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Chase lights program for IMSAI 8080


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  Chase lights program for IMSAI 8080 by Bill Degnan - 05/15/2010 19:34
Here's a program you can toggle into your IMSAI 8080 that should
display the "chase the lights" effect in your programmed output
section. Text edit suggestions by Andy Meyer and Bill Dromgoole, program suggestion by Mike Loewen.

First, turn on your IMSAI and toggle the STOP switch, them the RESET
switch, then STOP again.

Second, flip all of the data switches down and flip the Examine switch up.
(This says "I want to work with address location 0000")

Third, enter the following instructions into memory.

(NOTE: DEPOS is a bi-directional momentary switch - it will not stay
up or down.
When you flip the switch up, you're telling the computer to deposit a
value into the memory location you EXAMINE(d). When you flip it down,
you're telling the computer to deposit a value into the NEXT memory

IMPORTANT! All ADDRESS - DATA switches should always be in the down
position (OFF) unless indicated below.
The ADDRESS - PROGRAMMED INPUT should always be down, you don't need them.

For example:
Instruction C1 means ADDRESS - DATA switches 7,6,0 should be up, all other DATA - ADDRESS switches should be down.

Each time you enter a value, the DATA BUS lights above the ADDRESS -
DATA lights will change to match what you have toggled.


3E (DATA switches 5,4,3,2,1 up, the rest should be down, then push DEPOS up. This is the only
time you will flip DEPOS up.)

01 (DATA switch 0 up, then depress DEPOS DOWN. (i.e. NEXT)

0F (switches 3,2,1,0 up then depress DEPOS down = NEXT)

3E (switches 5,4,3,2,1 up; depress DEPOS down = NEXT)

FE (switches 7 through 1 up; NEXT)

D3 (switches 7,6,4,1,0 up; NEXT)

FF (switches 7 through 0 up; NEXT)

11 (switches 4 and 0 up; NEXT)

01 (switch 0 up; NEXT)

00 (all switches down; NEXT)

21 (5,0; NEXT)

00 (all down; NEXT)

00 (all down; NEXT) (you're repeating the previous command again)

31 (5,4,0; NEXT)

D2 (7,6,4,1; NEXT)

0D (3,2,0; NEXT)

00 (all down; NEXT)

07 (2,1,0; NEXT)

00 (all down; NEXT)

00 (all down; NEXT)

00 (all down; NEXT)

00 (all down; NEXT)

00 (all down; NEXT)

00 (all down; NEXT)

00 (all down; NEXT)

00 (all down; NEXT)

00 (all down; NEXT)

00 (all down; NEXT)

C3 (7,6,1,0; NEXT)

05 (2,0; NEXT)

00 (all down; NEXT)


Fourth step:

With all of the DATA switches still in the down position, flip EXAMINE
up. This starts you over at 0000 in memory. At this point The DATA BUS
lights above the ADDRESS - DATA row of lights should read 5,4,3,2,1 on
= 3E in HEX).


Press RUN.


Are the lights slowly blinking in order within the PROGRAMMED OUTPUT?
... Congratulations, you did it!

Not working? press STOP and toggle all of the DATA switches down.
Press EXAMINE up. The ADDRESS - DATA row of lights should read
5,4,3,2,1 on - press NEXT to step through each instruction, making
sure the lights match the data you toggled in above.

Don't have an IMSAI 8080 - Try this:

  Better Solutions by Bill Degnan - 05/16/2010 22:55
The program in the original post does not work yet, so I am going to keep working on it. I need to add a delay. It's weird because it works in the emulator, but I have received more than one report that it's too fast in a real IMSAI.

IN the mean time, check out these links


Here's a newer thread with a working version. I totally forgot I made this thread. (me 7/23/2023)



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