Why always 8085...why not 8051 you will almost learn a lot more than 8085 and its avaliable and cheap INR 40.00 or may be less.

Remember health is everything,they say "Health is wealth" but I say "Health is more than wealth".I learnt my lesson I was ill about 3 months and I could do nothing.It was all because of my habit of sitting in front of my computer all the day skipping meals and lot more.I will never take it lightly any more.

Take care..

 

I can understand, but my mind does not...

 

Alright guys,

I have changed 33pf to 22pf at pin 2 with GND and connected IO/M to pin 4 and 5 of 74138 decoders...
Result:- The output of 74138 was high, no pin was geting low and output at SOD was also low.
I have checked this by buzzer.

 

help me............

 

Help papa bravo.................

 

I'm sorry but if you can't produce an accurate and readable schematic and verify that the hardware is hooked up that way then there is nothing more I can do for you.

 

My schematic as it is as you have tell............
I have removed that LED and checking with buzzer and the 22pf is connected to pin 2 with GND ...
the IO/M is connected to 4 and 5 pin of 74138 decoder and pin 6 with vcc....

I don't understand my code are right and when i connect PROM with 8085 Board the code get changes when seen in home made EEPROM programmer...
OK, one more thing I am programming according to
d0......to d7
eg: LXI h code 21H
so i write as D0..........D7
0010-0111B

 

Ritesh,

You need to either turn the diode around (anode towards pin 4, cathode towards the resistor) or, you need to attach the resistor to VCC, not to ground. I will not work the way you have it drawn right now.

Can you do one of those?


Also, can you get the schematic for the SBC at that link you gave? It might just be easier to build that computer.

I have to go help my son get his race bike ready for a race tomorrow, so I will not be back for a few days.

 

You need to either turn the diode around (anode towards pin 4, cathode towards the resistor) or, you need to attach the resistor to VCC, not to ground. I will not work the way you have it drawn right now.

Can you do one of those?

Hi again,

I have disconnected the LED connected in backward and testing with a piezoelectric buzzer there is not output and the lower addr line are flipping very fast than higher A15 .....

 

Hi again,

But i have checked all lines using Multimeter......

 

Have you thought about using a proven design for your first project? As I suggested, why not use the design for the board at the site right here.......

I am having real trouble following your schematic. If you wish us to help, you need to give us a schematic that we can read. It would really help you a lot to use a design that has already been proven, follow it carefully and learn from it.

For all we know, the 8085 might be bad, but since we have no way of knowing how you built your system (schematic is not complete/readable), we can't tell. You are basically asking us to work in the dark on this.

Here would be another great place to start http://www.8052.com/sbc/schematics/

Then you could get a lot of help from that site if you have trouble getting it to work. You already have mos of the parts you need.

 

OK, i have connected my IO/M to pin 4 and 5 of 74138 3 to 8 decodr and pin 6 to Vcc......is th
is correct??

I don't understand my code are right and when i connect PROM with 8085 Board the code get changes when seen in home made EEPROM programmer...
OK, one more thing I am programming according to
d0......to d7
eg: LXI h code 21H
so i write as D0..........D7
0010-0111B

 

Hi Ritesh,

I have done up a schematic for you. It includes some suggested changes and represents what should be a working hardware model.

Look at the reset circuitry and the LED as well as other small changes.

 

OK, one more thing I am programming according to
d0......to d7
eg: LXI h code 21H
so i write as D0..........D7
0010-0111B

No. If you are writing it with D0 (LSB) on the left and D7 (MSB) on the right, then

21h = 1000-0100
      ^^^^ ^^^^
      DDDD-DDDD
      0123-4567

But why are you doing it this way? This seems to me to be around backwards. MSB is usually on the left and LSB is usually on the right.

 

... when i connect PROM with 8085 Board the code get changes....

Look at the schematic I made. Pin 27 (*WE) on the 2864 must go to VCC while in the circuit to protect it from overwriting. Since you are entering your code wrong (see my last post) you are probably overwriting the EEPROM.

You need to get that code entered properly and attach pin 27 to VCC. In fact, just make sure you follow my schematic.

 

Here is a listing of your program with addresses, HEX, Binary and the binary reversed to D0.....D7 for your programmer.

 

Here is the spreadsheet I used to create the listing in the previous post.

 

One more thing.

While putting the stack at 4010h should work for this program, it will generally not be a useful place for it.

On the 8085, the stack builds down, not up. So, as Papabravo said, you should initialize the stack at 5FFFh.

 

No. If you are writing it with D0 (LSB) on the left and D7 (MSB) on the right, then

Code:
21h = 1000-0100
^^^^ ^^^^
DDDD-DDDD
0123-4567 Select All
But why are you doing it this way? This seems to me to be around backwards. MSB is usually on the left and LSB is usually on the right.

I think this was aproblem that ihave done i will try to fix this up soon..



Thanks for help.

 

I think this was aproblem that ihave done i will try to fix this up soon..



Thanks for help.

I fixed it for you. See post #56. The file attached there has all you code in the format you need to enter it.