Amiga questions you've always been too embarrassed to ask

[vroom6sri]

Why do some Amiga games make the floppy drive produce those unhealthy grinding sounds? What's actually making the noise and why?

[dgurv]

What fuse should I use in a POWER SUPPLY A500 P-No 312503-02?

It is one of the light weight original power supplies. The fuse has green corrosion built up over it so I’d like to remove, clean and add in a new fuse.

Thank you

[modrobert]

Originally Posted by dgurv

What fuse should I use in a POWER SUPPLY A500 P-No 312503-02?

It is one of the light weight original power supplies. The fuse has green corrosion built up over it so I’d like to remove, clean and add in a new fuse.

Thank you

I think the fuse is 0.5A / 250V, the rating might be printed on the board next to the fuse unless you can read it on the metal part of the fuse itself (it's stamped into the metal).

[NLS]

Originally Posted by vroom6sri

Why do some Amiga games make the floppy drive produce those unhealthy grinding sounds? What's actually making the noise and why?

Most of the times it is not games actually doing it, but the way data are written on the disk AND allowing more than one reads (or even writes) happen at the same time.
OS allows for it, but floppies and floppy controllers do not love it.
So if it happens to read 2-3 files at the same time, trackdisk is trying to jump all over the floppy and proceed with these in parallel, making the sound AND slowing down things too.
Games taking over disk I/O makes for way smoother experience (something devs realized soon, except some didn't care).

[dgurv]

Originally Posted by modrobert

I think the fuse is 0.5A / 250V, the rating might be printed on the board next to the fuse unless you can read it on the metal part of the fuse itself (it's stamped into the metal).

Thank you Modrobert. 0.5A corresponds with the value on the bottom of the case, but on the circuit it says T 1A 250V. Safer to go with 0.5A regardless?

[Daedalus]

If it says T1A on the board then I'd go with that. Is the 0.5A rating on the bottom of the case a fuse rating or just the input rating? A random PSU I've just picked up has both: 300mA (0.3A) embossed for the input, and T 1A for the fuse rating.

The fuse has to deal with the inrush of current when it turns on, which can be significantly higher than the standard consumption when it's up and running. The T designation is part of that (Time delay), but you don't want the rating too close to the normal operating current.

[NorthWay]

Can a PiStorm be designed to plug into the side of an A500/A1000?

[nogginthenog]

Originally Posted by NorthWay

Can a PiStorm be designed to plug into the side of an A500/A1000?

Should be possible in theory. There are A500 accelerators that do this. e.g. GVP A530.

[SquawkBox]

Originally Posted by kremiso

perhaps i had missed out on a better alternative to the original megadrive pad

After the criticism the SJ-200 joystick received, Sega had to come up with something better, so they offered their customer the :
SJ-300

All of this took place before the release of the SMS since these joysticks were made for the SG-1000. I've got one of these, it's a solid 2-independant-btton-safe-for-the-miggy joystick if you're not after any bells and whistles (no autofire etc.). Having said that, mine had a strong smell for being stored in a cellar or a similar place for much too long, presumably. Tried to clean it, but the musty smell hasn't gone completely.

[modrobert]

Originally Posted by dgurv

Thank you Modrobert. 0.5A corresponds with the value on the bottom of the case, but on the circuit it says T 1A 250V. Safer to go with 0.5A regardless?

Originally Posted by Daedalus

If it says T1A on the board then I'd go with that. Is the 0.5A rating on the bottom of the case a fuse rating or just the input rating? A random PSU I've just picked up has both: 300mA (0.3A) embossed for the input, and T 1A for the fuse rating.

The fuse has to deal with the inrush of current when it turns on, which can be significantly higher than the standard consumption when it's up and running. The T designation is part of that (Time delay), but you don't want the rating too close to the normal operating current.

Agreed, go with T 1A 250V.

[Weasel Fierce]

So in games that let you hook up two amigas over serial for multiplayer, how did that actually work?

Did you just connect the cable and the game did the rest? Did you have to configure things first? Does this still work if using WHDLoad?

[MrClump]

Originally Posted by Weasel Fierce

So in games that let you hook up two amigas over serial for multiplayer, how did that actually work?

Did you just connect the cable and the game did the rest? Did you have to configure things first? Does this still work if using WHDLoad?

You would use a null modem cable, which was just a serial cable that swapped over the send and receive wires, so that the send on one amiga was connected directly to receive on the other and vice versa. You then had to tell the game what speed (baud rate) to use over the cable, generally most games worked OK on the slowest speed (9,600 bps I think)which was more reliable.

I remember games of Populous that had gone on for some time would get pretty slow as you gathered more and more land and people and the link would struggle with the volume of data being sent back and forth. You could mitigate this by playing at a higher baud rate, but then ran the risk of the game losing connection.

The biggest limitation was you were of course limited to just two Amigas, so two-player games. There was a game on a certain other 16-bit micro called Midi Maze that used the built-in midi ports to daisy chain several computers together. I remember many fun hours playing 4-5 player games of that back in the day.

Not sure on using WHDLoad, though I'm hoping it does still work as I have a null modem cable and am hoping to have some multi-player games of Populous at Workbench '22 next month. :-)

[Weasel Fierce]

Thanks! Its one of those things I always wanted to try but never was in a position to do so.

[NLS]

Remember Firepower had this.
Damn... life was simple.

[Firestone]

Why do some games or even applications make these flickering colors on screen when loading/decrunching etc?

Is it something happening as a consequence of doing some wierd stuff in memory, or is the effect created by the author on purpose as some kind of progress bar? It was very common in the 1.3 days at least...

[paraj]

Originally Posted by Firestone

Why do some games or even applications make these flickering colors on screen when loading/decrunching etc?

Is it something happening as a consequence of doing some wierd stuff in memory, or is the effect created by the author on purpose as some kind of progress bar? It was very common in the 1.3 days at least...

Yes, its so you can see something is happening and it's not stuck . You could have a real progress indicator (like a loading bar or saying 42% decrunched), but integrating that is more complicated (and takes up code space) that just changing a custom register (usually the background color). You very often see the same thing on other platforms (e.g. the C64).

[turrican3]

winuae can emulate an amiga with 8 meg chip why the vampire can't or didn't do it ? Is it possible in theory ?

[Nightshft]

@Firestone:
Yes it was already extremely common on the C64. Some crunchers did let you choose the effect register.
Background color (IIRC $D020), foreground color ($D021), horizontal screen offset ($D016) or even the sound volume register (I think it was $D418). Choosing the latter and and there would be no color bars but some scratching noise during unpack.
I also remember that you also could choose "none" and then there was absolutely no effect, while waiting.

Like paraj I think it was both. Nice and also to let you know the pgm doesn't hang. Like those moving circles you now see everywhere on many different platforms when you wait. Hey, they could replace them with color bars

[demolition]

Originally Posted by turrican3

winuae can emulate an amiga with 8 meg chip why the vampire can't or didn't do it ? Is it possible in theory ?

V4 has 12 MB chip memory according to http://www.apollo-core.com/v4.html.

[Thomas Richter]

Originally Posted by turrican3

winuae can emulate an amiga with 8 meg chip why the vampire can't or didn't do it ? Is it possible in theory ?

Whether it is possible I do not know, but it is at least not advisable. The trouble is that some software uses hard-coded offsets/addresses to distinguish between chip mem and expansion RAM, and then takes action according to the outcome of this comparison. One particular piece of software that comes to my mind is the old P96 release you find in Aminet. It uses such a comparison to understand whether it can offload a blit to the native blitter, or needs to emulate it with the CPU.