Search found 882 matches

by JudgeBeeb
Sun Sep 29, 2019 9:19 am
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

Multiwizard wrote:
Sun Sep 29, 2019 9:15 am
Ok, it was just an :idea: ...
I am genuinely grateful for all the advice in this thread. However, in my clumsy hands, there is always the significant potential to do more harm than good...
by JudgeBeeb
Sun Sep 29, 2019 9:00 am
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

And when compared with the screws that came with my Atom, it explains why the posts have split. #-o
by JudgeBeeb
Sun Sep 29, 2019 8:57 am
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

Thanks Mark, that's really helpful.

BTW, I know where your case screws are. They are with my cable ties, the mains lead for my EPROM programmer, and Mrs JudgeBeeb's Russian Rat Snake :shock:
by JudgeBeeb
Sun Sep 29, 2019 8:09 am
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

On a separate note, my Atom clearly did not come with the original PCB and case screws and, as a result, some of the mounting pillars in the case have split slightly (and will need to be repaired). The Technical Manual simply describes the screws as 2 short and 4 long self-tapping screws. I would gr...
by JudgeBeeb
Sun Sep 29, 2019 7:53 am
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

Multiwizard wrote:
Sun Sep 29, 2019 7:06 am
I would try the option to drill little holes, I can see on one of the pics 1 hole wouldn't damage any tracks...
Looking at this and this, I am not sure that's a good idea. It does seem awfully close. Plus, you haven't seen what I am like with a drill. :shock:
by JudgeBeeb
Sun Sep 29, 2019 7:02 am
Forum: upcoming and recent events & exhibitions
Topic: ABUG SOUTH 22 to 24 November 2019 - NOW FULL - but accepting names for reserve list
Replies: 72
Views: 2165

Re: ABUG SOUTH 22 to 24 November 2019 (Hampshire) BOOKING THREAD

UPDATE: There is still, apparently, a discount to be had, online, using the code, for booking 3 nights. It appears to be cheaper to book 3 nights and just not use the third night than to book 2 nights. Using this method, the overall cost is £112.50 for single occupancy and £165.00 for double occupan...
by JudgeBeeb
Sun Sep 29, 2019 6:45 am
Forum: upcoming and recent events & exhibitions
Topic: ABUG SOUTH 22 to 24 November 2019 - NOW FULL - but accepting names for reserve list
Replies: 72
Views: 2165

ABUG SOUTH 22 to 24 November 2019 (Hampshire) BOOKING THREAD

It appears that the promo code has stopped working, at least online. If you have yet to book a room, it might be worth either calling the hotel direct (01252 860444) or calling the main booking number (0345 608 6040) to see whether they are still prepared to apply the discount.
by JudgeBeeb
Sun Sep 29, 2019 6:37 am
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

One of the requirements of a repair like this, determined by the QA department of Rank Hi-Fi, was that any damaged PCB tracks should have epoxy glue applied to secure any associated components. I think this would qualify for this procedure!! So, I recommend the connector sould be glued down to prev...
by JudgeBeeb
Sat Sep 28, 2019 10:08 pm
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

So this is what I have managed to do. IMG_0510.jpg I know that some of the pins look as if they have not been soldered. Three of these are not in use in any event. The others have been successfully soldered on the other side of the board where their traces are (just) intact. In addition to the visib...
by JudgeBeeb
Sat Sep 28, 2019 6:23 pm
Forum: upcoming and recent events & exhibitions
Topic: ABUG SOUTH 22 to 24 November 2019 - NOW FULL - but accepting names for reserve list
Replies: 72
Views: 2165

Re: ABUG SOUTH 22 to 24 November 2019 (Hampshire) BOOKING THREAD

I do hope you manage to get a room where dogs are allowed. It would be great to see you after your having to withdraw from Cambridge. Also, as far as I am concerned, whilst snakes are barred, puppies are very much welcome.
by JudgeBeeb
Sat Sep 28, 2019 6:09 pm
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

What I am trying to understand is how so much damage was done. I suspect that the owner initially soldered in the wrong connector and then struggled to desolder it. Having said that, there is only a small number of connectors that could be soldered into a 2x13 footprint. Whatever connector he used i...
by JudgeBeeb
Sat Sep 28, 2019 6:00 pm
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

My next task is to deal with the butchery that was done to the printer port by the previous owner: IMG_0498.jpg After carefully considering my options and not without a significant degree of uncertainty, I decided to (very gently) desolder the original connector (which was also a horrid blue affair)...
by JudgeBeeb
Sat Sep 28, 2019 5:02 pm
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

I have the facia off the case at the moment (as the adhesive was failing) and I noticed these two holes.

