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This question is about the old MSX-1 computers. I have a game I wrote, as a ROM file, and I now want to play it on a real MSX computer by putting the game into cartridge form. The game has been tested on an MSX emulator and it works. So my question is what is the simplest circuit for building an MSX-1 16K ROM cartridge or 32K ROM cartridge (using modern easy to get components)?. I have an Atmel AT28C256 EEPROM available to use. I am asking for a 16K and 32K circuit because there are two versions of the game.

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  • Releasing two versions of a MSX game kinda goes against the philosophy of the MSX platform. If the full version needs 32k RAM and you want to be able to play the game on a 16k computer, perhaps you could slap 16k of RAM in the cartridge. – Dampmaskin Nov 7 at 8:33
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    github.com/apoloval/msx-cartridge ("Schematics and PCB designs of cartridges for MSX systems") doesn't seem to go below 64kb, but is it nevertheless helpful? – Tommy Nov 7 at 18:35
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    @Dampmaskin If I'm understanding correctly the two versions just require different amounts of ROM (16k vs 32k), not RAM. – mnem Nov 7 at 19:27
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    Oh, it's ROM not RAM. Ok, but what I still don't get is the purpose of having two versions of the circuit. Are there MSX machines out there that are unable to run a 32k ROM? Sorry if I'm being dense. – Dampmaskin Nov 8 at 23:24
  • Maybe have a look at github.com/apoloval/msx-cartridge (can't say if it's good though) – JeanPierre Nov 11 at 17:30
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16 KB cartridge does not require any additional components, you connect OE to the /CS1, and CE to the /SLTSL signal.

32KB cartridge also does not require any additional components, you connect OE to the /CS12 signal, and CE to /SLTSL signal.

And of course all address and data pins must be connected to the bus.

All above mentioned signals are present on the slot connector.

The design is very simple.

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So my question is what is the simplest circuit for building an MSX-1 16K ROM cartridge or 32K ROM cartridge (using modern easy to get components)?.

As described in this answer, there is no need for any additional circuitry (*1). This is true for up to 64 KiB (512 KiBit) in size. Only such larger as 64 KiB (often dubbed as Megabit cartridges) do need mapper logic/chips.

These Boards are quite simple:

enter image description here

(Picture taken from a thread on MSX.org about EPROM test boards)

I have an Atmel AT28C256 EEPROM available to use. I am asking for a 16K and 32K circuit because there are two versions of the game.

You may use the same board/circuit for both. MSX design was made with lowering cartridge cost in mind - at least for sizes imaginable in the early 80s :) Next to all boards available today (and even several from original games) are configurable.

Since MSX is well supported by new developments, several companies offer simple cartridge boards (and housings) like you need. RC.SE does not favour any such, thus use the engine of your choice and search for 'MSX Cartridge Kit' or 'Empty MSX Cartridge' or 'MSX cartridge PCB'. you'll be surprised about the offers available. Some already include Flash chips like yours.

Now, if you really want to go all the length, several comments on the question have recommended this Githup repository which, on first sight, seams quite adequate. They are made using KiCad. If KiCad isn't your thing, there's a project for a similar PCB up on EasyEDA.


*1 - A buffer capacitor to ease power issues is always welcome.

  • So to make a cartridge is it as simple as the following? So if I write by game onto an at27c256 chip and solder, with the capacitor, it into the cartridge PCB, given in the photo, in your answer, and IGNORE the modifications explained by the red lines, then will the constructed cartridge work when plugged into an MSX-1 machine? – Rosemary 2 days ago
  • @Rosemary Yes, basically it is. Except, it depends on the card you use. So pleast consider its description if one or two bridges need to be soldered as well. – Raffzahn 10 hours ago

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