Author Topic: X-MEM, a new memory expansion for all CPC.  (Read 112111 times)

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Offline SyX

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Re: X-MEM, a new memory expansion for all CPC.
« Reply #150 on: 04:39, 12 June 14 »
I recall from MegaFlash Progress that ROMDIS 7 wasn't considered possible on (at least some of) the "classic" CPCs (any replacement DOS without hardware mod had to use a lower and potentially incompatible ROM number),
No, it's not possible to replace ROM 7 without a hardware mod, because those CPCs not disable this rom when the ROMDIS pin is enabled, it's an Amstrad bug.

But having Parados in ROM 6 (and i have used that config since the first day of my Megaflash) is not incompatible per se (even uses the same work ram than amsdos), it's more a problem of faulty software that only reinitialize the ROM 7, the same case of software that only works from drive A or software that crash the keyboard in CPC+.

As in last two cases, you need to get a fixed version or fix yourself the software to initialize the position of your Parados ROM or even better, all the roms in case you have other disc/hd roms. This is something pretty easy to do and i need to find yet a program that doesn't let me to patch it.

Offline OCT

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Re: X-MEM, a new memory expansion for all CPC.
« Reply #151 on: 09:44, 12 June 14 »
I recall from MegaFlash Progress that ROMDIS 7 wasn't considered possible on (at least some of) the "classic" CPCs (any replacement DOS without hardware mod had to use a lower and potentially incompatible ROM number),
but feasible on the Plus (with the replacement such as ParaDOS still appearing at number 7 when in X-MEM?).
No, it's not possible to replace ROM 7 without a hardware mod, because those CPCs not disable this rom when the ROMDIS pin is enabled, it's an Amstrad bug.
So unlike we assumed in the thread linked above, this hardware bug persists on the Plus?
I thought ROMDIS had been fixed for the CPC6128plus, hasn't it?
Quote
But having Parados in ROM 6 (and i have used that config since the first day of my Megaflash) is not incompatible per se (even uses the same work ram than amsdos), it's more a problem of faulty software that only reinitialize the ROM 7, the same case of software that only works from drive A
Sure, Vortex and Dobbertin also used the "lower ROM number" workaround at least as an option, but not much software will get fixed after 30 years (though arguably most of us know CPC MC down to opcode level and your program will come to help :) ).

Offline TotO

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Re: X-MEM, a new memory expansion for all CPC.
« Reply #152 on: 10:10, 12 June 14 »
The ROM7 have to be provided by the floppy drive expansion to be compatible with all CPC and programs.
The ROM7 is not intended to be disabled, because it handle hardware than should make for CPC no more working properly.

Than mean:
- A CPC w/o floppy drive don't have to provide a ROM7.
- The DDI-1 external expansion provide the ROM7 and the floppy controller.
- The CPC 6128 and 6128 PLUS internal expansion provide the ROM7 and the floppy controller.
- An external ROM Board shouldn't provide the ROM7, because it not provide a floppy controller.

Parados (or any other DOS) should be used instead of AMSDOS (physically replacing it) or after the AMSDOS initialization.
If programs are not properly written and don't allow to work under ROM 7, don't use them. (they probably done more bad things)
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Offline CraigsBar

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Re: X-MEM, a new memory expansion for all CPC.
« Reply #153 on: 11:08, 12 June 14 »
The ROM7 have to be provided by the floppy drive expansion to be compatible with all CPC and programs.
The ROM7 is not intended to be disabled, because it handle hardware than should make for CPC no more working properly.

Than mean:
- A CPC w/o floppy drive don't have to provide a ROM7.
- The DDI-1 external expansion provide the ROM7 and the floppy controller.
- The CPC 6128 and 6128 PLUS internal expansion provide the ROM7 and the floppy controller.
- An external ROM Board shouldn't provide the ROM7, because it not provide a floppy controller.

