Problems with IFEL ROMRAM Board and VideoNuLA ROM

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MelBat
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Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by MelBat » Thu Mar 08, 2018 8:30 pm

Am hoping people in the community might be able to help me with a problem i'm experiencing with my BBC Model B (Issue 4 board).

I've recently fitted an IFEL ROMRAB board

https://www.ebay.co.uk/itm/Acorn-BBC-Mi ... 2867285984

A great bit kit that gives you 8 banks of programmable RAM (battery backed) and 8 Banks of on board flash programmable ROM.

My current setup is programmed :
Capture1.JPG
Image 1
So far so good. All working perfectly.

Then I installed another great bit of kit. The VideoNuLA graphics enhancer
The install went fine and the card does exactly what is says on the tin.
Then I installed the VideoNuLA ROM image into bank 0 of the ROMRAM board.
Initially everything worked fine but upon pressing BREAK the machine came back
with many of the ROM images on the ROMRAM board missing.
In fact this is what it seemed to be left with:

Capture2.JPG
Image 2
Powering the machine off and on brings back a fully working system until the BREAK key is pressed.
I've tried installing the VideoNuLA ROM image in different banks but get exactly the same problem of
banks 0 - 7 dissapearing on BREAK.

If anyone is able to suggest anything I could try that would really be appreciated.

RobC
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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by RobC » Thu Mar 08, 2018 8:46 pm

Hi,

Unfortunately, I've not got that type of ROMRAM board so it's not something I've tested the VideoNuLA ROM with...

Do you get the same issue with the VideoNuLA ROM in slots 8-15? Also, what happens if you only have BASIC and the VideoNuLA ROM present? I'm just wondering whether it's an incompatibility with one of the other ROMs...

I can send you my contact details if it's easier to communicate by e-mail or phone.

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hoglet
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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by hoglet » Thu Mar 08, 2018 9:17 pm

I do have one of these RAM ROM boards, but not a Video NuLA.

Do you get the same symptoms if you write protect the RAM ROM board, by removing links (1) and (3). Do this after you have loaded the Video NuLA ROM, but before pressing BREAK.

I also suspect a conflict with one of the other ROMs.

Dave

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Lardo Boffin
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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by Lardo Boffin » Thu Mar 08, 2018 9:41 pm

I used to have one of those ROM RAM boards and found that certain ROM combinations caused problems. Particularly if you had two ROM management ROMs installed. Others also caused issues though.
I would suggest removing all of your ROMs and adding them back in until it starts to play up.
In the end I gave my board away and went back to an old school board!
As a random aside I found that Ghouls crashed after you died with that board installed. Weird.
BBC model B 32k issue 4, 16k sideways RAM, Watford 12 ROM board, Retroclinic Datacentre + HDD, Viglen twin 40/80 5.25" discs, acorn cassette, Acorn 6502 coproc
BBC model B 32k issue 7, turboMMC, Opus Challenger 3 512k, Pi 3 coproc
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hoglet
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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by hoglet » Thu Mar 08, 2018 10:02 pm

A couple of further suggestions from a helpful on-looker:
B-Utility has facilities to turn off ROMs when Break is pressed. It's by means of two bytes somewhere, with a bit used as a flag to indicate whether or not to turn off a ROM. Try deleting B-Utility, it may be clashing with Videonula.
and
And delete ADT for similar reasons.
I agree with this. It seems very likely this is a memory usage conflict between the VideoNuLA ROM one one or other of these ROM manager ROMs.

Dave

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jgharston
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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by jgharston » Fri Mar 09, 2018 2:41 am

I've looked very closely at image1 and image2, and they're exactly the same!

Code: Select all

$ bbcbasic
PDP11 BBC BASIC IV Version 0.25
(C) Copyright J.G.Harston 1989,2005-2015
>_

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danielj
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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by danielj » Fri Mar 09, 2018 6:28 am

jgharston wrote:I've looked very closely at image1 and image2, and they're exactly the same!
I think red denotes those that have vanished.

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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by RobC » Fri Mar 09, 2018 8:02 am

I'm in the middle of refitting our kitchen but if you can send me (or point me at) the ROM images you're using, I'll see if I can identify if there's a memory clash.

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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by jgharston » Fri Mar 09, 2018 8:31 am

Something's probably using the "spare" bytes in the cassette workspace which are normally used for VDU extensions (eg GXR and friends). And anything that implements an INSERT/UNPLUG bitmap really should be using the same locations as Acorn at &D6E/&D6F.

