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

53
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 ...
41
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 ...
31
votes
2answers
2k views

What modification is required from a PC floppy for use in Amiga?

Around the end of the time of Amiga popularity, obtaining a replacement Amiga floppy drive was a nuisance, while PC drives were ubiquitous and cheap. One could install a PC drive in Amiga after ...
24
votes
4answers
4k 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 ...
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 ...
24
votes
1answer
713 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 ...
24
votes
1answer
1k 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 ...
23
votes
5answers
1k views

Did any Amiga 500 games or programs (apart from paint programs) use more than 32 colours?

While the Original Chip Set (OCS) and Enhanced Chip Set (ECS) Amiga computers had the 32 x 2 colour EHB (Extra Half-Brite) and 4096 colour HAM (Hold And Mofify) screen modes, where these ever used ...
22
votes
2answers
984 views

How to obtain 256 arbitrary colors with limitation of 64 per line in Amiga (ECS)?

The game Universe for Amiga boasted ability of use of 256 different Amiga colors available through the ECS chips, with only limitation of 64 colors in halfbrite palette (32 arbitrary + 32 at half ...
21
votes
2answers
875 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, ...
20
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 ...
20
votes
1answer
674 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. ...
20
votes
1answer
2k views

How to convert Amiga DMS to ADF?

Our demoscene group managed to release only one demo before it fell apart, but these being the early days of the Internet in my country, and me getting lucky with obtaining access to it and creating ...
19
votes
3answers
1k 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 ...
19
votes
1answer
4k views

Why do all the Speech Synthesizers have that same Voice?

The first time I ever played with software speech synthesis on a microcomputer (not hardware synthesis, like in TI's Speak & Spell) was around 1983, using S.A.M for the Commodore 64. A year later,...
19
votes
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?
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 ...
18
votes
7answers
2k views

Was Amiga the last of the home retrocomputers sold?

The Commodore-Amiga was offered for sale to home users from 1985 (original A1000 in North America) until 1996, when Escom stopped selling the A1200. By 1996, Apple was selling PowerPC-based Macs for ...
17
votes
2answers
649 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 ...
17
votes
2answers
775 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 ...
17
votes
2answers
446 views

What should I do when some of the keys of my Amiga 600 have stopped working?

I opened up an Amiga 600 to install a hard drive, and after reconnecting the keyboard ribbon and powering the computer up, at least one column of keys no longer works. What did I do wrong and what ...
17
votes
1answer
1k views

Was it possible to get more than 8 sprites per scanline on an Amiga with the copper list?

I've read in the past that it was possible to overcome the 8 sprites per scanline on the Amiga (OCS) using the copper list. However, I can't seem to find any actual references to what may have used ...
17
votes
1answer
962 views

Change Amiga Shell keyboard layout in Workbench 1.3

I'm using Workbench 1.3 in Amiga 500. I managed to change the Spanish keyboard in "SetMap", as shown in the following figure: And I can write text with special spanish characters (ñ,ç,ó,á,...) from ...
16
votes
4answers
832 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 ...
16
votes
1answer
982 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 ...
16
votes
1answer
550 views

What size screws were used in the Amiga desktop cases?

On the Amiga 500, 500+, 600, and 1200, what size screws were used to hold the chassis together? Is it the same size screw for all, different screws per machine, different screws front and rear, or ...
15
votes
2answers
902 views

How does the Kickstart ROM load and start workbench?

As I understand, on the Commodore Amigas, the kickstart copies itself into a region of memory which is later made read-only. Does kickstart also copy workbench into this region? How does kickstart ...
15
votes
4answers
454 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 ...
15
votes
1answer
252 views

How to create a switchless multi-system 2 button Atari joystick?

All systems that use the Atari 9 pin joystick standard make use of the following pins in consistent ways, with each direction and the fire button being connected to the ground pin when pushed. 1 - up ...
14
votes
3answers
4k 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 ...
14
votes
1answer
479 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 ...
14
votes
1answer
824 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 ...
14
votes
2answers
1k 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
951 views

Creating a new language support for AmigaOS

Looking through the LO (localisation) disk for Workbench 3.1, I see that the language files are binary. I'd like to create a Gaeilge (Irish) localisation file. How is this done on Amiga? Update: ...
14
votes
1answer
215 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 ...
13
votes
3answers
1k views

How can you connect an Amiga 500/600/1000/2000 to a modern monitor?

I have an Amiga 500 that I'd like to get up and running again, but the 1084 monitor with which I used to use it has flyback transformer issues. What options are available to hook it up to a modern ...
13
votes
1answer
355 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-...
13
votes
2answers
476 views

What was exactly the Amiga Ranger?

Amiga's history includes something called "Ranger" that supposedly was either meant to be the next generation system to be released after the Amiga 1000 was released, or the codename for the next ...
13
votes
1answer
264 views

How do Amiga “Monitor” drivers work?

A "Monitor" driver for an Amiga is a file which, when placed in DEVS:Monitors, enables additional screenmodes. The standard PAL or NTSC driver, which provides screenmodes compatible with consumer TV ...
12
votes
2answers
396 views

What's the meaning of __saveds in Amiga C code?

What's the meaning of __saveds in Amiga C code? It's applied to function prototypes, and is required for functions that are to be called by assembler code, if I understand correctly.
12
votes
1answer
363 views

Where are the blueprints of MOS chips?

Atari historians have been able to find documents and tapes of chips and hardware developed at Atari. E.g. http://atariage.com/forums/topic/154479-new-gtia-chips/ . Nothing like this is happening ...
12
votes
1answer
286 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 ...
11
votes
2answers
462 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
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?
11
votes
1answer
436 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 ...
11
votes
2answers
454 views

How does the Amiga chipset RGA bus work?

The RGA bus is the bus that connects Agnus/Alice with Denise/Lisa and Paula. What is it used for? I guess at a minimum to write/read registers in Denise/Lisa and Paula, and I guess to feed data to ...
11
votes
2answers
266 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 ...
11
votes
1answer
579 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 ...
11
votes
2answers
335 views

What interface did Video Backup System use?

I remember the Video Backup System for Amiga advertized in Polish computer magazines of late 90s, "store hundreds of diskettes on a single VHS tape!" I seriously considered buying it (and a VCR since ...
10
votes
3answers
865 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?