Parados (or any other DOS) should be used instead of AMSDOS (physically replacing it) or after the AMSDOS initialization.
If programs are not properly written and don't allow to work under ROM 7, don't use them. (they probably done more bad things)

As far as parados is concerned this is not true. Parados is a direct replacement for amsdos. Half of the parados EPROM is  basically a amsdos clone with all the funky stuff in the other half, where a normal amsdos EPROM has Dr logo.

So parados in slot 7 (as I have in my symbifaces) firstly does disable the internal. Amsdos, but is also 100% compatible with all software. Parados in slot 7 is the way to go.

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Offline TotO

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Re: X-MEM, a new memory expansion for all CPC.
« Reply #154 on: 11:38, 12 June 14 »
Parados is not an exception. It's a ROM like others and only its priority allow it to replace previous code into the memory.
If you put it at ROM 7, yes it fully replace AMSDOS. (like other DOS)
If you put it at ROM 6,5,4,3,2,1, it will override the ROM 7. (like other DOS)
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Offline CraigsBar

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Re: X-MEM, a new memory expansion for all CPC.
« Reply #155 on: 12:11, 12 June 14 »
Parados is not an exception. It's a ROM like others and only its priority allow it to replace previous code into the memory.
If you put it at ROM 7, yes it fully replace AMSDOS. (like other DOS)
If you put it at ROM 6,5,4,3,2,1, it will override the ROM 7. (like other DOS)

Except romdos and rodos both need amsdos to work and therefore if you put them in slot 7 they don't work, and neither does the disc drive. Because parados also has a amsdos clone in the first half of the EPROM it can be put in slot 7 to completely replace amsdos.

And therefore it will work even if software does only initialise slot 7, whereas romdos and rodos are incompatible in these situations.

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Offline TotO

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Re: X-MEM, a new memory expansion for all CPC.
« Reply #156 on: 12:51, 12 June 14 »
They are not DOS, but DOS patchs. (or upgrade if you prefer)
It's better because, as AMSTRAD done, the ROM7 was not intended to be replaced.
« Last Edit: 12:56, 12 June 14 by TotO »
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Offline CraigsBar

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Re: X-MEM, a new memory expansion for all CPC.
« Reply #157 on: 13:00, 12 June 14 »
They are not DOS, but DOS patchs. (or upgrade if you prefer)
It's better because, as AMSTRAD done, the ROM7 was not intended to be replaced.

With the exception of Parados, which is designed to be used in slot 7, a task it does perfectly.
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Offline TotO

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Re: X-MEM, a new memory expansion for all CPC.
« Reply #158 on: 13:12, 12 June 14 »
As no CPC allow to replace the ROM7 without hacking... no.
The fact that it work fine is an other thing. (thank to the authors for it)
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Offline CraigsBar

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Re: X-MEM, a new memory expansion for all CPC.
« Reply #159 on: 13:20, 12 June 14 »
As no CPC allow to replace the ROM7 without hacking... no.
The fact that it work fine is an other thing. (thank to the authors for it)

I am not sure on this point either.
My symbiface replace slot 7 without and hardware mod on the plus. I cannot remember if it does the same on the Cpc tho.

Craig

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Offline TotO

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Re: X-MEM, a new memory expansion for all CPC.
« Reply #160 on: 13:28, 12 June 14 »
Sure, putting Parados at ROM 7 work as it's a full DOS.
Probably, the PLUS not avoid to replace it like the 6128/DDI-1 does.

To be CPC friendly, the best is to not done thinks that not work on all of them.
Personally, I don't use Parados because it's useless today. (but everybody is free to do what they wants...)
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Online gerald

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Re: X-MEM, a new memory expansion for all CPC.
« Reply #161 on: 13:41, 12 June 14 »
I am not sure on this point either.
My symbiface replace slot 7 without and hardware mod on the plus. I cannot remember if it does the same on the Cpc tho.
The plus is the only one that allow disabling ROM7 externally. While on 464 the AMSDOS ROM is on socket and can be easily replaced by PARADOS one, on 664 and 6128 you need to unsolder the internal ROM for doing so. That's not an easy task !


