Search found 2696 matches

by Prime
Mon Apr 22, 2019 12:59 pm
Forum: acorn atom and system
Topic: Atom Noise Killer @ 2MHz
Replies: 28
Views: 526

Re: Atom Noise Killer @ 2MHz

Welll......none of those things seemed to help :( I've posted a video of the noise I'm getting here : https://www.youtube.com/watch?v=C5XY52Fh1X4 First half of the video is displaying menu with the sta #8000 loop. I then hit break and just boot the mmc, which displays the standard games collection m...
by Prime
Sun Apr 21, 2019 2:23 pm
Forum: acorn atom and system
Topic: Atom Noise Killer @ 2MHz
Replies: 28
Views: 526

Re: Atom Noise Killer @ 2MHz

I rather suspect it's noise that's getting onto the Y line, as it only appears in areas of the screen where the Y signal is used. If you change the test program to: [ LDA #8000 JMP #9C00 ] do you still get noise? I'm wondering if during CPU writes there is a brief bus conflict, where momentarily bo...
by Prime
Sat Apr 20, 2019 5:50 pm
Forum: acorn atom and system
Topic: Atom Noise Killer @ 2MHz
Replies: 28
Views: 526

Re: Atom Noise Killer @ 2MHz

Right I've done some more playing with my lashup..... For both R/C delay circuits I have used the following values : R = 1.1K C = 27pf Reason being that they give approx the correct delays and the board already has those values elsewhere so helps keep the number of different component values down. I...
by Prime
Sat Apr 20, 2019 5:38 pm
Forum: other vintage computer hardware, software and games
Topic: Apple IIe & Disk II with issues
Replies: 10
Views: 186

Re: Apple IIe & Disk II with issues

The machine is the original model of the IIe, it does not have the 'Enhancement' kit with the 65C02 CPU and new ROMs Once you get it going of course...... You can use the WDC65c02 + programming some Eproms to upgrade to the enhanced version, I've done that with one of my IIe machines. Cheers. Phill.
by Prime
Thu Apr 18, 2019 12:00 pm
Forum: acorn atom and system
Topic: Atom Noise Killer @ 2MHz
Replies: 28
Views: 526

Re: Atom Noise Killer @ 2MHz

And I'm sure you meant try increasing R by ~50% to 150R...... Sorry, I ended up changing to using 100pF and 220R (rather than 220pF and 100R). I didn't update the earlier schematic. Anyway, I'm expecting to have to fiddle with the values a bit more. Ahhh so same as on the /WE circuit then :) That's...
by Prime
Thu Apr 18, 2019 9:36 am
Forum: acorn atom and system
Topic: Atom Noise Killer @ 2MHz
Replies: 28
Views: 526

Re: Atom Noise Killer @ 2MHz

Looking at the scope trace the total latch time is coming out at around 575ns, the odd thing is if I rest my finger lightly on the R and C the latch time goes up by about 10ns and the snow goes away, so I may need to just adjust the C slightly to slightly lengthen the pulse. It could of course just...
by Prime
Wed Apr 17, 2019 10:55 pm
Forum: upcoming and recent events & exhibitions
Topic: ABUG Cambridge 28th - 30th June 2019 BOOKING THREAD
Replies: 49
Views: 1099

Re: ABUG Cambridge 28th - 30th June 2019 BOOKING THREAD

Also, who's the resident floppy archiver (flaxcottage?). At the moment I think I only have a couple of requests relating to Atom and System, so don't expect to take too much of anyone's time. If you can get a chance any software for the System 6809 card would be good to test my clone out :) I know ...
by Prime
Wed Apr 17, 2019 10:52 pm
Forum: acorn atom and system
Topic: Atom Noise Killer @ 2MHz
Replies: 28
Views: 526

Re: Atom Noise Killer @ 2MHz

Ok, So I've tried Dave's circuits on the Mk5.9 board and they apper to mostly be working. The Write pulse shortening circuit works as designed, giving about a 70ns write pulse which should be long enough for 55ns RAM. Modified R/C values would of course be required for slower say 70ns or 100ns, but ...
by Prime
Wed Apr 17, 2019 8:20 am
Forum: hardware
Topic: Last Gasp for the 8271
Replies: 12
Views: 410

Re: Last Gasp for the 8271

Yeah I'd be interested in 2-3 8271s, just as spares for Atom / System. Though for the Atom I did produce a 177x disk interface, so the code for that exists and is as far as I can tell compatible with all the software I've seen as there didn't seem to be much Atom / System software that made direct a...
by Prime
Tue Apr 16, 2019 2:16 pm
Forum: acorn atom and system
Topic: ICET-6809
Replies: 15
Views: 585

Re: ICET-6809

Just to comment, The Dragons in question work as normal with a standard 6809 in them, so hopefully the fault's not there :)

Cheers.

