I want to make my own cassette for the Famicom.
- Information collection
- Find the cassette substrate of the mapper 0.
- Find the EPROM.
To make my own ROM cassette, I need to do the following :.
- Obtain a cassette board
- Writing programs and data in ROM
- Replace the ROM on the cassette board with the ROM on which it was written.
Substrate of the cassette
There are many different types of circuit boards in the cassettes of Famicom. This is because the amount of program and image data that can be accessed by the CPU and PPU of the Nintendo-Famicom is not enough to make the game more interesting and elaborate, and because complex memory access is required.
For this reason, a function has been added to the cassette to convert only necessary areas in the large memory space that cannot be directly accessed by the Nintendo-Famicom. This special circuit is called a mapper and has more than 100 types.
The top board is the board for “Passion！Professional Baseball”.
It is a highly functional cassette with a 1M bit character ROM, a 512k bit program ROM, and an audio playback IC.
This time, I want to make a board called the mapper 0 which is simple and has no special circuit.
There are 3 main types of ROMs that can be written to and erased.
- UV EPROM
- Flash ROM
About 13V is required to write data.
The 32 KBytes (256 kbit) EPROM model number is 27 C 250 6.
The data sheet also described the writing procedure.
This is an EPROM that can be electrically erased because it is troublesome to erase the EPROM.
Since it is a relatively new IC, the pin pitch is narrow, but if you can convert this pitch, you can use it in the Famicom.
EPROM and EEPROM can be written with the above writer.
I may be able to write if I convert pins, but I don’t know.
Even if you don’t have a writer, if you follow the writing procedure of the data sheet, you can write using arduino.
Find the cassette substrate of the mapper 0.
Search titles in Nintendo-Famicom Cart Database
You can find which game title is the number of the mapper on the site called “NES Cart Database”.
Search results are here.
110 titles found.
Purchased at a recycling shop
I bought “4 hit mah-jongg”x3 and “baseball”x2.
I bought “mah-jongg” as a bonus.
Now, is there a usable board?
Result of the shell cracking
4 hit mah-jongg
I bought 3 different types.
831018, 851224, 880920.
I opened them.
Other than that, the IC was directly attached to the substrate and sealed.
The way of making is different depending on the lot.
I bought an old label and a newer one with a picture on it.
The mah-jongg I bought as a bonus was a type with IC directly on the board.
Mapper 0 Get 2 Boards
If I need more in the future, I will buy 831018 “4 hit mah-jongg” or a “baseball”with pictures.
Find the EPROM.
Which EPROM to use
Another reason is that it is easy to obtain.
We decided not to use flash ROM because we have to make a conversion board.
If you search by 27 c 6, there are many.
It is important to include “NEW” in the search.
Some cheap shops sell used ROM.
There are some shops that have a lot of orders, so you should avoid them if there is used information in the feedback.
Please refer to this article for information on how to get a refund.
This article happened a long time ago, so it’s much easier now.
I don’t need used ones).
If the shop owner is a good person, he may ask you “Used but OK?” and the possibility of sending a new one may increase.
UV EEPROM Get
I don’t know if it’s genuine.
Also, I think I’ll make a device to erase ultraviolet rays.
2019.6.4 Postscript : I experimented with lighting an ultraviolet light bulb.