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About trag

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  • Location
    Austin, TX
  • Interests
    Model & Amateur Rocketry

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  1. trag

    Carrera040 Info / Hacking Thread

    Is this a correct summation of the problem: --------------------------------------------------------------------------- The SE/30 has only an 8 bit data path to the VRAM (D24 - 31). This requires byte-wise writes to the VRAM, instead of using the 680x0's normal 32 bit data path. This uses a feature of the 680x0 chips called Dynamic Bus sizing. The 68030 uses a different control signal scheme to signal/setup Dynamic Bus Sizing than the 68040. In some circumstances, the data for the VRAM which should have been on D24-31 would be on D16 - 23 (which the VRAM can't see) because the 68040 interprets the dynamic bus sizing scheme differently and the GALs/logic on the upgrade card doesn't compensate properly for that particular case. So software which sets Siz0-1 and A0-1 properly to get 8 bits of data out on D24-31 on the 68030 causes the 68040 to output that data on a different set of data lines? --------------------------------------------------------------------------- Cool work. What a wonderful job of investigation. I enjoy the way you just casually build interposers for your probing. I imagine there's much more labor spent on those tasks than your off hand mention would suggest. Seems disappointing to me that the data path to VRAM is only 8 bits wide. Aren't there two VRAM chips? Are they only 4 bits wide each?
  2. trag

    M0100 replacement parts

    Thank you for pioneering this. I looked at the dimensions in the datasheets after you posted the second emitter. The first one is shorter and narrower (by about 1 mm) but thicker. The second one is wider and taller and flatter. The second one also costs about twice as much at Mouser as the first one, although if you're buying one, the difference hardly matters. Ah, nice. The second one is also in stock at Digi-key and does not appear to be end-of-life like the first one.
  3. trag

    M0100 replacement parts

    Are the first ones you linked a little too thick?
  4. trag

    M0100 replacement parts

    According to DigiKey, these have a Last Time Buy date of 1/15/2020. I imagine there'll still be old stock kicking around after that, but they will no longer be manufactured. Might be time to stock up. But we so seldom need them. Unless all our mice are about to wear out because they've reached that age. DigiKey has 0 stock, but Mouser has them on hand, for those of us in the Americas.
  5. trag

    Advice for new 840AV owner

    Apple's Hardware Developer Note for the 840AV has a large section on programming to the DSPs. It is also helpful (necessary) to have the datasheet/user's manual for the AT&T DSPs. I think we had a thread about this some years ago...
  6. Are you bit banging the SCSI side of the interface using ports on the XMEGA microcontroller or do you have a SCSI chip on there too? Beautiful work, by the way. Very cool. How long have you been working on this?
  7. trag

    Looking for a New Flyback Transformer Macintosh SE

    Ouch. I guess Dalbani figured out they were valuable. About ten years ago they were selling flybacks for under $10.
  8. Yeah, after they cleared out from their first use owners, they seem to have disappeared from the market. There was one reseller who had stock, but they seem to have run out a couple of years ago. I picked up a few of them for a song (compared to new LCD prices at the time) several years ago. Feature-wise, they are fantastic. Also, brightness is very even, but dimmer than new LCDs. I may pick out the runt of the litter and try replacing the backlight tubes on it and see how that goes. I'm kind of surprised that the One to One feature is so hard to find, given how common it was in teh early days of LCDs. I guess there was more need then to support older resolutions. Newegg often has refurbished 1280 X 1024 LCDs from HP and Dell for about $50 each. It might be worthwhile to check the manuals on those models. https://www.newegg.com/dell-p1914s-19-sxga/p/N82E16824260224 https://www.newegg.com/p/0JC-0004-00HW5 https://www.newegg.com/hp-la1951g-19-sxga/p/N82E16824276607 That last one is $90, but I've seen it on sale for about $50.
  9. T85A (AKA part # 9519-AW1 ) from IBM has this feature. It can display resolutions as either expanded to full LCD resolution, or just fill the pixels on teh screen that correspond to the original resolution. It only goes up to 1280 X 1024 though. I'm not sure if it has the "ASPECT" feature listed above though. Or put it another way, I know it has either ASPECT or FULL, I'm not sure it has both.
  10. Modern supplies may be a little short on 5V current, but they usually have more than extra 12V capacity available. One could probably just use one or two of the affordable DC-DC switching "buck" converters available on Ebay to convert one of the 12V rails to 5V. The really cheap (~$1) ones only have a few amperes capacity, so carefully checking the conversion capacity of any DC-DC converter is important.
  11. trag

