Domesday Reloaded

on-topic acorn-related discussions not covered by the other forums
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flynnjs
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Re: Domesday Reloaded

Post by flynnjs » Wed May 25, 2011 9:07 am

As for mistakes I'm not sure if it is one but on the original the supply from the PSU is isolated from the rest of the logic and the logic gets the power via the SV1 connector pins 18 & 20.
Ah, you're right. Looks like the loop-through on the PSU spades was to keep the noise and load of the oscillator block off the SV1 connector. That's easy to fix and makes routing easier.
Also another query is the original had what I think is a cap at the end of most ICs lettered A on the board.
Do you know, I was thinking there should be more decoupling, but it was getting late and didn't have the wits to look at the original board sitting on the shelf about 20inchs above my head!

Come this morning, I'm sort of tempted to redo this board with a CPLD to avoid routing it, keep the costs down and shrink the size further. Got a boring course today so I'm sure I'll get time to think about it. I'll post the updated board tonight.

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Re: Domesday Reloaded

Post by Darren Grant » Wed May 25, 2011 10:01 am

The trouble being that I think there would be nowhere to mount it at this size, I'll have to look inside the master and see where the standoffs are.

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Re: Domesday Reloaded

Post by ianSmalls » Wed May 25, 2011 10:39 am

Another quick query

Is there going to be a problem with noise on the ribbon cable to the master board if it is longer. From memory with the Tube interface and 1MHz bus every second wire is 0V but this does not have that luxury so could be affected if memory serves.

As for the routing, If you can etch with the track going between the IC legs then the the large ICs can be vertically above each other with relative ease. This is where the non surface mount has its benefits.

With the decoupling of the Clock near the top it may be possible to relocate depending upon cable length of the PSU leads and the SCSI connector does not need to be in that location.

The board would ideally be the size of the three mounting holes so don't try too had to shrink it down.

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Re: Domesday Reloaded

Post by flynnjs » Wed May 25, 2011 5:56 pm

re: size, I have an original board here and I'll make sure it is sensible to mount, don't fear!
There are two factors for PCB size:
- Fabrication cost
- Licensing of PCB design tool

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Re: Domesday Reloaded

Post by Darren Grant » Wed May 25, 2011 6:14 pm

Ah yes the EAGLE software is very expensive for larger size boards.

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retroclinic
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Re: Domesday Reloaded

Post by retroclinic » Wed May 25, 2011 8:39 pm

flynnjs wrote:- Licensing of PCB design tool
Phooey to Eagle, I use RS DesignSpark now, it can import all Eagle projects, files and libraries (altho I do admit it's a long winded process to do), and best of all is the cost - £0.00, with no restrictions.

Only downside I've found to it, is the autorouter isn't as "swish" as Eagle - for the 6502 Master CoPro, I routed it all manually for neatness, although I routed 90% of the DataCentre Issue 2 manually on Eagle too, as the Issue 1 boards that were routed fully auto were a flipping mess of tracks.

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Re: Domesday Reloaded

Post by flynnjs » Thu May 26, 2011 9:49 pm

OK, all routed and a few bugs fixed on the way too!

Schematic:
AIV-SCSI-sch.png
AIV-SCSI-sch.png (65.98 KiB) Viewed 3828 times
and layout:
AIV-SCSI-brd.png
AIV-SCSI-brd.png (37.55 KiB) Viewed 3828 times
Forgot to measure the mounting holes on the genuine board again but I will re-jig it all in due course.

I've done a rough run on costs at qty 15.
Components = £181
PCB = £125

Therefore unit cost is just over £20 inc VAT but excluding assembly or delivery.

Now need to get some idea of how many are in demand.

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paulv
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Re: Domesday Reloaded

Post by paulv » Thu May 26, 2011 10:26 pm

Ummm...I think I'd be interested... :-k

Paul

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Re: Domesday Reloaded

Post by Darren Grant » Thu May 26, 2011 10:33 pm

I'll take one.

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Re: Domesday Reloaded

Post by ianSmalls » Thu May 26, 2011 10:56 pm

Ill take one and thanks for all of the hard work!