IMG_0501.jpg

Does anyone know why they are there? Was there a late abandoned plan to have keyboard LEDs like they ultimately did on the Beeb?
by JudgeBeeb
Sat Sep 28, 2019 4:17 pm
Forum: upcoming and recent events & exhibitions
Topic: ABUG SOUTH 22 to 24 November 2019 - NOW FULL - but accepting names for reserve list
Replies: 72
Views: 2165

Re: ABUG SOUTH 22 to 24 November 2019 (Hampshire) BOOKING THREAD

Does anyone have any info on the possibility of bringing a puppy? I looked on their website but found no info, so I will call and enquire if nobody already knows. This if from the webpage here: https://www.greenekinginns.co.uk/hotels/ely/ This is a pet friendly hotel. There is limited availability ...
by JudgeBeeb
Fri Sep 27, 2019 11:02 pm
Forum: upcoming and recent events & exhibitions
Topic: ABUG SOUTH 22 to 24 November 2019 - NOW FULL - but accepting names for reserve list
Replies: 72
Views: 2165

ABUG SOUTH 22 to 24 November 2019 - NOW FULL - but accepting names for reserve list

ABUG South I am pleased to announce that booking is now open for the next ABUG South. UPDATE: All places are now taken. However, I am taking names for a reserve list as people do occasionally drop out nearer the time. Venue The event will take place from Friday 22nd to Sunday 24th November 2019 at ...
by JudgeBeeb
Fri Sep 27, 2019 7:32 pm
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

So what actually turned out to be the problem in the end ? Bad ROM I'm guessing? Yes. a dead ROM. I have done a fair bit of desoldering and soldering on this board this week and it had to be one of the most unpleasant things I have ever done. (And those who know my background will know I have done ...
by JudgeBeeb
Fri Sep 27, 2019 3:37 pm
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

Tada! IMG_0500.jpg And because I know it will make Dave (hoglet) happy, there's also this: SCR06.PNG I would seriously like to thank Dave and everyone else for all your awesome advice and help. What with this and my schematic capture of the Atom mainboard, I have learned loads about this computer. I...
by JudgeBeeb
Fri Sep 27, 2019 1:30 pm
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

I set up the logic analyser to look at the data bus and none of it makes any sense. The logical levels are switching all over the place in no way related to the clock cycles. There is nothing that can be recognised as part of the reset sequence and, notably, it is different every time I press the BR...
by JudgeBeeb
Fri Sep 27, 2019 10:54 am
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

Is it you that has the fancy Dataman-40Pro EPROM programmer? These can read 24-pin 8Kx8 ROMs (e.g. the NEC upd2364) which are compatible with the Atom ROM. So you could try reading the ROM. The 40Pro can indeed read upd2364s. However, I have the even more fancy 48Pro2C which whilst being compatible...
by JudgeBeeb
Fri Sep 27, 2019 9:35 am
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

I haven't yet identified why C11/R38 wasn't properly controlling the reset circuit. However, I have, at least temporarily, replaced them with a DS1813 reset controller . As a result, it now resets properly. The first image shows a power on: SCR01.PNG And the second shows a reset using the BREAK key:...
by JudgeBeeb
Fri Sep 27, 2019 6:34 am
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

Some more zoomed out captures. As can be seen, there is a massive amount of bounce on the RST line. This is so regardless of whether the BREAK key is pressed or the power is cycled. I have tried replacing C11, but this doesn't make any difference. R38 is in spec and there is no problem with the cont...
by JudgeBeeb
Thu Sep 26, 2019 10:55 pm
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

Here is PHI2: SCR01.PNG And here is the capture of nRST, RnW, PHI2 and SYNC SCR02.PNG SCR03.PNG It's not entirely clear exactly when the CPU comes out of reset as there is a lot contact bounce on the BREAK key which doesn't appeared to be addressed adequately by C11. C11 is fitted and is, in fact, 2...
by JudgeBeeb
Thu Sep 26, 2019 8:19 pm
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

bprosman wrote:
Thu Sep 26, 2019 8:05 pm
acorn_roms.zip
Thanks. I assume I need Atom_Basic.rom and Atom_Kernel.rom. Which is located at the bottom of the ROM and which is at the top?
by JudgeBeeb
Thu Sep 26, 2019 7:58 pm
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

Can you please post a good quality photo of the whole board? Have you tried re-seating the 6502 and are the tracks around the 6502 ok? No other cut tracks? Photos attached. I have tried not only reseating the 6502 but also replacing it with two other 6502s that I had spare. I have been all over the...
by JudgeBeeb
Thu Sep 26, 2019 7:19 pm
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

I have just discovered that my EPROM programmer can test 2114s. All but one of mine test good. The four currently in the machine for its basic configuration all tested good.
by JudgeBeeb
Thu Sep 26, 2019 7:00 pm
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

I have pulled and tested all the logic ICs. My (fancy) EPROM programmer tells me that the 74LS393 in IC44 is faulty. I happened to have another 74LS393 from a couple of years ago still sealed in its anti-static bag from RS. My EPROM programmer told that that was differently faulty which made suspici...
by JudgeBeeb
Thu Sep 26, 2019 5:23 pm
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

That's as I would expect, as the keyboard is controlled via the 8255 and the 74xx(1)45, so without the 8255 (or a possibly faulty one), I would expect the keyboard to not be being read. I should have been clearer. Ctrl-G does not work with the 8255 present. That was the first thing I tried when I c...
by JudgeBeeb
Thu Sep 26, 2019 3:57 pm
Forum: acorn atom and system
Topic: My new poorly Atom
Replies: 86
Views: 1407

Re: My new poorly Atom

So I removed the 8255 and tied nA/G to 0V and this is the rock steady crystal clear result: IMG_0493.jpg (Although, curiously, I still have to connect the video lead the wrong way round.) Ctrl-G does not work. This was something I noticed a while back; but thought I could address when I got the vide...