Hello,
I populated the video section of the Apple-1 computer with ICs (left the computer section out) and when I turn it on, I get the following scanning screen for about 2-3 seconds which then turns into a screen with solid white columns (second image). Does anyone know what could be the issue? I've checked a lot of the pins of each IC, trying to trace from the video out to see if I could spot any weirdness but so far I'm not sure what could be the issue. The only thing that is strange to me is that IC D8 (74161) is always HI for pins 12, 13, 14 except when LOAD is enabled for that IC, which is when it drops to LOW for a split second and then goes back to HI. My assumption is that, since it's always HI, the lower dots are displayed for each character and the upper dots are displayed for a split second. The other address pins for the 2513 are all HI except for pin 22 which is LOW. It appears to be showing an underscore but it's always showing the lower dots only which explains the white columns. I just have no idea why it's doing that.
Additionally, why it would be showing an underscore instead of a blinking @ and _ is another question.
Thanks in advance
I populated the video section of the Apple-1 computer with ICs (left the computer section out) and when I turn it on, I get the following scanning screen for about 2-3 seconds which then turns into a screen with solid white columns (second image). Does anyone know what could be the issue? I've checked a lot of the pins of each IC, trying to trace from the video out to see if I could spot any weirdness but so far I'm not sure what could be the issue. The only thing that is strange to me is that IC D8 (74161) is always HI for pins 12, 13, 14 except when LOAD is enabled for that IC, which is when it drops to LOW for a split second and then goes back to HI. My assumption is that, since it's always HI, the lower dots are displayed for each character and the upper dots are displayed for a split second. The other address pins for the 2513 are all HI except for pin 22 which is LOW. It appears to be showing an underscore but it's always showing the lower dots only which explains the white columns. I just have no idea why it's doing that.
Additionally, why it would be showing an underscore instead of a blinking @ and _ is another question.
Thanks in advance