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20

Yes, it is possible. There are a number of ways: If your TV has a SCART connector, you need a cable adapter from DIN 6 to SCART, wired like this (the audio is taken from the audio out using a standard stereo 3.5'' jack): (taken from CPCwiki) If your TV does not have SCART, but composite video input, you must Either use a RGB to CVBS adapter (using for ...


16

Amstrad used an off-the-shelf component, and did the best they could. For generating video addresses, sync timing, etc, Amstrad used the 6845 CRTC, which was originally designed for text displays. In particular it is designed for a linear text area, looking up character graphics from a font ROM, so e.g. if you’ve set up a 40-column display with 8px ...


13

All text is painted as bitmaps. The highest-resolution built-in mode is 640x200 pixels, so that provides an 80x25 text mode. 80-column modes were used in business software (e.g. DBase II) and even in the CP/M 2.2 and 3.0 OS. The CPC uses a CRTC6845, which is wired up atypically to create linear scan lines but nevertheless can still hardware scroll in ...


13

There seems to be a slight misunderstanding: The CPU in a computer is (almost) never doing nothing (excluding power save states which was largely unknown at times the Amstrad was en vogue). So there's no such thing as "workload of a processor" going up or down - The CPU in an Amstrad is constantly running at 4 MHz, constantly under the same workload. If ...


11

Especially for writing the sound registers, it is advisable to use the built-in routines. According to the Schneider CPC firmware guide, the reason is the following: The CPC keyboard is directly connected to the AY chip - Thus, the keyboard service routine (which runs as an interrupt service routine) is accessing the AY ports directly. Accessing the sound ...


9

To elaborate on drawing text on Amstrad CPC and its screen addressing: The first row of every character position on screen is at the memory address range from &c000 to &c7ff, and thus can be calculated as &c000 + y * 80 + x. FOR I=&C000 to &C7FF: POKE I, &FF: NEXT The subsequent lines of every character are &800 bytes apart ...


7

What you possibly can hear, however, is the CPU repeatedly doing the same thing, like operating in tight loops that can, through electrical or mechanical interference (with the monitor or audio signal, for example), create audible frequencies that you may hear. That was definitely not an intended feature. - tofro In addition to what tofro has answered, I'd ...


7

This effect is typically caused by a conflict of interrupts. My experience of the CPC specifically is limited, but I've seen this on other machines from this era. Most computers of this vintage used interrupts from the video controller chip to feed information to the display. Analogue displays would provide an interrupt for frame start and often further ...


6

As I was expecting, it was an error in my code :) pelrun was very kind and found the bug (see my question on CPCWiki's forum) so props to him. I'll try to explain the issue: Notice I'm hooking into the jump entry by setting up a FAR CALL. Notice how that's a FAR CALL and not a JUMP? There's an extra return address there that shouldn't be pushed into the ...


4

My best mental reverse engineering of the constraints applied to the CPC bus, based on reading alone, is that it has a period of four cycles. Disclaimer: I'm not much of an electronics person, just an avid schematic reader as an offshoot of emulator authorship. The Z80's WAIT, which is the recipient of the gate array's READY is signalled for three out of ...


4

The nearest I can think of — though still very far from CBM prg Studio's integration — is CPCtelera. It's mostly for C development, and the BASIC and debugging components that make prg Studio so clever aren't there. I didn't find any shining stars in the Programming:Cross Development - CPCWiki category. I've mostly made do with a mix of z88dk's appmake and ...


3

The Amstrad CPC range supported 3 basic screen modes: mode 0 - 160x200, or 20x25 characters, with a palette of 16 colours mode 1 - 320x200, or 40x25 characters, with a palette of 4 colours mode 2 - 640x200, or 80x25 characters, with a palette of 2 colours Any of these colours could be selected from a total palette of 27 colours, which is based on 3 settings (...


1

It's likely that parts of the drive mechanism are worn, out of adjustment, or need lubricating. Tape cassette decks are all very similar to each other in principle, so I suggest looking for a generic repair guide. Even some aspects of VCR repair guides are likely to be relevant.


1

In Spain the computers must have the ñ key. The old ZX Spectrum 48K didn't have it. The ZX Spectrum + 2 solved it. The law says: "Todos los aparatos de funcionamiento eléctrico o mecánico qué se utilicen para escritura, impresión, retransmisión de información y transmisión de datos", reza el artículo 2 del anteproyecto, "deberán incorporar, en el momento ...


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