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PowerBook Duo LCD swap? 280C -> 230

Shalroth

New member
Hi folks, first post! I used to be active on Lowendmac quite a bit but not so much lately; Sean from Action Retro on youtube speaks very highly of this forum so I thought I'd try my luck here!

A few years ago, my beloved PB Duo 280C started leaking the magic blue smoke, and not surprisingly, it hasn't worked since. I haven't investigated a repair yet, I suppose it might be possible with a re-cap, but it's a bit beyond my skill level. (I did just plug it in again after eight years or so out of morbid curiosity, but I yanked the power out as soon as I started to smell ammonia...)

I did, however, inherit a PB Duo 230 (with desktop dock!) before the 280C caught fire, and was able to backup the 280C's hard disc to it, so the contents are safe (for now - I don't like the loud clicking noise the HDD in the 230 is making every minute or so).

I got it out of mothballs tonight to use as a *slightly* more portable alternative to my G3 PDQ for backing up and installing apps on my Newton MP2000 (and maybe MP120 as well).

My question, friends, is - do any of you know if I can install the LCD from the 280C in the 230? I've successfully installed an LCD assembly from a PowerBook 165C into either a PB160 or PB165 in the past (twenty years ago - so I don't remember which) and to my amazement it worked perfectly! I was hoping that internally they'd be similar enough that it could work, and I don't want to risk opening up a healthy 230 only to find the displays are electrically (and / or mechanically) incompatible.

I look forward to hearing from you!
 

Fizzbinn

Well-known member
Hi @Shalroth and welcome!

Unfortunately I’m pretty certain the Duo 230 motherboard can’t electrically drive the newer Duo 280c 640x480 color display …and also has a different physical display ribbon cable to boot.

I think the 230 MB might be able to use the newer, but still 640x400, Duo 250 active matrix b&w display but that’s not going to help your situation. :-/

I believe the Duo 270c, 280, 280c (of course) and 2300c motherboards can drive the 280c display. I’m less certain though about the internal display ribbon cable connector needed for those combinations. I seem to recall the moved around the motherboard connector.
 

Trash80toHP_Mini

NIGHT STALKER
Welcome aboard!

Yes, Grayscale and Color connectors are in two different locations. 2300c board has both and can drive any Duo's display as it was the PPC upgrade path Apple promised all Duo customers. 2300c board also has the internal SCSI connector for using stock drives when upgrading older Duos along with its native IDE setup.

@Fizzbinn has it right, your 230 board is only gonna drive the 640x400 grayscale displays.
 

Shalroth

New member
Hi @Shalroth and welcome!

Unfortunately I’m pretty certain the Duo 230 motherboard can’t electrically drive the newer Duo 280c 640x480 color display …and also has a different physical display ribbon cable to boot.

I think the 230 MB might be able to use the newer, but still 640x400, Duo 250 active matrix b&w display but that’s not going to help your situation. :-/

I believe the Duo 270c, 280, 280c (of course) and 2300c motherboards can drive the 280c display. I’m less certain though about the internal display ribbon cable connector needed for those combinations. I seem to recall the moved around the motherboard connector.
Thank you! You know, it hadn't even occurred to me that the 230's display was 640x400 (like the PB1xx), so that does make sense.
 

Shalroth

New member
Welcome aboard!

Yes, Grayscale and Color connectors are in two different locations. 2300c board has both and can drive any Duo's display as it was the PPC upgrade path Apple promised all Duo customers. 2300c board also has the internal SCSI connector for using stock drives when upgrading older Duos along with its native IDE setup.

@Fizzbinn has it right, your 230 board is only gonna drive the 640x400 grayscale displays.
Interesting... I didn't know that about the 2300C - which of course is the holy grail of the Duos, sadly they never seem to crop up on UK ebay, or if they do the seller knows exactly what they're selling and they're priced accordingly!
 

DracheMitch

Well-known member
Interesting... I didn't know that about the 2300C - which of course is the holy grail of the Duos, sadly they never seem to crop up on UK ebay, or if they do the seller knows exactly what they're selling and they're priced accordingly!
The 2300c, while sounding great on paper, isn’t. To make it compatible with the Duo docks, Apple ran it on a 32-bit bus. In contrast, the 5300 uses the same processor and bus speed, but is on a 64-bit bus, which makes it faster doing everything.

They went so far as creating a new Dock that didn’t have the L2 cache or 68882 (Duo Dock+), I don’t know why they didn’t just upgrade it for PPC.
 

Trash80toHP_Mini

NIGHT STALKER
Where did you get that information about the 2300c?

