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TulioAdriano

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Hi everyone.

So I tried buying NEC D27C1000A non-JEDEC eproms to use on System 16B conversions... but my last two purchases were less than successful.

I bought it from ebay, the same seller that had sold me good D27C1000A eproms, and 3 weeks later they arrived, marked slightly discolored but oh well... then when I went to program them, it was failing programming, chip ID revealed a CE0E which is actually for a Macronix M27C010, same capacity but JEDEC pinout. I started a return and got a full refund without needing to return it. Weird but... ok.

Ordered again, same seller, this time I put a note in the order asking to make sure the chip ID is not CE0E, but 1016, which would be the correct ID. Another 4 weeks passed, and this time they didn't even bother to find a chip with the right marking, and I got a D27C100. Chip ID inspection revealed the same CE0E...

So yeah, I don't think I'll try ordering from this seller again... problem is: eBay doesn't have many options at the same price range (20 chips for $25), and all options still come from China which mean having to have another 3 to 4 weeks to get it before I can find out if it's the right one... so...

Does anyone know a good source of NEC D27C1000A, D27C1000D, or any compatible non-JEDEC 128KB EPROM?
 
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Tyson1911

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you could try with a MX27C1000PC-12 flash, I don't know if they are not JEDEC or if they are
 

TulioAdriano

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It all comes down to that pin 2 and pin 24, which are swapped.
I checked for a MX27C1000PC datasheet but I cannot find it. I did find something about MX27C1001 being non-JEDEC, but they seem rare on eBay.
1659059620484.png


Well at least I have one alternative... will keep looking. If anyone else has a good source, I'm still looking for it. Looking to get around 40 or so.
 

Tyson1911

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It all comes down to that pin 2 and pin 24, which are swapped.
I checked for a MX27C1000PC datasheet but I cannot find it. I did find something about MX27C1001 being non-JEDEC, but they seem rare on eBay.
Basically ebay and aliexpress have been selling a lot of eeprom at gold price and most of them are defective and even almost cannot be erased. in the 27c801 to make me a UMK3 it cost me a lot to find functional and why talk about the 27C400 for CPS1 B 91635B-2. It has been too difficult to find functional eeprom, the replacements that I have seen functional (I have not tested them) is to make a dip32 base with some Tsop chip to emulate that eeprom
 
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TulioAdriano

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Yeah, I think that's just what I'm going to do. Will get the TSOP version of SST39SF040 and mount it on a DIP32 size PCB and add some solder jumpers to configure JEDEC/Non-JEDEC, and to configure the EPROM size (128/256/512KB), and call it a day. Won't look so cool but will save me from the weeks waiting to be frustrated ordeal.
 

TulioAdriano

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That should do it. Slap a TSOP SST39SF040 on it and solder the pads on the bottom to configure as desired. I choose solder jumpers because mechanical jumpers would not only look uncool, but would add unnecessary cost. I'll most likely manufacture those as a black PCB for a less disruptive look.

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Tyson1911

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There should be something similar for all eeproms (27c400,800,160,322) although it must be taken into account that since eeproms are NOR they have greater durability than NAND memory, you can still find cheap flash to replace. It is a good economic option.
 
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