Cartridge with Ram inside?

[youki]

Hi,

 

Question to coleco's hardware gurus.

 

Would it be possible to create a cartridge that would contain for instance 28k of ROM and 4k of ram , and that that ram could be adressed directly to read and write?

 

Does lord of the dungeons uses this kind of cartridge?

 

thanks

[Pixelboy]

From what I've been told, the ColecoVision lacks the ability to write data to the cartridge ROM adress space, in the way you are proposing. There's probably a way to implement RAM inside the cartridge via an indirect and complicated method (in a similar way to the EEPROM I/O method in my Activision PCB) but ultimately, you're better off just creating a RAM expansion cartridge that plugs into the front expansion port of the CV console. The electronics will be easier to design and manufacture, and this setup will also be much easier to use software-wise, because you'll simply be using the "reserved for expansion" address space (2000h to 5FFFh, if I remember correctly) as RAM.

 

Creating the electronics of a RAM expansion cart is the easy part, if you can find a good source for female connectors, that is. The real challenge is the plastic casing. One thing you can do is reuse the casing from an ADAM AutoDialer, which is perfect for such a purpose, given that your RAM expansion PCB is designed to fit precisely inside it. If you're ready and able to put more money into it, you can ask a plastics company to take the Adam AutoDialer and create a metal mold which will allow you to manufacture all the RAM carts you want.

 

But all this is moot, since Opcode has already created such a RAM expansion, which is just one of the features of the SGM.

[+5-11under]

Hi Youki,

 

The PCB for the LotD re-release uses 24K ROM plus 2K RAM (volatile or non-volatile is fine). I haven't tested it yet, but the new PCB was also designed to handle 24K ROM plus 4K RAM (volatile only - gets erased on power-off). The amount of "space" required for the RAM is double, because you need 1 set for writing, and 1 set for reading (no access to R/W line). The 2K RAM set-up is obviously the same as LotD; the 4K RAM set-up has the upper 4K as read (up to FFFF), below that is 4K for write, and the lower 24K is for the ROM, of course.

 

If you have a program available sometime, I could easily test the 4K RAM mode for you.

 

I have plenty of these PCBs still available, since I thought they might be useful for some SG-1000 conversions in the least (if <24K ROM). This is a relatively low cost solution (J-F, it's a fair bit less than the LotD if regular RAM is used ). In the future, Retroillucid and I will have the WaferCart available, which will be more powerful (bankswitched ROM/RAM), but will cost more.

[Pixelboy]

Hi Youki,

 

The PCB for the LotD re-release uses 24K ROM plus 2K RAM (volatile or non-volatile is fine). I haven't tested it yet, but the new PCB was also designed to handle 24K ROM plus 4K RAM (volatile only - gets erased on power-off). The amount of "space" required for the RAM is double, because you need 1 set for writing, and 1 set for reading (no access to R/W line). The 2K RAM set-up is obviously the same as LotD; the 4K RAM set-up has the upper 4K as read (up to FFFF), below that is 4K for write, and the lower 24K is for the ROM, of course.

 

If you have a program available sometime, I could easily test the 4K RAM mode for you.

 

I have plenty of these PCBs still available, since I thought they might be useful for some SG-1000 conversions in the least (if <24K ROM). This is a relatively low cost solution (J-F, it's a fair bit less than the LotD if regular RAM is used ). In the future, Retroillucid and I will have the WaferCart available, which will be more powerful (bankswitched ROM/RAM), but will cost more.

Well, I guess I stand corrected.

[youki]

humm.. it is what i was afraid of. The hardware prevent to write on Cartridge space even if it is ram.

 

I don't like the idea to put something on the expansion port to play a game i would do.

 

#edit...oups... i didn't read that 5-11under posted ... i come back!

Edited February 10, 2011 by youki

[youki]

Hi Youki,

 

The PCB for the LotD re-release uses 24K ROM plus 2K RAM (volatile or non-volatile is fine). I haven't tested it yet, but the new PCB was also designed to handle 24K ROM plus 4K RAM (volatile only - gets erased on power-off). The amount of "space" required for the RAM is double, because you need 1 set for writing, and 1 set for reading (no access to R/W line). The 2K RAM set-up is obviously the same as LotD; the 4K RAM set-up has the upper 4K as read (up to FFFF), below that is 4K for write, and the lower 24K is for the ROM, of course.

 

If you have a program available sometime, I could easily test the 4K RAM mode for you.

 

I have plenty of these PCBs still available, since I thought they might be useful for some SG-1000 conversions in the least (if <24K ROM). This is a relatively low cost solution (J-F, it's a fair bit less than the LotD if regular RAM is used ). In the future, Retroillucid and I will have the WaferCart available, which will be more powerful (bankswitched ROM/RAM), but will cost more.

 

it sounds very interresting. Now the question, is there an emulator that is able to emulate that mode? And does AtariMax cartridge could handle that as well?

 

thanks

[+5-11under]

Hi Youki,

 

The PCB for the LotD re-release uses 24K ROM plus 2K RAM (volatile or non-volatile is fine). I haven't tested it yet, but the new PCB was also designed to handle 24K ROM plus 4K RAM (volatile only - gets erased on power-off). The amount of "space" required for the RAM is double, because you need 1 set for writing, and 1 set for reading (no access to R/W line). The 2K RAM set-up is obviously the same as LotD; the 4K RAM set-up has the upper 4K as read (up to FFFF), below that is 4K for write, and the lower 24K is for the ROM, of course.

 

If you have a program available sometime, I could easily test the 4K RAM mode for you.

 

I have plenty of these PCBs still available, since I thought they might be useful for some SG-1000 conversions in the least (if <24K ROM). This is a relatively low cost solution (J-F, it's a fair bit less than the LotD if regular RAM is used ). In the future, Retroillucid and I will have the WaferCart available, which will be more powerful (bankswitched ROM/RAM), but will cost more.

 

it sounds very interresting. Now the question, is there an emulator that is able to emulate that mode? And does AtariMax cartridge could handle that as well?

 

thanks

I can't remember if BlueMSX will allow you to change the RAM set-up. It's pretty close to the LotD set-up, so it should be easy for either a user or the programmers of BlueMSX to add. At the same time, if required, I'm sure steve/classics could easily add the 24K+4K mode to the SD multicart.

[+Yurkie]

 

it sounds very interresting. Now the question, is there an emulator that is able to emulate that mode? And does AtariMax cartridge could handle that as well?

 

thanks

 

Being that the SD multi-cart is like a mini computer there may be some good games possible if the Programmer works with Steve Tucker. This could be a game that is released on an SD card. This could help Steve sell the remaining inventory of SD multi-carts too.

[classics]

The SD multi-cart support a hybrid mode where you can read/write the entire 512KB of RAM via bank switching.

 

You enable windows that are 'write only', then bank switch back to locked read only after making your writes to memory. The method and bank switching scheme are documented here:

 

http://www.atarimax.com/flashcart/forum/viewtopic.php?f=15&t=951&start=15

 

The cartridge also supports the LoD method of read/write to cartridge RAM, which is similar just with a lot less RAM. If you wanted to implement save RAM in a cartridge for very little cost, the LoD method would work well, at the cost of some ROM area.

 

Steve