Code: Select all

$ bbcbasic
PDP11 BBC BASIC IV Version 0.25
(C) Copyright J.G.Harston 1989,2005-2015
>_

cmorley
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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by cmorley » Fri Mar 09, 2018 8:52 am

I don't think you can *UNPLUG the TurboMMC ROM... it doesn't respond. I just tried it on my dev machine. MMFS will for example but TurboMMC A3 ignores *UNPLUG. So memory trampling disabling ROMs, it wouldn't disable TurboMMC...

Also, if it is Rob's ROM trampling memory then it would fail on any B specification. Someone would have spotted this months ago surely?

If ROMs 0-7 vanish then that sounds more hardwarey to me... just happens to be ROMSEL yyyy1xxx. Remeber that this is the triangular IFEL board which occupies the 6502 processor socket & ROM socket and not the old one which was ROM sockets & fly leads.

Perhaps some vnula init code runs an instruction sequence that the IFEL board interprets as a "disable banks" or some mode command/flash program mode etc?

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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by jgharston » Fri Mar 09, 2018 9:12 am

cmorley wrote:Perhaps some vnula init code runs an instruction sequence that the IFEL board interprets as a "disable banks" or some mode command/flash program mode etc?
I think it's more likely that one of the ROM Manager ROMs is using a memory location for its INSERT/UNPLUG bitmap at the same location that VideoNULA uses as VDU workspace to store the current nULA state., For instance, VideoNULA stores &00 at &39F after *VNVDU OFF and &04 after *VNVDU ON, if a ROM Manager also uses &39F as an UNPLUG bitmap, then the ROM Manager will think that the user wants (eg) ROMs 0-7 unplugged and will unplug them.

As mentioned upthread, I'd recommend removing ROMs one at a time until it works, then re-inserting them one at a time until it stops working again to isolate the problem.

Edit: can be sped up with a binary chop: remove half the ROMs, then half again, then insert half, etc.

Code: Select all

$ bbcbasic
PDP11 BBC BASIC IV Version 0.25
(C) Copyright J.G.Harston 1989,2005-2015
>_

cmorley
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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by cmorley » Fri Mar 09, 2018 9:36 am

jgharston wrote: I think it's more likely that one of the ROM Manager ROMs is using a memory location for its INSERT/UNPLUG bitmap at the same location that VideoNULA uses as VDU workspace to store the current nULA state., For instance, VideoNULA stores &00 at &39F after *VNVDU OFF and &04 after *VNVDU ON, if a ROM Manager also uses &39F as an UNPLUG bitmap, then the ROM Manager will think that the user wants (eg) ROMs 0-7 unplugged and will unplug them.
Would the ROM manager do this by intercepting the various ROM service calls and preventing them being forwarded to the ROM if it is 'off' in the bitmap?

Unplugging, erasing slot 11 or programming over the ROM manager image would confirm this then... (assuming of course there is a way to reprogram/reinstate the ROM manager after you erase it - if the FLASH load routine is in the ROM!)

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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by jgharston » Fri Mar 09, 2018 9:38 am

cmorley wrote:Would the ROM manager do this by intercepting the various ROM service calls and preventing them being forwarded to the ROM if it is 'off' in the bitmap?
No, just by storing &00 in the ROM table at &2A1+X.

Code: Select all

$ bbcbasic
PDP11 BBC BASIC IV Version 0.25
(C) Copyright J.G.Harston 1989,2005-2015
>_

cmorley
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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by cmorley » Fri Mar 09, 2018 9:56 am

jgharston wrote:
cmorley wrote:Would the ROM manager do this by intercepting the various ROM service calls and preventing them being forwarded to the ROM if it is 'off' in the bitmap?
No, just by storing &00 in the ROM table at &2A1+X.
That doesn't kill the TurboMMC ROM (OP's slot 3)... I tried *UNPLUG (from ADT) and editing memory with Exmon and I can't disable it. So if that is missing too then I don't see how it can have been software unplugged.

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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by Lardo Boffin » Fri Mar 09, 2018 9:58 am

From memory the older version of this board comes with a CD with loads of software on including a program you can load into RAM to program the ROM sockets.
BBC model B 32k issue 4, 16k sideways RAM, Watford 12 ROM board, Retroclinic Datacentre + HDD, Viglen twin 40/80 5.25" discs, acorn cassette, Acorn 6502 coproc
BBC model B 32k issue 7, turboMMC, Opus Challenger 3 512k, Pi 3 coproc
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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by jgharston » Fri Mar 09, 2018 10:00 am

cmorley wrote:That doesn't kill the TurboMMC ROM (OP's slot 3)... I tried *UNPLUG (from ADT) and editing memory with Exmon and I can't disable it. So if that is missing too then I don't see how it can have been software unplugged.
If you do ?&2A4=0 then *HELP does TurboMMC appear?