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Re: Domesday Reloaded

Post by BeebMaster » Tue Jun 21, 2011 12:32 pm

Not sure if it's too late to chip in with this - but what is the plan for the connector to the Master motherboard? The straggly bit of ribbon cable on the Acorn version is hopeless, you get about 2 attempts at pushing the wires into the Master before it all frays and becomes practically unusable.

Also some Masters have a row of pins instead of the "Domesday" connector. Perhaps the new SCSI board could just have a connector of some sort, to which a custom cable could be attached, with the right sort of connector at the Beeb end?
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Re: Domesday Reloaded

Post by BeebMaster » Tue Jun 21, 2011 12:39 pm

ianSmalls wrote:
Slightly Different Topic........

Could someone burn the VFS EPROM as my original one is fried, well the AIV cart does not detect so I'm guessing EPROM as there isn't much else that can go wrong in there!
I can make you a VFS ROM if you still need one, just let me know. It has to run in ROM because the Domesday System uses all 4 banks of Sideways RAM.

Perhaps our Retroclinic friend can make a special MOS with VFS instead of View/Viewsheet?
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Re: Domesday Reloaded

Post by station240 » Tue Jun 21, 2011 1:11 pm

BeebMaster wrote:
ianSmalls wrote:
Slightly Different Topic........

Could someone burn the VFS EPROM as my original one is fried, well the AIV cart does not detect so I'm guessing EPROM as there isn't much else that can go wrong in there!
I can make you a VFS ROM if you still need one, just let me know. It has to run in ROM because the Domesday System uses all 4 banks of Sideways RAM.

Perhaps our Retroclinic friend can make a special MOS with VFS instead of View/Viewsheet?
I'm sure I can make one.
Have to do something like that up anyway, as it seems MOS 4.0 and the 512 board don't get along.

You'll have to get Mark to burn it for you though.

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Re: Domesday Reloaded

Post by exile » Mon Aug 15, 2011 11:06 am

Hello,

I occasionally lurk on here so apologies for not having seen this thread sooner, I could have saved someone a lot of work.

I don't know where flynnjs has got up to with his recreation of the Master AIV SCSI interface as things seem to have gone quiet. If that plan has stalled I may be able to help.

I've had a Domesday system for a long time that was complete except for the SCSI interface, it didn't look like any were ever going to appear on ebay so finally got around to making my own:
AIV_SCSI_1.jpg
SCSI Board for Domesday system
AIV_SCSI_1.jpg (118.2 KiB) Viewed 3656 times
The only problem I have is that my co-processor seems to be faulty and won't play nicely. It appears to hang at some point during the boot sequence, it's difficult to tell where as the video introduction plays normally but things stop responding before the end of it. Apart from that the SCSI interface would appear to work...

However, as I've not had the time to sit down with it and work out what's wrong I haven't been able to offer working boards.

I don't wish to step on anyone's toes but if people are still interested in SCSI boards and there's not an alternative on offer I have five spare boards available (but missing some parts to complete the fifth one). As I can't be definite that the problem isn't with my board I would prefer to confirm that it works first. If there is someone with a working system (and ideally who also wants a spare board) who could check it that would help me any anyone after a new board.

Any interest?

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Re: Domesday Reloaded

Post by ianSmalls » Mon Aug 15, 2011 12:22 pm

Looks Good.

Im interested in one of each type I can get my hands on!

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Re: Domesday Reloaded

Post by exile » Mon Aug 15, 2011 2:48 pm

ianSmalls wrote:Im interested in one of each type I can get my hands on!
Well that's good to know!

I was going to send you a PM but I've not figured out how to yet...

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Re: Domesday Reloaded

Post by station240 » Mon Aug 15, 2011 5:41 pm

PM is disabled for new users, due to some dodgy PM trading in recent past.

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Re: Domesday Reloaded

Post by retroclinic » Mon Aug 15, 2011 6:55 pm

Hi.

Yes, board looks good. Whilst the AIV system is not really my thing, I can repair the co-pro for you, if you have no luck yourself. It's more than likely to be the ULA or a RAM chip failed causing the problem.

