Search found 1994 matches

by jonb
Sun Sep 24, 2017 3:02 pm
Forum: off-topic
Topic: Cheap USB logic analyser - recommendations?
Replies: 1
Views: 27

Cheap USB logic analyser - recommendations?

Hi Looking to buy a cheap USB logic analyser - up to 16 channels with trigger capability with timing and state analysis. Up to 100mhz (25 or 50 is probably OK as I need it for fixing retro pooters). Anyone got a recommendation? Needs good, intuitive software that works with Windows 10 64 bit. Cheers...
by jonb
Sat Sep 23, 2017 12:17 pm
Forum: other vintage computer hardware, software and games
Topic: What to do with a Grundy Newbrain?
Replies: 19
Views: 798

Re: What to do with a Grundy Newbrain?

Regarding the picture showing the BASIC prompt - looks to me like a vertical line of pixels is missing on the right hand side of each character. Check the character ROM / generator chip's output lines, as well as the shift register I assume it is using to clock characters to the screen.
by jonb
Wed Sep 20, 2017 2:00 pm
Forum: hardware
Topic: Challenge of the month - Troubleshooting?
Replies: 18
Views: 348

Re: Challenge of the month - Troubleshooting?

In any case, I look forward to reading more troubleshooting threads :D Yeah.. there's enough busted pooters to go round I am sure. Will soon be resurrecting the Superbrain threads (starting with the single board - done). I've had a rest from them as they are frustratingly annoying, but I need to &q...
by jonb
Wed Sep 20, 2017 2:00 pm
Forum: other vintage computer hardware, software and games
Topic: Superbrain #2: The Board
Replies: 21
Views: 540

Re: Superbrain #2: The Board

Does anyone have any suggestions as to what I might try next?

..before I break out the DSO and start cursing the 8-bit gods...
by jonb
Tue Sep 19, 2017 1:59 pm
Forum: general
Topic: Today I received.....
Replies: 4144
Views: 216003

Re: Today I received.....

I'm surprised you'd bother with an ElCheapo thing like that, Mark. Surely you have an Avo or something similar in your workshop?
by jonb
Mon Sep 18, 2017 9:41 am
Forum: for sale / freebies
Topic: Worth Taking a Look At
Replies: 2450
Views: 164035

Re: Worth Taking a Look At

Complete working BBC Domesday system:

http://www.ebay.co.uk/itm/263213672285

Opening at £299... what do we think it is actually worth?
by jonb
Sat Sep 16, 2017 6:24 pm
Forum: other vintage computer hardware, software and games
Topic: Graphics on the Multicomp
Replies: 4
Views: 130

Re: Graphics on the Multicomp

Hi Dave Probably a bitmapped display, as a graphical terminal (that is, not using the Z80's memory). Would need to have graphics primitives accessible via escape sequences (although sprite manipulation is very slow on the P2000C). This Z80 ROM, do you mean the one the Multicomp has inbuilt? If so, G...
by jonb
Fri Sep 15, 2017 3:28 pm
Forum: other vintage computer hardware, software and games
Topic: Graphics on the Multicomp
Replies: 4
Views: 130

Graphics on the Multicomp

Hi chaps This post is a bit of an idle ramble about Grant Searle's Multicomp: http://searle.hostei.com/grant/Multicomp/index.html Without reiterating the content of that page, it is a machine based on an Altera FPGA board (EP2C5T144C8N Cyclone II). Grant's scheme allows you to pick and mix a combina...
by jonb
Tue Sep 12, 2017 3:02 pm
Forum: for sale / freebies
Topic: FS: Control Universal EuroBEEB
Replies: 7
Views: 174

Re: FS: Control Universal EuroBEEB

Finally...

IMG_0987.JPG
All together and powered up. Well, the light is on, at least.. You can hear the switched mode PSU starting up and I have tested the voltages which seem good.

I have it standing up on its feet so you can see it presents at an angle to the user. These fold down if a more level appearance is preferred.
by jonb
Tue Sep 12, 2017 2:52 pm
Forum: for sale / freebies
Topic: FS: Control Universal EuroBEEB
Replies: 7
Views: 174

Re: FS: Control Universal EuroBEEB

Some more pr0n..

