- Welcome to CPCWiki forum.
The ultimate Amstrad CPC community!
News:
Printed Amstrad Addict magazine announced, check it out here!
Recent posts
#1
Just wondering: If the Gemini is used on a Plus 464, what's happening to C3 paging? Is that handled by Gemini (shadowing)? Is it ignored and not present? Or does the Plus 464 handle C3 anyway?
#2
Hi,
just tried both versions you uploaded to cpcrulez.fr. They work, but not 100% - in the menu, there is always the first entry missing. Makes no difference if I use the disc or tape version, tried it on a physical CPC and also in various emulators. Maybe there went something wrong while making the copy?
Can you please verify this behavior if it's also with your copy of Matrix?
With kind regards,
Egon
just tried both versions you uploaded to cpcrulez.fr. They work, but not 100% - in the menu, there is always the first entry missing. Makes no difference if I use the disc or tape version, tried it on a physical CPC and also in various emulators. Maybe there went something wrong while making the copy?
Can you please verify this behavior if it's also with your copy of Matrix?
With kind regards,
Egon
#3
Quote from: lightforce6128 on Yesterday at 23:41The idea of dithering is to mix a signal with ...In other words, it is local PWM.
Samples 33333333444444444
Can be replaced with...
333334343434344444
This means that
33333 /3.5, 3.5, 3.5, 3.5/ 44444
#4
Applications (CPC and CPC-related) / Re: CPC6128 - CP/M System Disk...
Last post by eto - Today at 07:22You can find an overview of PCW system disks here:
https://www.habisoft.com/pcwwiki/doku.php?id=en:sistema:indice
You are probably right that one set is 8000 series and the other 9000 series.
If I remember right Locoscript is not a CP/M application so it will not run on a 6128.
CP/M on the CPC should be a standard CP/M. Afaik they only adapted the parts which have to be adapted to make sure CP/M can run on that architecture. But of course the CPC still needs to be able to read the disk format. If you want to try out some other CP/M programs you probably have to transfer the files to a disk (image) that is supported on the CPC.
https://www.habisoft.com/pcwwiki/doku.php?id=en:sistema:indice
You are probably right that one set is 8000 series and the other 9000 series.
If I remember right Locoscript is not a CP/M application so it will not run on a 6128.
CP/M on the CPC should be a standard CP/M. Afaik they only adapted the parts which have to be adapted to make sure CP/M can run on that architecture. But of course the CPC still needs to be able to read the disk format. If you want to try out some other CP/M programs you probably have to transfer the files to a disk (image) that is supported on the CPC.
#5
Applications (CPC and CPC-related) / Re: CPC6128 - CP/M System Disk...
Last post by McArti0 - Today at 06:50Quote from: tubs74 on Yesterday at 20:59Onto CP/M on the 6128, it boots with 61k available - on my spectrum +3 and C/PM I then have an M drive, that is the rest of the RAM - does CP/M on the 6128 have full access to 128k of RAM in a similar way?61kB are in the second 64kB. In the first 64kB are CPM and screen.
There are some CPM modifications to support memory larger than 128kB.
There is CPM 2.2 for cpc
#6
OUTI ;5
INC B ;1
NOP ;1
NOP ;1
1000/8=125kHz
INC B ;1
NOP ;1
NOP ;1
1000/8=125kHz
#7
In our Wiki I found this additional information about the sound chip AY-3-8912:
1) There are four different known versions of the chip used for the CPC. Maybe these versions behave differently, maybe not.
2) Internally the chip works with 125 kHz. This means even if its registers are updated with 166 kHz, it will nevertheless only update the volume with 125 kHz.
3) There are no additional control lines on the chip to acknowledge or synchronize with something. This means: If the chip is programmed to read in register values written by the CPU through the PPI (BDIR=1, B1=0), it will do this non-stop. The PPI will remember the last written value and keep it available (latch). What is not clear is if the PSG stops normal operation as long as registers are written. From my observation: It does not care and simply continues its normal work. This means: One can change register values (e.g. the volume level) during operation without altering the mode. This saves two OUT commands per sample.
4) Only the envelope shape register (#0D) somehow recognizes writing and restarts the envelope.
1) There are four different known versions of the chip used for the CPC. Maybe these versions behave differently, maybe not.
2) Internally the chip works with 125 kHz. This means even if its registers are updated with 166 kHz, it will nevertheless only update the volume with 125 kHz.
3) There are no additional control lines on the chip to acknowledge or synchronize with something. This means: If the chip is programmed to read in register values written by the CPU through the PPI (BDIR=1, B1=0), it will do this non-stop. The PPI will remember the last written value and keep it available (latch). What is not clear is if the PSG stops normal operation as long as registers are written. From my observation: It does not care and simply continues its normal work. This means: One can change register values (e.g. the volume level) during operation without altering the mode. This saves two OUT commands per sample.
4) Only the envelope shape register (#0D) somehow recognizes writing and restarts the envelope.
#8
Quote from: lightforce6128 on 01:24, 11 May 25We can send samples at 166 kHz. Should be enough ...
Quote from: BSC on 20:08, 11 May 25Is this supposed to be some kind of competition for the retro-computer sample-replay world-record?
Quote from: McArti0 on 21:52, 11 May 25you didn't take dithering into account
Dithering? ... Yes that is exactly what I had in mind: Dithering ...
No
In fact I remembered a glorious article about high-end sound with the C64 at 48 kHz (and a big bunch of memory). So yes, I had some kind of competition in mind. Also you are absolutely right: Everything above 44 kHz will not be audible.What brings us back to dithering: The idea of dithering is to mix a signal with a low resolution (e.g. 1 bit or 4 bit) with noise that will push the single samples sometimes below and sometimes above the bit levels. With this the resolution can be enhanced greatly, lowering or even removing noise artifacts caused by the low resolution.
But the dithering noise itself is added. Although this is a neutral sound, it nevertheless is clearly audible - except you push it above the 16 kHz level. With 44 kHz there is not much room to do this, but with 166 kHz there is. With this, the audio resolution can be increased, noise artifacts can be reduced, and the dithering noise maybe can be lowered until it gets inaudible.
However, professional equipment uses frequencies of more than 1 MHz for this trick.
#9
#10
General Discussion - Introductions / Re: FUN FACT: Amstrad was the ...
Last post by GUNHED - Yesterday at 22:27Quote from: Prodatron on Yesterday at 13:08Oh, thanks for the information. My informations were different. But one can learn every day something new.Quote from: GUNHED on 22:40, 11 May 25Its great Multitasking OSNo, in Rosanne there is no multitasking at all. There is not even "multi-programming".
As soon as you go back from the current program it has to store its document and shut down itself again before you can do anything else. When returning from a program and switch to another one, which was already running before it lost all its states and needs again to load an existing document or start a new one.
The UI concept is similiar to the NC100/200, nice designed, lot of easy to use keyboard shortcuts.
But Rosannes display routines are just terrible slow. The screen is 38K, but the CPU is 4x as fast as these of the CPC and NC, and you can watch, how it is plotting things from up to down line by line.
Maybe some like this because it gives some retro feelings, but with a 16MHz Z80 you can expect a lot more.
Hot candidate for a SymbOS port I would guess...