Take a look at the block diagrams in the developer notes. The 2300c, 5300 and 1400 are all but identical but for the vagaries of IR/PCMCIA/FDD/CD. RAM/ROM and CPU are on the same fast bus on the same PBX memory controller/bridge. All are stepped down to 32bit at 25MHz(?) on the slow I/O bus by PBX.

Slow I/O bus of all three is a 32bit 68030 bus with everything but ROM/RAM/CPU running on that bus. DuoDocks are an extension of that 32bit slow I/O bus. They amount to a multi-function expansion card at $E. Yes, the FPU was accessed on a 32bit bus in the DuoDock, but that's a minor performance hit as compared to having none at all. Given the dearth of PowerBooks shipping with FPU on board it was a big plus when docked.

Performance of 2300c is on a par with the 5300.
 
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Trash80toHP_Mini

NIGHT STALKER
They went so far as creating a new Dock that didn’t have the L2 cache or 68882 (Duo Dock+), I don’t know why they didn’t just upgrade it for PPC.
Forgot about that part:

Excising those features of the improved Dock II would be the adaptation to PPC, which made both redundant. Any 68K Duo should be paired with the DuoDock II where the L2 cache increases performance, but is not needed by the PPC 2300c. But for the 270c with its integrated FPU, all benefit from the integrated FPU in the 68K era DuoDock II. Deleting vestigial FPU and the SRAM reduced parts count/cost of the DuoDock+ for the 2300c PPC era Duo System.
 

DracheMitch

Well-known member
Forgot about that part:

Excising those features of the improved Dock II would be the adaptation to PPC, which made both redundant. Any 68K Duo should be paired with the DuoDock II where the L2 cache increases performance, but is not needed by the PPC 2300c. But for the 270c with its integrated FPU, all benefit from the integrated FPU in the 68K era DuoDock II. Deleting vestigial FPU and the SRAM reduced parts count/cost of the DuoDock+ for the 2300c PPC era Duo System.

The Duo Dock+ came standard with a hard drive, so I don't know how much savings there was for Apple over just selling the original Dock again. I've read conflicting reports that the Duo Dock II's cache and FPU doesn't work with the LC '040, but it was released at the same time as the Duo 280 (I have a 280 and a Dock II running 8.1, but I'd need an app that shows cache and FPU to know). It seems weird to release a new Dock that could only benefit the first three Duos, who weren't hurting for a Dock…
 

Spidey01

Well-known member
FWIW, I believe MacBench shows cache and FPU somewhere in the current system details. I recall seeing the FPU and other hardware details when running MacBench 1.0 on my Duo 230, and thinking that’s the best info I’m getting without hunting down fancier hardware inspection tools.
 

Fizzbinn

Well-known member
The Duo Dock+ came standard with a hard drive, so I don't know how much savings there was for Apple over just selling the original Dock again. I've read conflicting reports that the Duo Dock II's cache and FPU doesn't work with the LC '040, but it was released at the same time as the Duo 280 (I have a 280 and a Dock II running 8.1, but I'd need an app that shows cache and FPU to know). It seems weird to release a new Dock that could only benefit the first three Duos, who weren't hurting for a Dock…

The Plus kept the other upgrades in the II, namely built-in Ethernet and improved video with 1MB VRAM. I'm sure the Duo Dock (optional) and Duo Dock II 68882 FPU only work with 68030 Duos. Likewise the Duo Dock II 32k L2 cache only works with 68030 Duos, I've never found a utility that reports the presence of 68030 L2 cache other than the utilities that came with some 3rd party ones (e.g. DayStar PowerCache), it would be neat if there is one!

I agree the Duo Dock II release date is a bit odd I guess it might be thought of as an upgrade for the 68030 Duos? The 32k cache providing ~10% speed boost when docked?

Timeline:

October 1992
- Duo 210 and 230
- Duo Dock (can be upgraded with 512k more VRAM and FPU only used by 68030 Duos)

October 1993
- Duo 250 and 270c
- Duo Dock lid upgrade to accommodate thicker 270c and future color Duos
- Duo Dock started shipping with taller lid (I think)

May 1994
- Duo 280 and 280c
- Duo Dock II (Taller lid, adds built-in Ethernet, 1MB VRAM/improved video and only for 68030 Duos 32k L2 Cache and FPU)

May 1995
- Duo Dock Plus (removes the 32k L2 Cache and FPU keeps other II improvements)

August 1995
- Duo 2300c
 
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Trash80toHP_Mini

NIGHT STALKER
I've never seen the DevNote for the Dock+ has anyone found it? I'd love to have it, I'm doubtful, but curious to see if they updated it to NuBus90?
 

