4M-16 Bit EPROM ?

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IronGiant

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What is the EPROM equivalent of a 40-pin '4M-16Bit' mask ROM?

I ask as I'm currently working on a Konami 'Bells & Whistles' PCB with an empty mask ROM socket at 3K. All other chips (custom and otherwise) are fine. Have tried the same mask ROM from a fully working Bells & Whistles and that works perfectly in this board, so I just need to program up a suitable EPROM with the binary.

There is provision on the board for a 40-pin or 42-pin chip (the mask ROM is 40-pin).

I've tried a 40-pin 27C4000 EPROM but no luck (although I believe that this SHOULD work!). Have also tried assorted 42-pin EPROMs .......... still no luck.

The size of the binary is 512K

Any ideas please?

Ta.
 
Xian Xi

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Use a MX27C4100. That's what I used for a TiT PCB. It has a slightly different pinout than the 27C4000 and can run in 8 and 16 bit modes.
 
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Thanks - how does the 4100 differ from the 4000 ? I ask as I have datasheets for both and the pinouts (and internal data specs) are exactly the same. :)
 
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Hitachi (and according to the Hitachi 27C4000 datasheet and the Macronix MX27C4100 datasheet they match exactly).
 
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IronGiant

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The 40 pin mask ROM works perfectly in both boards.

I can't read/verify the mask ROM as a 27C4000, not sure what to check it as, but I'm certain that it's fine as there are no graphics problems when it's inserted into either of the two Bells & Whistles boards that I have here. The problem is finding the EPROM equivalent.
 
mainman

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Your using the wrong chip, a 27c400=27c4100 not a 27c4000 which is a 32 pin device
 
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Xian Xi

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Probe pin 2 on the board, if it's grounded then you might need a 4002.
 
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But according to the datasheet, the (Intel and AMD) 27C400 has the same pinout and internal data layout as the 27C4000 and 27C4100. :)
 
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IronGiant

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IronGiant said:
But according to the datasheet, the (Intel and AMD) 27C400 has the same pinout and internal data layout as the 27C4000 and 27C4100. :)
Click to expand...

Pin 2 isn't Grounded, and a 4002 has a very different pinout (for example, it needs _5 volts on pin 40, yet on my board +5 is on pin 21).
 
Xian Xi

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Just read in the data sheet for the Hitachi 27C4000 that it isn't a 5v only eprom, it is a 6.25v eprom.
 
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Xian Xi said:
Just read in the data sheet for the Hitachi 27C4000 that it isn't a 5v only eprom, it is a 6.25v eprom.
Click to expand...

That's interesting - I've used HN27C4000's on other boards (Konami and otherwise) that only run at 5 volts with no problems.

Puzzling ............
 
Xian Xi

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IronGiant said:
That's interesting - I've used HN27C4000's on other boards (Konami and otherwise) that only run at 5 volts with no problems.

Puzzling ............
Click to expand...

Could be a bad chip, who knows. I've always used MX4100 and never had problems. But like I said check the data from the romset you are using a la mame.
 
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Xian Xi said:
Could be a bad chip, who knows. I've always used MX4100 and never had problems. But like I said check the data from the romset you are using a la mame.
Click to expand...

I've tried a fair few HN27C4000's but no luck. They can't all be bad. :)

I can't check the mask ROM against the MAME dump as I don't know what to read the mask ROM as (have tried a 27C4000 but it won't verify).

However, I did read the mask ROM as a 27C4000 and then program up a 27C4000 EPROM and it's NEARLY there .......... colours are much better, but the sprites have a couple of horizontal lines in them (there's no line when using the original mask ROM).

Should I trying reading it as something else?
 
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Update: Have resolved the problem!

A 27C4000 IS the correct EPROM type to use.

Causes of the problem were as follows:

a) My Galep-4 programmer wasn't correctly reading/writing 27C4000 EPROMs - once I tried my Wellon VP-280 programmer all was well (but due to point b (below) I had to read the original mask ROMs - I could then correctly program a 27C4000 from the new binary with the Wellon).

b) Most importantly, the Bells and Whistles binaries that I was using (and which I downloaded some time ago) were incorrectly dumped/corrupt. I would like to ensure that I am using the latest binaries - have they been re-dumped? If so, where is the best place to download the latest dumps? I would naturally like to verify the binaries that are being made available. Obviously they work in MAME ......... so why not when programmed onto an EPROM and used on a PCB?
 
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