Apple II+ Bad Memory/ROM?

[dog_cow@macgui.com (D Finnigan)]

Posted on behalf of torindkflt:

Hello all. I am a newcomer to the board. I recently purchased an Apple II
Plus from eBay. Aside from a 16K expansion card, it is a bare system. No
monitor, no disk drive or controller, no other expansion cards. Just the
computer itself (I've separately purchased a disk drive and controller,
still waiting for them to arrive). However, I know that the computer will
still boot into the BASIC prompt even if no disk drive is attached, so I
decided to play around with it anyway.

However, while doing so, I noticed some odd glitches that I'm fairly sure
shouldn't be happening. Keep in mind that 95% of what I know about the Apple
II Plus is based off 20 year old childhood memories, so my troubleshooting
expertise when it comes to this old system is fairly nonexistent. However, I
did try a few different things that I was readily able to recall from
memory, and came up with the following symptoms:

1. Attempting to use the LIST command almost always kicks it into the
program monitor at address E851, but sometimes instead it returns a divide
by zero error, then freezes. The only exception to this problem is if no
program code exists in memory, in which case LIST just displays a blank line
and returns to the BASIC prompt, as it is supposed to do.

2. Attempting to assign a variable (For example, setting X to equal 10)
kicks it into the program monitor at address E916.

3. Attempting to run the following invalid one-line program:
10 GOTO 20
Returns "UNDEF'D STATEMENT ERROR IN" with no line number given for the
error, then immediately after kicks it into the program monitor at address
E851

4. Attempting any math function (1+1, 9*64, 3/0, etc.) kicks it into the
program monitor at address E916.

As previously mentioned, the computer did come with a 16K expansion card.
However, the problems persist even with the card removed.

So, I felt it necessary to turn to the experts here for assistance.
Childhood memories that consist almost entirely of just using the system to
play games really isn't enough for me to solve this problem on my own. I
appreciate any assistance.