IMG_0983.JPG
ASTEC power supply ratings

IMG_0984.JPG
Left: unpopulated breadboard + bus connector, Middle: EuroBEEB CPU card, Right: CUBIO parallel I/O card. The ROM above is the original CU ROM the card came with; fitted is the ROM I created for serial access using the BASIC ROM utility (see other thread).

IMG_0985.JPG
CPU card component side, close up

IMG_0986.JPG
CPU card solder side, close up
by jonb
Tue Sep 12, 2017 2:49 pm
Forum: for sale / freebies
Topic: FS: Control Universal EuroBEEB
Replies: 7
Views: 174

Re: FS: Control Universal EuroBEEB

Some pr0n for you all...

IMG_0979.JPG
Case top & side.

IMG_0980.JPG
Case top (other side) and rear. Note fuse holder and AUX power supply connector.

IMG_0981.JPG
Front flip up feet intact.

IMG_0982.JPG
Power supply and quality wiring, with 2 floppy drive power connectors (and another one at the back that looks like the BBC's aux power connector).
by jonb
Tue Sep 12, 2017 2:16 pm
Forum: for sale / freebies
Topic: FS: Control Universal EuroBEEB
Replies: 7
Views: 174

Re: FS: Control Universal EuroBEEB

Oooh, cruel, cruel... :cry:

I'm sure you will bring it back to life - check your PMs.
by jonb
Tue Sep 12, 2017 1:44 pm
Forum: for sale / freebies
Topic: FS: Control Universal EuroBEEB
Replies: 7
Views: 174

Re: FS: Control Universal EuroBEEB

OK Mark.

You know what condition it is in don't you? I think you advised me on the other threads... I'll PM you.
by jonb
Tue Sep 12, 2017 8:00 am
Forum: for sale / freebies
Topic: FS: Control Universal EuroBEEB
Replies: 7
Views: 174

FS: Control Universal EuroBEEB

Hi all I've decided I need to let my CU EuroBEEB go as I have way too many computers here. Mine is not working properly as I have documented on StarDot (search the forum for EUROBEEB and you'll see what I mean). There is some battery corrosion evident (battery was removed ages ago) although I can't ...
by jonb
Sun Sep 10, 2017 9:20 am
Forum: off-topic
Topic: LOLPRICE
Replies: 2630
Views: 166456

Re: LOLPRICE

This Commodore 65 (no, not a typo) went for nearly £14,000 from a starting bid of just $1: http://www.ebay.co.uk/itm/222630201237 It is missing a VIC III chip, which can only be obtained from another C65. I'm going to have to ask - has the market gone completely mad? Or is this another "Apple I...
by jonb
Sun Sep 10, 2017 8:26 am
Forum: general
Topic: Today I received.....
Replies: 4144
Views: 216003

Re: Today I received.....

I would not build it. My first computer was a ZX81 in kit form. It took me 3 hours to build - so that is all the gratification you'll get for the huge loss in value that building it would entail. On the other hand: we all prefer retro computers to be used instead of languishing in some "collect...
by jonb
Tue Sep 05, 2017 7:09 am
Forum: off-topic
Topic: Fine Ales
Replies: 18
Views: 403

Re: Fine Ales

danielj wrote:You've now reminded me of one of my all time favourites... Hopback Summer Lightening. Alas it doesn't make its way north very often...

d.


Harveys Sussex Best for me, every time.

https://www.harveys.org.uk/beers/cask-a ... st-bitter/
by jonb
Mon Sep 04, 2017 7:44 am
Forum: hardware
Topic: Retro Cassette recorders
Replies: 12
Views: 389

Re: Retro Cassette recorders

..and a USB plug...? Gosh.
by jonb
Sun Sep 03, 2017 7:54 am
Forum: off-topic
Topic: Early 50's Zenith hearing aid (electronics)
Replies: 9
Views: 199

Re: Early 50's Zenith hearing aid (electronics)

What a beautiful object.

