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Thanks all, for the game recommendations...... Seems it helps to have a real C64 lead, found the lead I made up a few years ago and labled C64/VIC20 and the video is much better through that get proper (and much brighter) colours and they stay that way. Hopefully the svideo cable will be better stil...

Thanks for those,

Having played a few games on the machine I found they where all nice and sharp but in greyscale....so I somewhat suspect the current monitor lead is not wired correctly, I've got one on order from ebay along with a couple of the fixers that you linked to.

Cheers.

Phill.

No that I have my sd2iec & kernal rom switcher working......it would be good to get some software on there to actually play on this machine.... So does anyone know if there's a software collection for the commodore 64 like the STH Beeb or Atom collections? Other thing is the video output on this mac...

Does anyone have any success or experience building the target under windows? Andrew from Australia I woorked out how to do this if you have cygwin installed further back up the thread here : https://stardot.org.uk/forums/viewtopic.php?f=44&t=9655&start=570#p186385 Dave, might be an idea to grab th...

I use BeebDis https://github.com/prime6809/BeebDis . An emulator with a debugger built in might help also. The documentation for BeebDis is awful isn't it? It's seemingly written from the point of view of someone who already has in depth knowledge of how the thing works. That's exactly how it's wri...

vanpeebles wrote: ↑

Tue May 07, 2019 8:27 am

I have a megadrive joypad with the dragon logo on the box, did they(or related) move into other stuff?

I have a USB -> IDE case with the Acorn logo on it in much the same way......

i.e. Origional company goes pop, someone buys the ip and uses the logo on their products.

Cheers.

Phill.

The Dragon & CoCo also used a block based tape format, though unlike the beeb they didn't have a block number and the error correction wasn't as good....you couldn't rewind the tape to retry like you could on the beeb, I guess because of the lack of a block counter. As Dragon / CoCo basic is effecti...

Note this isn't specifically aimed at Ramtop, though it's his post I quoted, more of a general reply to this thread..... They're basically a coco - the display is awful (al-la-atom), but the guts aren't too shabby with a 6809? It's quite a poor computer overall, with the exception of the CPU. The gr...

Hi all,

This is mostly for Daniel and Marcus, here are the fitting instructions for the RAMROM and AtomColour boards.
Any problems with them please feel free to ask.

Cheers.

Phill.

hoglet wrote: ↑

Fri Apr 26, 2019 6:25 am

Those levels look very close to what I measured, assuming that was a green screen (i.e. medium white).

Yeah that was clear 4, displaying the MMC menu.

Cheers.

Phill.

BTW who's gonna be around for drinks this evening and what time are people getting there?

I would imagine for Lesley and I will be sometime 7.00pm-8.00pm

Cheers.

Phill.

danielj wrote: ↑

Fri Apr 26, 2019 6:52 am

Mixing it up. No one will notice. Promise.

I could bring a Dragon too......

Cheers.

Phill.

I've captured these with the Rigol software, what I have found is that the Rigol tends to read slightly high with respect to both of my multimeters not sure why that is but both my DS1052 and DS1054 do it!
Cheers.

Phill.

Another quick question. Can you set the threshold pot to the best position, and measure the following: 1. The voltage across C9 (the Y comparator threshold voltage, mine is 1.46v) 2. The voltage across C17 (the back porch clamp level, mine is 0.98v) 1: measured at the pot wiper, 1.27V 2: Measured a...

Here's the CPLD files. AtomColour580-2019-04-25.zip I'm only actually using luminence to detect green and buff, so hopefully that shouldn't be a problem, certainly as you also found, detecting the other colours by their AH/AL BH/BL values is much less prone to noise. As for using a separate 3.3V reg...

Hi all, Following on from Hoglet's suggestion in the Noisekiller thread I've broken this into it's own thread. I'm still getting some noise on the display of the new Colour board as displayed in this youtube capture : https://www.youtube.com/watch?v=C5XY52Fh1X4 The first half of the video the atom i...

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...

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...

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...

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.

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...

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...

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 ...

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 ...

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...

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.

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,...

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...

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...

(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) ...