Problem running megaSCC+ SD on 7 Mhz

Prophet (2510)

19-06-2013, 14:11

Hi,

It seems that this cartridge is not working at 7 Mhz because the clock speed is to high on the slot.
Is there a way to switch back the clock signal to 3.5 Mhz on the slot ?
And what about the speed, when running the MSX on 7 mhz but the slot on 3.5 ?

By edoz

Prophet (2510)

19-06-2013, 14:12

I have a MSX 8280 with 7 Mhz. (forgot to say it

By enribar

Paragon (1233)

19-06-2013, 22:30

me too, same problem on a Philips NMS 8280 with Kit 7Mhz.

By edoz

Prophet (2510)

22-06-2013, 09:59

... lucky i'm not the only one Question is, how can we solve it and still have the benefit of 7 Mhz...

By jltursan

Prophet (2619)

22-06-2013, 12:55

Has anyone tested the MegaSCC+SD on a Panasonic MSX2+ machine using the turbo mode. Maybe 5,38Mhz is in the verge of what's usable by the cart.

I suppose that the device will need an internal clock source to work reliably...

By edoz

Prophet (2510)

22-06-2013, 19:15

I asked, but the megaSCC+SD is only supporting 3.5 Mhz on the slot, and it is using the clock.
Anyway.. how can i change the slot to 3.5 Mhz while the MSX is still running on 7 Mhz.. Is this a small change ?

By Guillian

Prophet (3541)

23-06-2013, 11:40

edoz wrote:

I asked, but the megaSCC+SD is only supporting 3.5 Mhz on the slot, and it is using the clock.

Well, what I said was that the MSX standard says the clock in the slot must be 3.5MHz and that I had not checked on 7MHz computer.

Today I made some tests:
- It works on Panasonic WX at 5.58MHz
- It works on a modded 8235 (VDP 9958, Z80H at 3.5/7 MHz...) made by usuario_msx2

The clock signal in the slot of the 8235 seems to be 7MHz because the SCC sounds weird.

So, the cartridge works fine at 7 MHz. Now we need to know what is different in your 7MHz mods and the one made by usuario_msx2

By edoz

Prophet (2510)

23-06-2013, 15:27

Guillian wrote:

Well, what I said was that the MSX standard says the clock in the slot must be 3.5MHz and that I had not checked on 7MHz computer.

I'm sorry. You are right about that!

Cool that you did some tests today! I don't know exactly which turbo Kit i have. It's a long time ago, i put it in my MSX i think somewhere late in the '80 ..

But i have a high resolution photo from my Motherboard .. maybe this helps:

FOTO

Does anyone know which kit is used ?

By msd

Paragon (1533)