After my Apple1 power failure is resolved, now there will be only one@ no /after clearing the screen. Only one letter P plus@
I also checked that each voltage is normal, and the 40 pin of 6502, the voltage on the pins 34 of 6821 is 5 volts. Short keyboard 1-9 will turn 0V.
DRAM I use
I changed the bad 2504 just now, and the starting screen would be gone after rolling up.
IMG_4786.MP4
The problem of rolling upwards was solved, and the loss of the back slope did not appear. Does anyone have related experience? I also checked the solder joints and replaced 6520 and 6502
After executing Clear Screen, there will be a@,Automatically input after executing Reset
6502's 40pin will not change to 0V after the REST, and the measurement is 1V
IMG_4817.MP4
Can you elaborate a bit more about what you're doing in the video? It sounds like you're pressing buttons in the background.What seems to be happening is that you start up the computer. Clear the screen. Then press reset? And reset keeps generating '\' ?
edit:A step by step reproduction of the steps would be very helpful. Action followed by response. As an example:Step 1: Applied power - Screen came on with @_ repeated.|Step 2: Pressed "Clear screen" - Screen went blank and only a single @ was visible.
1. I started Apple1 and appeared correctly @_.
2. I take a short 12-16pin and execute the clearing, just @
3. I picked up 1-9pin shortly and executed the reset, and it kept appearing\
What is the situation caused by this? Thank you for your answer
Well, what were you expecting to happen?
The Wozmon is very simple (it is only 256 bytes of machine code) and does not display a prompt. The only feedback you get is a
"\
"
When the computer is RESET or the ESCAPE key is struck. This is all in the manual. Have you read it?
Thank you for your answer, I won't appear after resetting it\@
After resetting \ will always enter, not
\
@
11111.MP4
So if the monitor outputs a "\" character, it means the code
Output it.
was executed. But instead of running the next instruction after the call at FF1F (GETLINE), the computer looped back to ESCAPE. This probably happened because it got reset again. To call a subroutine and then return, the 6502 needs to read and write to the stack in page $01 (addresses $0100 to $01FF). A fault accessing memory could therefore cause what you're seeing.
You should probably try to stick to one troubleshooting thread.
UncleBernie already pointed out that you probably want to look at the cursor state machine circuitry: https://www.applefritter.com/comment/105880#comment-105880