Does it work?
by jonb
Sat Aug 26, 2017 7:30 pm
Forum: other vintage computer hardware, software and games
Topic: Superbrain #2: The Board
Replies: 21
Views: 540

Re: Superbrain #2: The Board

No need to. Remember I have three others to restore, and these are always handy to have around.
by jonb
Thu Aug 24, 2017 7:17 pm
Forum: other vintage computer hardware, software and games
Topic: Superbrain #2: The Board
Replies: 21
Views: 540

Re: Superbrain #2: The Board

Thinking perhaps it is the kooky DRAM I replaced Bank 3 with (they are those U256D chips floating round eBay), I switched the original RAM chips back into the bank. The good news is that these appear to be OK. I'd switched them after discovering failures in the memory tests that occur after the star...
by jonb
Thu Aug 24, 2017 6:48 pm
Forum: other vintage computer hardware, software and games
Topic: Superbrain #2: The Board
Replies: 21
Views: 540

Re: Superbrain #2: The Board

Oh, scratch that idea then. :( What about the middle trace? Meanwhile.. OK ===> q S..V.. A=C0 BC=2000 DE=0000 HL=C3A2 S=F3FF P=C338 RRA ...... A'=00 B'=0000 D'=0000 H'=0000 X=0000 Y=0000 I=00 OK ===> l c333 Err ===> l c000 C000 00 NOP C001 FF RST 38 C002 00 NOP C003 FF RST 38 C004 00 NOP C005 FF RST...
by jonb
Thu Aug 24, 2017 6:03 pm
Forum: other vintage computer hardware, software and games
Topic: Superbrain #2: The Board
Replies: 21
Views: 540

Re: Superbrain #2: The Board

Scope traces. This is running in Quit mode (contrary to what I said previously, it is showing Refresh and RAS on 0,1,2): DS1Z_QuickPrint33.png The other Quit mode (which I noted): DS1Z_QuickPrint34.png Blue is RAS3 which is running, whereas the other signals are oddly dead. I can't remember how I go...
by jonb
Thu Aug 24, 2017 5:24 pm
Forum: other vintage computer hardware, software and games
Topic: Superbrain #2: The Board
Replies: 21
Views: 540

Re: Superbrain #2: The Board

The ICE runs in Quit mode most of the time when I am testing. From the manual: When the ICE is in Quit mode, the Z80 executes bursts of NOP instructions to provide for refresh of any DRAM present in the target system. This takes up about 25% of the processor’s time, so if you know that your system d...
by jonb
Wed Aug 23, 2017 8:51 am
Forum: other vintage computer hardware, software and games
Topic: Superbrain #2: The Board
Replies: 21
Views: 540

Re: Superbrain #2: The Board

Before you go off on a hunt, have you either confirmed that the 74LS245 fitted in Z62 position is properly driving the data bus within spec or tested by replacement or swap? Just in case one of the output drivers is a bit weak and not always managing to drive to the correct voltage for the logic le...
by jonb
Wed Aug 23, 2017 8:41 am
Forum: other vintage computer hardware, software and games
Topic: Superbrain #2: The Board
Replies: 21
Views: 540

Re: Superbrain #2: The Board

Hi Mark. I have assumed the 245s are fine because the LDIR seems to be working OK, and I can also use the ICE to copy it across. The corruption is occurring after the copy operation. Read on.. I was trying to trace the boot code to see at what point the memory got corrupted. Look at this output from...
by jonb
Wed Aug 23, 2017 6:10 am
Forum: off-topic
Topic: LOLPRICE
Replies: 2630
Views: 166456

Re: LOLPRICE

Well I think it stands out from other computers because it looks "a bit crap".

:lol:
by jonb
Wed Aug 23, 2017 6:08 am
Forum: other vintage computer hardware, software and games
Topic: Superbrain #2: The Board
Replies: 21
Views: 540

Re: Superbrain #2: The Board

I'm not at that stage yet, although I nearly ordered a new PPI for it. You can perhaps see where this is going? We need to get CPU1 running and have all the memory working along with its paging mechanisms first. I think we're nearly there, but for this seemingly random corruption. It's most odd, but...
by jonb
Tue Aug 22, 2017 8:26 pm
Forum: off-topic
Topic: LOLPRICE
Replies: 2630
Views: 166456

Re: LOLPRICE

I nearly fell off my chair!

http://www.ebay.co.uk/itm/272814698296

I mean.... really?
by jonb
Mon Aug 21, 2017 3:12 pm
Forum: software: classic games
Topic: "Unfixable bug" in BBC B Elite
Replies: 32
Views: 1275

Re: "Unfixable bug" in BBC B Elite

I set email to Ian Bell to ask if he knew what "the bug" was. He kindly replied, saying: The only bug I remember in BBC Elite was the no-asteroids-in-disk version that affected the first disk print run, and that did not require freed memory to fix. For a bug to have had no room to fix it w...

Go to advanced search