adding bytes with 4-bit full adders and getting the o/p on 7 segment(s)

[ericgibbs]

hi,
The 184 is BCD to Binary convertor, its the 'opposite sense' for the 185 Binary to BCD convertor.

 

[Duellist]

gosh....
k isnt there any way around this with any kind???
like cant i use it in anyway...

-hussein

 

[ericgibbs]

hi hussein,

Its not possible to use the 74184 to do what you want.

Do you want to wait until the 74185's are in stock?

 

[Duellist]

i am not sure i have much time coz when i asked the guy he said they didnt receive any shipping for the 74185....but they used...

so i am not sure wat i wanna do....
maybe i will try to figure anything abt this project and when i come up with it i will let u all guys know

thanks
-hussein

 

[ericgibbs]

hi hussein

Can you get a EPROM or EEPROM programmed by anyone.?

Consider a 8 * 256 EEPROM.The type of EPROM that is addressed with 8 lines and has 8 data lines. They are not very expensive and it would a simple solution for the Bin to BCD decode. You will require 2 EEPROMs

Program them with a Binary to BCD decode pattern.
As you are only adding two max values of b1111,1111 the max sum will be b1,0000,0000
[0xFF, #255 requiring, 8 bit address] .

ie; The ROM addresses would be the Binary 8 bit byte output of the 2[4+4] bit adder and the Carry bit. The data output from the ROM would be arranged as two BCD bytes, which would drive the two , 7447's

 

[Duellist]

to tell u the truth i dont know how to program the IC
even though i thought abt it for a while
but i am willing to go through it...by the force of curiosty and experince
just tell me the steps i have to do and the equipemnts i require to go through this process to finish it

thanks
-hussein

 

[ericgibbs]

hi,
If you decide you want to try EEPROM for the decoders, I would suggest that you speak to your component supplier and see what EEPROM he has in stock.

You require EEPROMs that are 'parallel' addressed and are 8 data bits wide.
They should be at least 256 bytes long, you may be able able to get cheaper EEPROMS that are bigger than 256 bytes,
say 2K bytes, that not a problem.

So a 256 x 8 , would have 8 address pins and 8 data pins and 2 or 3 control pins.
A 2K x 8 would have 11 address pins, got the idea?

Let me know what you decide.

 

[ericgibbs]

hi,
To help you understand the decode, I have attached a partial decode table.

 

[Duellist]

dear ericgibbs
we found a way around the IC 74185

after the 9 bit come out of the 74283 ICs..we r gonna put a led on each output indicating when its 1 it will light and 0 when the bit is 0
then we would calculate the output.....instead of the seven segment

even though it was one hell of an idea

but thanks all of u guys again

 

[arod]

You really didn't find a "way around" the 74185 if you are having to convert your binary to BCD through calculations.

 

[ericgibbs]

hi hussein

My previous post of the 27Apr.

>>> The simple way would be to have a 220R on each 'S' output pin on the adders and drive a single type LED,
the result could be then read in binary.

Sounds familiar?

Regards