Expansion Wierdness.

[arnoldemu]

I think Megaflash, Megarom and X-mem/x-mass fully decode the rom index.

[gerald]

Yep that one runs with no issues. Here's the results....


First X-Mem, X-Mass, PlayCity & Multiface clone.
[attach=2]


And Second Symbiface
[attach=3]


Some red appears to be an understatement.

It's clear that the expansion rom selection in not fully decoded.
I cannot do anything to fix this as there is no way to have a rom selected in the cartridge range when the symbiface is connected.
Can you tell me what ROM did you put in the symbiface ? I am surprised to see only 3 symbos/futureos instead of 4.
Also, does the cartridges game work with the symbiface connected ?

[arnoldemu]

brunword would have a similar problem Craig. It also doesn't decode the roms fully.

[CraigsBar]

brunword would have a similar problem Craig. It also doesn't decode the roms fully.

My Existing Brunword module or any potential Brunword c4cpc hack? Which I woudl LOVE by the way



Edit: Well this answers that question...


http://www.dropbox.com/s/ayfzt6425cqjj9e/2015-06-12%2019.57.38.jpg


Weirdly the forum will not let me attach this one directly, the other 2 were fine... Apparently this picture fails security checks

[Bryce]

You could add the additional decoding in between the CPC and the Symbiface, but it's a messy solution.

Yes, the MegaFlash fully decodes the address bus and ROM selection bits, so it won't clash with the C4CPC or any other fancy cartridges.

Bryce.

[CraigsBar]

You could add the additional decoding in between the CPC and the Symbiface, but it's a messy solution.

Yes, the MegaFlash fully decodes the address bus and ROM selection bits, so it won't clash with the C4CPC or any other fancy cartridges.

Bryce.

Is there any way this can be implemented? I have abandoned my X-MEM and X-MASS on the 464plus simply because I was getting annoyed with the constant power supply oddites. However I am now stuck with a plus that does not play nice with the c4cpc. Is there a possibility of a c4cpc firmware update or some other solution to resolve the problem. I realise that there is no hope of a fix on the Symbiface side, so hopefully there is a c4cpc or other hack/fix/solution


Craig

[TotO]

As read previously, the problem look to came from the SF2 ROM address decoding.
So, while you will need to use it you can't fix that on the other boards (C4CPC, ...).
May be it is possible to disable this feature to no more conflict?

[gerald]

Is there a possibility of a c4cpc firmware update or some other solution to resolve the problem. I realise that there is no hope of a fix on the Symbiface side, so hopefully there is a c4cpc or other hack/fix/solution

Even if I fix the way the CPC communicate with the C4CPC uC by using the lower rom mapping instead of  the uppper one, all of the cpr done with nocart will not work. The floppy data is accessed using the upper rom mapping. Lower rom mapping is limited to 8 banks out of 32.

[CraigsBar]

It's clear that the expansion rom selection in not fully decoded.
I cannot do anything to fix this as there is no way to have a rom selected in the cartridge range when the symbiface is connected.
Can you tell me what ROM did you put in the symbiface ? I am surprised to see only 3 symbos/futureos instead of 4.
Also, does the cartridges game work with the symbiface connected ?

Yes, cart games work. And the dip switch selection on the c4cpc also work fine. So I have a fw3.15 CPR in c4cpc slot 1 and a default cart cpr in c4cpc slot 0 and can switch between the 2 perfectly. However it's just the selector CPR that does not work. I guess I can live with 16 images for the plus. Most games are played on the gx4000 these days anyway.

[Bryce]

Unfortunately I don't have the SF2 schematics, but it should be easy enough to add the extra decoding with a single "piggy-backed" IC on one of the SF2 ICs or at worst a small daughter board, but I would need an SF2 here to test that.

Can you confirm that the SF2 really is repeating the ROMs ie: Can ROM 15 also be seen in positons 31, 47, 63 etc?

Bryce.

