Search found 302 matches

by simonm
Mon Sep 23, 2019 9:31 pm
Forum: hardware
Topic: LCD/Modern Display for BBC Master
Replies: 6
Views: 293

Re: LCD/Modern Display for BBC Master

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 ...
by simonm
Tue Aug 27, 2019 11:10 pm
Forum: hardware
Topic: A blitter for the beeb?
Replies: 103
Views: 10110

Re: A blitter for the beeb?

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 :lol:
by simonm
Sat Aug 10, 2019 3:15 pm
Forum: projects
Topic: Retro style low-res or not?
Replies: 10
Views: 585

Re: Retro style low-res or not?

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.
by simonm
Sun Aug 04, 2019 10:51 am
Forum: hardware
Topic: Failed RTC chip in the Master 128?
Replies: 10
Views: 370

Re: Failed RTC chip in the Master 128?

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...
by simonm
Wed Jul 31, 2019 10:25 pm
Forum: hardware
Topic: Failed RTC chip in the Master 128?
Replies: 10
Views: 370

Re: Failed RTC chip in the Master 128?

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.
by simonm
Wed Jul 31, 2019 8:11 pm
Forum: hardware
Topic: Failed RTC chip in the Master 128?
Replies: 10
Views: 370

Re: Failed RTC chip in the Master 128?

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...
by simonm
Wed Jul 31, 2019 5:15 pm
Forum: hardware
Topic: Failed RTC chip in the Master 128?
Replies: 10
Views: 370

Re: Failed RTC chip in the Master 128?

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)...
by simonm
Wed Jul 31, 2019 2:33 pm
Forum: hardware
Topic: Failed RTC chip in the Master 128?
Replies: 10
Views: 370

Re: Failed RTC chip in the Master 128?

danielj wrote:
Wed Jul 31, 2019 2:29 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.
by simonm
Wed Jul 31, 2019 1:30 pm
Forum: hardware
Topic: Failed RTC chip in the Master 128?
Replies: 10
Views: 370

Failed RTC chip in the Master 128?

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...
by simonm
Mon Jul 29, 2019 11:27 pm
Forum: emulators
Topic: Sampled sound on the sn76489 -- tests
Replies: 35
Views: 1217

Re: Sampled sound on the sn76489 -- tests

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. =D>
by simonm
Mon Jul 29, 2019 2:06 pm
Forum: emulators
Topic: Sampled sound on the sn76489 -- tests
Replies: 35
Views: 1217

Re: Sampled sound on the sn76489 -- tests

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...
by simonm
Sun Jul 28, 2019 9:39 pm
Forum: emulators
Topic: Sampled sound on the sn76489 -- tests
Replies: 35
Views: 1217

Re: Sampled sound on the sn76489 -- tests

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...
by simonm
Sun Jul 28, 2019 2:43 pm
Forum: emulators
Topic: Sampled sound on the sn76489 -- tests
Replies: 35
Views: 1217

Re: Sampled sound on the sn76489 -- tests

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...
by simonm
Sun Jul 28, 2019 2:01 pm
Forum: emulators
Topic: Sampled sound on the sn76489 -- tests
Replies: 35
Views: 1217

Re: Sampled sound on the sn76489 -- tests

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...
by simonm
Sun Jul 28, 2019 2:18 am
Forum: hardware
Topic: A310 restoration
Replies: 74
Views: 2870

Re: A310 restoration

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 ...
by simonm
Sat Jul 27, 2019 12:54 pm
Forum: emulators
Topic: Sampled sound on the sn76489 -- tests
Replies: 35
Views: 1217

Re: Sampled sound on the sn76489 -- tests

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...
by simonm
Sat Jul 27, 2019 12:03 pm
Forum: emulators
Topic: Sampled sound on the sn76489 -- tests
Replies: 35
Views: 1217

Re: Sampled sound on the sn76489 -- tests

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 - ...
by simonm
Wed Jul 17, 2019 12:25 pm
Forum: software
Topic: How to copy software to the arquimides
Replies: 9
Views: 546

