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Interesting to see your wip Dave. You're braver than me, I didn't feel any urge to build my own at all; not least because I dont have any individual components! It's also good to hear a similar solution will work for RiscPC's as I have one of those too, albeit with a missing battery but working RTC....

I've got an A5000 with a poorly CMOS RTC on my workstation at the moment, so I'm considering my repair strategy. I've read with interest the various threads and challenges around replacing the chip - lost pads/continuity checks/battery replacements etc. I also read Retrokit's article about making a ...

For what it's worth I put all of my Beeb hobby projects out as MIT. I have no desire or expectation to profit from or require attribution for them, nor do I have any concerns about how they are used/copied/derived. If they are useful to the wider world, thats just fine with me. I know some projects ...

On compression, we've used Exomizer in a lot of our projects. It's fairly fast, and compression ratios are pretty good. Exomizer Homepage here: https://bitbucket.org/magli143/exomizer/wiki/Home Some beebasm ported example code here: https://github.com/bitshifters/bbc-nula/blob/master/lib/exomiser.as...

This is unbelievably good. Never heard anything like it before - amazing stuff! And so many tunes on one disc!

I get the feeling you get what you pay for with these converters, there's quite a few on the market at sub £15 now, but very variable reviews. Seems you need to keep an eye on them supporting RGB input for best quality (as WrightStuff mentioned), plus also watch out for latency in the conversion. I ...

Yes indeed, I'm following with great interest, but it is voodoo and magic to me, not sure I have much to contribute other than say that this is very cool stuff

Pixel style aesthetic is evergreen I think. Plus fewer pixels to draw usually means faster frame rate.
If you have the inclination, I'd certainly consider optimizing away from floating point to integer maths as using software fp runtimes is much much slower.

Update on this. Annoyingly, it's held settings for over 4 days on battery backup power now, even though nothing has changed in the machine, so I'm pretty confident the RTC chip is ok now. I now have a horrible and sneaking suspicion one of the batteries wasn't fully inserted since when I was setting...

Still got 4.18V on IC11 after 2 hours, powered up and config is still ok so far.
Gonna leave it overnight now and see what happens.

The +5V supply to IC11 (HD146818) has a silicon diode (D8) to prevent the battery from trying to power up the whole machine. Hence when on mains, the +v supply to IC11 will be approximately 0.4V to 0.7V less than the +5V from the PSU. The battery pack also contains a silicon diode to prevent the PS...

Thanks Mark, so full measures are as follows: Battery pack output - 4.85V Out of the PL connector - 4.5V ON = powered on, OFF = powered off Across Pin 12/24 Vss/Vcc - 4.59V (ON) 4.18V (OFF) Pin 13 /CS - 4.55V (ON) 4.18V (OFF) Pin 14 /AS - 63mV (ON) 0V (OFF) Pin 16 /STBY - 0.3mV (ON) +/- 0.02mV (OFF)...

danielj wrote: ↑

Wed Jul 31, 2019 3:29 pm

And the voltage is there when you're powered down? (I think that's how it reads but just want to be sure).

Yes.

I've got a Master 128 that won't preserve CMOS RAM settings and I'm wondering if it's the RTC HD146818AP chip that might have failed. The machine has a replacement 4.5V AA battery pack with inline diode & resistor, brand new duracells and 4.7V measured voltage from the batteries, and this voltage is...

That's great work Tom. Seems as long as the WE bit is in a known state, data can be pumped to the SN chip as fast as it can handle it.

Is it the case that all 8-bits of data are presented by the VIA to the SN chip instantaneously - Ie. within one cycle? This would be necessary to ensure the SN never reads partially set data bits/bytes. As an exaggerated example, there were situations from home brew projects using SN76489 with an Ar...

P.S. the nesdev forum post says the LFSR register rotates left, but John K's page and Maxim's page say it rotates right... Strong possibility that the nesdev poster meant to type "left [to right]" I wonder? The captures of the white noise sequence that are on SMS page all show an initial sequence o...

I personally consider the mystery solved! Those links you shared were very interesting Chris, and I think I've finally reached the same conclusion. There is no scenario in the TI or Sega VDP variants of the SN76489 where oscillations can be stopped or generate a constant output level, they just hav...

It's great that even after all these years the level of understanding about these simple components continues to be expanded. Yes, I think this conflicting opinion is a source of a lot of propagation of incorrect information (and emulation!) There's a good source here where someone actually tested s...

Finally came back to this and sorted it out - on closer inspection one of the legs on the new chip wasn't connected properly, so I fixed that and it's all good now. Thanks again everyone. --- In other news, I've acquired a third A310 (yes, I may need counselling :lol: ), which unfortunately is even ...

Just a note that I have read conflicting opinion on whether or not setting the tone register to 1 generates a square wave or a constant level. If the chip logic is: decrement counter if 0, flip output bit, reload counter Then we'd expect a 125Khz square wave if the tone register is set to 1. However...

This is a very interesting topic. I'm unsure how it might work though, because as I understand it, the noise LFSR is reset such that the top bit (bit 15) is set and the low bit (bit 0) is clear (0x8000), and it is the low bit 0 that is output to the mixer, so that means the output is low on reset - ...

Just use a USB->IDE thing with a CF-IDE dongle on it :) It should recognise it. d. This is very interesting indeed, could we explore the detail of this a bit. Am I correct in understanding then that a suitable USB->IDE->CF widget when connected to a host PC can be detected by a RISC OS emulator as ...

I'll chip in with the same chorus of how brilliant bbcmicro.co.uk is. It is an amazing resource. Ideas and opinions are always in plentiful supply, but seeing ideas through to something that actually works takes a lot of effort and is a rare commodity that's to be applauded. So I've a lot of empathy...

Great job! I do enjoy seeing a nice restoration of old kit.

Fantastic thanks! This looks perfect. Will an SN74LS74AN do the trick?

Hi folks, I've got an electronics question that Google hasn't been able to help me with, and I know wizards live here. Are there any clever tricks to get a 2Mhz clock signal out of a 4Mhz crystal? I have a project where I want to drive two chips - one at 4Mhz and one at 2Mhz but I only have 4Mhz cry...

Thanks Dan. Yes it is - the Ultimate IDE one.
As per topic here: viewtopic.php?t=7900

This one is better then?

I've been lightly following the various topics on the CF compatibility and Wizzo talk, but not fully upto speed yet, so my question is:

I have two IDE upgrade options for my A3010 - one is a HCCS IDE board, and the other is a Castle IDE.
Which one would you say is the best one to keep/use?

Love it. So smooth and the colours are great! Plus I'm a big fan of how you use the arcade fonts too.