Quick Questions Regarding Mac IIci Video

[CC_333]

Hi there!

I was shuffling some RAM around between the Quadra 950 and Mac IIci today, and now, for some reason, the IIci no longer puts out video.

What I wanted to know is whether that could be caused by flakey RAM. If not, then the monitor cable and/or monitor itself would be the next thing to look at with suspicion.

Also, do all eight RAM slots need to be filled for things to work properly?

The IIci is otherwise working, by the way. I can hear it boot from the hard drive, and I can turn it off by pressing the power button on the keyboard, then enter.

???,

c

 

[spiceyokooko]

The Macintosh IIci shares its RAM with the on board video, but you can also use a nubus video card for video as well.

Only bank A needs to be fully populated with 4 x SIMMS, you don't have to fill both banks, but they do need to be of the same capacity and speed.

Funnily enough I still have a bunch of 16Mb 30 pin SIMMS I pulled from a working Q950 and they work fine in the IIcx and II I have so they should work fine in the IIci as well. My IIci needs recapping so not working at the moment.

 

[trag]

Does Bank A have to be populated for the IIci to boot? I am thinking that C might have only Bank B populated, so the machine is booting, but there's no memory for the video, and that is why it's not outputting any video. But I can't remember if a IIci will boot at all with no memory in Bank A.

 

[spiceyokooko]

Does Bank A have to be populated for the IIci to boot?

Yes it does AFAIK. I think all the II series (II, IIx, IIcx, IIci) need to have some ram in bank A to boot.

 

[CC_333]

The Macintosh IIci shares its RAM with the on board video,

So, then, it's conceivable that intermittent RAM could manifest itself as a lack of activity on the built-in video, because it can't initialize it's share of the memory (due to some kind of damage in the area it normally occupies), while still allowing the machine to boot normally, correct?

Only bank A needs to be fully populated with 4 x SIMMS, you don't have to fill both banks, but they do need to be of the same capacity and speed.

They all look the same (I think they're 4 MB pieces), and I think I put them in bank A (because the machine wouldn't operate at all otherwise).
I could try filling them all up (the machine was configured with 4x1 MB in bank A and 4x4 in bank B originally, so maybe I'll try that).

Thank you,

c

 

[spiceyokooko]

...then, it's conceivable that intermittent RAM could manifest itself as a lack of activity on the built-in video, because it can't initialize it's share of the memory (due to some kind of damage in the area it normally occupies), while still allowing the machine to boot normally, correct?

Something like that, yeah!

From memory the video uses about 30% of the machine RAM capacity for video and the rest for the machine and I'd imagine the machine grabs its share of the memory first and the video takes whats left. What might be happening if you're only using say 4Mb RAM (or 1Mb if they're 256's) is that the machine is grabbing so much of the system heap the onboard video can't function. That depends of course on how much memory the System takes and that depends on how 'fat' your system folder is.

I'd certainly clean the RAM pins and connectors and make sure you put the 4Mb SIMMS into bank A and the smaller ones into bank B. I can't remember from memory which is which but I think Bank A is nearest the Hard drive caddy. It's certainly that way on my cx and it's annoying you have to take out (ideally) the caddy to access bank A. Make sure they're all the same size and speed, you can't mix them in these earlier machines, but you can use ones from different manufacturers, ideally they'd all be the same.

 

[CC_333]

I can't remember from memory which is which but I think Bank A is nearest the Hard drive caddy.

That would mean that I put the RAM in Bank B, then. I should switch it and see.
c

 

[dougg3]

I have a IIci sitting here so it was a quick check...indeed, the motherboard silkscreen says Bank A is the bank closest to the hard drive.

 

[CC_333]

the motherboard silkscreen says Bank A is the bank closest to the hard drive.

Yes, I too saw that once I bothered to look.
So, of course, I accidentally put the RAM in Bank B, assuming it was A. I moved it from B to A, and now the video's back!

Odd design, for sure.

It's probably kind of silly to post about a problem I can't seem to solve when I know better and could probably fix it if I just stared at it awhile.

But I guess I'm not the only one who does this from time to time!

And I admire your extraordinary work with the Mac II-SE/30 ROM SIMM, dougg!

c

 

[dougg3]

But I guess I'm not the only one who does this from time to time!

Definitely not there are so many little gotchas like that on the old classic Macs, it happens to us all!

And I admire your extraordinary work with the Mac II-SE/30 ROM SIMM, dougg!

Thank you!

 

[CC_333]

And I admire your extraordinary work with the Mac II-SE/30 ROM SIMM, dougg!

Thank you!

You're very welcome!!!!! I hope to see more progress with the NewWorld G3 version!

If I knew more, I'd volunteer something!

c