Hi
I have 2 Apple IIe motherboard and a power supply
when I power the first board, the screen is cleaned and then the simple word "Ram:" is written on the top left corner...
nothing else. I deduced (I may be wrong) that the board is working but lack peripherals and specially a keyboard
(if I remove the 74LS154 decoding the IO I get "Apple II and a prompt"
on the second board, the screen is filled with little colored squares (I guess it's just low resolution) an nothing else.
if I put the rom of the previous board to this one, I columns on screen patterns containing '*'
apparently on of the set of eprom is enhanced the other set standard
any idea to what I should look to solve the problem of the board with the screen filled with colored squares ?
I try to swap many parts without real success...
any idea ?
thanks
I Recall reading somewhere that on the Apple ][e, if there is no keyboard, the computer goes into a test mode, with the Blinking Squares..
Can you use the Keyboard to start the Self Test ( Ctrl-Closed_Apple-Reset )
MarkO
I dont have any keyboard right know, I'm waiting for a adapter to plug an usb keyboard...
I'm not to worried about the first board, I guess it has a good chance to work with a keyboard and a disk.
but for the board with the screen filled with small colored squares I'm more worried
something is obvious broken
I checked a pdf of hardware failure on Apple IIe but I've not seen this case described
by swapping parts, I get strange results
Apparently I detected 2 bad rams chip, I replaced them
on the board with standard rom/6502 I get a black then white screen then a kind of reset and it starts again
if I remove the 74LS154 I get "Apple ][ on the screen and a prompt"
on the board with enhanced rom/6502 I get 2 alternating screens composed of small squares...
at some time on the one with enhanced rom/6502 I got a patten RAM 0 0 0 1 0 0 0 0
the pattern was changing when I swapped the ram chips since I replace the chips I dont get the pattern anymore
on the standard rom mother board, it just displayed "Rams" on top of the screen
I didn't read everything carefully, but I did see you didn't have a keyboard. An Apple IIe will not boot without a keyboard (or test fixture) plugged in. If you don't have a keyboard, it will cycle through the self-test (colored squares for ever). Some type of burn in process I presume.
Jay
thanks
it's good news, it probably means that after having fixed the broken ram, both board are just probably working
and waiting for a keyboard
thanks to all
Hello,
You describe the diagnostic screens with unenhanced and enhanced ROMs.
This is the normal behaviour since no keyboard is plugged in.
If this appears, you probably have defective RAM chips. 1 show the positions of bad RAM chips according to the motherboard layout.
with a keyboard, both motherboard works
1/ still had some memory problem fixed by changing the bad ram chips.
the screen is very clean, the characters are really nice. (even in 80 col)
2/ the second board works but in 40 Col the characters are slightly blurred..
in 80 col it's almost totally usuable.
any idea for this blurred characters ?
thanks for your help
Hello,
A picture would help but here is a starter if you're using a PAL motherboard and a B&W display. There is a switch located at B-C 15, on the right side (see enclosed picture).
With a monochrome display, you have to select the MONO position. Otherwise (in the COLOR position), the characters will be blurry.
I'm using 2 ntsc motherboards with an adapter + vga flat screen
video composite --> HDMI --> vga
works fine one a board
blurred on the other