PDA

View Full Version : Need help with Mac LC , can't set 640x480



twolazy
May 16th, 2012, 05:15 PM
Ok I'll make this pretty short and sweet. I recently purchased an LC, and have since upgraded it as far as it can go (10mb ram, 512kb vram, Ethernet and 400mb hdd). Today I upgraded the 256k video simm to 512k. Everything works great, thousands of colors etc. Problem is , its stuck in 512x384 or whatever, and no option to use 640x480. I know the RGB monitor I own wont work at that resolution, but I do own alot of monitors that will, as well as have the db15 (vga) adapter.

Anyone know how or if there is a way to force 640x480? Or, do I have to reset the pram after installing the vram simm upgrade for the option to show?

twolazy
May 17th, 2012, 01:42 AM
I am going to go out on a limb and say the mac to vga adapter I have won't work as intended. Even though its an OEM NEC multisync adapter, it doesn't have any dip switches. Guessing I need one with dip switches?

olePigeon
May 17th, 2012, 08:52 AM
It's possible. If you get one with dip switches, you can set the signal to correct timing. Also, make sure the VRAM is plugged in OK.

twolazy
May 18th, 2012, 02:48 AM
Dbl checked the vram, working fine. Swapped back, and back to 256 colors max. Swapped in, thousands of colors works great. Tested playing simant in 16bit mode, works great. Kinda at a loss here other then needed a different vga adapter w/ jumpers. :(

olePigeon
May 18th, 2012, 08:12 AM
I checked out the specifications on the LC, and it'll only do 640x480. That's its max resolution even with the VRAM. If you want to go higher, you'll need to buy a LC PDS video card.

twolazy
May 18th, 2012, 03:48 PM
I checked out the specifications on the LC, and it'll only do 640x480. That's its max resolution even with the VRAM. If you want to go higher, you'll need to buy a LC PDS video card.

You seem to missed the problem >.<

Its stuck in 512x384 with no option for 640x480 listed, even with the 512k vram installed. :(

glitch
May 18th, 2012, 04:16 PM
It's most likely your Mac -> VGA converter. I soldered one up for my LC, and originally couldn't get higher than 512x384. I ended up with a diode between two of the pins on the Mac side of the converter, which "unlocked" the higher resolutions for me. A few of the pins on the Mac DB-15 are used as "sense" pins, and would tell the video card the intended resolutions of the attached monitor.

Here's a good guide on sorting your converter out:

http://www.saragossa.net/intfcing.html

Naturally, putting together such an adapter will let you drive your monitor at possibly incompatible resolutions. Most likely no harm will come of it, but you'll need to reset the resolution to make the system usable again.