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It's not a good idea to use the 300Hz interrupt to schedule background processing, for the reasons you've encountered. The interrupt is useful for synchronising things to specific areas of the screen (e.g. if you want to split the screen into multiple sections with different palette/mode/CRTC settings.) Music/control input/game logic just has to happen once a frame, and can all be done immediately after Vsync.

You then have the entirety of the time until the next Vsync to update the framebuffer. If you make sure that you don't draw on a scanline until after the beam has passed it, then you don't have to worry about tearing, either.
Programming / Better understanding of interrupts. Help needed
« Last post by SpDizzy on Today at 13:37 »
Hi guys,
First of all, excuse me if this was asked before on the community, but could not find an exact answer for my question.
I have a working example with interrupts being called every 52 scanlines, 6 times per frame, for precise timings.
On each one of these interrupts, different code is performed to achieve needed tasks (scan keyboard, collisions, play sound,...) as well as drawing sprites to screen without the need of double buffer.

So far so good.
I'm facing the problem of drawing a bigger sprite for a boss, where more than 52 scanlines will be needed for that.Let's say drawing call comes on 3th interrupt and it will took more cycles than an interrupt, 1.5 ints for example, or 5000 microsecs (as each int is roughly 3300 microsecs).
Here my questions:

1/ May I expect then to lose 4th interrupt, or will be the whole interruption system being affected and corrupted since that delay?

2/ Had done some test but could not find and exact answer. The fact is that music, called on 6th interrupt, is still playing with no delay. It does confuse me.

3/ On the case of whole interruption system affected, how to deal with that problem not to lose the precise timing? Split the routine for drawing the sprite on 2 interrupts so each drawing take less than an interrupt? Disable interruptions after drawing, wait for Vsync, and re enable interruptions? In that case I lose 4th, 5th and 6th ints.

Thanks so much for your time and support,
Amstrad CPC hardware / Re: USB game controllers and mice
« Last post by MiguelSky on Today at 12:50 »
Thanks. But I think the HID reports are for your mouse and not the Predator gamepad. Please select correct device and dump it again.
You're right! Sorry, I chose the wrong device. I join the proper one now.
Amstrad CPC hardware / Re: USB game controllers and mice
« Last post by Duke on Today at 11:26 »
One suggestion I’d like to make if I may; would it be possible to configure the speed of input per device? For instance the MS IntelliMouse is not quick in Windows until you adjust the settings so if something similar were configurable on the Imperium Solo that would great.
Unfortunately, the general problem is that mouses are too slow using the generic mouse as joystick method.
In software it is easy to change sensitivity, but I cannot do much from the hardware side without using variable data (ie. my 5 bit mode, where you could add a multiplier in the hardware to increase sensitivity/speed).
 Right now I can only set signals UP/DOWN/LEFT/RIGHT and let the software interpret it.
I can do some smoothing and keep the signal a little longer than it actually is, but nothing that will speed it up significantly in current software.

Hi, Duke! I received my adapter, it works great with my PS4 controller. I have an old Trust Predator gamepad for PS2 that I usually use with my PC, but it doesn't work. I join the report.
Thanks. But I think the HID reports are for your mouse and not the Predator gamepad. Please select correct device and dump it again.
i have all three files in the root of my SD card in the M4 (this is on a CPC6128 no other mods etc)

CAT shows they are present.  I enter RUN"tn  and the program loads and runs but says RSX NOT FOUND, EXIT TO BASIC three times before asking me for the IP.

Yes when running tn.bas it shows "CPC telnet client v1.0.2 beta / Duke 2018" before printing RSX NOT FOUND, EXIT TO BASIC 3 times in a row.
thanks for the response

Aaaah, Jon,

For CP/M, yes, it's 16 user areas.

But for LocoScript, it's only 8.   The other 8 are used for 'Limbo' files.

Ah yes, I forgot...!
Thanks Jon -

Just tried and it correctly allocates 4 drives (C D E and F)

Rather than keep bugging you - is amending the .FID easy (ish) to do should I want to have a play?


The FID is a set of routines written in Z80 assembler with a special header at the start followed by a vector table. You can patch it if you are handy with a binary file editor. Open XDRV.FID and look at offset 01C0h. You should see a sequence of hex values: AF 03 3C FE 10. The 10 (hex) is the maximum number of drives the FID can theoretically allocate (16, as in A: to P:). If you reduce this value and save the file down you can choose any number of drives you like (up to 16 of course.. well, the maximum uIDE drive count is 13 because you have A: B: and M: already).

Don't forget if you are patching XDRV4.FID the sequence is AF 03 3C FE 04.

It wouldn't be too hard to write a utility to do this.
Other retro / Re: Supah Mario Bruddahs on C64...
« Last post by andycadley on Today at 09:51 »

It's a very niche bit of software for an already niche market. The guy got his 15 minutes of fame (and probably more coverage than he ever imagined), the game will live on and remain distributed through a myriad of channels (if Nintendo can't stop distribution of ROMs of their own carts, will they really stop every C64 distribution?)

If the guy behind it didn't anticipate this response, I'd be surprised. But it isn't really going to have a substantial impact on how many people will play his version.
Classifieds / Re: Latest on ebay
« Last post by shifters74 on Today at 09:50 »
OK, I have received them...  ;)
@Duke have you sold your stock?
I had to pay £23 for one of these on ebay last month!!!  :o :o

The 1989 release by choice (Beach Volley) was awful, sprites are horrible...

The Master System port by Tecmagik was excellent.

Once finished, maybe we would have a liquid kids/super water bomb port.
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