Techknight™ - SE/30 Greyscale MOD /w IIsi video card

[techknight]

Yes in theory. But if the line frequency goes too far out, you'll move outside the circuit resonance and HV will be poor, and the horizontal linearity will severely suffer, and will have foldover. (dont ask how i know this). This deflection stage is designed to operate at peak efficiency within the correct frequency range, give or take a few KHz.

However if the monitor ID bits are set correctly. "Apple 12" RGB" then we wont have any issues, it will go into 512x342 and stay there.

 

[Macdrone]

I have an Asante etheternet card for the IIsi and SE/30 and it looks basically like the Supermac version of the riser and of course fits. My question is can a direct 90 PDS female to male be made so the IIsi video card will fit inside without losing the hard drive and floppy area? I would be grateful to know if you could make one for me, only two tabs would need to be removed after that and it would fit stock (as I stare at mine pulled apart).

Of course I know you are still working on the greyscale mod which I would love at this point. At this point my SE/30 has my full attention.

It needs de yellowed and cleaned but works. Looking at getting some ram (cheap is always good).

Might put a bigger scsi drive in it.

Already have a apple caddy cd rom to put under it so I can do all that I need with it.

And as always great work on the project all! Thank you.

 

[Trash80toHP_Mini]

If I'm understanding you: ISTR going through that with techknight(?) and showing it wouldn't really work out the way it was envisioned, but there may be a better way to do it.

 

[bigmessowires]

Isn't the 12 inch RGB resolution different from the internal CRT B&W resolution? 12 inch RGB is 512x384, 9 inch B&W is 512x342.

 

[genie_mac]

Isn't the 12 inch RGB resolution different from the internal CRT B&W resolution? 12 inch RGB is 512x384, 9 inch B&W is 512x342.

I think that's correct, also I think my LC allows me to change the resolution from 512x384 to 560x384 to support the IIe card (which I really really want ).

I think that's why the 12" RGB has a slightly higher horizontal refresh rate compared to the compacts to account for the extra lines. Would the SE/30's board be able to cope with the extra 10% or so (IIRC)?

 

[techknight]

oohh. i knew my dislexia would get me eventually. I didnt see that.

I dunno, it depends on how far off the horizontal scanrate is compared to the original.

 

[Trash80toHP_Mini]

Dang, I missed that tooI

Nice catch, big.

 

[uniserver]

or maybe we pull a minerAI and just change the freakin CRT. 1024x768, 9" greyscale from something.

nnnnnaaaaaa never mind forget i said that. we like originality? i mean, we like originality! well sorta ! )

 

[Trash80toHP_Mini]

The Pivot Card still gives you 151% more COLOR pixels of extended desktop. That's closing in on half a million pixels altogether!

That beats a measly 178,168 grayscale pixels through the periscope any day of the week and twice on Sunday. :approve:

 

[Macdrone]

So will the radius card does not allow for the correct resolution of the internal CRT then?

I guess that would make sense as there were not any external monitors with that resolution.

That would be why the Micron Xceed card was made just for that purpose then?

 

[bigmessowires]

I don't really know what I'm talking about, but would it be possible to replace whatever part of the analog circuitry is responsible for the horizontal scan rate?

Also, just because the vertical resolution is different doesn't 100% mean that the horizontal scan rate is different. You also need to consider the number of invisible lines in the vblank region. For instance with VGA at 640 x 480, there are actually 525 lines, but 45 of them are invisible. So if the total number of visible + invisible lines is similar for 9" B&W and 12" RGB, it might still be OK.

I just looked it up, and the 9" CRT has a horizontal scan rate of 22.25 kHz, while the 12" RGB has a horizontal scan rate of 24.48 kHz. That's a difference of about 10%, which is a little better than the difference in the vertical resolution, but not by much. Hmmm.

 

[techknight]

Any r/l/c networks for the yoke would have to be changed to suit the freq. Maybe not within 10% though.

I do know the analog board wont do 640x480. I tried that and the horizontal linearity was way out and had barkhausen noise along with severe foldover.

The vertical, and crt modulation was fine. Its the horizontal deflection that became a problem

 

[uniserver]

so are you pretty sure 512x384 is possible?

 

[techknight]

Only one way to find out...