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Questions tagged [amiga]

For questions related to the Commodore Amiga family of personal computers.

19
votes
4answers
2k views

Why does MP3 audio decoding overwhelm retro CPU's?

Many retrocomputers from the late 80s and early 90s had audio DAC hardware support. This includes the Amiga, Classic Macintosh, and PC's with SoundBlaster add-on cards. Despite the fact that the MP3 ...
11
votes
2answers
284 views

What happens when a floppy track contains multiple sync words?

This question is specifically aimed to the Amiga hardware. Let's assume a floppy track is read via DMA using sync word to trigger the start. Let's also assume the track contains the sync word ...
8
votes
2answers
2k views

Amiga-looking keyboard for PC

I would like to use an Amiga-looking keyboard on my PC. (I prefer not to use my old original A2000 keyboard with an adapter, partly because it lacks many keys present on modern 105-key keyboards, and ...
12
votes
1answer
318 views

What are all the fixed addresses of AmigaOS?

I was reading Richard Downer's excellent response about how Amiga libraries work and one sentence in particular got my attention: Yes, a pointer to exec.library is always at $4, and this is (in ...
26
votes
1answer
876 views

How did the Amiga DCTV work

This is an unusual question since I'll answer it right away because it was a truly unique device and there is absolutely nothing about the technology it used on the internet. I spoke with the hardware ...
17
votes
2answers
929 views

How are Amiga libraries structured?

In this Crash course to Amiga assembly programming, the author loads A6 with a constant, and then regularly jumps to offsets from that constant. He explains: All functions within that library can be ...
54
votes
6answers
6k views

Reason for the Amiga clock speed

The Amiga used a CPU rated for 8 megahertz, but clocked at 7.14 megahertz. What was the reason for this number? I remember it was something to do with a multiple of the frequency of the video ...
4
votes
0answers
107 views

Can a modern 1.44MB floppy drive work with an Amiga 2000? [duplicate]

Can an Amiga 2000 (or even A500) be made to easily work with modern 1.44 MB drives? Meaning, is it just a matter of pin mappings or are the drives just too incompatible? I realize there are other ...
15
votes
4answers
540 views

Appropriate battery replacement for my A3000

I know the interwebs are full of information relating to the replacement of batteries for various computers, and the Amiga's are no different. But before I do anything rash, I wanted to ask for some ...
16
votes
1answer
303 views

Seeking details relating to Amiga 3000 serial numbers

I am the original owner of my Amiga 3000. As I remember it, I purchased the machine fairly early after release. I'm cleaning and detailing the machine, and I took a quick picture of the serial ...
8
votes
3answers
690 views

Replacing Amiga 9 pin D-Sub mouse cable

I have an original Amiga "tank" mouse, the PCBs are good, but the cable is clearly faulty as the Y axis and left mouse click doesn't work when it is tilted to the right. I need to replace the cable ...
8
votes
3answers
541 views

What limits Amiga 68030/40/60 accelerators to 256 MiB of RAM?

Even today there are companies that still make accelerators for the 68000-based Amigas, but I've never seen any such accelerator with more than 256 MiB of RAM. If the 68030+ can address 4 GiB, then ...
24
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4answers
5k views

Can I image Amiga Floppy Disks on a Modern computer?

Is there any way of reading Amiga floppy disks to PC hard-drive? Can I use a standard Floppy drive with a firmware program that will translate it? Do I need an external drive or a working Amiga ...
14
votes
1answer
519 views

What is the Kelly chip?

The Amiga 3000+ DevCon 1991 notes says: On the A3000+, these resources include the Amiga "Pandora" chip set (Alice, Lisa, Kelly, and Paula), However, a Kelly chip is not part of the official ...
10
votes
1answer
487 views

What was the A1200 Flash ROM support meant for?

Question inspired by this answer's last paragraph: https://retrocomputing.stackexchange.com/a/1307/2155 The Revision 1 A1200 schematics show that the system originally had support for a two internal ...
10
votes
1answer
224 views

What does the H protection bit mean under classic AmigaOS?

The AmigaOS file protection bits allows for Read, Write, eXecute, Delete permissions on files, similarly to Unix (save for the Delete permission). Additional bits are Archive (reset when a file is ...
21
votes
2answers
977 views

Was the MC680x0's TAS instruction forbidden on Amiga systems only when operating in CHIP memory?

(Note: a previous version of this question asked about the CAS instruction, that was added by Motorola from the MC68020; the original one is the TAS instruction). TAS is the acronym for Test And Set, ...
12
votes
3answers
1k views

Is the metal shielding required in all-in-one Amiga models?

