My saga of building and troubleshooting an Apple II Plus from scratch

[retrogear]

This all started with a collection of parts I received in the 90's from a retired high school electronics teacher. Included was a nice shiny Apple II+ motherboard in an opened original box. Something is very wrong in this photo. Can you see it?
I did not see the problem when I took this picture. No cheating if you saw this on the Apple II Enthusiasts FaceBook page:

 

[retrogear]

So here's all the pieces I purchased separately on Ebay except the motherboard:

I assembled them, turned it on and got this lovely screenshot:

I noticed the fine vertical lines and remembered helping Gary2000 finding a bad video rom in his IIe, so I looked at the character generator rom and ... dang !!!

The Vcc and Vss are opposite pins diagonally so this put reverse polarity power to the char gen rom so it was fried ...

 

[retrogear]

I removed the character generator rom which removed the lines but brought me back to this:

Now I had the beep at power on or reset but typing random keys and pressing enter would not give me a syntax beep.
With beep on reset, I knew the 6502 and ROM were good, executing the reset routine. However, the keyboard input buffer is at $200 in the 1st 16k of memory
so I rotated the three 16k rows of memory up or down a row and noticed the 1st row a couple chips seemed loose, not seated very well. Now it was responding to commands !!
HGR got me this:

TEXT and HOME produced this (I saw the cursor block move to the top for HOME)

So I ordered a char gen ROM and a couple 4116 ram chips just in case. I put in the new ROM and I got the lovely APPLE II and ] !!!
I went into the monitor and filled $800 to $BFFF with $FF and noticed the $4000-8000 was returning $DF. I booted AppleCillin and the
memory test of the 2nd 16K bank gave me a screen full of ERROR = $20. I noticed both involved the same bit which turned out to be a bad chip third from the right in the middle row.
I put in the chip and now memory passed. I ordered a 16k memory card and added it:

I booted into Integer Basic and ran Kaleidoscope but noticed I still had vertical stripes:

Now my text characters are good but graphics had the stripes. I noticed in SAMS CC1 p37 that UB4 and UB9 are shift registers that clock out the graphics data.
Since they were identical part#'s I exchanged them and now it's good !! They must have just needed reseating. Now I have a Videx card on order to install next ...

Fun stuff !!!

Larry G

 

[gary2000]

Excellent. Those stripes did look familiar.

 

[retrogear]

I realize now in this progression, when a beep can be generated at power on, it is a big clue that all address and data lines are functioning because the beep tone is actually
a program being executed in rom by the processor. Anything shorting a bit on the address or data lines (such as shorted ram?) would prevent the program from running.
However on the IIe, the MMU isolates the memory address lines ...

Larry G