Atom OS rom choice for AtoMMC

discussion of games, software, hardware & emulators relating to the Acorn Atom and Acorn System machines.
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jms2
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Atom OS rom choice for AtoMMC

Post by jms2 » Wed Dec 18, 2013 10:03 pm

I'm getting an AtoMMC for Christmas! \:D/

I have read on previous threads that the best place to put the firmware is at #E000, and that is what I intend to do. I have a Combikaart, which provides two hardware-switchable rom sets which appear at #C000, D000, E000 and F000. In total 2x 4x 4k roms = 32k in all, contained in a single 27256.

At the moment, I think my rom contains:

#C000 = Basic
#D000 = FP
#E000 = GDOS 1.66
#F000 = Atom OS, but patched so that the banner is "ATOM" not "ACORN ATOM"

As far as I can tell, switching to the other bank of roms makes no difference, so I guess they are just duplicates of the first set.

My question is this: given that I need to burn a new 27256 anyway, what should I put onto it as the Atom OS? The version I've already got, or something else?

Also, given that I have two rom sets available, should I put something different into the other rom set to maximise compatibility or whatever? I'm not interested in retaining GDOS, or normal Atom DOS either for that matter as I don't ever intend to get a disk pack.

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Re: Atom OS rom choice for AtoMMC

Post by roland » Wed Dec 18, 2013 11:02 pm

Hello John,

There is a suitable ROM available at http://www.stardot.org.uk/forums/viewto ... def#p73821

This is the ROM I use at the moment - at least I think so :)

This ROM contains patched OS (but with Acorn Atom) and Floating Point rom. It has AtoMMC2 at #E000 and also Branquart in the #Exxx address space.

There is however one drawback: the Branquart is assembled for 8 rom banks at #Axxx and you might have 16 banks. So it won't let you get the maximum out of your Atom. The sources of Branquart are also available in the AtoMMC source files, so you can easily adjust it.

There's no need for duplicate content in the eprom as you have to switch manually with a switch. You can also burn some version of BBC Basic in the second part of the eprom. That's what I'm also going to do somewhere in 2014. After I have my GODIL up and running, My SID working, my Branquart patched for my modified combikaart etc. I hope 2014 has enough days for all those tasks :)

Greetings,
Roland
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Re: Atom OS rom choice for AtoMMC

Post by jms2 » Wed Dec 18, 2013 11:19 pm

Thanks Roland,

The image you referenced is 64k in size, but I notice that the "middle" 32k is blank, so there's actually the required 32k of data present. Do you know why it's organised like that?

I just wonder what will happen when I throw it at my Eprom programmer..!

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Re: Atom OS rom choice for AtoMMC

Post by roland » Wed Dec 18, 2013 11:48 pm

Ah ... I do remember now. This file was especially constructed this way for my first steps with my current combikaart. You only need the first 16kb. It's no problem to leave the second half of the eprom blank. Or just burn the os twice in the eprom, also no problem.

Just be sure to make a backup of the current content of the eprom. You'll never know ... :lol:
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Re: Atom OS rom choice for AtoMMC

Post by hoglet » Thu Dec 19, 2013 11:45 am

Another slightly more involved option would be to use one of the ROM sets for BBC Basic.

Take a look towards the end of this thread:
http://www.stardot.org.uk/forums/viewto ... f=2&t=6387

This uses the following locations:
#A000-#AFFF - Relocated BBC Basic (first 4K)
#C000-#EFFF - Relocated BBC Basic (last 12K)
#F000-#FFFF - BBC Basic MOS (4K)

Would this arrangement be possible with your hardware?

Dave

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Re: Atom OS rom choice for AtoMMC

Post by jms2 » Thu Dec 19, 2013 12:57 pm

Yes it would (I think), but presumably any attempt to switch the rom at #A000 would result in a crash. I'm not too worried about that, so having a BBC Basic option sounds like a good one. Thanks Dave!