All-in-one Amiga computers (500, 600, 1200) have metal shielding surrounding the mainboard. It is in two parts, one below the mainboard and one on top. The mainboard is physically linked to the lower ...
7
votes
1answer
542 views

How do I add multiple internal drives to an Amiga 2000?

The default configuration of an Amiga 2000 has a single internal floppy drive. Can I add a second internal floppy drive? Can I add a third or fourth drive too?
10
votes
2answers
220 views

Official explanation for offering both BOOPSI and GadTools?

Was there ever an official explanation on why AmigaOS 2.0 offered two similar GUI gadget toolkits, in the form of BOOPSI and GadTools? Or, to put it in another way, why were not GadTools gadgets ...
8
votes
1answer
305 views

Why would a PAL Amiga sometimes start up in NTSC display mode?

For an OCS Amiga (Workbench 1.2 or 1.3) I remember sometimes after a Guru Meditation/software failure reboot, Workbench would be restricted to NTSC size displays (200 non-interlaced vertical lines in ...
8
votes
1answer
520 views

What exactly are the differences between Kickstart 1.2 and 1.3?

The only very known difference is that Kickstart 1.3 fixes the silly bug that prevented Kickstart 1.2 to boot from a hard disk (a routine in the boot code uses A6 loaded with an incorrect library base,...
7
votes
2answers
459 views

Why did Commodore not upgrade OCS straightforwardly to 32-bit architecture?

This is somewhat of a speculative question... Amiga's 1985 Original Chip Set is inherently a 16bit architecture (the data bus is 16bit, registers are 16bit, the blitter itself is 16 state machines ...
9
votes
4answers
3k views

How do I attach and use a CD-ROM drive to an Amiga?

I would like to add a CD-ROM drive to an Amiga. I have not tried this for several years and I remember things failing to work without giving any useful errors, multiple choices of device and ...
7
votes
3answers
1k views

Extended ROMs on the Amiga CD32 and CDTV

Continuing my series of questions about Amiga ROMs :-) The Commodore CDTV contained a normal Kickstart 1.3 ROM, plus an "extended ROM". From http://www.l8r.net/technical/cdtv-technical.html: The ...
21
votes
5answers
1k views

Why is the Amiga ROM at a high memory location, and RAM in low memory?

When a 68000 CPU powers up, it reads a few words at memory location zero to get the initial stack pointer and program counter. That suggests to me that a computer system designer would put the system ...
6
votes
1answer
391 views

How did the Amiga 1000 WCS (write controlled store) for Kickstart work?

Most Amiga computers have Kickstart (the core of the operating system) on ROM. But the original Amiga 1000 instead loaded Kickstart from disk. It had boot ROM that would run some self tests and then ...
11
votes
3answers
2k views

What is the benefit of increasing Amiga chip memory?

For example, an Amiga 500+ has 1MiB of chip memory, but it can be expanded to 2MiB. What would be the advantage?
8
votes
2answers
577 views

Replacing the Floppy drives in my Amiga 3000

My Amiga 3000 is starting to show its age, and recently one of the two internall floppy disk drives appears to have given up the ghost... I'd like to replace the drive but the A3000 case doesn't have ...
11
votes
1answer
746 views

Practical differences between the three Amiga 500 rev 5 motherboards?

The Big Book of Amiga Hardware lists three different versions of the Amiga 500 rev 5 motherboard which it names Type 1, Type 2, and Type 3. Were the changes made only to simplify manufacturing, or ...
16
votes
1answer
1k views

I've taken my Amiga computer out of storage after several years and it doesn't work. What's the likely cause?

I've had an Amiga on a shelf for a long time. Today I took it down and tried to use it but it's not working. There's some basic activity - the power LED illuminates, and there is a video signal - but ...
7
votes
1answer
793 views

Black Amiga 500 Keys

I am creating a black Amiga 500 casing for my retro pi unit. I have already bought the casing, a 1200 keyboard and keyrah unit to convert the keyboard to USB. I have some vinyl dye paint for the ...
9
votes
1answer
366 views

HxC floppy emulator on Amiga 1200, second virtual drive disappears after reboot

I've recently purchased a HxC/Lotharek SD Card floppy drive emulator. It's working well replacing DF0: but I'm seeing some odd behaviour with its emulation of DF1:. On the first boot after power-up, ...
25
votes
1answer
2k views

What are the Amiga 1200 timing fixes?

