19 July 2021, 05:48 | #321 | |
Banned
Join Date: Sep 2011
Location: Cardiff, UK
Age: 51
Posts: 2,871
|
Quote:
Or didn't the Americans give a stuff about overseas territories at the time? Would be typical of the Yanks to do so. |
|
19 July 2021, 09:00 | #322 | |
Registered User
Join Date: Jan 2019
Location: Germany
Posts: 3,307
|
Quote:
There is no way for a TV signal to represent red color bars on green background with a hi-res output (try that!). |
|
20 July 2021, 07:12 | #323 | |
Registered User
Join Date: Mar 2018
Location: Hastings, New Zealand
Posts: 2,719
|
Quote:
But the reason for the divide between PAL and NTSC is much older. The TV frame frequency was set to the AC mains frequency to reduce the visual effect of hum (which was impossible to eliminate in valve TV sets). In the early days of electrical power distribution many different frequencies were used, often to match the device being powered (eg. 16.66Hz for induction motors, 133Hz for lighting) but in America 60Hz was popularized by Westinghouse while in Europe AEG set the standard at 50Hz. With modern TVs it isn't a problem anymore, as most support multiple standards. However I have 2 Samsung LCD TVs that do not support 50Hz over HDMI. This is a pity because it means I can't use the Vampire RTG resolution that I want (1024x768). Luckily I have a cheap 26" LCD that does it perfectly. |
|
23 July 2021, 02:25 | #324 |
Registered User
Join Date: May 2017
Location: Munich/Bavaria
Posts: 2,426
|
I would add: financing
Amiga (the startup) did not get enough money to bring its computer to the market on its own. First they needed additional money from Atari, which then led to the commodore buy-out .... Some members of the original team learned from the experience and tried a licensing model with the 3DO console. But that did not turn out any better in the end. (too expensive and a year or two too late... ) With better financing and a working prototype in 1984 a licensing model might have worked out for Amiga, like it did for Microsoft with the MSX - at least for a while. In the 90s simply every alternative computer platform* died - no matter if it was a "home computer" or a "workstation". *) Apple only survived with the help of MS |
11 August 2021, 20:19 | #325 |
Registered User
|
Not allowing TAS/CAS/CAS2 instructions is really one thing they did wrong from day 1.
After studying multithreading I realized how incredible useful those instructions are really. They would have allowed, for example, sharing data between PPC and 68k without using locking (mutexes) and therefore without context switches (which were really expensive with >= 1ms duration)! cas2 for example, allows implementing linked lists and queues without any blocking mechanism like Semaphore. Have you ever wondered why every 68k accelerator disables the on-board already present CPU? Though it could have been used as a second core? It's because of this! Last edited by BastyCDGS; 11 August 2021 at 20:34. Reason: Added single core m68k only on Amiga notes |
11 August 2021, 22:12 | #326 | |
Registered User
Join Date: Apr 2017
Location: France
Posts: 646
|
Quote:
By "not allowing" you mean "not safe due to hardware design" I suppose. I had to find this thread to understand why you said that. |
|
12 August 2021, 00:13 | #327 |
Banned
Join Date: Sep 2011
Location: Cardiff, UK
Age: 51
Posts: 2,871
|
I'm surprised that the stock Motorola 68000 even supported multithreading back in the 1970s, if that's what this is about. But the Amiga chipsets were designed for the 68000, but single core and single threading only (AFAIK). I'm just guessing here, BTW.
|
12 August 2021, 01:59 | #328 | |
Registered User
Join Date: Feb 2011
Location: Italy/Rome
Posts: 2,344
|
Quote:
|
|
12 August 2021, 10:37 | #329 | |
Registered User
Join Date: Jan 2019
Location: Germany
Posts: 3,307
|
Quote:
Well, this is really over-simplifying the problem. It is not because of the instructions (or rather, this is only the tip of the ice) not being supported by the bus. It is also a matter of the design of the board to release the 68K for working. Actually, on the P5 PPC cards, the 68K and the PPC are working on the same local bus (namely that of the card) and there, in their isolated territories, could have used TAS/CAS - or maybe they even do. As the communication only happens on the same board, and does not go to the outside then, TAS/CAS would have been fine. The problem is that if for every data exchange you have to wait for one CPU or the other, you loose performance, i.e. every communication from the PPC to the system has to go ping-pong to the 68K is the problem Not exactly how this communication works. I do not know enough on these boards to say how exactly they worked. In principle, you could get away with bus snooping (both PPC and 68K support this) and read/modify/write instructions, all provided you can design a bus interface for both CPUs that support this. Whether P5 hardware works this way I do not know, but nothing on the Amiga side prevents a TAS/CAS as long as the RMW-instruction does not leave the board. It becomes problematic if the target of RMW is in chip ram (unsupported) or in Z-II/Z-III RAM. |
|
12 August 2021, 10:41 | #330 | |
Registered User
Join Date: Jan 2019
Location: Germany
Posts: 3,307
|
Quote:
Multi-core(!) has some impact on the bus design, and this is where we have the problem, but multi-core was not realistic back then. |
|
12 August 2021, 12:14 | #331 | |
Amiga user
Join Date: Nov 2008
Location: Sofia / Bulgaria
Posts: 472
|
Quote:
The 68000 can work independently from the Agnus (Blitter, Copper), the Denise and the Paula. The Paula can do DMA, the Blitter can blit data, while the 68000 does other tasks. |
|
12 August 2021, 13:59 | #332 |
Registered User
Join Date: Jan 2019
Location: Germany
Posts: 3,307
|
Hardly. If so, the C64 was "multicore" and the PC was "multicore" as well. I mean SMP, to be precise, and this the current bus design does not allow.
