Sega Aurail, EPROM ??s

XianXi

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I'm fixing a PCB I bought on here back in 2009 and now I have it running and can play it but have some missing GFXs in the background and some random text on the screen.

I wanted to verify the roms and I could only do half of them.

I don't know what type to read it as. I tried 256, 512, 1000, 1001 and it just says not all pins connected. The other half read has 512 and they all have the same size file.
 

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AFAIK, the largest 28-pin EPROM is the 27512. The 27010/271001, 27020/272001 etc. are 32-pin devices.
 
AFAIK, the largest 28-pin EPROM is the 27512. The 27010/271001, 27020/272001 etc. are 32-pin devices.

Exactly. I was surprised that these don't read as 512.

Well, I'm gonna try and read the 2nd half as 512 as well. Maybe there's more than 2 bad roms that just happen to be those chips.

I'll report back.
 
27C301 is the non-JEDEC version of a 1Mb EPROM. It's an easy replacement for the 28 pin 23C1000 mask ROM. Try reading as that.
 
But is the 27C301? Take a look at the 2 for pinouts. ;)
 
27C301 is the non-JEDEC version of a 1Mb EPROM. It's an easy replacement for the 28 pin 23C1000 mask ROM. Try reading as that.

Hmm, I keep coming across these chips. What USB programmers can read them? Mine can only read the 32 pin eprom version of the HN27C301.
 
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Both my TopMax and my ChipMax programmers support the MACRONIX MX23C1000PC

:D
 
For the correct way to make an adapter see post #23.
http://forums.arcade-museum.com/showpost.php?p=2034301&postcount=23


Read this on system11:

"The 1mbit 28 pin mask roms can be read as 27C1000s if you build a tiny adapter. take a 32 pin socket, bend pin 30 outwards, and run a wire from pin 32 to that leg. Plug rom into this and any eprom reader should cope with it."

It doesn't make sense though.

Take a 32 pin socket
Bend pin 30 outward (So it won't go in reader)
Then run a wire from pin 32 to the leg of pin 30

or does it mean bend out pin 28 on the rom and connect that leg to pin 32 of the socket?
 
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Yes, pin 28 is Vcc on the 23C1000

Move it to pin 32 which is Vcc on the 27C301
 
Read this on system11:

"The 1mbit 28 pin mask roms can be read as 27C1000s if you build a tiny adapter. take a 32 pin socket, bend pin 30 outwards, and run a wire from pin 32 to that leg. Plug rom into this and any eprom reader should cope with it."

It doesn't make sense though.

Take a 32 pin socket
Bend pin 30 outward (So it won't go in reader)
Then run a wire from pin 32 to the leg of pin 30

or does it mean bend out pin 28 on the rom and connect that leg to pin 32 of the socket?

I just made an adapter with pin 32 of the socket connected to pin 28 of the chip with the leg lifted and it does NOT get read when chosen as a 27C1000.

It says these legs aren't connected:

2,13,14,15,17,18,19,20,21,31
 
I just made an adapter with pin 32 of the socket connected to pin 28 of the chip with the leg lifted and it does NOT get read when chosen as a 27C1000.

It says these legs aren't connected:

2,13,14,15,17,18,19,20,21,31

If the chip is suspected to be dead then this is not surprising, when masks roms go bad my reader often complains about blocks of pins being "out of spec".
 
If the chip is suspected to be dead then this is not surprising, when masks roms go bad my reader often complains about blocks of pins being "out of spec".

That's what I first thought so I checked the others and got the same results. I pulled some from a working game and the same again so I know it isn't the chips. I think my reader isn't being fooled.

I think it's time to upgrade to a programmer that can read these.
 
eeTools TopMax or ChipMax will read those...

TopMax will program chips up to 27C322 - 32Mb ones used in some Neo Geo carts. ChipMax only has a 40 pin socket.

There is a ChipMax 2 out now that is USB instead of parallel. I haven't looked at what it will program yet.

RJ
 
I just made an adapter with pin 32 of the socket connected to pin 28 of the chip with the leg lifted and it does NOT get read when chosen as a 27C1000.

It says these legs aren't connected:

2,13,14,15,17,18,19,20,21,31

Well, pins 2 & 31 aren't connected, no real surprise there. The others (13-15 & 17-21) are your data pins. It sounds like the chip isn't being properly enabled/selected for data output, so the data pins appear "dead".

I think there's some confusion in the conversation about part numbers... XianXi talking about having a mask rom, which channelmanic ID'd as a 23C1000. CM can read it as such, because he has a programmer that supports it. XX doesn't, so he's trying to read it as a 27C1000 on his GQ-4X programmer, by building an adapter so the 28-pin device can be read via a 32-pin socket. I think CM is talking about reading it as a 27C301 (which the GQ-4X also supports), not as a 27C1000. Further confusion arises because different sources show different pinouts for some of these. For example, the MXIC datasheet for the MX27C1000 shows pin 24 as an /OE pin with pin 2 as A16. Whereas this page: http://www.arcadiabay.de/source/item.aspx?id=2738 shows 27C301 == 27C1000, and pin 24 as A16 and pin 2 as OE. I'm not sure which is correct, but I'm thinking the discrepancy may explain why the chip won't read.
 
You need to read it as a 27C301

There are different manufacturers of the 27C1000 and 27C1001 EPROMs and there is NO standard as to which # is JEDEC (27C010 type) or Non-JEDEC (27C301)... Some manufacturers use 27C1000 as JEDEC while others use 27C1001.

Bottom line, use 27C301 when reading it with an adapter.
 
I actually have a TOP2049. I tried reading as both 27C301 and 1000 both with swapped 2 and 24 it still shows the PGM pin (31) disconnected. I read in an old post here:

To replace the 28-pin 23010 with a 32-pin 27010, you need to wire:

23010:pin 20 to 27010:pins 22 and 24 (/OE, /CE)
23010:pin 22 to 27010: Pin 2 (A16)
23010: Pin 28 to 27010:pins 30-32 (+5V).

The rest of the pins are the same.

When I do this the only pins I don't have a connection with are the data pins.
 
Tried another game that uses the 23C1000 and the adapter works fine. The other game rom doesn't verify so I need to replace the 23C1000, do I use a 27C1000 or a HNG27C301?

Also am I right saying that I need to lift pins 1, 2, 24, 30, 31, 32. Run a wire from pin 32 (27C301) to Pin 28 of the socket. Then run a wire from pin 24 of the socket to Pin 2 of the 27C301, correct? Do I need to do anything with A16 on the 301?
 
You use the 27C301... OR you verify that the specific manufacturer/make/model of EPROM that has 27C1000 on it is a non-JEDEC pinout type EPROM before you use it.

A16 on the 27C301 should be in the same spot as on the 23C1000 which should mean that you should do nothing.
 
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