burning a 27c512 - IGT clear prom - error?

[FOXSSLOTS1]

I have a BYTEK burner/gang programmer - I am trying to make a copy of IGT clear prom. The prom is good as I use it regularly to clear when I change batteries etc on S+ machines. I want to make a copy of it and my programmer keeps give me a "BUSS ERROR or BAD INSERTION".
I cannot find any info in my docmentation for my burner - the port I am using is working as I can read other 27c512 proms - all of them are Texas Inst.  Are these clear chips protected somehow from being copied???

[jay]

No copyprotection on a 27c512.

I often write 27c256 chips onto a 27c512 using an offset. This allows me to buy 27c512s in bulk and get them cheaper.

So... what I am getting at is if you are set to read a 27c64 it will read (part) of your 27c512 fine but it may give you an error when writing.

Its also possible that the chip you are writing too is too slow or not blank for your settings.

I don't know your burner so I am just speculating on a lot of this.....

[FOXSSLOTS1]

I have 2 burners - one is a BYTEK-135 gang burner - the other is a burner I hooked up to my 486?(Like OLD) pc with a software/card I purchased thru JDR in San Jose. The PC burner does not care about the eprom manufacturer and in the case of this Clear eprom - read it without any problem - copied it. My BYTEK however requires knowledge of the prom manufacturer making it very difficult to use as it doesn't like mixing eproms. In the case of the CLEAR PROM - the one BYTEK didn't like my PC did and the COPY from my PC BURNER reads without a problem on my BYTEK. Now I need to find a way to hook the 2 together so I can store Programs on my PC using the R232 ports.

[blueridgeslots]

Burn the clear (IVC-006) on a 27C256, not a 512

[Op-Bell]

EPROM programmers shouldn't care what make the EPROM is for reading - all EPROMs of a type read the same way. When it comes to programming them, there are many different algorithms that differ in voltage, pulse width, overprogramming and other arcane parameters that you find in the small print, so you generally have to tell the programmer the right make and part number. Most programmers can find this out for themselves - all EPROMs have a couple of identification bytes that read out the manufacturer code and part number by taking address pin A9 to 12V, then the programmer uses this to look up the algorithm in a library. The BYTEK should have that feature built in.

But why are you fiddling around with an old JDR programmer, when you can get a modern one for less than $100? Your wasted time must be worth more than that. Check out the choice at this link - http://www.mcumall.com/comersus/store/comersus_dynamicIndex.asp - I rather like the EasyPRO 90 myself ($120). If you had that, you could read and burn the 40 pin chips as well.

[Op-Bell]

Burn the clear (IVC-006) on a 27C256, not a 512

You can burn a 512 as a 256 - just burn the same data twice, once at offset 0000 and again at offset 8000. That way it doesn't care what is the state of A15, which isn't used on the 256.

[blueridgeslots]

Not all understand the offset on eproms, and was just a recommendation to simplify getting the job done, I take it he thought that since a SP (Game chip) was on a 512, then the Clear would be as well, but was made on a 256 from IGT

[Op-Bell]

Not all understand the offset on eproms, and was just a recommendation to simplify getting the job done, I take it he thought that since a SP (Game chip) was on a 512, then the Clear would be as well, but was made on a 256 from IGT

Ah, well the offset is just the address of any byte in the EPROM starting from the bottom. So a 27256 has 32,768 bytes starting at 0 and going up to 32767 (0000-7FFF in hexdecimal). A 27512 has 65536 bytes numbered 0-65535 (0000-FFFF in hexdecimal). You can also think of a 27512 as having two banks of 32768 bytes, a low half and a high half starting at address 0 (0000 hexdecimal) and 32768 (8000 hexdecimal) respectively. (EPROM programmers invariably expect you to understand and talk to them in hexdecimal). It has one more address pin than a 27256, to select between the low half and the high half.

So, if you put a 27256 into a socket meant for a 27512 its contents will appear twice, at address 0 and again at address 32768, since it doesn't have a pin to tell the difference between these addresses.

27256s are getting hard to find, as they aren't being made any more, so you can substitute the easier-to-get 27512 if you copy the same data into both the low half and the high half. Then, just like a 27256, the same contents appear twice, at address 0 and again at address 32768.

[tjkeller]

Not all understand the offset on eproms, and was just a recommendation to simplify getting the job done, I take it he thought that since a SP (Game chip) was on a 512, then the Clear would be as well, but was made on a 256 from IGT

Ah, well the offset is just the address of any byte in the EPROM starting from the bottom. So a 27256 has 32,768 bytes starting at 0 and going up to 32767 (0000-7FFF in hexdecimal). A 27512 has 65536 bytes numbered 0-65535 (0000-FFFF in hexdecimal). You can also think of a 27512 as having two banks of 32768 bytes, a low half and a high half starting at address 0 (0000 hexdecimal) and 32768 (8000 hexdecimal) respectively. (EPROM programmers invariably expect you to understand and talk to them in hexdecimal). It has one more address pin than a 27256, to select between the low half and the high half.

So, if you put a 27256 into a socket meant for a 27512 its contents will appear twice, at address 0 and again at address 32768, since it doesn't have a pin to tell the difference between these addresses.

27256s are getting hard to find, as they aren't being made any more, so you can substitute the easier-to-get 27512 if you copy the same data into both the low half and the high half. Then, just like a 27256, the same contents appear twice, at address 0 and again at address 32768.

Ummm..........yeah. You know......uhh, like everything he just said....Yeah...THAT'S the way it is! ??? 



Really though, THANKS OP-BELL for the info.
Keep up the good work.

[FOXSSLOTS1]

the BYTEK for whatever reason will not read any eprom unless you set it up for that MANUFACTURER and TYPE.  MY JDR just requires the TYPE. I have been using the JDR on for 20 years!!!! Since the only applications I needed it for was writing E-series programs and maintaining a library - my old work horse 386 then 486 were adequate for the tasks at hand. Even going into IGT proms was also not a problem. The only reason I bought the BYTEK was to program BIPOLAR proms. A side benefit was the ability to gang program as the JDR was one at a time. For me both work - this is the only glitch I have run into - my initial reaction was the thought that the CLEAR CHIP was protected in someway. Looks like a got a lot of reaction and interesting FACTS about Eproms for all to read. thank you all.

[uniman]

27256s are getting hard to find, as they aren't being made any more, so you can substitute the easier-to-get 27512 if you copy the same data into both the low half and the high half. Then, just like a 27256, the same contents appear twice, at address 0 and again at address 32768.

Universal game (reel) chips in the older games are on 24-pin 2732's. But the eprom sits in a 28-pin socket. 28-pin eproms such as 27128, 27256, and even 27c512's will work as replacements. Just have to copy the file 4, 8, and 16 times for the 27c512's.