G3 B&W needs constant PRAM reset to boot... please help!

[Chrispy]

Hey all. My B&W 400MHz G3 powermac keeps needing me to do the Command + Option + P + R thing on it for it to boot up everytime. If I don't then I just get a black screen and nothing happens. I have a new graphics card, CPU and Hard Drive on order that will be arriving tomorrow but I don't want to keep the stuff if it won't fix this problem. Does anyone have any advice on what is causing this? Thanks all

 

[CanadaRAM]

Have you replaced the PRAM battery?

Should be about US$8 -- 1/2AA 3.6V lithium cell

 

[Chrispy]

Haha nope sure have not. Having been a PC user for too long as assume this is the same thing as the CMOS battery on a PC? Do you know where I can pick up one of these things cheap? Thanks!

 

[CanadaRAM]

Haha nope sure have not. Having been a PC user for too long as assume this is the same thing as the CMOS battery on a PC? Do you know where I can pick up one of these things cheap? Thanks!

Yes, it's the equivalent of a CMOS battery.

Your local Radioshack or electronic supply store should have it, otherwise you can mailorder from http://www.datamem.com/viewcat.asp?C=1025, part #B-260 $5.95

 

[Chrispy]

Thanks I will pick one up on my way to work tomorrow

 

[CanadaRAM]

Take the old one with you, or remember its the 1/2AA 3.6V Lithium, with a nipple on the + terminal but no pigtails.

PS - Make note of the way the old battery is oriented BEFORE you take it out. You don't want to swap + for - when you reinstall.

 

[Project Alice]

So, I’m reviving this thread. My B&W has just started doing this today. I was using it all last week with NT 4 and it was working fine.

I am pretty sure I replaced the battery a few years ago but being as the clock is never right I’m sure its dead. I’ve removed it, but I still need to do constant PRAM resets to get anywhere. My other Macs will work fine without the PRAM battery. I’m assuming the B&W being as temperamental as it is, needs a PRAM battery to function?

I can’t use NT 4 like this, because it defaults to 640x480 and I can’t change the resolution. If I boot into Mac OS to get the correct resolution I have to PRAM reset to get back into Windows NT, which due to the PRAM reset is back to 640x480.

What a hobby I’ve chosen to have 🙄

Edit: This showed up in google, I figured it was in the PPC Mac section. Apparently not. Lol sorry for reviving this😂

 

[DeltaMac]

Yes, try the battery. It's a 1/2 AA lithium battery, without leads. (just as a reminder)
Test the replacement battery before installing -- I occasionally see dead batteries, or simply low voltage, sold as new.

 

[Project Alice]

Test the replacement battery before installing -- I occasionally see dead batteries, or simply low voltage, sold as new.

That’s pretty good advice. I never thought about that. Thank you

 

[Rairii]

I actually didn't know that the option ROM on some cards will set the open firmware resolution to whatever's set in Mac OS.

Nice to know, at least some cards on yosemite/yikes won't be stuck in 640x480 under NT!

(Although if Mac OS says your card can't do a resolution in 32bpp then don't set it, ARC firmware and NT drivers are hardcoded for 32bpp!)

 

[Project Alice]

(Although if Mac OS says your card can't do a resolution in 32bpp then don't set it, ARC firmware and NT drivers are hardcoded for 32bpp!)

The card I’m using for this is a 16MB ATI Rage 128 Pro. I usually have a Geforce 5200FX in it though.
NT has been running at 24 I think. I remember setting it to 32 in the setup process, but upping the resolution forced it to drop down.

Once I get a new battery for my B&W I’ll be able to clarify

 

[joevt]

I actually didn't know that the option ROM on some cards will set the open firmware resolution to whatever's set in Mac OS.

Nice to know, at least some cards on yosemite/yikes won't be stuck in 640x480 under NT!

(Although if Mac OS says your card can't do a resolution in 32bpp then don't set it, ARC firmware and NT drivers are hardcoded for 32bpp!)

For New World Macs like the B&W G3, the settings are in the aapl,pci nvram variable.
The settings are device path/property pairs which are applied to the device tree after probing.
You can use the print-aapl,pci command in Open Firmware to print the list.

For Old World Macs like the Beige G3, the settings are in an area of NVRAM between 0x1400 and 0x1800. The device path is encoded a bus number between 0 and 3, followed by up to six 5-bit PCI bridge device numbers (assumes bridges always use function number 0) followed by the device/function numbers of the device. The device path format limits saved properties to PCI devices only and only those with a path depth no greater than 6 bridges. The property length is limited to 8 bytes which is not enough for some newer cards. I don't think Old World Macs process the list of properties in Open Firmware. That has to be done by the OS or OS boot loader.
I made an extension for Mac OS 9 to allow saving and restoring properties longer than 8 bytes so my Power Mac 8600 can show the classic macOS happy Mac icon at higher resolutions with a Radeon 7000 (makes the happy Mac smaller).
XPostFacto's BootX (for Old World Macs) has code to load the properties for Mac OS X but that also requires modification to allow properties longer than 8 bytes.