*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?*
Actually, I checked them millions of time by probing the WAIT and CLEAR
(pins 2&3 of 1802). In load mode, both of them are low, in run mode they're
high and TPA%TPB send timing pulses. Also, the SC0 pin goes high/low as you
flip the load and run switches. I cannot think of any other means of
testing the run and load switches but they seem to work and the 1802
behaves accordingly. However, the 4013 still doesn't work properly. I have
trouble understanding how it works. It seems to me that when the input
button is pressed (or released), the Q_ should send a pulse to DMA IN then
the SC1 should change its state (since DMA IN's state changed) and send a
short pulse back to 4013. In other words, once the Q- output sends a pulse
to DMA IN and SC1 sends a pulse in return, which resets the flipflop. Am I
right? At the moment SC1 doesn't do a damn thing (since DMA IN doesn't get
a pulse). Any ideas? I'm beginning to grow a beard, chain smoke and eat
cold leftover from the fridge. Wife's worried and complains. Any help would
be appreciated!
Greg
On 15 March 2012 16:06, Ethan Dicks <ethan.dicks at gmail.com> wrote:
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_0Sc3OKIxotL1IU5hk3dMTjNZETYmyPJy0l…
,
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