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Re: Domesday Reloaded

Post by exile » Mon Aug 15, 2011 7:42 pm

retroclinic wrote:I can repair the co-pro for you, if you have no luck yourself. It's more than likely to be the ULA or a RAM chip failed causing the problem.
Thanks, I didn't realise you did repairs. I'll bear that in mind.

In theory I should be able to sort it out myself I just haven't had the time to sit down and work out what's going on. The master it's in seems to have suffered from being on a horizontal surface and has currently disappeared under a pile of paper ;-)

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Re: Domesday Reloaded

Post by BeebMaster » Mon Aug 15, 2011 10:02 pm

Yes, I'd like to help, I can certainly test the board with my Domesday hardware. It will be a great excuse to get my Domesday System out again, I put it all away last week after a month's solid use!

Just a few pointers, not sure if any of this will help:

Can you mount an LV-ROM disc in VFS and catalogue it? If you can autoboot and get the "Domesday system starting" message and then the introductory video then it must mean that VFS and the SCSI interface are working. I can't see why the introductory video would freeze, as it's set to play from the beginning up to about frame 1200 on the Community Disc, which is the main UK map, or about frame 800 on the National Disc which is the starting point in the Domesday Gallery.

It could be a glitch on the disc, does the starting sequence play straight through if you put in the disc and close the tray without the BBC switched on?

You can press ESCAPE during the video to skip it, that might be a way of missing out the problem area.

If it looks like a problem with the co-processor, you don't necessarily need the internal 65C102 co-pro if you can't find a spare; the Domesday System will work equally well with an external cheese wedge. In fact, you don't even need a second processor to use the Master AIV computer system per se, but you do need it for the Domesday discs.
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Re: Domesday Reloaded

Post by exile » Tue Aug 16, 2011 12:00 pm

Thanks BeebMaster, it would be good if we could sort something out. I'd like to know if my boards do actually work and I think Ian is keen to get his system working quickly.
Can you mount an LV-ROM disc in VFS and catalogue it? If you can autoboot and get the "Domesday system starting" message and then the introductory video then it must mean that VFS and the SCSI interface are working. I can't see why the introductory video would freeze, as it's set to play from the beginning up to about frame 1200 on the Community Disc, which is the main UK map, or about frame 800 on the National Disc which is the starting point in the Domesday Gallery.
There don't seem to be any problems cataloging the discs or booting from them, I think the video gets to the end where the micro should then take over and do something rather than simply freezing. I'd been using the National disk as the intro is a bit shorter but the Community disk responds in the same way. At some point after booting, before the video stops, the Shift lock and Caps lock LEDs stop responding to the keys.
It could be a glitch on the disc, does the starting sequence play straight through if you put in the disc and close the tray without the BBC switched on?
The auto play is off, the video only starts playing after a Shift Break. Before the SCSI interface I have played the discs on their own but it's not something you'd want to watch for long!
You can press ESCAPE during the video to skip it, that might be a way of missing out the problem area.
That doesn't seem to get me any further.
If it looks like a problem with the co-processor, you don't necessarily need the internal 65C102 co-pro if you can't find a spare; the Domesday System will work equally well with an external cheese wedge.
Yes, I'd seen that on your site. I've been keeping an eye on ebay for Co-Pros but the prices they've been going for recently are a bit more than I can really justify - I've got more than enough old computers that I really should make more use of ;-)

When the Master is configured to run with the internal Co-Pro it's always been a bit tricky to get it to boot, it's as if it needs to warm up a bit. As it's done this since I got it so it didn't initially occur that this was the problem. I started looking for problems in the SCSI board before having one of those D'oh moments! I did find the service guide for it (or its cheese wedge cousin) but haven't been through it yet.

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Re: Domesday Reloaded

Post by BeebMaster » Tue Aug 23, 2011 12:05 pm

I've not had that happening before, it might be a memory fault in the co-pro. Domesday doesn't do any sensible checks before starting, like whether the Tube is on, whether it works, whether the SRAM is properly configured, whether DFS is inserted etc.!