|
28 August 2021, 17:30 | #333 | |
Registered User
Join Date: Sep 2019
Location: Essen/Germany
Age: 55
Posts: 463
|
Quote:
The M68000 doesn't support multithreading. The Amiga OS does that, but this can be done on any machine. I did it on an 8086 back then, and also on the C64. But of course, if you try to generalize that you run into the problems that modern OSes and MMUs are solving. So running multiple threads is rather easy to do. |
|
15 October 2021, 00:07 | #334 |
Commodore Collector
Join Date: Aug 2001
Location: Austria
Age: 53
Posts: 944
|
Since I had used a C64 for many years before the Amiga, for me the biggest Amiga disappointment from day 1 was that no operating system was built into the machine, not even a minimal one.
Whenever you wanted to do anything, you needed to boot the Workbench disk first. And even after loading, it needed to load every single Amigados command from disk separately! So, with a stock Amiga 500 without a second external diskdrive, you practically couldn't do anything except playing games without getting frustrated from permanently swapping disks. |
15 October 2021, 09:07 | #335 |
Registered User
Join Date: Jan 2019
Location: Germany
Posts: 3,307
|
|
15 October 2021, 09:40 | #336 |
Commodore Collector
Join Date: Aug 2001
Location: Austria
Age: 53
Posts: 944
|
|
15 October 2021, 16:53 | #337 | |
Registered User
Join Date: Jan 2019
Location: Germany
Posts: 3,307
|
Quote:
Just in case you didn't know, those things are all in the kickstart, just waiting to be used, just that there is at this point not yet a program using it. The only thing it waits is a boot disk that calls InitResident() on the dos.library. Once that is done, you get already your boot CLI, your boot window, the ROM functions, intuition... The Amiga is not a toy computer, unlike the C64. They did right *not* shipping it with a bad excuse of a Basic in ROM. Last edited by Thomas Richter; 15 October 2021 at 17:03. |
|
15 October 2021, 17:35 | #338 |
Commodore Collector
Join Date: Aug 2001
Location: Austria
Age: 53
Posts: 944
|
Thanks for the explanation, ofcourse I know that the kickstart is an operating system.
But you already answered it yourself: It is just not accessible from the start of the computer! When you turn on your Amiga, the operating system is not there, it is not complete, yet, und you cannot access and use it until you boot an additional, missing part, which is called 'Workbench disk'..... And this is the problem which did make everything so tedious. You couldn't do anything with your Amiga 500 until you waited 1 minute to boot the Workbench, and then you became a diskjockey if you wanted to do anything on a disk which was not the Workbench disk. Developers forgot that it is complete bullshit to boot the operating system from a disk. This is something which only works from a harddisk. But harddisks were expensive as hell back then, and so only few people had them. Most just invested in a second diskdrive, which was mandatory on the Amiga if you wanted to do anything else than gaming. But you are correct, the Amiga is not a toy computer, it is more a gaming console, than a computer 90% of all Amiga users I know never did anything else than putting a disk in the drive to play games. This is very different for the C64 users I know, including myself. The C64 gave the possibility do write programs and explore the system right from the start. I think the Atari ST did it correct, and had it's TOS in ROM, afaik? |
15 October 2021, 17:49 | #339 | ||||||
Registered User
Join Date: Jan 2019
Location: Germany
Posts: 3,307
|
Quote:
Quote:
Quote:
Voila, you have your operating system all ready, from an empty disk! Quote:
Quote:
Quote:
You still don't get it. The Amiga has its Kickstart in ROM as well. That's all there, it just needs activation. |
||||||
15 October 2021, 19:17 | #340 |
Registered User
Join Date: Dec 2014
Location: germany
Posts: 439
|
But a user cannot get into the OS without having a prepared disk. So without that, you can't even list disk contents or format an empty disk. It is IMHO an oversight not to have a minimal, user accessible system running solely from ROM. AFAIK you cannot even enter romwhack without a disk or some hardware modification that provokes a guru - despite the fact that everything is already there in ROM. I fail to see a good reason for that.
|
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests) | |
Thread Tools | |
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Non-Amiga things that remind you of Amiga things? | Fingerlickin_B | Retrogaming General Discussion | 1056 | Yesterday 08:36 |
wanting to experiment, using Amiga (emulator) as my day to day machine, need advice | mmace | New to Emulation or Amiga scene | 14 | 19 March 2020 11:32 |
Why game companies didn't make better games for Amiga | ancalimon | Retrogaming General Discussion | 35 | 17 July 2017 12:27 |
New Year Day = throw CD32 in the dishwasher day | Paul_s | Hardware mods | 16 | 03 January 2009 19:45 |
Amazing things you've done with your Amiga | mr_a500 | Amiga scene | 67 | 05 July 2007 19:45 |
|
|