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I'm trying to upgrade my IIx past 8MB of RAM.  The issue is that none of the RAM I've tried seems to be accepted.  I know the PAL is needed, and SIMMs with less than 8 chips are also no dice.  I got four SIMMs similar to the ones...

Was this the IIfx that came with the Portrait Display?

Well that's disappointing -- the lead ended up going nowhere! If you manually run the ROM checksum test (critical test 4) what does it say?

If it's saying the ROM checksum failed then maybe there's a problem with the lines going to the ROM SIMM.  Did you try checking continuity of the pins in the ROM SIMM slot?  Another test you could try would be to swap the ROM with that of another machine that uses a compatible ROM (like the...

I'm not the most knowledgable person here (as evidenced by the fact that I keep posting IIx help threads with no replies), but I can suggest something which gave me the crucial info to figure out why my IIx was death chiming when I first got it.   Since in almost, if not all, cases when the IIx...

Update:  I hit every pin in each slot in Bank B with a logic probe.  There seems to be data going through each pin -- none of them seem to be stuck at 0 or 1.  What else should I check?

Alright thanks, looks like I'll have to probe all the lines.  Do you know how the memory probe works?  Does it just walk through the addresses until it can't write anymore, and then decide that that's the top of memory? Also, does anyone know of any memory test software that performs its own...

I'm having trouble with RAM being intermittent.  The machine currently has 8 sticks of 1MB each installed.  The problem, however, is that about half the time, it only detects 4MB of RAM.  If I remove the upper bank, it still only detects 4MB, which leads me to believe the problem is in the upper...

So I've been playing with this, and what I've found is that it appears that the signal the IIx is putting out is interlaced, which my LCD monitor is interpreting as "480i" (it shows it as a shrunken image proportional to a full 640x480 image).  I tried it with a IIsi, and got a clear picture on...

The card does output at the correct resolution -- if I power up the machine with no display attached, it defaults to 512x384, and I can attach another monitor that displays that resolution, and the Monitors control panel confirms it.  But the same issue occurs when I then connect the 12" RGB.

I'm trying to get a Mac 12" RGB display to work with my Mac IIx.  The IIx has a Mac II High Resolution video card installed, which according to this supports the weird 512x384 resolution the monitor demands.  However, I get the weird pattern shown in the attached photo.  This seems to be some...

Turns out the distortion was because one of my jumped traces (from messing up one of the RAM chip replacements) wasn't soldered very well.  As for the Sad Mac and stripes, it was because the CAS0 line between the TSM and RP3 was broken somewhere.  I had tested continuity from each chip to the...

I had tried it on the Classic II running 7.6.1.  Perhaps that's why it refused to work?

The SE and Plus boot from an external SCSI2SD that is shared between them, so I can easily get whatever System I need onto them; currently it has 6.0.8.   So I was able to figure out how to at least get a boot floppy by downloading an image from another site that specifically listed it as a...

I have access to a Mac SE, non-FDHD, a Mac Plus, and a Mac Classic II.  I currently have 400k dsk images for System 4.0 on the SE, but Disk Copy 4.2 doesn't recognize them at all, and Disk Copy 6 refuses to write floppies claiming that I need a drive that can write 400k floppies, which the SE...

Update:  I cleaned the board with alcohol and the distortion disappeared.  I then put the replacement chip back in and the distortion was back, but this time cleaning the board did not help.  Is there something weird about the buffers on this board that prevents me from just replacing them with...

I'm currently trying to resurrect a dead 512k that until this morning gave a good chime and displayed a Sad Mac with vertical stripes.  However, after replacing one of the LS244 buffers, the chime is now distorted, as are the visible parts of the screen.  I put back the original LS244, but...

I verified continuity from one RAM chip to another (for the 14 pins that are all connected in each row), plus continuity from the Data pin of each chip to the 68000 and continuity from the RQ pin to the 74LS166 shift registers, the 74LS244 buffers, and the 74LS161 counters. However, at some...

There was one on one of the sweep lines but I fixed it.

That’s right.