You kids better get to sleep right now (TAM)

[ClassicHasClass]

Having never had a TAM before, it seems to keep a couple of the fans on when it sleeps. This got better after I pulled the PCI USB card, but it still has some (much quieter) fans running. There is a Comm Slot II Ethernet card still on board, but those should be compatible with sleep. TAM owners, is this normal?

 

[Byrd]

It doesn't really sleep so far as turning the LCD off. The fans, subwoofer fan etc still run. What's good is that line-in still works when "sleeping" so you can continue to pipe your iTunes through like I do

 

[ClassicHasClass]

Well, that's handy. Still not quite as nice as my whisper-silent iMac G4, but it's good to know you can still use it as an audio system in "sleep" mode.

I'm now thinking of some hacks, such as a floppy disk image to bring it up with a minimal system and a CD player. I thought about doing that from OpenFirmware, but OF on the TAM has some extremely unique and possibly insurmountable challenges.

 

[Trash80toHP_Mini]

I've never even dreamed of owning a TAM, nice find.

I've always been curious about this beast though. Dr. Bob, back in the 'fritter heyday, said a that big hunk of its production cost was the custom PCB Apple did to get it to work with the LCD for this relatively short production run machine.

Can anyone give this PCB some high resolution photographic attention next time you crack the case on one? The "impossible dream" pre-LVDS PowerBook LCD controller resides within the TAM, or so I would surmise. Now that we've got a crack 68kMLA Special Forces Team working in close cooperation in the "Jolly Roger" thread, it might be a good time to throw some light on this conceptual model/hardware anomaly living amongst us.

ARRRRRR!!!!!!!!!!!!!! }

 

[ClassicHasClass]

"Impossible dream" ?

 

[Byrd]

I've got a faulty LCD controller board from my TAM, which required replacement. Knowing I couldn't get the part I tried everything imaginable to try to get it to work, but I suspect it was a faulty IC or flex ribbon cable. I ended up finding a replacement part from the Netherlands, popped it in and haven't looked back.

What the board does is interface the standard VGA output of the 5500/6500 board to display video on a PB3400 LCD panel. It's not a pretty board and doesn't look particularly hackable. I've noted before how much of a mess the TAM is inside; piles of ribbon cables, custom boards here and there, mostly off-the-shelf parts with customised extras on top. Good then that the outside skin looks so nice, but it's like a renovated old house: looks good on the outside, but take a look on the other side and check out all the bad things patched up

 

[Trash80toHP_Mini]

"Impossible dream" ?

Yep, how to use a PowerBook LCD for anything other than running off the the controller on that particular LCD's connector on compatible PowerBook models used to be one of the common questions here and over on 'fritter back in the pre-LVDS day. The answer from Dr. Bob, our own Gorgonops (Eudimorphodon in his previous incarnation) and others who understood the hurdles, was that it "can't be done." This news for the the hacker's proposition was invariably softened with the caveat that it would take an amount of effort by someone with the training and ability to pull it off and, therefore, knew that it just wasn't worth it.

Kind of like changing the startup sounds and icons in the Mac's ROM . . .

 

[Gorgonops]

Yep, how to use a PowerBook LCD for anything other than running off the the controller on that particular LCD's connector...

I'm not sure what you're hoping for here, Trash. The part in question from the TAM is just an early (and clunky) implementation of exactly what the answer to that question has always been, IE, you need a VGA->to->LCD converter board, usually called a "controller". It does exactly what those $40-off-eBay-from-China controller boards do except it's designed around the quirks of a particular mid-nineties LCD (rather than configurable for any arbitrary number of LCDs) and undoubtedly requires umpteen-times the components and board real estate to do the job.

If your idea is that it's somehow simple enough (due to its age) for a hobbyist to "clone" out of household materials on his workbench, well, I doubt it. Not having seen the board in question I'd venture that at the very least it uses an oddball unobtanium surface-mount ASIC or two. And here's the really salient point about "homebuilding" an LCD controller: Even lowly bog-standard VGA, 640x480@60hz, has a pixel clock of about 25Mhz. Go up to 800x600 you're looking at 40Mhz. XGA, 65Mhz. At its very simplest the heart of an LCD controller is three analog-to-digital converters which, again, need to run at *at least* 25Mhz and more practically *much* faster. (And of course on a "real" implementation the ADCs are just one step.) Designing something that performs well at speeds like that is *not trivial*, and it's highly unlikely you'll undercut the cost of "$40 from China" building it at home even if you're capable of doing it.

But, hey, if you really want to try the mountain is there waiting to be climbed. All above said it probably *can* be done in an appropriate FPGA, but... again, what would that have to do with the TAM board?

Kind of like changing the startup sounds and icons in the Mac's ROM . . .

Conflating the degree-of-difficulty level of burning a custom ROM with that of a from-scratch high-speed analog/digital conversion board construction project is a little... silly. (I'm not trivializing the level of work that went into figuring out what needed to be "hacked" in the Macintosh ROM by saying this, but when it comes to physical implementation burning a ROM is a lot simpler than building an LCD controller.)

 

[Trash80toHP_Mini]

It's all a bit tongue-in-cheek. I was actually thinking more along the lines of BMOW's Classic implementation project, which is still kinda silly to tackle on the level of a PowerBook Screen Hack. [)] ]'>

Maybe the Portable though! [}] ]'>

 

[Gorgonops]

It's all a bit tongue-in-cheek. I was actually thinking more along the lines of BMOW's Classic implementation project, which is still kinda silly to tackle on the level of a PowerBook Screen Hack. [)] ]'>...

Aaah.

Well, that's different. Assuming you've implemented, say, a Mac Plus in an FPGA it wouldn't be a huge stretch to redesign the video section to output to an LCD rather than a VGA port. You'd just need the data sheet for the LCD.

(I do know from reading datasheets that some old pre-LVDS panels require some very non-CRT-ish refresh techniques. For instance, I remember in particular the data sheet from a given 640x480 monochrome panel describing how the top and bottom halves of the LCD were separate fields that were refreshed simultaneously, IE, during the same clock pulse you needed to send the pixel data for dots on both line 1 and line 241. If you wanted to use something like that you'd have to change the memory/framebuffer scanning pattern appropriately and it's possible that might introduce a low-level timing incompatibility with some piece of software that, for instance, tries to exactly time a page flip or other mode change based on the position of the CRT raster. But software like that is I'm sure vanishingly rare in the Mac world.)

 

[Trash80toHP_Mini]

LOL! I'm still using MacPortrait on a topsy-turvy 21" ViewSonic G Series CRT . . .

. . . but then, I'm cloistered in an OS9 world of my own.