If the old mac has the high density 15 pin connector, then it should work with 
any monitor with that connector.

The older ones with the two row 15 pin connector (which you do not ever plug a 
PC joystick into, or an old Mac monitor into a PC's joystick port) require some 
of the pins in the monitor plug to be connected together.

That's how the Mac detected which resolution the monitor supported, before 
multi-resolution monitors came along. In the 68040 era, Apple expanded the 
sense pin thing using diodes rather than simple connections. That method did in 
some cases support more than one resolution with the monitors using it.

The main gotcha with connecting a new monitor to a really vintage Mac (mostly 
68k CPU ones) is they used sync on green while the VGA standard (and its 
various extended modes) used separate or composite sync signals. Composite sync 
simply connects the horizontal and vertical sync lines together.

Connecting a modern VGA monitor to a two row 15 pin Mac video port that 
*doesn't* use sync on green is easy. Either find the sense pin arrangement that 
matches a resolution the old Mac supports then build an adapter just for that 
one use, or buy a multi-resolution Mac to VGA adapter that has DIP switches or 
a rotary switch. Those are rather common and inexpensive. With a DIP switch 
style, typically the ones with more switches (IIRC 10 of them) support more 
resolutions and have the diodes for the extended sense pin codings.

If your old Mac uses sync on green, then you need a special adapter that 
separates the sync signals from the green signal. Griffin made one such which 
could adapt any modern analog VGA monitor to ANY Mac with the 2 row 15 pin 
video port. It only cost around $50, which is more than any Mac that outputs 
sync on green video is worth. Buying one of those used is the way to go, unless 
you can find a circuit diagram to build a sync signal separator into a homebrew 
monitor adapter.

--- On Wed, 12/15/10, Todd Brayer <[email protected]> wrote:

Stupid question: Aside from VRAM limitations, is there anything that is 
stopping me using a large LCD screen on an old mac? The connectors are the same.


      

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