Amiga questions you've always been too embarrassed to ask

[Daedalus]

As for the multiplexing on the MD pad, the select signal needs to be held either low or high, high being the default (buttons B, C and the D-pad enabled), with low disabling left and right and enabling buttons A and start. There's no latching so as soon as the low pulse ends the pad returns to default mode.

That is strange indeed... Buttons B and C are treated identically by the MD pad and are routed to fire lines 1 and 2 on the Amiga - if a game can read one it should be able to read the other. The only thing that might be an issue there is if pin 5 is left low, which would stop power to the mux and cause all sorts of weirdness. But even then I'd expect both buttons B and C to have problems, so you shouldn't get just one working. I don't have a Mastersystem pad to examine, but from the looks of it it's simply wired like a 2-button Amiga stick so I really can't understand how one would work and the other not, provided pin 5 is left high. So games that support a MS pad would also support a 2-button Amiga joystick. And games that support a 2-button Amiga stick tend to be usable with an MD pad (again, given the pin 5 caveat).

I'm intrigued by this now and have a sudden urge to do some testing with those games and a scope...

On the Amiga side the second (and third) fire buttons are indeed slightly funky to read like that. However, the pins only need to be set up once when your software loads, after that reading them is fairly straightforward and provided they're left alone (i.e. nothing tries to read an analogue stick or CD32 pad), you don't have any delay on reading and they can be detected with a bitmask just like the standard fire button.

[Mrs Beanbag]

it would be interesting to compare the joystick reading code from one game to another, to see what's different, and perhaps work out some way to make both work at once. If both kinds of pad can be read with different code presumably they can both be read with a common routine, even if it just does both techniques and Logical ORs the results! But some things are never as simple as you think...

A MD pad connected to Amiga without an adapter has its Select line held high by the +5V line anyway, right? But how does it get its actual +5V supply...

[Toni Wilen]

(Perhaps joystick topic should be moved to separate thread)

One known "problem" is that some games don't set pin 5 in output mode, some do and if I remember correctly, POTGO input/output bits are also set differently under KS 1.x vs KS2.x+. KS 1.x always sets all to output mode, KS2.x only sets pins to output mode that are in use by OS.

[Daedalus]

(A new thread might be an idea...)

But an MD pad gets its +5V supply from pin 5 of the Amiga. If that's low, as can be the case, it won't work, or will work in strange ways. This may explain why some games support one pad and not the other, but doesn't explain why one of the buttons on the MD pad still works - it should be both or none really...

[Mrs Beanbag]

but both buttons are not wired up equally at the Amiga end, buttons 2 and 3 go into Paula, buttons 1 go into one of the CIA chips. we have to think about the circuits, not just isolated voltage potentials. i don't know enough about electronics. How exactly the multiplexer is implemented in the MD pad might also be important - is there any connection at all without a power supply? Bear in mind Amiga only cares about a connection to ground to detect the button press.

[Daedalus]

In the MD pad, both buttons (B and C) are treated equally. In theory these should be high impedance if there's no power supply, i.e. the input should be determined by the pull-up or pull-down so should show nothing as far as the Amiga's concerned. But sometimes logic chips can behave in strange ways, partially working or giving random output when connected that way. Either way though, it would not be reliable.

Yes, that's true that they're wired to different chips and that internally they're different because Paula has A/D capabilities that can be connected to the pins. But in joystick mode they still respond to standard logic inputs, which the MD pad gives (when powered). Unpowered it's anyone's guess, but I really can't see how there can be such a difference between fire buttons. I'll have to do some investigations!

[idrougge]

Aren't there pullups in the Amiga joystick port?

[Toni Wilen]

Originally Posted by idrougge

Aren't there pullups in the Amiga joystick port?

No. I assume it would have made analog joystick support impossible. Pullup is pin in output mode and data=1. (as documented in HRM)

[s2325]

Is there some backstory for intro for Lemmings? Why and from where they arrive in balloon? It's not made by them as it's out of scale.

[Arnie]

They stole it; thieving lemmings

[Leffmann]

Originally Posted by s2325

Is there some backstory for intro for Lemmings? Why and from where they arrive in balloon? It's not made by them as it's out of scale.

Another game but sort of related, I always wondered about the zeppelin in the clouds in Shadow of the Beast 1, it was a pretty cool detail that hinted that there was some back story and something more to the game world.