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Offline TotO

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Re: X-MEM, a new memory expansion for all CPC.
« Reply #162 on: 14:07, 12 June 14 »
While on 464 the AMSDOS ROM is on socket and can be easily replaced by PARADOS one
On DDI-1 I suppose? Or magic 464? :D
In this case, you have to know that is not always socketed and some are soldered too. (need to find the pictures)
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Offline OCT

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Re: Reasons for alternate ROM 7 via X-MEM
« Reply #163 on: 14:50, 12 June 14 »
Sure, putting Parados at ROM 7 work as it's a full DOS.
Probably, the PLUS not avoid to replace it like the 6128/DDI-1 does.
The ROM 7 replacement being the most inconvenient on the Plus (as cartridge clones incl. ACID are not commonly available), it should be tested whether PARADOS (or a Vortex variation) can actually be installed on X-MEM slot 7 and toggled on the fly to switch between AMSDOS and its replacement(s) between resets.
In the affirmative, this is a feature worth advertising.

BTW, for your MotherX4 board, wouldn't a reset and pause switch (the latter possibly with a clock divider these days to obtain a synchronous version of the CPC-Bremse / Slow-Motion, as seen here) prove a useful addition with very minimal components?

Quote
To be CPC friendly, the best is to not done thinks that not work on all of them.
Au contraire, as a replacement ROM 7 can be piggy-backed on the original one (unsoldering just one Enable pin thereof) on the classic CPCs (where the lack of ROMDIS ought to be considered nothing but a routing flaw) but not on the Plus.
Quote
Personally, I don't use Parados because it's useless today. (but everybody is free to do what they wants...)
"Useless" unless you need its (or any other DOS's) utilities and/or have a pile of aging disks of various sizes that need to be salvaged to image files before they demagnetize entirely.
« Last Edit: 15:17, 12 June 14 by OCT »

Offline Munchausen

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Re: X-MEM, a new memory expansion for all CPC.
« Reply #164 on: 14:55, 12 June 14 »
As no CPC allow to replace the ROM7 without hacking... no.
The fact that it work fine is an other thing. (thank to the authors for it)


Is it not ROM7 that can be used externally on some 6128s and not others? IIRC I have at least one 6128 where it _does_ work, and on my other two it does not.

Offline TotO

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Re: Reasons for alternate ROM 7 via X-MEM
« Reply #165 on: 14:56, 12 June 14 »
Au contraire, as a replacement ROM 7 can be piggy-backed on the original one (unsoldering just one Enable pin thereof)
That is hack.
There is enough space free on the ROM boards to put it under ROM 7 if needed.

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Offline OCT

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Re: Reasons for alternate ROM 7 via X-MEM
« Reply #166 on: 15:05, 12 June 14 »
That is hack.
Of course, but as I suggested in X-MEM, a new memory expansion for all CPC. (see also with respect to the MotherX4 Board) ...
There is enough space free on the ROM boards to put it under ROM 7 if needed.
... there just isn't that space inside a Plus cartridge.
Hence the Plus is where an override for ROM 7 would be particularly useful, if you find it does work after all.
« Last Edit: 15:12, 12 June 14 by OCT »

Offline OCT

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Re: Overriding internal/cartridged ROM 7
« Reply #167 on: 15:08, 12 June 14 »
Is it not ROM7 that can be used externally on some 6128s and not others? IIRC I have at least one 6128 where it _does_ work
Probably one of the later "cost-down" versions that pre-empted some of the Plus circuitry?
That would support my point that the trace for ROMDIS 7 was probably forgotten (rather than omitted on purpose) when AMSDOS got bolted on in the usual hurry, then fixed in later revisions.
« Last Edit: 15:10, 12 June 14 by OCT »