Hang on a minute though - presumably with that config there is no scope for any mass storage at all? Unless the Atommc rom could be paged into #A000 without crashing BBC Basic.

Coming from a BBC Micro background, I am finding the whole subject of Atom Roms a steep learning curve. Not being able to type *roms or even *help, and not being able to activate roms via a star command is really strange! The fact that most of them have a Dutch background (and partially or wholly Dutch manuals) complicates things quite a bit as well!

I have realised (by skimming through the manuals) that Atom roms generally seem to work on the basis of providing enhancements to Atom Basic. Is this the right model to keep in my head, or have I misunderstood?

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Re: Atom OS rom choice for AtoMMC

Post by roland » Thu Dec 19, 2013 4:53 pm

Coming from a BBC Micro background, I am finding the whole subject of Atom Roms a steep learning curve. Not being able to type *roms or even *help, and not being able to activate roms via a star command is really strange!
The Atom was never designed with multiple expansion roms existing next to each other, such as the beeb and elk do. So unlike those computers the Atom lacks native support in the operating system rom. * commands were only used for tape and later disc access. So yes, I agree it is a steep learning curve :)

Branquart offers some support for using multiple roms "simultaneously" by handling the automatic switching between roms. Another thing that the beeb and elk handle natively.

If there's no Branquart available, you can switch between the utility roms by writing the rom (or ram) number to #BFFF. That's a defacto standard method for switching banks at #Axxx.
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Re: Atom OS rom choice for AtoMMC

Post by jms2 » Thu Dec 19, 2013 5:59 pm

Why is the rom switching software called Branquart? Is that simply someone's name, or does it mean something?

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Re: Atom OS rom choice for AtoMMC

Post by roland » Thu Dec 19, 2013 7:04 pm

The story tells Branquart was a specialist on compilers for computer languages. He thought computer languages should be able to work with only one stack. He did not succeed and his project(s) went wrong. His work is known as the Branquart-method.

There is a piece of work described at http://books.google.nl/books?id=C4w8AAA ... od&f=false (hope this link works)
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Re: Atom OS rom choice for AtoMMC

Post by jms2 » Fri Jan 03, 2014 9:18 pm

I have recompiled Branquart to scan 16 roms at #A000, and the combined AtoMMC2+Branquart rom seems to work fine when tested in Atomulator.

When I say "tested", I didn't check it thoroughly because I wasn't sure how to make Atomulator emulate 16 roms being present. But it didn't crash, and was able to pass on commands to the various utility roms that were present; so I think it works.

I have burned it into an EPROM and put it in my Combikaart. In the real Atom, my results are somewhat mixed...

1) When the machine boots, all I get is "ACORN ATOM" as a banner, not "ACORN ATOM + ATOMMC2". However, by pushing on my dodgy video card in certain places I have been able to make the latter appear, but not reliably. Atommc2 is certainly present, because typing LINK #EFCC gives the correct response.

2) When I start the machine, or press break, I don't actually get a prompt. The only way to get one is Ctrl-Break.

3) I tested Branquart by typing "SALFAA" and the SALFAA rom responded accordingly by listing all its commands. However, when I tried this again subsequently I found this didn't work (ERROR 94). :?

Does anyone have any ideas? My Atom's video system is decidedly flakey but the symptoms that I've seen don't seem to be confined exclusively to video performance.

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Re: Atom OS rom choice for AtoMMC

Post by hoglet » Fri Jan 03, 2014 9:39 pm

One little thing to try - quite often I find Branquart powers up in the locked state (i.e. locked to ROM 0)

Try typing UNLOCK and see if executing commands is more consistent.

