4 watt resistor that (I believe) he said > was supposed to be connected to the DTACK line of the 68000 (My > memory on the DTACK portion is a little hazy, the rest is not.) That's reasonably correct, but not quite. During the 4.3 run, we switched from a Gary gate array made for us by Toshiba to a full custom Gary made at MOS. The change's significance was mainly in the DTACK* signal created by Gary. On the Toshiba part, this was an active output that went 3-state when taken over (like when OVR* is asserted by an expansion bus device). On the MOS part, this was an open drain output. The original A2000 design had a 4.7K pullup on DTACK*, basically just to make sure that DTACK* was kept high when no device was driving it. With the open-drain or open-collector parts, a pullup resistor is necessary, and is essentially responsible for determining how long a particular signal will take to go high. So, for production, we required that any machine built with MOS Gary also have a 470 Ohm pullup added to it, so that DTACK* would rise fast enough. > GVP claimed that they had been in touch with Commodore, and that >earlier this Monday they had concluded that this was why the Series II RAM's <were failing. He said that this was Commodore's fault, and that it was a >random occurance as to which rev 4.3 boards were missing this resistor. Well, the existence or non-existence of that pullup is certainly Commodore's fault. The failure of GVP's controller is based on GVP's failure to take into account this difference. Of all the hard disk controllers on the market, this new GVP controller is apparently the only one that has a sensitivity to this. Also, it's not guaranteed that the Toshiba part can properly sink DTACK* when you have the effective 427 ohm pullup on DTACK* resulting from the addition of the extra 470 ohm resistor. So if you're adding the resistor and the system gets flakey, go out and get a MOS/CSG Gary while you're at it. This difference, by the way, has been documented at the last few DevCons, as well as on the net here and on bix. It's not like we're trying to hide it or anything. > *****Is their really such a problem with the rev 4.3 motherboards? I >hope someone from Commodore can help out here, because I don't know who to >call or email to to find out the scoop from Commodore's side. I do not want >to unfairly malign Commodore if GVP is trying to pass the buck. (GVP was >very courteous and helpful, though.) There is a difference, as I have described. GVP thinks it's a problem, but they seem to be the only ones. Obviously, if you can avoid having ANY electrical difference between revisions of a system, that's a good thing. But it's not always possible to have 20/20 foresight. It is always possible to have 20/20 hindsight, and it sure looks like GVP may need some glasses to avoid this kind of thing in the future. -- Dave Haynie Commodore-Amiga (Amiga 3000) "The Crew That Never Rests" {uunet|pyramid|rutgers}!cbmvax!daveh PLINK: hazy BIX: hazy Standing on the shoulders of giants leaves me cold -REM