I have read that the Amiga 1200 may need certain "timing fixes" to be applied to the motherboard in order to use CPU accelerators. What are these timing fixes and why are they needed? Is there one ...
44
votes
6answers
3k views

Are there any modern compilers that can generate Amiga/m68k executables?

I would quite like to resurrect my openkick project. As I note on that project's README.md, it is stalled because GNU GCC is not fit for purpose. Sadly, there do not seem to be any other modern ...
7
votes
1answer
172 views

Are there any trapdoor slot video cards for a non-tower Amiga 1200?

Are there any trapdoor slot video cards for a non-tower Amiga 1200 ? (That excludes Zorro expansion cards, PCI mediator cards and BlizzardPPC+BVision - as all of those require tower case, also ...
24
votes
1answer
1k views

How do Amiga 600 CPU accelerators work?

The Amiga 1200 has a trapdoor expansion for CPU accelerators. The Amiga 500 has a side expansion port and its CPU is socketed. But Amiga 600's expansion port is only useful for memory expansion ...
16
votes
4answers
952 views

Is there a Linux client for Amiga Explorer?

I have some Amigas that I would like to be able to transfer files to/from using my primary desktop machine, a PC running Linux. My Amigas do have CrossDOS installed, but transferring things in 720K ...
19
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4answers
2k views

How did the Amiga 500 left-side expansion port work?

On the Amiga 500 there is an expansion port How did the expansion port work?
15
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3answers
5k views

How can I adapt a modern mouse for use with Amiga?

Death of the Amiga platform predated introduction of optical mice of reasonable quality by a couple years. The Amiga mouse was a box of problems, with non-ergonomic shape, crud-accumulating rollers ...
10
votes
3answers
1k views

What advantages are there to replacing Kickstart 3.0 with Kickstart 3.1?

I have an Amiga that has the Kickstart 3.0 ROMs installed. What advantages are there to replacing the Kickstart ROMs with 3.1? Is there any software that requires Kickstart 3.1 to function?
22
votes
1answer
784 views

Why are there two, different, Kickstart 1.3 ROMs with the same 34.5 version number?

The Kickstart 1.3 ROM file that is supplied with Cloanto's Amiga Forever (amiga-os-130.rom) is very slightly different to that which you'd get by dumping a real 1.3 ROM from an Amiga 500. ...
13
votes
1answer
423 views

How was 8-channel audio achieved on Amiga?

Oktalyzer was a Tracker style program for Amiga, that allowed composing and playing music with 8 channels instead of the "hardware-natural" 4. So far I learned it achieved that by splitting the 4 8-...
14
votes
1answer
989 views

How could Amiga computers play 14 bit sound?

The "Paula" chip used for sound output in all Amiga computers had 4 8bit sound channels (arguably comparable to 9bit stereo). There were programs/libraries which could play 14bit stereo on the Amiga ...
10
votes
2answers
310 views

What did disk-validator do?

...besides relabelling the disk to 'Lazarus' and helping the Saddam virus spread? I know it was supposed to 'fix' corrupted disks that were ejected during a write operation. I don't think I've seen a ...
11
votes
1answer
452 views

What does Personal Paint documentation actually refer to by “unmaskable interrupt” for its “crash protection feature”?

Personal Paint was a gfx program for Amiga that introduced many novel concepts, some quite ingenious, some... controversial. Among all, it had a "crash protection" feature, that was meant to enable ...
17
votes
2answers
751 views

How did programs/patches stopping Amiga idle floppy drive noise work?

The Amiga computers would by default automatically detect a disk being inserted and respond by reading from it and displaying its icon. Polling the drive(s) for a new disk would produce a clicking ...
14
votes
2answers
2k views

Booting an Amiga 1000 directly to the hard drive without Kickstart floppy

The Amiga computers such as the Amiga 1000 required a Kickstart floppy to be able to boot directly into a hard drive. I have a Amiga 1000 as well but missing the Kickstart floppy. I would like to ...
14
votes
2answers
619 views

What information is encoded in the 22-digit barcodes on the Amiga's case?

What information is encoded in Amiga's 22-digit barcodes? For example: 0103791363642010121234
19
votes
2answers
1k views

What were the differences in floppy disk formats between Amiga and IBM/PC compatible computers?

The capacity in Amiga Old File System format (OFS, OS version 1.x) was 840KB, with the Fast File System ("FFS" (!)) introduced for OS 2.x onwards able to store 880KB. The PC format stored 720KB on the ...