Phill.
by Prime
Tue Apr 16, 2019 8:00 am
Forum: acorn atom and system
Topic: ICET-6809
Replies: 15
Views: 585

Re: ICET-6809

Actually, the lack of a keyboard isn't actually blocking me, as the issue occurs during the startup sequence, or when just idling. A couple of Dragon questions.. When boot and idling, what's actually going on? Are interrupts routinely happening for example? Boot sequence : Init Hardware, PIAs, SAM,...
by Prime
Mon Apr 15, 2019 11:08 pm
Forum: acorn atom and system
Topic: ICET-6809
Replies: 15
Views: 585

Re: ICET-6809

Ok, I tried your updates to the timing, still doesn't seem to improve things. Running through a buffer board (buffering address and data with LS245s), does seem to make some improvement but not much :( One thing I have notice is that often the Dragon will power up with less than 32K of memory availa...
by Prime
Mon Apr 15, 2019 10:59 pm
Forum: acorn atom and system
Topic: Atom Noise Killer @ 2MHz
Replies: 28
Views: 526

Re: Atom Noise Killer @ 2MHz

Right Interesting work there, Will have to try replicating as it would certainly possibly make things easier to not have the 74xx123 in there :) Though the two boards I have ready to go out will go out with that circuit on, as they are being delivered at the Riscos show :) Your findings with relatio...
by Prime
Sun Apr 14, 2019 9:46 pm
Forum: acorn atom and system
Topic: Using PC Floppy Drives ?
Replies: 6
Views: 195

Re: Using PC Floppy Drives ?

(80-track drives outside the PC world are Quad Density, 40-track are Single/Double Density.) That may have been how drive / media manufacturers described things but it's slightly misleading. The single / double density thing is the encoding method of the data, single uses Frequency Modulation (FM) ...
by Prime
Sun Apr 14, 2019 9:36 pm
Forum: upcoming and recent events & exhibitions
Topic: ABUG Cambridge 28th - 30th June 2019 BOOKING THREAD
Replies: 49
Views: 1099

Re: ABUG Cambridge 28th - 30th June 2019 BOOKING THREAD

I'll most probably not be able to make this one as I'll be on holiday (on the Isle of Wight) the week before so most probably won't make it back in time.

If I do come it will be a flying visit on Sunday, and won't have any kit with me.

Cheers.

Phill.
by Prime
Thu Apr 11, 2019 1:15 pm
Forum: acorn atom and system
Topic: ICET-6809
Replies: 15
Views: 585

Re: ICET-6809

I'll dig out my Dragon 32 board today and give it a try. Not having a keyboard limits the testing I can do, but I've been able to reproduce the unreliability just by letting it sit there at the OK prompt. I'm seeing random junk get written to the screen, and occasionally the relay clicks. Yeah that...
by Prime
Wed Apr 10, 2019 10:44 pm
Forum: acorn atom and system
Topic: ICET-6809
Replies: 15
Views: 585

Re: ICET-6809

Phill, Thanks for PMing me a link to the schematics. I don't see anything them that gives me cause for concern wrt replacing the 6809E with a GODIL. I've been looking at the VHDL a bit more, and I did spot a possible issue with the data bus. According to the data sheet, the data bus should only be ...
by Prime
Mon Apr 08, 2019 9:54 am
Forum: acorn atom and system
Topic: ICET-6809
Replies: 15
Views: 585

Re: ICET-6809

Right, First sorry for resurrecting an old thread..... Now trying to do some debugging on a Dragon. For some reason the ICE doesn't seem to like the Dragon 64, and is very flakey on the Dragon 32, especially if I have anything (e.g. DragonMMC) plugged into the expansion bus. It almost seems to be ad...
by Prime
Wed Mar 27, 2019 11:28 am
Forum: software: other
Topic: Drawing a circle in BBC BASIC
Replies: 44
Views: 1543

Re: Drawing a circle in BBC BASIC

The Speccy, Dragon and Oric all have a circle command I believe. To be fair they all came out after the BBC Micro, and I suspect the Spectrum influenced subsequent machines. For example Oric 1 BASIC supports the INK and PAPER statements which I think derive from Spectrum BASIC. Though also to be fa...
by Prime
Mon Mar 25, 2019 11:26 pm
Forum: software: other
Topic: Drawing a circle in BBC BASIC
Replies: 44
Views: 1543

Re: Drawing a circle in BBC BASIC

What kind of supprises me is that BBC basic doesn't have a Circle command, as most other basics of the time did.

Cheers.