    PowerLogix UltraCache 1MB UC1MB

    Interesting. It's just a plain old 32K X 8 SRAM. No Tag function. I guess the comparators are on the PPC or built into the memory controller. It's a fast SRAM, so the 32K X 8 parts I have on hand at 55ns, wouldn't do the trick. Sigh. Huh. I may have typed to soon. Looks like I have 457 MCM6206B in the attic. However, only the fastest speed rating would replace the N341256SJ-12. Unfortunately, I didn't note down the speed rating in my inventory. Chances of them being 12ns are pretty low. Also, still having the same puzzlement I had in this posting: Near the end of that post, I note that a PCI PowerMacintosh cache module that I examined contains 32K words of cache storage, but only 8K of Tag RAM. The number of address bits in both should probably match, unless the cache scheme is always storing 4 words at a time. Happily, your Ultracache also has 4 times as many storage addresses as Tag addresses (32K vs. 128K) so at least there's consistency. jt, I imagine the extra chip positions on the module are there so that the module could be built from lower density parts. The example Jessenator has uses two 128K chips. But they might have built the same module with eight 32K chips. The fact that there's only room for one set and size of TAG chips suggests that the cache capacity will always be the same on this module, but the same capacity might be built out of varying numbers of different capacity chips.
  12. trag

    PowerLogix UltraCache 1MB UC1MB

    On the PowerBoost Pro, which is a CPU card, not a cache card. The PowerBoost Pro is a PPC604e based CPU card with a microcontroller helping with some of the clock adjustment tasks. I haven't looked up the extra chip on the Ultracache, but it is almost certainly a Tag RAM to complement the static RAM. That component could be hard to come by... Nobody seems to manufacture discreet tag RAMs any more. You can make one out of fast comparators, another SRAM and a little logic....
  13. trag

    PowerLogix UltraCache 1MB UC1MB

    I haven't found a datasheet specifically for that B36-7 yet, but I did find a note that Cypress bought Galvantech and the GVY71128B36T-7 changed to CY7C1345A1-117AC. The closest current Cypress part I could find uses that same pinout supporting that it is a standard. PCN010021 - Galvantech Part Marking Change for Cypress Marking .pdf CY7C1345G.pdf
  14. trag

    PowerLogix UltraCache 1MB UC1MB

    If that bridge is on both chips, I'm not sure what to tell you. If soldering is easy for you, then I'd say, sure, give removing the bridges a try. If it's more of a challenge then I'd avoid the risk. The only way I can think of, that there would be a bridge like that on both chips, and that would be unwanted, is if the machinery at assembly time was making the same mistake on every instance of that package. But that doesn't make a lot of sense to me either. If it was a solder stencil problem, I would expect the stencil to be for the whole circuit board, not per chip. I suppose it could have been a human error, instead. How automated was assembly back then? I could maybe see some kind of automated solder paste squirter that doesn't use a stencil, getting it wrong in the same place on that package because of a software bug or something. @MOS8_030, do you have any insight into the assembly process? Or were you more on-chip? Thank you for the offer to send me the cache. Let me put that on a back burner for a while. I would probably ohm out the connections pretty rapidly, but I'd need to set aside some time, so I don't hang on to it for too long. Right now I'm mainly curious whether there are any components on the DIMM besides the SRAM chips. Ignoring resistors and caps, of course.
  15. trag

    PowerLogix UltraCache 1MB UC1MB

    I suppose it's possible, but I find it very difficult to imagine a circumstance in which one would want the bytewise control tied to a chip enable. If the PCI Macs supported 24 bit mode, then it might make sense (suppress the upper byte) but they don't. It's also a little odd that they used X36 parts. I don't think there's any parity support on those Macs. Maybe the price or availability was better than for the X32s at the time. I would recommend carefully removing that solder bridge, especially if it is not on both chips. Just to confirm... The PowerWave works with the 225/45 card without the cache DIMM installed? 45 MHz is on the low end of the bus speeds supported, so speed should not be an issue. Especially since the press release says it supports up to 60MHz. Apple only supported 40 - 50 MHz bus speeds in its PowerSurge products, but it included settings in the chip registers for speeds at least to 60. Apple used three bits to set the motherboard bus speed (pins tied to ground on the CPU card) which implies eight set points. Each "point" seems to encompass a 5MHz range, which gives something like a 40 MHz range of speed settings. The PowerBoost Pro included a little microcontroller on board that adjusts those CPU card speed setting pins (CLKID_0-2) as one adjusts the bus speed, so that the CLKID pins are always set approrpriately for the chosen bus speed. The lack of this adjustment on most upgrade cards is probably why most of them won't adjust far off of 45MHz. I would be interested in seeing a complete scan of the cache. Apparently, I have forty-eight of the D32-5Is in the attic. It might be possible to manufacture copies.