Carnivore2 : First impressions and bugs...

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By 8bits4ever

Resident (51)

Аватар пользователя 8bits4ever

30-09-2017, 18:58

Alexey wrote:

Btw, I hope that 8bits4ever could give you a discount as a gratitude for your work on the English translation of the FMPAC bios.

No doubt!

max_iwamoto wrote:

So, when I receive my assembled cartridge from 8bits4ever, I will not be able to save game data in SRAM? Would be possible to update cartridge firmware and save data into FLASH so no backup battery required?

Contact us before you order; we can give you a "developer" coupon Wink

By Alexey

Guardian (3239)

Аватар пользователя Alexey

30-09-2017, 19:37

max_iwamoto wrote:

Is it hard to install the battery? Or it needs to be soldered? And to what area it will save? Would that area be damaged if you use it as RAM or some other way?

There are 2 holes on the board to soder wires from a battery. The battery must be up to 5v. A 3v Lithium battery (for example 2032) could fit, but you will need to either solder wires to its body or to place it in a battery holder somewhere inside the case and use wires to connect the holder to the board. None of us has done this so far.

I also had an idea to use "goldcaps" - powerful low-voltage capacitors as a backup power source for the RAM chip, for example those ones:
https://www.aliexpress.com/item/2Pcs-ultra-capacitor-5-5v4f-...
Those capacitors need to be connected to +5v to be always charged and then 2 wires need to be connected to the board. I bought these capacitors, but haven't modified my cartridges yet.

The FMPAC RAM area is outside of normal RAM. And uploading games into the unused megabyte of RAM using the c2ramldr utility should not affect it either.

By Vampier

Prophet (2386)

Аватар пользователя Vampier

01-10-2017, 01:52

would it be possible to intercept SRAM IO operations (read/writes) and redirect this to a file somewhere on the memory card?

By Alexey

Guardian (3239)

Аватар пользователя Alexey

01-10-2017, 02:36

Vampier wrote:

would it be possible to intercept SRAM IO operations (read/writes) and redirect this to a file somewhere on the memory card?

Not a chance. For writing to a CF card even bigger change will be needed in the firmware.

By max_iwamoto

Hero (548)

Аватар пользователя max_iwamoto

01-10-2017, 03:40

8bits4ever wrote:
Alexey wrote:

Btw, I hope that 8bits4ever could give you a discount as a gratitude for your work on the English translation of the FMPAC bios.

No doubt!

max_iwamoto wrote:

So, when I receive my assembled cartridge from 8bits4ever, I will not be able to save game data in SRAM? Would be possible to update cartridge firmware and save data into FLASH so no backup battery required?

Contact us before you order; we can give you a "developer" coupon Wink

Thank you for the offer, unfortunately my cartridge already ordered and on the way here Wink

Maybe I can order another one with CMOS battery at a discounted price so I can save data into FMPAC Wink

By Vampier

Prophet (2386)

Аватар пользователя Vampier

01-10-2017, 08:06

@Alexey: I thought I would mention it... I did something similar with openMSX once (I was the first to implement PSG2SCC for example) I don't know much about FPGA programming and how it interacts with the MSX. I guess it's all communicating with the MSX directly and there is no room for overheard and other operations outside the 'MSX realm'

By Alexey

Guardian (3239)

Аватар пользователя Alexey

01-10-2017, 13:51

Well, as you mentioned it, how did you do that? The redirection of writing into RAM to writing into FlashRom may be possible. For example writing into the last block of the Flash chip instead of RAM. But this sounds quite complicated for the firmware, you will need to "teach" the firmware how to operate the Flash chip - erasing and saving data into a fixed block. There's no space in the firmware for such complex change.

What can be done is the modification of FMPAC bios so that instead of writing into RAM, it could save the data to a fixed file on the IDE device (if it is enabled, writeable and has free space). But this means a major rework of bios code and this requires special skills. If anyone could do that, only the FMPAC bios will need to be changed. Unfortunately I don't have enough skills to write bios code.

By max_iwamoto

Hero (548)

Аватар пользователя max_iwamoto

01-10-2017, 16:57

Alexey wrote:

Well, as you mentioned it, how did you do that? The redirection of writing into RAM to writing into FlashRom may be possible. For example writing into the last block of the Flash chip instead of RAM. But this sounds quite complicated for the firmware, you will need to "teach" the firmware how to operate the Flash chip - erasing and saving data into a fixed block. There's no space in the firmware for such complex change.

What can be done is the modification of FMPAC bios so that instead of writing into RAM, it could save the data to a fixed file on the IDE device (if it is enabled, writeable and has free space). But this means a major rework of bios code and this requires special skills. If anyone could do that, only the FMPAC bios will need to be changed. Unfortunately I don't have enough skills to write bios code.

I can write the BIOS code, I just need the code on how to program FLASH. I believe 1 block of FLASH should be 8K or 64KB based on the chip you using.

By isaiasmalaga

Champion (349)

Аватар пользователя isaiasmalaga

01-10-2017, 17:25

Hello Alexey:
Could a 50 / 60Hz selector be included in the main selection menu of Roms, or in the discs executed by Emufile? This way if we use Carnivore 2 in MSX2 we can see the games at 60Hz.

Thank You!..

By Alexey

Guardian (3239)

Аватар пользователя Alexey

01-10-2017, 17:42

isaiasmalaga wrote:

Hello Alexey:
Could a 50 / 60Hz selector be included in the main selection menu of Roms, or in the discs executed by Emufile? This way if we use Carnivore 2 in MSX2 we can see the games at 60Hz.
Thank You!..

Isn't that a hack? Technically such modification is possible in the boot block. The selected 50/60 Hz state can even be saved into the small EEPROM, like the volume setting. But what is the benefit?

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