On Wed, Mar 14, 2012 at 11:17 PM, Gergely L?rincz <alkopop79 at gmail.com> wrote:
This bit helped a lot to understand what's going
on. Took out the 4013 and
tested it on a separate breadboard, worked fine. Put it back and still
cannot see anything on pin 12 (*Q*). Tested all the conditions over and
over and seems that SC1 does not change after the input button is pressed.
On the other hand, if I set the DMA IN pin low, SC1 goes high. Created a
somewhat amateurish
diagram<https://picasaweb.google.com/lh/photo/r9_0Sc3OKIxotL1IU5hk3dMTjN…nk>,
green means tested and working, red means doesn't work. I wonder what N2
does. It never seem to change from low state. Thank you for your help in
advance!
N2 is one of the "N lines" - they are used to select the correct
device for the 6X IN/OUT instructions.
One of the neat things about the Elf design is that most of the I/O
serves two purposes depending on what the processor is up to. If you
are in "LOAD" mode, the input button triggers /DMA_IN pulses that gate
in the state of the switches, and the TIL311s latch memory bus data.
In "RUN" mode, the toggle switches can be read with an INP 4
instruction and the displays can be written to with OUT 4, and the
input button can be sensed on /EF4 with a branch/skip instruction
Could you be having a problem with your RUN/LOAD switches so that the
processor is _not_ in LOAD state when you think it is?
-ethan