It is quite an challenge to modify internally the 8250 to deliver NTSC
encoded composite output. Have a look at www.geocities.com/msxhans for the
8280 service manual if you want to see how the circuit looks like (the
8250/55/80 are mostly identical).
The best solution, as said by many before is to get hold of a RGB monitor.
Even cheap television sets have this feature nowadays (but check!) here in
Europe.
Hans
-----Original Message-----
From: Maarten ter Huurne [mailto:[EMAIL PROTECTED]]
Sent: 25 February 2001 15:15
To: [EMAIL PROTECTED]
Subject: Re: SCART to composite
On Saturday 24 February 2001 20:39, you wrote:
> I already have a cable that plugs into the SCART port on the MSX2, and on
> the composite plugs on the television. This outputs an RGB signal, and,
> since RGB is the same for either PAL or NTSC, I should be getting the
> image, displaying in proper colours, correct? (It would still be rolling
> until I use vdp(10)=0, of course.)
If the cable plugs into the composite input of the TV, it cannot possibly
deliver a RGB signal. Like Maico Arts said, a SCART plug contains both RGB
and composite signals, your cable is probably using only the composite
signal.
I think the only way to get color from a 8250 on an NTSC display is find a
monitor or TV with RGB input. I'm running NTSC PlayStation games on my PAL
TV
using an RGB cable with no problems. However, I did need to buy an RGB
cable,
the cable that came with the PlayStation is one with a three tulip plugs to
SCART converter, which only supplies composite video.
It may be possible to adapt the 8250 internally to change the color
encoding,
but I have no idea how difficult that is. I do know that the 8250 has a
rather large audio/video board (the orange one above the green main board),
it has few integrated components there so replacing the color encoding is
probably not too hard once you know how.
About the disk drive:
AFAIK, 8250 drives don't have a rubber belt. The rubber belt problem occurs
with the 8235/8245 and the turbo R models.
You can easily replace a 8250 drive with a standard PC disk drive. The only
modification you need, is to place a jumper over pin 33 and 34 of the second
drive connector on the main board. Pin 33 is ground and pin 34 is /RDY, the
ready signal, a signal that modern PC drives no longer have. Connecting the
pins will tell the 8250 that the drive is always ready, the 8250 DiskROM has
no problems with that.
Bye,
Maarten
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