Code: Select all

$ bbcbasic
PDP11 BBC BASIC IV Version 0.25
(C) Copyright J.G.Harston 1989,2005-2015
>_

cmorley
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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by cmorley » Fri Mar 09, 2018 10:09 am

jgharston wrote:
cmorley wrote:That doesn't kill the TurboMMC ROM (OP's slot 3)... I tried *UNPLUG (from ADT) and editing memory with Exmon and I can't disable it. So if that is missing too then I don't see how it can have been software unplugged.
If you do ?&2A4=0 then *HELP does TurboMMC appear?
No it is gone. It won't stay dead on a BREAK press so therein lies my confusion.

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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by RobC » Fri Mar 09, 2018 12:58 pm

Just on a lunch break from doing the kitchen but I suspect Jonathan is right and there's a clash over memory usage with one or more of the other ROMs.

If the VideoNuLA ROM image is being loaded into writable sideways RAM, I could probably cook up a version that uses sideways RAM rather than main memory to store flags etc.

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MelBat
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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by MelBat » Fri Mar 09, 2018 1:35 pm

Hi, Just following up on my post yesterday.

I firstly removed the ADT Disc Toolkit Rom image. No change.
Next I removed the B-Utility image and Bingo, it all started working :D
Conclusion there must be some clash beween B-Utility or both images together and the VideoNuLA ROM.
Luckily B-Utility and ADT were images supplied on the ROMRAM board when shipped and I'm not too bothered about loosing them.

Thanks to Dave for the fix suggestion and all the others who took the time to reply yesterday.
Good luck with the kitchen Rob !

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KenLowe
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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by KenLowe » Fri Mar 09, 2018 2:18 pm

MelBat wrote:Next I removed the B-Utility image and Bingo, it all started working :D
Conclusion there must be some clash beween B-Utility or both images together and the VideoNuLA ROM.
Luckily B-Utility and ADT were images supplied on the ROMRAM board when shipped and I'm not too bothered about loosing them.
FWIW, I was also having some issues with the B-Utility supplied with the ROMRAM board and had a bit of dialogue with the seller. My issue was fairly straight forward, and was on a system without VideoNuLA installed:
I'm looking for a bit of help. I get a Language? error when I do a Ctrl-Break after playing Elite & Exile. Only way to recover is to carry out a power on reset. This wouldn't be too much of an issue, but Exile relies on carrying out a Ctrl-Break in order to save current position (pressing Shift-F9, before Ctrl-Break). I've tried moving BASIC & file system (MMFS) to highest priority flash banks (F & E) but that didn't make any difference. I've tried various other ROM locations, and E00 based MMFS as well, but all give the same error. I've also tried removing jumpers from the expansion board, but that didn't make any difference either. Any thoughts why this might be happening?
This was (part of) the response I got:
I've had a quick look at the code for B-Utility and it uses &39F and &3A0 as two memory locations to use as flags to disable ROMs. These locations are not used by OS 1.20 and no doubt they seemed like a good choice at the time. B-utility had various tricks built into it to prevent its use in S/W RAM although I have taken some of them out now. One of the checks was that B-Utility would only initialise itself if it was present when a power-on reset occurred. This prevented it from being loaded into S/W RAM after switching on. However, if memory is cleared with eg *FX200,3 followed by Break then B-Utility thinks that it's been loaded after a power-up and doesn't work properly. It's not a bug as such, just the way it was designed to work at the time. A simulated power on reset (?&FE4E=127 followed by Break) will bring it back to life.

The ideal ROM disabler would perhaps be in battery backed S/W RAM and would use flags within the S/W RAM itself to indicate whether ROMs were to be disabled on Break. The only safeguards would be to make sure that the ROM could never disable itself and that perhaps that there was always at least one language in the machine to avoid the 'Language?' situation.
May be of some help. I also ditched B-Utility, because it was causing more problems than it was worth.

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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by RobC » Fri Mar 09, 2018 4:51 pm

Glad you've got a working setup.

If you do want me to mod the VideoNuLA ROM, I can probably find some time to look at it next week!

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Re: Problems with IFEL ROMRAM Board and VideoNuLA ROM

Post by jgharston » Sun Mar 11, 2018 2:56 am

RobC wrote:Just on a lunch break from doing the kitchen but I suspect Jonathan is right and there's a clash over memory usage with one or more of the other ROMs.
Good luck, I spent last weekend defrosting my drains and chiseling ice out of the pipes. ;)

Code: Select all

$ bbcbasic
PDP11 BBC BASIC IV Version 0.25
(C) Copyright J.G.Harston 1989,2005-2015
>_

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