Paperboy type 23256 PROM compatibility

baritonomarc

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Hi all,

my paperboy has a ROM error. I was wondering if the 23256 PROM (not programmable with my EPROM burner) may be substituted with an EPROM. For example, championship sprint System 2 board uses type 27256 EPROMs... are 23256 PROM and 27256 EPROM compatible?

thanks
 
Hi all,

my paperboy has a ROM error. I was wondering if the 23256 PROM (not programmable with my EPROM burner) may be substituted with an EPROM. For example, championship sprint System 2 board uses type 27256 EPROMs... are 23256 PROM and 27256 EPROM compatible?

thanks

Yes, you can use a 27256 in it's place.
 
Some came through with eproms, some with proms. Some even had both, it was whatever they had on hand when the board was assembled. The proms were used to save money since they are alot cheaper.
 
Ok, today i was substituting paperboy PROMs with EPROMs and noticed that there are not only 23256 but also 23128, one 2364 and one 2356(?).

Are also 23128 PROMs compatible with 27128 EPROMs? What's that 2356?? Could it be a typo error (possible considering that in the manual there are not 2356 reported)?

EDIT: Let me ask also for another thing: even if possible to use, i have not a spare 2764 to replace the 2364. I have some spare 27128 and 27256: how can i use one of those to replace the 2364? Consider that i am using MAME rom images that are ALL about 16K when decompressed...

Thanks alot :)
 
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(sorry for doubleposting)

Googling here and there i read that 27256 can be used in place of 27128 by "stacking the image twice". I need some light on this point because:

- MAME images in my hands are all 16K (the right for 256? If this is matter of "bit" and "byte" 16 should be right for 27128 EPROMs...)

- i'm really a n00b on this and don't really know how to "stack" the image twice...
 
(sorry for doubleposting)

Googling here and there i read that 27256 can be used in place of 27128 by "stacking the image twice". I need some light on this point because:

- MAME images in my hands are all 16K (the right for 256? If this is matter of "bit" and "byte" 16 should be right for 27128 EPROMs...)

- i'm really a n00b on this and don't really know how to "stack" the image twice...

The number after the 23 or 27 is the size in KiloBits. (See here)

a 27128 is 128 KBits, or 16K. A 27256 is 256 Kbit or 32K.

If you can't find 27128 EPROMS, then you can use a 27256 in it's place. You need to take the binary image for the ROM and create a new binary image that is basically two copies of the same image concatenated together.

NewImage = Image A + Image A
 
EDIT: Let me ask also for another thing: even if possible to use, i have not a spare 2764 to replace the 2364. I have some spare 27128 and 27256: how can i use one of those to replace the 2364? Consider that i am using MAME rom images that are ALL about 16K when decompressed...

Thanks alot :)

You would have to look at the pin out of the chips and see if they are compatible or not.

Here is the datasheet for the 27128:
http://pdf1.alldatasheet.com/datasheet-pdf/view/22823/STMICROELECTRONICS/27128.html

Here is the datasheet for the 2764
http://pdf1.alldatasheet.com/datasheet-pdf/view/230402/NEC/UPD2764-2.html

It looks like they would be compatible, the 2764 Pin 26 is NC (Not Connected), which on the 27128 is A13 which is the address line.

There may be other factors for compatibility such as Speed, etc... but chance are they would still work in the majority of cases.
 
Thank you very much.

Is there a freeware program that can be used to create the concatenated image? I suppose the notepad is not enought... :)

Just to state the obvious: to create the concatenated image, i only need to open the image, copy everithing from top to bottom and then paste on the first free line?
(sorry for the stupid questions)
 
Thank you very much.

Is there a freeware program that can be used to create the concatenated image? I suppose the notepad is not enought... :)

Yeah, DOS :) copy /b rom + rom combinedrom
I think that's the proper command and switch (/b for binary). (if I'm wrong, please feel free to post a correction). I don't think Notepad will work, as it won't open and save it in binary.
 
Yeah, DOS :) copy /b rom + rom combinedrom
I think that's the proper command and switch (/b for binary). (if I'm wrong, please feel free to post a correction). I don't think Notepad will work, as it won't open and save it in binary.

Hmm, DOS is not an option because i am working under Vista :(
 
Weird...I tried it on the PC with Vista before posting and it worked. I did a test with a rom file I had that was 4096 bytes and did the following:
copy /b d10 + d10 d10new
and ended up with a file called "d10new" that was 8192 bytes long.
 
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