DracheMitch

Well-known member
I've never seen the DevNote for the Dock+ has anyone found it? I'd love to have it, I'm doubtful, but curious to see if they updated it to NuBus90

The Duo Dock+ is literally a Duo Dock II with the cache and FPU removed. There's solder spots on the board for them.

Apple upgraded the Duo Dock II NuBus, but they just describe it as "smaller NuBus transceivers". NuBus 90 on Quadras only lets the cards talk to each other directly, it doesn't have the faster bus speeds. I don't know how prevalent NuBus 90 was for actual cards, because only the PPC NuBus Macs use it. My guess is almost none.

Apple constantly refers to the NuBus implementation on the Duos as "pseudo-NuBus", but it has a NuBus controller. I don't understand this. I know the Dock connector on the Duos is just a PDS slot, but there's lots of PDS to NuBus adapters for Macs, and Apple doesn't refer to them as pseudo.
 

Trash80toHP_Mini

NIGHT STALKER
IIRC, Pseudo-Slot refers to things like onboard Video which is usually located at $E as it it one the SE/30, IIsi and IIci if memory serves. It's not a SLOT in physical form, but appears as such to the Slot Manager. DuoDocks of any type are multi-function expansion cards located at $E on the 68030 PDS, whether straight up on 68030 Duos or bridged in the case of 68040(?) or the 2300c PPC Duos. The Docking Connector is called the "Main expansion connector" in the Duo System DevNote.

Slots of any type can be "further _________" in the Slot Manager Architecture. In the case of the DuoDock the NuBus slots $_ and $_ are derived/further_________ from the baseline $E location of the Expansion Slot/Docking Connector.

That's likely why you've seen them referred to as "pseudo-NuBus." The controller is moot, it has to be there, the ___________ mechanism I can't recall offhand (I am about 300 miles from my reference material) would be the key.

I don't recall seeing "pseudo-NuBus" can you give a reference? By then I might be able to fill in the blanks so to speak.
 

Trash80toHP_Mini

NIGHT STALKER
. . . but there's lots of PDS to NuBus adapters for Macs, and Apple doesn't refer to them as pseudo.

Forgot that part. The only case of which I am aware would be the IIsi and the NuBus adapter in that case had its own, hardwired NuBus Slot identifier signal on its PDS. In the case of the DuoDock, such was not the case at all, hence "pseudo-NuBus" would be accurate the way I see it.



duo
docks that was not the case
 

cheesestraws

Well-known member
Apple doesn't refer to them as pseudo

IIRC, Pseudo-Slot refers to things like onboard Video which is usually located at $E as it it one the SE/30, IIsi and IIci if memory serves. It's not a SLOT in physical form, but appears as such to the Slot Manager

Nearly: a pseudoslot is a slot which occupies the same address space as a NuBus card would but is not actually part of a functioning NuBus (this term is all over Cards and Drivers and is defined in the introduction). It's used of cards and slots kind of interchangeably, which looks a bit confusing, but it's because you can have a PDS card that follows "SE Rules" and needs a loadable driver, or one that follows pseudoslot rules and gets a declaration ROM and loads drivers from that.

With that in mind, your hypothesis that it's because the NuBus slot doesn't get its own slot number aside from the PDS gubbins is plausible, though it could mean that some other feature or features of the NuBus slot are missing too.
 

Trash80toHP_Mini

NIGHT STALKER
Was tired last night so didn't think of those, thanks much. Never really had an interest in those but for the brilliant BODGE someone did to run NuBus and PDS at the same time. I'll put my money on those slots also having a dedicated NuBus ID line.

We need a dedicated Hacks thread about PDS->NuBus conversion architecture in general.

Pretty sure fill in for "further __________" above would be further decoded.

Nearly: a pseudoslot is a slot which occupies the same address space as a NuBus card would but is not actually part of a functioning NuBus (this term is all over Cards and Drivers and is defined in the introduction). It's used of cards and slots kind of interchangeably, which looks a bit confusing, but it's because you can have a PDS card that follows "SE Rules" and needs a loadable driver, or one that follows pseudoslot rules and gets a declaration ROM and loads drivers from that.

With that in mind, your hypothesis that it's because the NuBus slot doesn't get its own slot number aside from the PDS gubbins is plausible, though it could mean that some other feature or features of the NuBus slot are missing too.

Thanks for the clarification. I've been really tired. Took a peek at the PowerBook Duo System DevNote:

pseudo-NuBus-0.JPG
Page 18 underneath the standard memory map.

Matching up memory blocks isn't my thing, but someone might be able to noodle it out.

We've really gotta get this section of the thread broken out to a DuoDock NuBus Expansion topic in Hacks as it spans 68030-68040-PPC generations. We haven't had a technical discussion of that AFAIK.
 
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