Do you have a Sound Cartridge?

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By sdsnatcher73

Paragon (1523)

sdsnatcher73's picture

26-01-2021, 03:03

It is odd, I also expected the PCB to be the same and RAM just shifted on that PCB. It is possible that although very similar the PCBs are not entirely identical and the address lines on the SCC-I are connected differently.

BTW, did you notice the Snatcher cart registers an O on position FF? I suspect that is caused by a bug in your program, but I am not 100% sure.

By gdx

Prophet (4045)

gdx's picture

26-01-2021, 10:14

sdsnatcher73 wrote:

BTW, did you notice the Snatcher cart registers an O on position FF? I suspect that is caused by a bug in your program, but I am not 100% sure.

I noticed this also on OpenMSX with Snatcher. The last segment always remains filled with FFh, and since my program fills the segments with their segment number, the values read are same, so the routine thinks that the segment works.

Now that you've confirmed this oddity on real hardware, I refined the checking routine for the last segment, and the update is already done.

Download:
https://mon-partage.fr/f/m8oWAqEa/

I would like more feedback to close this story.

If you have an MFR SCC+ SD, you have to press the S key during the MSX start up and probably run SCRT from another disk interface.

If you have an Carnivore 2, see the paragraph "Notes for SCC+ mode" in the documentation.

By Pencioner

Scribe (1335)

Pencioner's picture

26-01-2021, 12:35

sdsnatcher73 wrote:

It is possible that although very similar the PCBs are not entirely identical and the address lines on the SCC-I are connected differently.

or even that PCBs are entirely identical but SCC and SCC-I differs internally (so same extrnal pins are really different address lines)

By sdsnatcher73

Paragon (1523)

sdsnatcher73's picture

26-01-2021, 13:03

The chips on both cartridges are SCC-I and have the same model numbers printed on them. Having different chips for such a variation seems unlikely (because it would be costly imho). The same goes for the board probably.

I think I may have spotted the difference. Above the chips on the right hand side there are 2 holes in the PCB, on the Snatcher cart they seem not filled and on SD Snatcher cart they are filled. This could work like a jumper (and possibly pull up one address line?).

By ToriHino

Hero (641)

ToriHino's picture

26-01-2021, 18:05

For what it's worth Tongue

I tried various combinations of booting with or without S pressed, run it from SD or from floppy but most of the times it is frozen (and one time a spontaneous reset) right after the text 'SCC+ RAM Checking...' (tried it on Turbo-R with MFR SCC+ and a Sony MSX2+ with the same MFR SCC+). Only once or twice it did show the RAM test, with all segments marked as 'BAD' which is expected.

Also tested it on GR8NET, which always shows cartridge found in slot 1-3 with all segments marked 'BAD' (probably also as expected).

Note that, although indeed it is very strange behavior, I am pretty sure the MFR is working fine, never had any issues with it until now.

By sdsnatcher73

Paragon (1523)

sdsnatcher73's picture

26-01-2021, 20:50

I tested Carnivore2 with the special SCCPLUS.RCP preset and it behaves exactly like the Popolon Cartridge.

By aoineko

Expert (94)

aoineko's picture

26-01-2021, 23:23

With SCRT 4.0 I only have XXX on my two cartridges :
- Mega Flash ROM SCC (4 Mb)
- Mega Flash ROM SCC+ SD (64 Mb)

EDIT : For the MFR SCC+ SD, I was enable to launch my SD-Padial even if I press 'S' to skip the MFR startup. As a result, I tested by launching the program from the MFR.

By gdx

Prophet (4045)

gdx's picture

27-01-2021, 02:38

sdsnatcher73 wrote:

I think I may have spotted the difference. Above the chips on the right hand side there are 2 holes in the PCB, on the Snatcher cart they seem not filled and on SD Snatcher cart they are filled. This could work like a jumper (and possibly pull up one address line?).

Right, the diffenrece is here:

There may be another under the chips.

By gdx

Prophet (4045)

gdx's picture

28-01-2021, 15:31

I updated SCRT to the v.0.5. I modified the SCC detection to search the SCC+ only. You can find it on GitHub. I will add it later in downloads.

By NYYRIKKI

Enlighted (5693)

NYYRIKKI's picture

28-01-2021, 17:36

gdx wrote:
sdsnatcher73 wrote:

I think I may have spotted the difference. Above the chips on the right hand side there are 2 holes in the PCB, on the Snatcher cart they seem not filled and on SD Snatcher cart they are filled. This could work like a jumper (and possibly pull up one address line?).

Right, the diffenrece is here:

I don't believe the filled / not filled is the issue... but if you look the DRAM pin 4 (/WE) you can clearly see it is implemented differently.

Ps. Note that in the pic SD-Snatcher is using older RAM chips than Snatcher. :)

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