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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: Speelgoedmannetje on November 30, 2003, 09:19:18 PM
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I thought the A1000, A500, CDTV and the A2000 has the OCS chipset, the A3000, A600, A500+ has the ECS chipset
Somehow sites and threads say the OCS and the ECS are the same
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I think people tend to group ECS and OCS together because they were more compatible with each other than with AGA, and are considered part of the same era of 16-bit Amigas. But there are some differences, higher resolutions and I think someone said VGA modes were supported from ECS onwards.
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But a game written for ECS is not compatible with an OCS system, for instance The Lost Vikings
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Yeah, it's possible to write software that only works on one of them, but the ECS's backwards compatibility was much better than AGA's. So that's why people tend to group them together. It is annoying though, maybe when you see errors like that you should email the webmasters responsible? :-)
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Well the problem is that late A500s and A2000s were delievered with an
1MB Agnus. Now this chip does feature being both PAL and NTSC in one
and the better blit-modes found in ECS, but not the 2MB-support normally
ascoiated with ECS.
So are these machines (with standard Denise) OCS or are thes ECS ?
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Can it handle 64 colors (wich as far as I know the A600 supported)?
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There are some examples of ancient a1000 demos not working on a500, but that could be more of an OS1.1+ 1.3 conflict.
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64 colors ?
Every Amiga (except few very early A1000s) do support 6Bit modes.
OCS/ECS only EHB and HAM,and AGA real 6Bit (well and 7Bit and 8Bit too).
The A600 didn't have anthing the A500+ didn't have in that field, the only difference
where the switch to SMD (bad), the PCMCIA-port and onboard IDE.
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Then why do most Amiga 500 games only support 32 colors (for as far as I know) and not 64 colors?
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OCS and ECS, when it came to games, were probably identical. There was no real speed boost in using ECS, and it couldn't show more colours at once.
The only difference I know what that ECS had extra screenmodes, like the fairly useless super-high res and some VGA modes.
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Then why do most Amiga 500 games only support 32 colors (for as far as I know) and not 64 colors?
An A500 and an A600 both could only show a maximum of 32 colours in normal mode, 64 in HalfBrite mode, and 4096 in HAM6 mode.
Only AGA pushed this barrier.
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Thanks KennyR,
now it's all clear to me :-)
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64 in HalfBrite mode
To expand, IIRC HalfBrite mode is where the first 32 colours are set as normal, and the next 32 are half the brightness.
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My A500 was equipped with 1Meg Agnus, so I just needed to replace Denise and put KS 2.05 in (into KS switcher of course) to get ECS A500 - a huge improvement as I also had a HD, turbo and extra RAM. Wow, wasn't it cool to load a WB with background pattern in Multiscan!
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"Well the problem is that late A500s and A2000s were delievered with an
1MB Agnus."
The so-called "Fatter Agnus" (as opposed to the "Obese" 2MB version). Best way to test the presence of this on your A500 is to reset and keep an eye on the power LED. If it dims (without extinguising completely), then chances are you have a Fatter Agnus.
However, this doesn't mean that any 1/2 MB RAM expansions situated in the trapdoor are automatically configured as chip RAM, even though Fatter Agnus can address a full Megabyte of Chip memory. The trapdoor RAM defaults to Fast, unless you buy a specific board and modify the motherboard.
"So are these machines (with standard Denise) OCS or are thes ECS ?"
ECS I believe. My own A500 was bought in February 1990, just a couple of months after my mate bought his and I believe that the A500's were unofficially equipped with ECS from December 89 onward.
There are certain compatability issues with ECS and OCS. Scoopex's brilliant "Mental Hangover" demo corrupts during the final scrolling sequence on ECS/AGA machines for example.
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I have two A500 (originaly OCS) ... In one of them I exchanged the Denise with a Super Denise (ECS), it also came with an 1MB Fat Agnus, so I made a hack, to make my 512kB slow RAM to CHIP memory ... so I could almost call my old A500 an A500+, but with my 68020card and AmigaOS 3.1 what should I call it ;-)
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PMC wrote:
"Well the problem is that late A500s and A2000s were delievered with an
1MB Agnus."
The so-called "Fatter Agnus" (as opposed to the "Obese" 2MB version). Best way to test the presence of this on your A500 is to reset and keep an eye on the power LED. If it dims (without extinguising completely), then chances are you have a Fatter Agnus.
No, this tells you that you have a REV6 or newer motherboard. (most of which were shipped with an ECS Agnus, however :-)
Sysinfo is a good way to quickly determine what's inside the box.
"So are these machines (with standard Denise) OCS or are thes ECS ?"
ECS I believe. My own A500 was bought in February 1990, just a couple of months after my mate bought his and I believe that the A500's were unofficially equipped with ECS from December 89 onward.
These are so called "half ECS" machines. The ECS consists of the Fatter/Obese Agnus and the Super Denise.
If you swap in a Super Denise, you've got full ECS.
With an ECS Agnus, you get more CHIP RAM, but for the enchanced video modes, you need KS2.x or better and the Super Denise.
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Kronos wrote:
64 colors ?
Every Amiga (except few very early A1000s) do support 6Bit modes.
OCS/ECS only EHB and HAM,and AGA real 6Bit (well and 7Bit and 8Bit too).
Some people call the non-halfbrite Agnuses ICS for Initial Chipset.. An unofficial name.
The non-halfbrite Agnuses are not very common - the chip was upgraded quite soon after the launch.
The slim Agnus was in the A1000 and the original A2000. The B2000 (A2000-CR) got the fat Agnus and the ability to be upgraded to ECS.
Just to be sure: the slim Agnus can do halfbrite too, it's just the very earliest revisions of the chip that can't.
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Speelgoedmannetje wrote:
Then why do most Amiga 500 games only support 32 colors (for as far as I know) and not 64 colors?
Halfbrite is slower.
Try it in an older version of DPaint some time.