Dave

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Re: Atom OS rom choice for AtoMMC

Post by oss003 » Fri Jan 03, 2014 10:01 pm

Hi jms2,
1) When the machine boots, all I get is "ACORN ATOM" as a banner, not "ACORN ATOM + ATOMMC2". However, by pushing on my dodgy video card in certain places I have been able to make the latter appear, but not reliably. Atommc2 is certainly present, because typing LINK #EFCC gives the correct response.
To boot Branquart automatically, the F-rom needs to be patched and the AtoMMC interface needs to be recognized.
2) When I start the machine, or press break, I don't actually get a prompt. The only way to get one is Ctrl-Break.
This means that the AtoMMC interface is not found. The software initializes the AtoMMC interface and wait for response before printing '+ ATOMMC2'. If the prompt stays away, there's something wrong with the AtoMMC interface communication. Probably bad connection on PL8.
3) I tested Branquart by typing "SALFAA" and the SALFAA rom responded accordingly by listing all its commands. However, when I tried this again subsequently I found this didn't work (ERROR 94). :?
Branquart uses memory from #400-#4xx depending of the number of ROMs to be scanned. This means that you have to have RAM at #4xx.

If Branquart boots with a ROM locked, press CTRL-ENTER after BREAK and the ROM is unlocked.

Greetings
Kees

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Re: Atom OS rom choice for AtoMMC

Post by jms2 » Fri Jan 03, 2014 11:38 pm

oss003 wrote:To boot Branquart automatically, the F-rom needs to be patched and the AtoMMC interface needs to be recognized.
Forgot to mention - I'm using Roland's CDEF rom image, which already contained Atommc2 in block E, and presumably a patched block F as well. At least I hope so - that's why I picked it as a starting point! :lol:
2) When I start the machine, or press break, I don't actually get a prompt. The only way to get one is Ctrl-Break.
This means that the AtoMMC interface is not found. The software initializes the AtoMMC interface and wait for response before printing '+ ATOMMC2'. If the prompt stays away, there's something wrong with the AtoMMC interface communication. Probably bad connection on PL8.
OK, that's very likely - I'll check.
3) I tested Branquart by typing "SALFAA" and the SALFAA rom responded accordingly by listing all its commands. However, when I tried this again subsequently I found this didn't work (ERROR 94). :?
Branquart uses memory from #400-#4xx depending of the number of ROMs to be scanned. This means that you have to have RAM at #4xx.
I was hoping that was the case - the combikaart has 32k ram on board. Actually if Branquart scans 16 roms rather than just 8, I think the ram usage extends into page 5 as well.
If Branquart boots with a ROM locked, press CTRL-ENTER after BREAK and the ROM is unlocked.
Another thing to try - thanks.

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Re: Atom OS rom choice for AtoMMC

Post by roland » Fri Jan 03, 2014 11:48 pm

I sometimes run into problems with Branquar if the shadow byte and the state of the switch register at bfff do not match. To sync them type ?#BFFF=0;?#FD=0 or maybe UNLOCK;ROM 0 has the same effect.
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Re: Atom OS rom choice for AtoMMC

Post by PhilYoung » Sat Jan 04, 2014 8:15 am

roland wrote:I sometimes run into problems with Branquar if the shadow byte and the state of the switch register at bfff do not match. To sync them type ?#BFFF=0;?#FD=0 or maybe UNLOCK;ROM 0 has the same effect.
I had a similar problem with the ROM switching being a bit hit-and-miss. As you say, ?#FD=0 and I used ?#BFFF=?#BFFF&#F0 to set the lower 4 bits to zero without altering the higher 4 bits solved this.

The only remaining problem I have noticed is that SDDOS works correctly except for *DCAT (which is supposed to list any .DSK files on the SD card). This returns 'SD ERROR 45 and ERROR 235'. Is there a known solution to this ?

This is with the v2.94 RAMROM image on one of Phill's boards.

Cheers,

Phil Young

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Re: Atom OS rom choice for AtoMMC

Post by jms2 » Sat Jan 04, 2014 12:07 pm

OK, I am pretty sure that the Branquart problem is as described above, and by resetting #BFFF and #FD it does go away. So I am not worried about that.

