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EPROM Equivalent for a 23C16000-15 Mask Rom


Berty

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Not nearly the same, and even have different pin count.

27C800 is a 1Mb ROM with 18 address bits.

23C16000 has 19 address bits, for which there is no reason unless the ROM is greater than 1Mb.

 

To read it you could put it in a programmer with pins 1 & 44 hanging off the edge of the socket and read it with software that expects a 27C800.

Read it the first time with A19 (pin 43) tied high, and again with A19 tied low, and those will be two completely different files.

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Was thinking you could use those two 27C800 on the board if you can make a small PCB carrier for both of them and a 74HC04.

Cascade two inverters in the 7404 by connecting the output of one into the input of another.

Connect the PCB pin for A19 to the input of the first inverter, and the output of the first inverter to the CS/Enable pin of the second EPROM,

and connect the output of the second inverter to the CS/Enable pin of the first EPROM (the one who’s file was read with 23C16000 A19 pin tied high).

All the rest of the EPROM pins should be in parallel, and piggyback all of those to the game PCB.

It’s courtesy to tie the four unused inputs of the 74HC04 permanently low or high.... and done.

 

This is all assuming you can’t just buy an EPROM version of the 23C16000 mask ROM.

 

I’ll bet you didn’t like the answer :D

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Was thinking you could use those two 27C800 on the board if you can make a small PCB carrier for both of them and a 74HC04.

Cascade two inverters in the 7404 by connecting the output of one into the input of another.

Connect the PCB pin for A19 to the input of the first inverter, and the output of the first inverter to the CS/Enable pin of the second EPROM,

and connect the output of the second inverter to the CS/Enable pin of the first EPROM (the one who’s file was read with 23C16000 A19 pin tied high).

All the rest of the EPROM pins should be in parallel, and piggyback all of those to the game PCB.

It’s courtesy to tie the four unused inputs of the 74HC04 permanently low or high.... and done.

 

This is all assuming you can’t just buy an EPROM version of the 23C16000 mask ROM.

 

I’ll bet you didn’t like the answer :D

 

I like the answer, but after looking at the layout of the PCB I don't know how I could physically fit this in the space I have available.

 

I'm going to go on the hunt for an original set of mask roms now. Thanks heaps @xArtx

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Can anyone confirm if a 27C800 is an equivalent to a 23C16000 mask rom? The only reference I can find is from here; http://www.jammarcade.net/donpachi-atlus-repair-log/

 

Or, if I dump the mask rom, is there a way to understand what chip might be compatible?

A 27C160 eprom should be a good starting point for you. A quick look at the pinouts on the phone showed they are very similar.

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A 27C160 eprom should be a good starting point for you. A quick look at the pinouts on the phone showed they are very similar.

 

^^ THIS!

 

http://www.datasheetarchive.com is your friend.

 

HOWEVER, check the state of pins 11 and 13 when the ROM is enabled. The polarity of the Chip Enable and Output Enable pins are user selectable on that mask ROM. If they are active high then you'll need to invert them to use the 27C160.

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^^ THIS!

 

http://www.datasheetarchive.com is your friend.

 

HOWEVER, check the state of pins 11 and 13 when the ROM is enabled. The polarity of the Chip Enable and Output Enable pins are user selectable on that mask ROM. If they are active high then you'll need to invert them to use the 27C160.

 

Howdy - dumb question but how does one go about inverting these outputs in practice?

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