Phill.
by Prime
Mon Mar 25, 2019 11:16 pm
Forum: hardware
Topic: 6847 Tester
Replies: 3
Views: 225

Re: 6847 Tester

First circuit : what Ian said...... The second one is the cicuit used in the Dragon200e, which adds an external character ROM to the 6847 to define an external character set for the text modes. The data from the video memory along with a 4 bit character row counter (row of pixels within a character)...
by Prime
Sun Mar 24, 2019 2:06 pm
Forum: general
Topic: Crimp tool for DIN plug cable clamp
Replies: 4
Views: 202

Re: Crimp tool for DIN plug cable clamp

I just wish there was such a thing as an IDC DIN plug (or socket). One of the real ball-aches with making up the AtomColour boards was wiring up the terminating 6 pin DIN socket, one wire at a time :( At least the other end of the cable terminates in a 2x5 IDC connector :)

Cheers.

Phill.
by Prime
Fri Mar 22, 2019 10:36 am
Forum: other vintage computer hardware, software and games
Topic: '80s computer geeks' pictures.....
Replies: 19
Views: 465

Re: '80s computer geeks' pictures.....

And for some reason the Nascom 3 seemed to be the choice for many of the Coventry schools from about 1982-1986/7. I think it may have had something to do with Lucas-Nascom being based in Warwick at the time. Needless to say they later moved over to Beebs but that was after I left school. Cheers. Phi...
by Prime
Tue Mar 19, 2019 6:19 pm
Forum: other vintage computer hardware, software and games
Topic: 6847 question.....
Replies: 2
Views: 146

6847 question.....

Hi all, As I'm simultaniously working on both the AtomColour and the DragonRGB, which have a lot in common. On the Atom I'm just taking the Y input from the onboard two transistor Amplifier, and feeding it into Hoglet's clamping circuit and that seems to work quite well. On the Dragon I have had to ...
by Prime
Tue Mar 19, 2019 9:37 am
Forum: hardware
Topic: 3.5" drive for Slogger Pegasus
Replies: 5
Views: 208

Re: 3.5" drive for Slogger Pegasus

danielj wrote:
Mon Mar 18, 2019 8:58 pm
Should do, yes. Or you can use any PC floppy drive (you might have to change the jumper - sometimes a 0ohm resistor - to make it drive 0 though!)
Or use a cabe with a twist between pin 10and 12.....note not the same twist as a PC cable, but works the same way.

Cheers.

Phill.
by Prime
Tue Mar 05, 2019 2:40 pm
Forum: acorn atom and system
Topic: System Clone design files....
Replies: 8
Views: 580

Re: System Clone design files....

bprosman wrote:
Tue Mar 05, 2019 10:26 am
Hi Phill,

What toolchain do you use to compile the Keyboard (AVR) files ?
Atmel Studio ? Or "native" AVRgcc ?
Usually the AVRgcc toolchain, I'm on windows so I (historically) installed WinAVR, and then updated it with the more recent Atmel command line package.

Cheers.

Phill.
by Prime
Sun Mar 03, 2019 11:56 pm
Forum: acorn atom and system
Topic: System Clone design files....
Replies: 8
Views: 580

Re: System Clone design files....

ask_nz wrote:
Sun Mar 03, 2019 6:49 pm
Hi Phil,
*COUGH* Phill *COUGH*
What do you use to program your CPLDs?
Xilinx webpack and one of the clone Xilinx usb programmers like the one shown on hoglet's wiki page here : https://github.com/hoglet67/AtomBusMon/ ... requisites

Cheers.

Phill.
by Prime
Thu Feb 28, 2019 4:51 pm
Forum: acorn atom and system
Topic: Just bought an Atom
Replies: 42
Views: 1360

Re: Just bought an Atom

Looks good, you have : 6K of CPU RAM, 2K of video RAM, Both integer & floting point ROMS. You don't have the printer port, bus buffers or 6522 fitted. And it looks like someone tried ignoring the advice in the Dragon manual not to feed coputers Tea and Coffee....... You do have the video header fitt...
by Prime
Tue Feb 26, 2019 4:16 pm
Forum: off-topic
Topic: LOLPRICE
Replies: 2918
Views: 251614

Re: LOLPRICE

And the award for the most expensive Electon system goes to :

https://www.ebay.co.uk/itm/lolprice/254109643297

Phill.
by Prime
Mon Feb 25, 2019 1:30 am
Forum: acorn atom and system
Topic: Just bought an Atom
Replies: 42
Views: 1360

Re: Just bought an Atom

roland wrote:
Sun Feb 24, 2019 7:35 pm
don't worry, Atom parts are easy to get and quite cheap. As long as the main board is in good condition all will be fine :D
Seconded all reasonably standard chips, weirdest ones are the 8304 and 81LS95, though I think the beeb also uses the latter.

Cheers.

Phill.