Re: How to copy software to the arquimides

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 ...
by simonm
Wed Jul 03, 2019 8:49 pm
Forum: bbcmicro.co.uk
Topic: Taking a break
Replies: 15
Views: 1731

Re: Taking a break

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...
by simonm
Thu Jun 27, 2019 10:12 pm
Forum: hardware
Topic: A310 case restoration
Replies: 8
Views: 571

Re: A310 case restoration

Great job! I do enjoy seeing a nice restoration of old kit.
by simonm
Sun Jun 02, 2019 1:15 pm
Forum: hardware
Topic: 2Mhz clock from 4Mhz crystal
Replies: 5
Views: 368

Re: 2Mhz clock from 4Mhz crystal

Fantastic thanks! This looks perfect. Will an SN74LS74AN do the trick?
by simonm
Sun Jun 02, 2019 12:41 pm
Forum: hardware
Topic: 2Mhz clock from 4Mhz crystal
Replies: 5
Views: 368

2Mhz clock from 4Mhz crystal

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...
by simonm
Mon May 27, 2019 12:07 am
Forum: hardware
Topic: A3010 - HCCS or Castle IDE?
Replies: 3
Views: 331

Re: A3010 - HCCS or Castle IDE?

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

This one is better then?
by simonm
Sun May 26, 2019 11:40 pm
Forum: hardware
Topic: A3010 - HCCS or Castle IDE?
Replies: 3
Views: 331

A3010 - HCCS or Castle IDE?

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?
by simonm
Sun May 26, 2019 2:40 am
Forum: software: new games
Topic: Moon Patrol for the beeb (New port, just starting)
Replies: 27
Views: 2348

Re: Moon Patrol for the beeb (New port, just starting)

Love it. So smooth and the colours are great! Plus I'm a big fan of how you use the arcade fonts too. =D>
by simonm
Wed May 15, 2019 11:15 pm
Forum: software: new games
Topic: Stunt Car Racer for BBC Master
Replies: 61
Views: 3979

Re: Stunt Car Racer for BBC Master

I also can't speak for Kieran, but I'm sure he'd agree that having a starting point of some existing source code + graphics for a game (even if its a different platform/language) is a significant motivator + boost for getting something going. I have a ton of respect for folks that create new or homa...
by simonm
Wed May 15, 2019 11:03 pm
Forum: off-topic
Topic: Making the most of the sun
Replies: 15
Views: 627

Re: Making the most of the sun

2019-04-21 14.24.14.jpg 2019-04-22 13.48.22.jpg I didn't even bother to disassemble this one and the keys came up lovely. 2019-05-12 14.26.41.jpg 2019-05-12 19.05.10.jpg 2019-04-21 13.24.31.jpg 2019-04-21 15.01.26.jpg 2019-04-22 15.15.21.jpg 2019-04-22 18.57.06.jpg 2019-04-22 18.57.21.jpg 2019-04-2...
by simonm
Wed May 15, 2019 10:54 pm
Forum: off-topic
Topic: Making the most of the sun
Replies: 15
Views: 627

Re: Making the most of the sun

This is glorious stuff, I love seeing machines getting restored colours. I've been doing the same recently (particularly over the easter sunny bank holiday) - it's SO satisfying! :lol: I've taken some almost-orange Archimedes keyboards and mice back to their former glory using the exact same method....
by simonm
Mon May 13, 2019 11:55 pm
Forum: hardware
Topic: Internal ideA Interface - Versions
Replies: 8
Views: 1471

Re: Internal ideA Interface - Versions

FWIW I can confirm that the v5 firmware does detect and work ok with a bog standard ebay IDE/CF adapter (using 512Mb sandisk ultra II card). However, I can't seem to get it to work alongside another drive (in either slave/master or master/slave configs). :(
by simonm
Mon May 13, 2019 1:12 am
Forum: hardware
Topic: A310 restoration
Replies: 74
Views: 2870

Re: A310 restoration

So I've decided to leave the faulty machine alone just now, and concentrate on harvesting the best bits to build a beast using the good motherboard. I've also transplanted the ARM3 CPU board into this mb Nicking the best bits then, I now have at least one good working, nicely retrobrited, salvaged &...