[B14ck W01f]

As far as late Amigas are concerned, why is the Kickstart stored on two ROM chips instead of just one? Does one chip hold the animation of the hand slipping the disk in, while the other contains the early startup menu?

[Jope]

Originally Posted by B14ck W01f

As far as late Amigas are concerned, why is the Kickstart stored on two ROM chips instead of just one? Does one chip hold the animation of the hand slipping the disk in, while the other contains the early startup menu?

No, it is due to the 32 bit data bus of the CPU. It's faster to read 32 bits in parallel from two smaller 16 bits ROMs, instead of doing two sequential 16 bit reads to get a total of 32 bits from a single larger 16 bit ROM.

The data is interleaved between the two chips, so both chips contain parts of the disk slipping in and parts of the ESM.

[thomas]

Originally Posted by B14ck W01f

Does one chip hold the animation of the hand slipping the disk in, while the other contains the early startup menu?

There is much more in the ROM than just the animation and the ESM. Actually the whole operating system is in the ROM. The disk-based parts are only additions.

[Cylon]

Originally Posted by Leffmann

Another game but sort of related, I always wondered about the zeppelin in the clouds in Shadow of the Beast 1, it was a pretty cool detail that hinted that there was some back story and something more to the game world.

SOTB1 was a showcase for what the Amiga can do at the time. So the developers found just a bit left power unused and needed to fill it with anything, in this case something slow moving beetween the clouds.
The sequels focused a bit more into gameplay and puzzles, hence the less impressive fx in parts. IMHO.

[appiah4]

Here's a question.. I was a kid and I was in a computer game shop, and I was looking through a foreign Amiga magazine. There was a screenshot of Shadow of the Beast II.. And what I saw was basically the hero fighting what seemed to be a dragon.. in a cavern.. with water.. and it reminded me A LOT of a similar fight in Shadow of the Beast I.. And then I played the game, and I don't remember ever fighting this boss battle.

What was it that I saw?

[s2325]

Your mind may merged these:

[slaapliedje]

Originally Posted by Toni Wilen

HDToolBox Low Level Format does nothing interesting. It never did. (I checked it long time ago, don't remember details but I think it rewrites/erases the RDB, possibly some older versions did normal full format).

Anyway, there is no Low Level Format IDE or SCSI command. It is just another Amiga harddrive myth.

Low Level Format option was probably originally designed for XT or MFM drives.

I realize this is a late reply, and not exactly Amiga specific.

But I do know that on old Adaptec SCSI controllers, they certainly have a low-level format which does exactly what others have said, clears it out and remaps bad sectors. I'm not sure if it's a newer SCSI command (my controller was an Ultra 160 one) or if it's just something Adaptec threw into their firmware.

I've also read it's bad to use full/low level format on CF cards, is that true at all?

[slaapliedje]

My embarrassing question;

Can someone help me fix my Amiga? :P It's mostly due to time, since I need to re-install things. Actually I was going to create a thread asking if anyone has made a recovery set, and what they would put on it if they did.

What I'm referring to is something like a custom 3.9 emergency disk (so as to have some driver (I have fast ata) / 060 libs etc) and then the default programs burned to a disk with the rest of the OS3.9 install, then with a list ordering what should be installed.

For my example, OS3.9, skip CD-ROM drivers, use fastata driver disk to install the driver and cdrom stuff, then from CD, I'd install boing bag 1+2, MMCD, Picasso (not sure if Picasso should go before or after mediator) bb 3+4, Roadshow, then other stuff.

Really it seems things work better / different if I install such things in different order. Of course somewhere in there Poseidon... I like the bundle setups, but it always seems something is not quite right in them, but then I always forget useful things when re-installing!

[Vot]

Originally Posted by slaapliedje

I realize this is a late reply, and not exactly Amiga specific.

But I do know that on old Adaptec SCSI controllers, they certainly have a low-level format which does exactly what others have said, clears it out and remaps bad sectors. I'm not sure if it's a newer SCSI command (my controller was an Ultra 160 one) or if it's just something Adaptec threw into their firmware.

As discussed 100 times before a real low level format disappeared very early. A real low level format means rewriting the sector markers on the drive. No drive has done that since the very early days.

Originally Posted by slaapliedje

I've also read it's bad to use full/low level format on CF cards, is that true at all?

Yes unless you need to wipe it for privacy. Basically your just wearing out the memory cells that have a limited number of rewrites.