Unfortunately now the system is giving me the 10CD 201 Error even with only 16k enabled on the board...

I've tried moving banks of memory around, and sometimes I got it to give me other errors like 1001 201 but I haven't gotten it to boot 🙁

The 4-digit number aabb tells you which chips are not working correctly.
aa=base address
bb=failing bit pattern

If you do not understand minuszerodegrees' explanations, look at the reference, the ROS source code. There the thing is explained in a detail that is almost impossible not to understand.

As you did wrong from the beginning by not interpreting this self-explaining message where the error is, and instead wildly mixing/shuffling the chips in question, you have to start over from scratch.
Remove the quadboard,
Then first install memories, as if you would stepwise expand your PC from 16, 32, 48, 64kB.
Put aside the chips that give errors.
Report back when you have got the mobo fully populated, so we go on to populating the quadboard.
Make sure that the installed memory size dip always is correct.

In the end it might be an old dip switch that no longer gives reliable contact, as the first error message (40xx) clearly indicates that your PC believed to have more than 256kB installed.

Also make sure to brush all the pins and contacts using some cleaning fluid as some of the memory errors in these boards are because of the corroded and dirty contacts and they might appear as a faulty mem chip error.

I did as retardware stated above, removed the quadboard, removed all memory (in order) and started repopulating banks as if upgrading the board from 16k to 32 to 48etc.

you might be onto something with the DIP switches not functioning correctly however, as the system will all but the base 16k still give me the 10CD 201 error. (Yes I've double and tripled checked the dip switch configurations)

which if I understand the explanation correctly is saying the machine believes it has a ram expansion card "10" and the "CD" indicates multiple bit failure?

sounds to me like the DIP switch bank isn't functioning correctly.

If I understand you correctly, in all settings except the setting for 16k (=only one memory bank on mobo), you are getting 10CD?

The base address can be interpreted as memory area aaxx:...
So 10 as base address means 1000:0, or 64k +1
Looks like a) the memory test did go farther than the dip setting you had, and b) the system found memory where it should not have been.

Obviously something is very wrong.
In case of strange problems with old computers it always is worth the few minutes to check if these persist with
a known-good power supply. Do you have one?
If the PSU is good, I'd look at the schematics.
Without looking into the schematics, my intuition (which is sometimes very wrong) says it could be a 74LS138 no longer multiplexing properly.

Alright.

So all ram except the soldered ram in bank 0 is removed and set aside.

All options are set correctly as per the Guide to Operations.

Now, My system has the early Bios which only supports 544kb of ram because the bios doesn't check DIP Switch 5 on SW2.

But, for some reason, with switch 5 in the off position (where it's supposed to be according to the guide to operations) and the bios shouldn't even check that switch.

The system won't post. It gives me 1 long beep followed by 2 short beeps which should be a video error. WTF?

Then if I switch SW2 #5 to the on position, the system will post,

But it gives me 108D 201 error and enters cassette basic

I'm going to try the power supply in my XT clone just in case.

But I'm seriously stumped. If there is something seriously wrong with the motherboard I don't have the expertise to diagnose that.

Could it be possible that you accidentally mixed piano 1 and 2?

Because, a wrong setting of piano 1 switch key #5 would explain the beeeep bip bip.

Please take a look at page 317 (e.g. D-10, System Board 11/12) in the reference manual: http://www.minuszerodegrees.net/manuals/IBM_5 … 25005_AUG81.pdf
and look at the descriptions of both pianos and their keys.

I can see what you're getting at but unfortunately its not that simple 😒 mixing SW1 and SW2 up certainly would cause some serious problems...

ive highlighted in this LOVELY MS paint creation the DIP #5 in question (yes I realize this is a 64-256k board, the photo is from Wikipedia shhh)

Yup. Still getting the 10CD 201 error.

Doesn't matter where SW1 DIP #3 and #4 are located I get the same error in all positions.

It is still strange that SW2 DIP #5 (pink in the picture above) when shut off is giving me the one long beep 2 short beeps.

retardware wrote:

Could it be possible that you accidentally mixed piano 1 and 2?

You know I must have been staring at the motherboard for so many hours my eyes went cross eyed.

No idea how I was able to repeatedly look at the board and have the switches backwards, but yes that was the issue. I repeatedly looked at the Manual, Minuszerodegrees, and I didn't notice.

Wow do I feel stupid 🤣.

But the system is working perfectly now.

pinkdonut666 wrote:

... the system is working perfectly now.

Great to read 😀

pinkdonut666 wrote:

Wow do I feel stupid 🤣.

Probably everybody has done some really embarrassing things.
I like when people can talk freely that they are human and not perfect like robots 😀