[CraigsBar]

If you can tell me how to check that all rom tools i have only show 0 - 31

I can always lend you a sf2 for testing as I have a spare lol. Perhaps you could check to see if the ram/rom  pld  is protected at the same time, and if not see if the overheating could be resolved by copying it to a new chip.

[Bryce]

If you can tell me how to check that all rom tools i have only show 0 - 31

I can always lend you a sf2 for testing as I have a spare lol. Perhaps you could check to see if the ram/rom  pld  is protected at the same time, and if not see if the overheating could be resolved by copying it to a new chip.

Maybe TFM or someone can write a quick routine to probe for ROMs right up to ROM Slot 128? Yes, I can check the CPLD while I'm at it. But first (before you go sending stuff around Europe) it would be good to know if that really is the problem.

Bryce.

[CraigsBar]

Indeed

[TFM]

If you can tell me how to check that all rom tools i have only show 0 - 31

You can use MAXAM and look by hand f.e.

[CraigsBar]

You can use MAXAM and look by hand f.e.

ERM... Yes, how exactly and I will.

[TFM]

ERM... Yes, how exactly and I will.

Ok, first look at your ROMs and take one which is occupied by something (but not BASIC). Let say this is number 10. 10 in hex is &0A.

- Start MAXAM with command !M,2
- Enter command S (Select upper ROM), then enter the value of your ROM (in our example 0A).
- Enter commend E (Edit memory), then enter value C000

Now you see the ROM content starting at &C000

- Enter command S (Select upper ROM), then enter the value of your ROM + &40 (in our example 4A).
- Enter commend E (Edit memory), then enter value C000


Do you see the same ROM again? If yes, then you have a ROM mirror




---------------------------------------




Other solution:

- Start MAXAM with command !M,2
- Enter command S (Select upper ROM), then enter the value of your ROM (in our example 0A).
- Enter commend M (Move memory block), enter values C000, FFFF, 4000

- Enter command S (Select upper ROM), then enter the value of your ROM + &40 (in our example 4A).
- Enter command C (Compare blocks), then enter values C000, FFFF, 4000

Now you will get differences if everything is fine. If a ROM shadow is there (bad!) then MAXAM will tell you: No differences.


Attention: The compare command needs some seconds to compare, it's ok. It didn't crash. 

[CraigsBar]

Thanks for that, yep certainly looks like the symbiface mirrors the ROMs any easy way to fix this... On the cable between the mother4x and the symbiface I guess.

[TFM]

There never was a symbiface I... but in case you talk about SF-II then I just remember that Dr. Zed (10 years ago or so) told something that he ran out of gates in that XilinX. But maybe I mix that up.


Can't somebody read out the VHDL and correct it? I lack the hardware.

[Bryce]

The device will need to intercept the buffered upper data bits and the CE Pin of the ROM (which will need to be cut). It's probably easier to do this directly on the SF2 PCB.

Bryce.

[CraigsBar]

The device will need to intercept the buffered upper data bits and the CE Pin of the ROM (which will need to be cut). It's probably easier to do this directly on the SF2 PCB.

Bryce.

So if I post you a symbiface board, could yo do the mod for me?

[Bryce]

Probably. I won't say yes, because there's a chance that some of the signals I need are only available inside the CPLD. If that's the case it will be difficult.

Bryce.

[gerald]

Can't somebody read out the VHDL and correct it? I lack the hardware.

If the VHDL was available, having a look would be easy 

Probably. I won't say yes, because there's a chance that some of the signals I need are only available inside the CPLD. If that's the case it will be difficult.

If it rely on the ROMEn signal, an easy fix is to add DFF that decode the missing upper bits and mask the ROMEn when rom selection is out of range.

[Bryce]

True, that would be a neat solution.

Bryce.

[dxs]

[ I'm late on that one but I'll still post if someone needs it one day. It's a simple basic program I found somewhere, it will tell you what ROM positions are occupied on the complete 0-255 range, and if so if you got Foreground or Background type. Usefull when checking your adress decoding actually works. Doesn't play nice with Winape but works ok on real hardware. ]

[Bryce]

Cool Very useful.

Bryce.