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Disabling additional monitors? (SE/30, Colorboard 264, System 7.1)

halkyardo

Well-known member
My SE/30 has a RasterOps Colorboard 264 in it, which is lovely, but it's not without its caveats - it does not seem to have any monitor-presence detection, and just presents a 640x480 screen whether there is a monitor connected to it or not. This is a bit annoying, since I don't always want to use an external monitor with my machine, and find my cursor disappearing off into a great big void. It's even more annoying if I accidentally leave the Colorboard set as the main display, because then I can't switch it back without connecting an external monitor!

On a clean install of System 7.1, the Colorboard's display is inactive until I open the Monitors control panel and click on the external display, but I can't for the life of me figure out how to undo this action - once the display has been configured, there seems to be no way to deactivate it again. Am I missing something here, or is the assumption simply that you'd always have a monitor attached to every graphics card? (not unreasonable back then, I suppose, but a bit inconvenient now!)

I was thinking about rigging up an external switch to allow me to disable the Colorboard's declaration ROM if I don't have an external monitor connected, but before I do something as drastic as that, I thought I'd better check that I'm not just missing something obvious. It's been a long time since I've played with the Classic MacOS in any serious capacity, so my memory is a bit rusty.
 

LaPorta

Well-known member
Unless someone knows a software workaround, this is just the normal behavior: a Mac II with video NuBus cards, for example, always has more than one "monitor" if there is a second card even if there is no monitor attached.
 

cheesestraws

Well-known member
As you've noticed, this is a card that's doing something a bit dodgy; not in that it's malfunctioning, but in its design. Cards are meant to not declare a second monitor if one isn't actually plugged in, per Cards and Drivers, and this is presumably why.

Does a PRAM reset make it go away again?
 

Bolle

Well-known member
PRAM reset should make it go away again until you open the monitors cp again.
A lot of cards are like that… they were often bundled with a specific monitor hence any sense lines were just left out on most of them.

A switch to toggle the declaration ROM is a good idea and I did the same mod on a few of my video cards as well. You could also build a little circuit that used the ground lines on the monitor connector to sense if there is something connected and have that circuit enable or disable the ROM.
 

robin-fo

Well-known member
I have a similar issue with my Lapis SE/30 DPD card: I installed it to test my SE/30‘s PDS connector. It now appears to completely disable the internal screen (just plain grey checkerboard). This is not the case when using it in my IIsi, so I don‘t know if the problem is related to the connector (transplanted from a battery bombed board) or if it just behaves differently on the SE/30…
The computer appears to work normal otherwise, but I dont‘t have a external TTL screen to confirm.
 

Trash80toHP_Mini

NIGHT STALKER
THE(video)TERMINATOR

Video Terminator.JPG

There are seven NC pins on the DA15 Video Connector, so connect two of them. You can't forget to remove this kluge, no video cable can be hooked up this gender changer connector bodge. :p

< Rube Goldberg >

DeclROM is invariably(?) socketed. So a PCB on the model of ROM Conversion PCB would not be simple, but it would be pretty.
Patch wire from solder cones of hardwired breakout cable.TERMINATOR headers to the cutout board would work for config board
If IDC header/cable connection on card/breakout board, a modified IDC ribbon cable build with extended NC (now jumpered) lines heading to the DeclROM bodge on ROM adapter PCB might be possible if headers at both ends.
Not likely, so bodge wire from header solder cones again employed.

< /Rube Goldberg >

< KISS >

No PCB, not pretty.
Lift the Chip Enable(?) or VCC leg of the un-socketed ROM, bend upward insert RA header into socket and solder both to IDC line extension (or bodge wires) to shorted NC cables to finagle CE or VCC grounded input from TERMINATOR to whatever OR(?) IC or circuit needed that's hot glued to the top of the DeclROM.

< /KISS >

Dunno, barely awake . . . just sayin' :sleep:


edit: oopsie, wrong forum? :oops: You were looking for a software fix?
 
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halkyardo

Well-known member
Does a PRAM reset make it go away again?
Ha, the extra-infuriating thing is that the Colorboard shows up as Display 1, and the internal video as Display 2, if I do a PRAM reset, video ends up on the external display 🙃. Had me worried for a bit when I first booted it up after recapping, and only got a grey raster on the inbuilt display!

A switch to toggle the declaration ROM is a good idea and I did the same mod on a few of my video cards as well. You could also build a little circuit that used the ground lines on the monitor connector to sense if there is something connected and have that circuit enable or disable the ROM.
I'm by no means allergic to hardware bodges, it seems like messing around with the DeclROM would be the way to go - thanks for the confirmation that I wasn't off in the weeds with that idea. That sense-pin suggestion is brilliant, going to have to give that some thought.

On the software side, though, I assume the Monitors control panel saves the current display arrangement in a resource or something (since there's no separate prefs file). Another approach might be to write a little extension that looks for some key combo at startup and restores it to some known-good configuration. Might be a bit more universally useful than a hardware switch.

Just depends on which tool I want to break out, the soldering iron or MPW :geek:
 

cheesestraws

Well-known member
I assume the Monitors control panel saves the current display arrangement in a resource or something

A quick peer at a disassembly of the Monitors cdev suggests you might want to look for 'scrn' resources in the System file... Start your ResEdit!
 

Breadymac

New member
Yes, in the System file, scrn ID 0:

I think if you delete this resource, it'll just revert to defaults
FWIW I have an SE/30 with a RasterOps 264/SE as well with the same problem. cheesestraws is correct; I deleted the key, defaults returned, i.e. as halkyardo explained, a "disabled" icon in the monitor control panel as if the card was just installed, and so long as it isn't clicked, the monitor isn't active, and the mouse won't leave the screen.

I had the security blanket of making a backup of the boot drive with RaSCSI in case deleting resources willy nilly from System didn't go well. :)
 

Breadymac

New member
FWIW I have an SE/30 with a RasterOps 264/SE as well with the same problem. cheesestraws is correct; I deleted the key, defaults returned, i.e. as halkyardo explained, a "disabled" icon in the monitor control panel as if the card was just installed, and so long as it isn't clicked, the monitor isn't active, and the mouse won't leave the screen.

I had the security blanket of making a backup of the boot drive with RaSCSI in case deleting resources willy nilly from System didn't go well. :)
Actually, just opening the Monitors control panel, not even clicking it, is enough to get the display enabled. "Solved" by disabling the Monitors control panel to prevent accidental opening and further ResEditing. Hardly ideal, but better than uninstalling the card. Also, I tested this on 7.5.3 as well but the scrn resource wasn't present in System, so it didn't work there.

Just in case someone else comes across this issue and wonders.
 

cheesestraws

Well-known member
Actually, just opening the Monitors control panel, not even clicking it, is enough to get the display enabled. "Solved" by disabling the Monitors control panel to prevent accidental opening and further ResEditing. Hardly ideal, but better than uninstalling the card. Also, I tested this on 7.5.3 as well but the scrn resource wasn't present in System, so it didn't work there.

Thanks for the clarification! :)
 
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