Communication between the Atom and the Atommc does seem to be faulty. When I press Break the "Busy" light flashes on the mmc card, but the software doesn't detect it. At first I had no SD card in the slot, but I added one and the behaviour is not changed. PL8 looks quite clean, and cleaning it has not made a difference.

As before, if I press on the video card it is possible to make "+ ATOMMC2" appear sometimes, so I think the poor connection is there rather than at PL8. Certainly the video card connections are really poor in general. Does the Atommc software make use of the upper area of RAM? If so this might explain the problem.

I am thinking of soldering in some new sockets for the 6847 and where the video card plugs in (several places). Of course the longer term solution would be to fit Prime's colour card, does anyone know which sockets this uses?

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Re: Atom OS rom choice for AtoMMC

Post by hoglet » Sat Jan 04, 2014 12:32 pm

One more thing to check...

With the E000 firmware, interrupts are not required for initialization, and the interrupt enable link (LK3) on the Atom board should be left open, because un-needing interrupts can cause problems (I think I read this somewhere)..

So, check your LK3 setting.

Dave
Last edited by hoglet on Sat Jan 04, 2014 12:48 pm, edited 1 time in total.

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Re: Atom OS rom choice for AtoMMC

Post by jms2 » Sat Jan 04, 2014 12:44 pm

Aha - I haven't checked that. I knew LK3 wasn't needed, but I didn't realise it can cause problems. Ta!

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Re: Atom OS rom choice for AtoMMC

Post by hoglet » Sat Jan 04, 2014 12:50 pm

The other thing that can cause problems is keyboard bounce on the reset key, causing multiple initializations in a short period of time. This is harder to resolve if your system is prone to this.

Dave

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Re: Atom OS rom choice for AtoMMC

Post by jms2 » Sat Jan 04, 2014 1:40 pm

I think mine is OK in that respect - it resets fine every time, and the problem is still present even on initial power-up.

EDIT:

Just checked and LK3 is not made on my Atom, so interrupts can't be the problem.
I am 95% certain that poor connections around the video board are the cause. I need to get some new turned-pin sockets I think. The ones in the Atom are very old white ones with grotty-looking contacts.

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Re: Atom OS rom choice for AtoMMC

Post by oss003 » Sat Jan 04, 2014 7:03 pm

PhilYoung wrote:The only remaining problem I have noticed is that SDDOS works correctly except for *DCAT (which is supposed to list any .DSK files on the SD card). This returns 'SD ERROR 45 and ERROR 235'. Is there a known solution to this ?
Hi Phil,

what version of SDDOS are you using?
You can check this by typing SDDOS and then *DHELP

Greetings
Kees

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Re: Atom OS rom choice for AtoMMC

Post by PhilYoung » Sat Jan 04, 2014 8:00 pm

oss003 wrote:
PhilYoung wrote:The only remaining problem I have noticed is that SDDOS works correctly except for *DCAT (which is supposed to list any .DSK files on the SD card). This returns 'SD ERROR 45 and ERROR 235'. Is there a known solution to this ?
Hi Phil,

what version of SDDOS are you using?
You can check this by typing SDDOS and then *DHELP

Greetings
Kees
Hi Kees,

Thanks for the reply, it's much appreciated.

I have SDDOS v3.24 [TURBO] , also ATOMMC2 v2.94E and Firmware 2.9

(Part of RAMROM v2.94)

It's not a huge problem because I can check the available disk images with *. *DSK before SDDOS, but if there is a solution that would be even better,

Regards,

Phil Young

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Re: Atom OS rom choice for AtoMMC

Post by roland » Sat Jan 04, 2014 9:09 pm

If you are going to replace the 6847 socket, please do it very careful. I did it also and some copper tracks left the board so I had to reconstruct them with pieces of wire.

