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How to Start hardware of 2864 EEPROM Self made circuit...??
Posted: Tue Jun 28, 2011 3:39 pm
by RITESH
Hello,
I want to use Intel 8085 up, for this an EEPROM programmer is needed please post it circuit.......
i found this great place for learning it..............!!
Thanks
Posted: Tue Jun 28, 2011 5:50 pm
by GARTHWILSON
If we give you an EPROM-programmer circuit, it will probably be 6502-controlled! 
(Actually then it would need an EPROM programmer for the 6502 as well though.) Seriously, if you don't already have a computer of some kind, the EPROM programmer would be completely hand-operated, that is, you set the address and data by hand using switches, then push a button which would give a timed programming pulse, and you do that for every single byte. That's what I did for my first one (in 1985), but it was so slow and so vulnerable to human error that it was almost worthless. Another problem however is that not all EPROMs program the same way; so you would have to get the specifications on the one you want to program, and make your circuit for that. Unfortunately the EPROM manufacturers don't always want to release the programming specifications, because they are protecting the programmer manufacturers' business. The normal thing to do is to buy a programmer that works with the PC. It will come with the PC software to operate it, and it will supply the voltages and pulse widths necessary for all the EPROMs it supports, which you select in software. There may also still be stand-alone programmers with a keyboard, but they are about three times as expensive than the ones that go in the PC and use its case, its power supply, etc..
Re: How to Start hardware of 2864 EEPROM Self made circuit.
Posted: Tue Jun 28, 2011 6:20 pm
by bogax
I want to use Intel 8085 up, for this an EEPROM programmer is needed please post it circuit.......
What EEPROM are you going to use?
What have you got to work with?
Garth Wilson is correct in what he says, but it may not apply.
At least some modern EEPROMs program themselves (I haven't kept
up, but I would have assumed that is the norm)
You basically write them like any RAM (but a block at a time)
and tell them to program themselves and wait while they do it.
Posted: Tue Jun 28, 2011 7:26 pm
by GARTHWILSON
Garth Wilson is correct in what he says, but it may not apply.
At least some modern EEPROMs program themselves.
Posted: Wed Jun 29, 2011 4:11 am
by RITESH
I want to make SBC of 8085 up, the EEPROM used is 2864.........!!
Posted: Wed Jun 29, 2011 8:42 pm
by GARTHWILSON
I think someone here made an SBC with a 28-series EEPROM that the processor could write to if the write-protect jumper were removed, right? Daryl, was it you? Whoever did could probably just give the link to the schematic so Ritesh could see the circuit. I really can't take the time to study the data sheets right now, but I think it was pretty simple. Ritesh, how do you plan to feed the information the programmer? PC's parallel port? Something else?
Posted: Wed Jun 29, 2011 11:12 pm
by 8BIT
Yes, my SBC-2 used an 28256 32k x 8 EEPROM and could be programmed in-system, as long the code to do so was already loaded on the EEPROM.
What I am understanding is that Ritesh wants to design an SBC using an 8085 MPU, along with an EEPROM. I assume he will need some sort of RAM and I/O also. Since I am not familiar with the 808x family, I cannot offer anything further as to how to design one.
I suggest searching for some other sites that use the 8085 for ideas.
To program a blank EEPROM, you could do it by hand using toggle switches and a push button. Wire the toggles switches to feed either +5 or gnd to each address and data input. Tie the /OE Pin to +5 and the /CS pin to gnd. Wire a pull-up resistor to the /WR pin and +5. Wire the push button between the /WR pin and gnd.
The sequence is to set the toggles for each byte, press the push button. The write should take place fast enough to allow you to set the next address and data values and press the button again. You could wire up a reader in the same manner, but instead of toggle switches on the data pins, use a buffer IC and LED's to show the outputs. In this case, /WR is held at +5 and /OE is connected to the push button.
A better way is to buy a programmer from ebay for about $50 to program the EEPROM outside of the SBC.
Hope this helps.
Daryl
Posted: Thu Jun 30, 2011 10:14 am
by RITESH
Hi again,
I don't have programmer, so i will found a way for this like Toggle switch.
Is there any timing to shot the pin while programing??& in 2864 there are 13 address pin's??
why they should be 14 pin's to have 64Kb....!!
First i will try in market that i am getting all chip which i want.....
Posted: Thu Jun 30, 2011 12:25 pm
by 8BIT
The 2864 is a 64k
bit device organized into 8k bytes (8k x 8 bits = 64k bits).
You need 13 address pins to address 8k.
Instead of spending time building a manual programmer, which can take a lot of time and would be very prone to errors, I suggest you purchase a programmer. If you intend to stay in this hobby, you will find that it is a great investment.
Try this one:
http://cgi.ebay.com/320684682105
Daryl
Posted: Thu Jun 30, 2011 3:08 pm
by RITESH
Posted: Thu Jun 30, 2011 3:17 pm
by BitWise
Personally I'd go for one that has the option of an external power supply.
I bought a TOPS programmer on eBay and it refuses to program anything on my main desktop and laptop because I doesn't think the USB is supplying enough power.
Posted: Thu Jun 30, 2011 3:52 pm
by RITESH
Why??
is there any problem in USB supply??
Posted: Thu Jun 30, 2011 4:30 pm
by BigDumbDinosaur
Personally I'd go for one that has the option of an external power supply.
I bought a TOPS programmer on eBay and it refuses to program anything on my main desktop and laptop because I doesn't think the USB is supplying enough power.
Did you trying connecting it to a powered USB hub? I had the same problem with that unit when I got it. I put a 4-port USB card into my PeeCee and that fixed the problem. Also, be sure you have the latest software.
Posted: Thu Jun 30, 2011 5:23 pm
by bogax
You haven't said what you've got to work with.
A bit of Googling will turn up lots of do it yourself
programmers, complete with the software to run them.
Here's parallel port programmer for a 2764 which could
probably be adapted to the 2864 (2864 would be simpler,
don't need the 12.5V programming voltage)
I know nothing of this programmer it's just a simple one
that turned up in Google.
http://dsaprojects.110mb.com/electronic ... g_SCH.html
http://dsaprojects.110mb.com/electronic ... m_prg.html
Posted: Fri Jul 01, 2011 12:07 am
by BillO
+1 on using a powered USB hub.
Also, there are the Willem programmers that can be had for about $30 including shipping.
http://cgi.ebay.com/Willem-Universal-EP ... 2eb091d647