Offline CraigsBar

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Re: X-MEM, a new memory expansion for all CPC.
« Reply #168 on: 15:14, 12 June 14 »
Oh Christ. Now I am going to have to check my scheider cpc 6128 and UK cpc 6128 tonight.
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Offline TotO

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Re: Reasons for alternate ROM 7 via X-MEM
« Reply #169 on: 15:37, 12 June 14 »
Of course, but as I suggested [...] there just isn't that space inside a Plus cartridge.
Hence the Plus is where an override for ROM 7 would be particularly useful, if you find it does work after all.
I don't plane to allow features on some CPC that not work on others. The goal is to reassemble the community, not to share it.
But, the PLUS can be used with ROM boards, like CPC does. Just put Parados in ROM 6. :D
What are the program that cause problems?
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Offline arnoldemu

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Re: Overriding internal/cartridged ROM 7
« Reply #170 on: 15:43, 12 June 14 »
purpose) when AMSDOS got bolted on in the usual hurry, then fixed in later revisions.
This suprised me:

"The games demo’d at the launch were loaded in off a floppy drive hooked up to the back of the demonstration 464."

at the launch of the 464 itself, there were disc drives and software loaded off it!!!

My games. My Games
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Offline OCT

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Re: Reasons for alternate ROM 7 via X-MEM
« Reply #171 on: 16:11, 12 June 14 »
I don't plane to allow features on some CPC that not work on others. The goal is to reassemble the community, not to share it.
I for one ain't ringing no division bell either: ;)
All I'm asking is whether the cartridge ROM 7 can be overridden just like ROM 0 by one from the X-MEM (in my cart at CentPourCent.net sure enough!).
If this works (if only because you don't take any measures to prevent it), nothing is taken away from any classic system anyway. :)
Rather, the Plus is made more compatible without a need for building bootleg cartridges with patched ROMs.
You certainly see people appreciate that in a Symbiface et al.

Similarly, the suggestion of adding Pause/SloMo besides Reset to the MotherX4 Board is simply something that comes to mind at first glance (again just sharing the thought rather than building my own on an MX4 connector).

Online gerald

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Re: Overriding internal/cartridged ROM 7
« Reply #172 on: 16:13, 12 June 14 »
Probably one of the later "cost-down" versions that pre-empted some of the Plus circuitry?
No, no, no  :D : Look at Arnold4 - CPCWiki
As for these CPC that works with external ROM 7, this is not an expected behaviour but rather a 'lucky' one.
There is a dedicated thread (Disabling ROM 7) where we can discuss that endlessly  :laugh:

That would support my point that the trace for ROMDIS 7 was probably forgotten (rather than omitted on purpose) when AMSDOS got bolted on in the usual hurry, then fixed in later revisions.
On 664/6128 amstrad only merged the DDI1 schematics to the main board. And I think it was left like this because Amstrad did not plan to have that specific rom disabled by external extension (and would have cost few gates ....)

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Re: X-MEM, a new memory expansion for all CPC.
« Reply #173 on: 16:17, 12 June 14 »
On DDI-1 I suppose? Or magic 464? :D
:P

In this case, you have to know that is not always socketed and some are soldered too. (need to find the pictures)
The DDI1 I've seen all had a socket, but they range from 85 to late 87. Want pictures !

Offline Munchausen

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Re: Overriding internal/cartridged ROM 7
« Reply #174 on: 16:41, 12 June 14 »
No, no, no  :D : Look at Arnold4 - CPCWiki
As for these CPC that works with external ROM 7, this is not an expected behaviour but rather a 'lucky' one.

Yes, this is right. I have no cost down CPCs, except my GX4000. I don't remember which one it was. One of my 6128s has a 40007 gate array instead of a 40010... maybe it is that one.

There is a dedicated thread (Disabling ROM 7) where we can discuss that endlessly  :laugh:
Great, you found it :D


And yes, I think the 6128s that work with an external ROM 7 are a very small proportion of all 6128s.


I wonder if any 664s can do it too!?
« Last Edit: 16:44, 12 June 14 by Munchausen »