And if you don't have a decent colour board yet ... you really should consider a GODIL VGA adapter 8)
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Re: Atom OS rom choice for AtoMMC

Post by oss003 » Sat Jan 04, 2014 9:57 pm

PhilYoung wrote:I have SDDOS v3.24 [TURBO] , also ATOMMC2 v2.94E and Firmware 2.9

(Part of RAMROM v2.94)
Hi Phil,

please try this one, replace v3.24 with this 3.25 version.

Greetings
Kees
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Re: Atom OS rom choice for AtoMMC

Post by PhilYoung » Sat Jan 04, 2014 10:02 pm

oss003 wrote:
PhilYoung wrote:I have SDDOS v3.24 [TURBO] , also ATOMMC2 v2.94E and Firmware 2.9

(Part of RAMROM v2.94)
Hi Phil,

please try this one, replace v3.24 with this 3.25 version.

Greetings
Kees
Thanks, I'll try that tomorrow I hope - I have to re-assemble my EPROM programmer first (which is an Arduino and a breadboard mainly),

Thanks for the quick reply,

Phil Young

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Re: Atom OS rom choice for AtoMMC

Post by PhilYoung » Sun Jan 05, 2014 11:44 am

oss003 wrote:
PhilYoung wrote:I have SDDOS v3.24 [TURBO] , also ATOMMC2 v2.94E and Firmware 2.9

(Part of RAMROM v2.94)
Hi Phil,

please try this one, replace v3.24 with this 3.25 version.

Greetings
Kees

Kees,

Many thanks for that, it now works correctly - that is the v2.94 ramrom.rom with SDDOS v3.25 substituted for the existing version, conveniently located as the first 4KB (or 4KiB as it seems to be called these days).

Since everything seems to be working, I suppose I'll have to get a GODIL and see if I can break things again,

Cheers,

Phil Young

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Re: Atom OS rom choice for AtoMMC

Post by roland » Sun Jan 05, 2014 12:03 pm

PhilYoung wrote: Since everything seems to be working, I suppose I'll have to get a GODIL and see if I can break things again,
If you want a real challenge, I'll break things for you :lol:
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Re: Atom OS rom choice for AtoMMC

Post by jms2 » Mon Jan 06, 2014 12:14 pm

I might actually leave the 6847 socket in place. It has turned pins which look gold plated. The 6847 itself has rather soft legs and one broke off when I removed it. It turns out that the previous owner had already broken this leg and had soldered on a new one, so I don't feel so bad!

I have successfully removed the two old 18 pin sockets now and just need to source some replacements.

Regarding gODIL... It looks great but might be a bit too cutting edge for me.

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Re: Atom OS rom choice for AtoMMC

Post by roland » Mon Jan 06, 2014 3:02 pm

Regarding gODIL... It looks great but might be a bit too cutting edge for me.
It was for me too ... but sometimes you have to be brave :lol: I can't wait to re-program it this evening for the new attribute-per-character feature. But it's a nice feeling that if your 6847 is loosing its legs that there is an affordable alternative.
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Re: Atom OS rom choice for AtoMMC

Post by jms2 » Mon May 30, 2016 11:24 am

I've got my Atom running now, and I decided to try out putting in Hoglet's BBC BASIC CDEF image as an alternative in the Combikaart - this is the "split" version of BBC basic (12k) plus Atom MOS 3.0 in the top 4k. Then in my A000 roms file I put BBC BASIC (4k) in slot 0 and the A000 version of Atommc in slot 1.

So in "normal" mode I am using Atommc at E000, whilst in BBC mode I was hoping that maybe the MOS might overlay the A000 version of Atommc as needed. However it doesn't seem to do this; typing *. just gives the message "Press play on tape".

I'm quite happy with this setup if that's all that is possible with BBC BASIC, but obviously it would be nice to be able to use the Atommc at the same time. Is there anything I can do to make this work, or am I already at the cutting edge?

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