Did SofRun 0.8 just erased my Omega MSX ROM ?

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By retrocanada76

Hero (538)

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16-05-2022, 23:01

Hi Louthrax,

Yes setting the default device to MegaRAM avoids the problem for now.

But the wrong detection of MFR SCC seems an issue. I don't have one, just the Mapper/Megaram SD. Notthing more. I do have a MFR SCC+ and it worked fine with the OPFX.COM. Didn't try SofaRun with it though.

By gdx

Enlighted (5491)

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17-05-2022, 02:50

According the picture at the link above, it's the jumper JP1.

When i made the Rom loader set (FL, FL8, FL16 and FLK4), i added a condition to avoid overwriting the flash ROM in Disk-ROM slot in the automatic search of the Rom flash mode. I (and Louthrax) also have to do this for the Main-ROM and Sub-ROM slots. That would fix the problem.

By retrocanada76

Hero (538)

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17-05-2022, 06:28

Sorry but it makes no sense to me. JP1 is just a bank select not a write protection, look the schematics.

In fact I see no protection at all in the schematics.

By retrocanada76

Hero (538)

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17-05-2022, 06:40

The omega spec asks for a SST39SF040 but I am using a MX29F040. This is because I bought a stupid kit on ebay instead of buying each component alone. And if you look the schematics (and I believe the MFR SCC uses the same flash) the MX29 uses the address 0x0555 for command address where the SST39S uses 0x5555. So I guess if you follow the specs you should not have this problem.

By gdx

Enlighted (5491)

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17-05-2022, 09:57

You are right, I read the other forum too quickly. There is no location. JP1 is used to switch between MSX2 and MSX2+ BIOSes (so useless).

So you have to add a switch as I said before. I think if you do as shown below dotted it should work.

The track must be cut (or pin lifted) to add the switch, so do it only if you are sure.

By retrocanada76

Hero (538)

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23-05-2022, 09:58

You know I think you are not wrong about the jumper to protect the flash. That's a side-effect.

The jumper function is to access the upper 256K bank but the programming codes for the flash they happen at the 0555h address for the MX29 and 5555h for the SST39. Setting the upper bank has as a side effect a flash protection because you cannot physically access the programming addresses anymore.

But again Sofa Run erases the MX29F040 (the same used in MFR SCC) but not the SST39SF040 as specified by omega. Anywa the jumper will protect both.

By retrocanada76

Hero (538)

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23-05-2022, 10:12

Forget what I just said...

". The system should generate the following address patterns: 555H or 2AAH to Address A10~A0 .
Address bit A11~A18=X=Don't care for all address commands except for Program Address (PA) and Sector
Address (SA). Write Sequence may be initiated with A11~A18 in either state"

SofaRun just erase my flash again :/

By retrocanada76

Hero (538)

retrocanada76's picture

24-05-2022, 00:24

Hey Lothrax,

You should consider adding to a future Sofa Run the logic to avoid false detecting the MFR (or any other flash). That' s simple: check if the detected flash rom is sitting on slot 0. If so, you have a flashrom bios (danger!). You can confirm the omega by probing slots 3-0, 3-1 and 3-2. If they all report the same flash rom device id then you indeed have an omega.

By gdx

Enlighted (5491)

gdx's picture

24-05-2022, 00:50

What is the omega's slots map? I would like to put it in the wiki.

retrocanada76 wrote:

You should consider adding to a future Sofa Run the logic to avoid false detecting the MFR (or any other flash). That' s simple: check if the detected flash rom is sitting on slot 0.

As I said above, it must probably check if the detected flash rom is not on the Main-ROM, Sub-ROM and Disk-ROMs slots. I.e. compare with system variables FCC1h, 0FAF8h and 0FB21h, 0FB23h, 0FB25h and 0FB27h. In fact, it depends on the page used to look for the Flash ROM. It may not be necessary for the Sub-ROM.

By retrocanada76

Hero (538)

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24-05-2022, 18:54

Slot 0 - 0x0000 - 0x7FFF - Main ROM (mapped to Flash ROM 0x00000 - 0x07FFF) - 32K
0x8000 - 0xBFFF - Logo ROM (mapped to Flash ROM 0x08000 - 0x0BFFF) - 32K
Slot 1 - External slot
Slot 2 - External slot
Slot 3-0 - 0x0000 - 0x3FFF - Sub ROM (mapped to Flash ROM 0x10000 - 0x13FFF) - 16K
Slot 3-0 - 0x4000 - 0xFFFF - User ROM #0 (mapped to Flash ROM 0x14000-0x1FFFF) - 48K
Slot 3-1 - 0x0000 - 0xFFFF - User ROM #1 (mapped to Flash ROM 0x20000 - 0x2FFFF) - 64K
Slot 3-2 - 0x0000 - 0xFFFF - Main RAM (memory mapper)
Slot 3-2 - 0x0000 - 0xFFFF - User ROM #2 (mapped to Flash ROM 0x30000 - 0x3FFFF) - 64K

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