My Domesday System doesn't autoboot, it hasn't done for years and I don't know why. I have to type *MOUNT then *RUN !BOOT. I've tried it with both players and every LV-ROM disc I can lay my hands on but it's always the same.

Are you using your own SCSI board or the Acorn one?
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Re: Domesday Reloaded

Post by exile » Tue Aug 23, 2011 2:29 pm

I'm using my own SCSI board. The system has been built up from bits acquired over many years, the Acorn SCSI board is the one thing I never managed to find. It wasn't until I found the schematic (thanks microcomputer.org.uk :-) ) that I was able to make progress.

I've not had any problems mounting the discs, CTRL+Q+Break works just like the ADFS equivalnet as does Shift+Break. Works with two different boards in two Masters (same Co-Pro).

It's possible the Co-Pro has a memory fault (I found another thread on here that has some code I'll have to try at some point) but the reluctance to boot initially made me think the crystal wasn't starting up but that seems happy enough on the oscilloscope. I found a service manual but haven't had a chance to go through it. I suspect a logic analyser will be the easiest way to get to the bottom of what's going on but I haven't got one (yet!)

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Re: Domesday Reloaded

Post by flynnjs » Mon Feb 06, 2012 8:12 pm

Did you get a batch of these made up? Or did you even
test your one? I still have the layout here ready to press
the button on but I've had a heap of other projects I've
been trying to clear.

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Re: Domesday Reloaded

Post by ianSmalls » Mon Feb 06, 2012 9:36 pm

Hi All,

I bought one of exile's prototype non tested SCSI cards for my Domesday system a few months ago and we could not get it to work initially.

With some communication and determination and trying multiple configurations of the Master and Co-Pro etc we both had identical faults which pointed to a problem on the new board.

A few weeks later I was emailed with photo's of a modification to the board that involved soldering 2 FETs along with a few resistors and removing 2 legs from one of the ICs from the solder pads.

Its a good job that i dont mind surface mount soldering....

This solved the problem and was apparently due to an error on the original schematic. I do not have the modified schematic or any layout information for the board and it is not my place to give the information without asking first as there was obviously a lot of work involved.

Ironically after almost 10 years of hunting for an original AIV SCSI board, the day after I made the new one work I had an original one delivered from Mark @ RetroClinic.

From what I gather from the emails exile only had 4/5 boards made but did not have enough components to populate them all.

Thanks to all involved for allowing me to complete a working system.

I now have two working Domesday Systems but am missing a second trackball.

Just need to find some more discs now and then fix my third player!

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Re: Domesday Reloaded

Post by retroclinic » Mon Feb 06, 2012 10:07 pm

ianSmalls wrote:.....but am missing a second trackball.
I can't have you waiting another 10 years... :wink: PM me.....
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Re: Domesday Reloaded

Post by ianSmalls » Tue Feb 07, 2012 12:00 am

I know you already have one as I spoke to you about 8 weeks ago about buying one form you but its been a hectic Christmas break with ....

Full time work
Uni
5 kids (1 in hospital for 8 weeks)
Final year dissertation needs to be handed in

And just to top it off about to move house!

When things have settled down at my end then I will probably be after a few Acorn Parts to restore more of my collection!

Todo:
New Batt (old one removed so no more damage can be done) in
A540
A3/4/5000
RiscPC 600 / 700 / SA
Fix
A4 (intermittent fault)
A440/1
Beeb B
Domesday Player No 3
Master 512 - it got very wet and crushed :-( Dont know if it can be done

Find an ARM3 card for a A540 with the FPA socket as I have the FPA but no socket!

So I have a busy couple of months ahead.

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Re: Domesday Reloaded

Post by exile » Tue Feb 07, 2012 11:38 am

Hi Flynnjs,

I did make up a small batch of boards and now have a working Domesday system!

I still need to test the spare boards but will offer them for sale here when I get them sorted out. After that I'm not really interested in going into production but I'm happy to contribute a working design back to the community if anyone wishes to build more. I've got corrected artwork ready so the next ones should be straightforward.


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Re: Domesday Reloaded

Post by flynnjs » Tue Feb 07, 2012 7:36 pm

@exile,
do you have details of the error on the original schematic?

cheers,
J

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