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trag

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    Austin, TX
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    Model & Amateur Rocketry

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  1. 1uF @ 50V and 10uF @? (16, 20V?) are also common. Well, the SE/30 uses a single 1uF cap and the SE/30 is common. The IIci has a couple of 10uF caps, but the LCs and Color Classic and such are full of them. For bypass capacitors (capacitors sitting across the power and GND) lines, you can vary the values as Franklinstein writes without much affect. And in almost all cases you can raise the Voltage rating of the cap without problems. For capacitors that are part of a frequency dependent circuit or a timing circuit, changing the capacitance could strongly affect behavior. Qualify the above with the observation that the average capacitor is built with a 20% tolerance. So, unless precision capacitors were used in the hypothetical timing/frequency dependent circuit mentioned above, the capacitor may already be as much as 20% above or below its listed value. The only reason why using a capacitor with a higher voltage rating might affect the performance of the circuit is that getting a higher voltage rating often affects the internal resistance/impedance of the capacitor.
  2. I saw the summons just now, but Franklinstein pretty much wrote what I would have said, and more. In summary: 1) Bus speed doesn't matter, except for calculating potential CPU speeds. All the processors you're looking at will run fine at the slow bus speeds that the Apple machines use. 2) There are no L3 caches and no external cache support on the 750CX, FX and GX. The 750 had support for an L2 cache. If the L2 cache is internal, then there are no external Cache signal pins. 3) As you concluded, bus multiplier is very important. The early PPC750 only went up to 8X. The 750L raised that to 10X. The early G4/7400 only went up to 9X. Later G4 models had higher multipliers, but I don't think that the later models are pin compatible with the PPC750. 4) Only the 740 was pin compatible with the 603. All other choices require a new board. 4) If you're considering a brand new board, then later G4 chips are back on the table with higher multipliers, on-board cache, and potentially, external L3 cache. But, Cost.
  3. trag

    2 Odd Nubus Video Cards

    Under "BUG" it says "Sapporo Japan" at the top of the card. Looks like the card model was Mac-VC Rev. B as several of the PLDs are labeled "PAL - MacVC" The D => A converter for the display (RAMDAC) is the largish BT chip near the rear plate. The three BUG chips before that do something else. Perhaps sling the data out of memory to the RAMDAC at the appropriate time(s).
  4. At some point I thought they changed the power supply connector in the desktop 7X00 machine. I thought it was with the 7600, but it might have been with the 7300. In any case, I would not expect the 7300 to have the same pinout as all the other metioned models. The 8600/9600 certainly don't.
  5. trag

    8100 and 8500 PSU pinouts

    I'm pretty sure the 8500 and the 7500 have the same power connectors. It's the same circuit board (logic board) populated slightly differently. So if you can find a power supply diagram for the 7500, it applies also the 8500. There's a good chance the 9500 uses the same scheme as well, but I'm less confident of that. The 8600 changed the power connectors a little. I think the 7600 did as well.
  6. trag

    Problem with FloppyEmu

    Remember, it's 64 Kbits. While probably still overkill, it may have been the smallest thing economically available at the time. And yes, definitely the SCC chip. 85C3008 specifically, IIRC.
  7. trag

    Problem with FloppyEmu

    Correct. The Outbound has it's own circuitry. Not a Plug logic board in there. Also, one could use either Plus or SE ROMs.
  8. trag

    Problem with FloppyEmu

    28 pin interface back to the logic board. I don't know how the pins are used or even if they are all used. 28 pins for the external floppy, which uses essentially the same interface board. 44 pins or some such on the internal connector. Whatever an IDE hard drive + power connectors would use. Also, that 28 pin external cable/interface is used both for the external floppy and the external SCSI adapter (one or the other). Both boards have an 85C30 at the input end, facing that 28 pin connector. The SCSI adapter pretty much just has a 53C80, and a GAL in addition to the 85C30. I can't remember if it also has a flash. I should check my notes at home. I've always assumed that the ROM is there as a simple logic translation device. If I have an input of 12 give me an output of 4F. That kind of thing. Again, would need to create a schematic for more information. Yep, no pictures on line that I've ever seen. Next time I did one out I'll take some photos. I wish I still had a scanner. Scans of circuit boards on a flatbed have always turned out better than my photography efforts, even when I remember to put the camera in Macro mode.
  9. trag

