SUMMARY: Sun monitors on DOS systems

From: Rick Fincher (
Date: Fri Jan 24 1997 - 14:26:53 CST

Thanks for all the replies,

We ordered the cable today from Sun.

The most complete answer is below.



>From Thu Jan 23 18:14:17 1997

On Thu, 23 Jan 1997 14:16:54 -0500 Rick Fincher
<> wrote:

> Hi Managers,
> We have a user that wants to use a spare Sun monitor on his DOS VGA system at
> home. Midrange Solutions sells a cable to do that but they tell us that it
> works with Windows, not in DOS mode unless you have a special video adapter
> rather than a run of the mill VGA adapter.

The reasons you can't simply connect a Sun monitor to a PC are:

   1. sync signals - Suns use a single composite sync, while PCs use
        two separate horizontal and vertical signals.

   2. frequencies - Sun monitors are traditionally high resolution,
        high frequency displays, and don't go down enough in frequency
        to be able to display a VGA signal, which is how all modern PCs
        power up (or work in DOS mode).

What a converter cable might be capable of doing is to either:

   a. connect to pins which are normally not used by Suns, but
        which allow the monitor to take separate H & V syncs, if the
        monitor is designed to allow this

   b. generate a composite signal with a small circuit hidden inside
        the cable.

What a cable can do nothing about is the frequencies. However Midrange
Solutions are wrong, in that at least one of your monitors definitely
can work fully with PCs. Sun's latest monitors have frequency ranges
which do go down far enough for PCs, and Suns publicity even says
explicitly that the mid-range 17" monitors (of which the 17E10 is one)
can be used with PCs - you can buy a converter cable from Sun. I had a
17E10 connected to a PC using my own special cable just a couple of
days ago. What I don't know is whether the Sun cable connects to
not-normally-used pins on the Sun connector, or whether it internally
generates composite sync in the cable. However, you should be able to
simply order this cable (I think they call it an HD15-13W3 adapter
cable) from Sun. My guess is that MS's cable would work also, with this

However, I doubt that the GDM 1662 will work this way - I don't have
one, but judging by the name, I guess it is a smaller version of the
venerable 1962B, and these are definitely high frequency monitors and
won't go down to VGA frequencies, just as MS described.

Incidentally, Sun don't claim that their entry-level 17" monitor is
cable of working with PCs, but the specs show that it can go down far
enough. I know that it definitely doesn't have the necessary separate
sync pins on the connector, but I've just finished making up my own
cable which generates composite sync inside the cable, and this seems
to work very nicely as a PC monitor.
> The user uses Linux on his system which, evidently, uses a DOS type video

Actually, if he uses Linux exclusively, your user probably _could_ use
the GDM 1662B, since although I'm not a Linux expert, as far as I
understand, it should be possible to set the Linux display mode to
Sun-type resolutions early on in the boot - certainly this is possible
as soon as X windows starts.

> The monitors we have are the Sun 365-1316 (GDM 17E10), and the 365-1159-01
> 1662B).
> Does anyone know of a cable that will allow either of these monitors to work
> with his VGA card?
> Thanks,
> Rick

George Cameron
Dept. BioMedical Physics
Aberdeen University
Foresterhill Fax: +44 (0)1224-685645
Aberdeen AB25 2ZD Telephone: +44 (0)1224-663123 ext 53210
Scotland, UK

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