    Problem with FloppyEmu

    That can't be the 85C30 for the serial ports, because the Outbound has serial ports and it doesn't always have a floppy drive. There's only room for either an internal floppy drive, or an internal hard drive. Not both. So when the hard drive is installed, there is no 85C30 in the drive cage. Circuitry on the Outbound is a load of logic ICs and probably some PLDs, but nothing is much bigger than 20 pin DIPs. I think there's an 85C30 actually on the board, though. No 53C80 because SCSI is an external option. I've always assumed that the Xicor chip is playing games with the voltage that drives the floppy motor to vary the speed in 800K mode. I really need to create a schematic some day. Without the controller board, the floppy mechanism is certainly fixed speed, and there are no special connections visible. It's always possible that Outbound opened every floppy case and did surgery prior to installation....
  10. Compatibility with SCSI cards was an early problem with the Nubus G3 upgrades. Newertech solved it before Sonnet did. Is it possible that you have an older version of the upgrade? I seem to remember that compatibility with the JackHammer was fixed first, but I might have that backwards. Does your 7100 boot okay without the SEIV. I've found that pretty much all 7100s need their CPU/Heat Sink grease cleaned off and replaced othewise they overheat shortly after booting up.
  11. trag

    Problem with FloppyEmu

    Someone might, but I don't. What I do know is: The floppy mechanism is a standard (unless stealth modifications were done) laptop style PC floppy mechanism manufactured by Citizen. Between the floppy interface and the Outbound is a circuit board. The circuit board contains an 85C30 (I think this handles whatever comm protocol that goes between the laptop and the floppy assembly), a WD37C65 floppy controller, a WD92C32 data separator, a 64Kb flash chip and a single 20 pin GAL PLD. Oh, and there's a Xicor (XC9030, IIRC) digital potentiometer, which almost certainly plays some part in the variable speed control of the floppy spin speed. On the Laptop itself, in addition to the Apple ROM on a SIMM, there are two 64Kb Flash/EEPROM chips which contain configuration code of some kind. These chips are updated when the Outbound installer runs. I know that they contain information on what internal device is installed (floppy vs. 20, 40, 60, 80 MB hard drive) and hte data is different for each size hard drive. They could also contain an extended floppy control routine. All the components are fairly simple, and there's only the two places where code could be stored in Flash (counting the pair of chips on the Laptop as a single place).
  12. I put the contents of the CDROM I used to ship with hacked R7000 cards in my web space. Has some rudimentary instructions for using the card with 8.6. https://www.prismnet.com/~trag/R7000/ATI R7000 Parts/
  13. trag

    Problem with FloppyEmu

    The Outbound Laptop Model 125 also adds 1.44 MB floppy support to a machine with Mac Plus ROMs.... I have an AEHD+ in the attic somewhere... Back when I got it, I opened the case, saw a giant (~88+ pin) PLCC FPGA and closed it right back up again.
  14. I know I got the R7000 working under 8.5 or 8.6. I had to hand install some extensions, IIRC. The card works fine under 7.6.1 but one may not be able to load all the drivers to enable acceleration.
  15. trag

    Macintosh Portable Video Adapter

    Thank you, techknight. I have several hundred little LCD displays (probably unused Pager stock) in the attic that have a chip-on-glass controller that looks like one of the standard Epson ones, maybe a 1335. I have the datasheet on an old drive at home that would tell me which controller I deduced it was. And an embedded flat flex cable to the controller. My (very old) plan has been to trace out the cable connections to the chip bumps with a microscope and then experiment to get it working. I can afford to blow a few in the process. On the other hand, I haven't started any projects that require a bunch of displays, so little motivation, what with all the life and procrastination going on. Kind of silly of me to buy the displays in the first place, but it was one of those Ebay lots one used to see (not so common any more) where it's something like 648 LCD displays; current bid $10.83. Heck, one might find a use for them some day, right?
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