Which Agnus chips did the good old A500 have?

Am I correct in thinking that some A500s were fitted with fatter Agnus chips? I know that the original A500 had a standard OCS chipset, but didn't some have the fatter Agnus upgrade? Is the fatter Agnus the same thing as super Agnus, or is that something different again. What about the Denise chips? Did the A500 only ever have ECS Denise?

Just curious peeps.

[Galahad/FLT]

A5oo 1.3 ECS had Fatter Agnes so did A5oo Plus/A6oo, anything pre 1.3 ECS was the OCS chipset (early 1.3's and 1.2's).

Thanks for that Galahad/FLT. I was pretty sure my A500 had the ECS chipset, but most of the web sites I've looked at describe the A500 as being an 'OCS' machine.

Apart from the different Kickstart and a bit more RAM, the A500/ A500+/A600 must be almost identical to each other, even though the A500 was released years earlier.

[Overdoc]

There was a lot of different combinations, I think. ( like always with Commodore products )

Very old Amigas with Kick 1.2 and first Kick 1.3 Amigas had the 8371 512K-Agnus.
Then, later Kick 1.3 Amigas had the 8372A 1MB-Fat Agnus.
The last A-500s already had the A-500+ board in them ( Rev. 8.1 ) and therefore even had the 8375 2MB-Super Fat Agnus. And I think some of these very late ones also had a 8373-Super-Denise for ECS instead of the OCS 8362.

ECS is a grafic mode that needs a Super-Denise. And further Super-Denise needs a 2MB Super-Fat-Agnus to operate in ECS grafic mode. So if your A-500 had ECS it must have had both the Super-Fat-Agnus & the Super-Denise !

The difference between A-500 and A-500+ is 512k Chipram more in the A-500+, and full ECS ( Super Fat Agnus & Super-Denise ), and also Kick 2.0 in the A-500+.
The A-600 is similar to the A-500+, but has a harddrive connector.

I hope I didn't tell no bullshit - please correct me if I'm wrong !

[jmmijo]

I'm pretty sure you're correct on this one Overdoc

[Shadowfire]

"ECS" referred to the Agnus chip.

OCS Agnus=512k chip
ECS Agnus=1mb chip (+ productivity modes, I think)

There is no such thing as an "ECS Denise". Denise only had 1 major revision (they added Extra Half-brite mode) but this revision was made before they shipped the first A500 & A2000's. Any revision Denise will work with any Agnus chip.

[Twistin'Ghost]

Perhaps it's a common myth, but I believe that the Denise revision occured at the same time as the ECS Agnus. It was offered to us when we had our A500 upgraded, but we didn't get the Denise upgraded. Whether it technically belongs to the ECS upgrade or not, I can't say (as I was not a dealer). But I have read that the Denise upgrade is a part of ECS and have always believed that, whichever version is true.

There has been some discussion in the past about whether games are ECS or OCS and I always contend that any game that requires 1meg chip is ECS since that version of Agnus was the first to achieve this (and you can't play say, Dungeon Master, on an OCS machine).

[Shadowfire]

the "breaking" of OCS-only games occurred because of 1 of 2 things-

poor use of registers (i.e. all of a sudden there were address bits in the chipset register space that were used)- not clearing unused bits, or not taking into consideration that chip ram might be located somewhere other than $00000000-$0007FFFF.

poor memory management (asking the OS if theres more than 512k, then tossing the OS & assuming that there's 512k of "slow" fast memory @ $00c00000 (not true on any non-ocs machine)

Is it fair to say that any upgrade from the OCS chipset, such as the Fatter Agnus, is an 'ECS' chip? Or is it best termed an upgraded OCS chip, since it has only 512k RAM?

If I remember rightly, one of the features of the Fatter Agnus 'upgrade' was the ability to switch between 50 and 60 Hz, so you could 'stretch' NTSC games to fill the PAL screen, using a scan-lines type effect. I don't think the OCS chip could do this.

Shadowfire, what do you mean when you say there is no such thing as ECS Denise? I thought ECS Denise chip was specifically emulated in WinUAE.

[Miggy2TheMax]

Hi guys,

I'm sure an ECS denise exists, it just gives you extra hi res screen modes. See url below for more details:

http://www.webworldinc.com/transdata/ami19.htm

[Twistin'Ghost]

Originally posted by Quickbeam
Is it fair to say that any upgrade from the OCS chipset, such as the Fatter Agnus, is an 'ECS' chip? Or is it best termed an upgraded OCS chip, since it has only 512k RAM?

If I remember rightly, one of the features of the Fatter Agnus 'upgrade' was the ability to switch between 50 and 60 Hz, so you could 'stretch' NTSC games to fill the PAL screen, using a scan-lines type effect. I don't think the OCS chip could do this.

1. It depends on what you call the Fatter Agnus. If you mean the ECS Agnus, then it was 1 meg of chip, not 512k. I will call this chip the ECS Agnus since there are so many conflicting accounts of the actual name. When we upgraded ours back then, the dealer told us it was the Fatter Agnus and CBM also referred to it as this when we spoke with their technical support people.

2. When the PAL and NTSC switching was introduced in the ECS Agnus, it allowed you to boot in these modes, but it never "stretched" the NTSC display that I am aware of (unless it did this on European machines). Here in the States, the old PAL games were shifted down under the overscan area at the bottom of the screen. After the upgrade, we were able to use PAL booters to shift it back up to the normal 256/512 lines display (as well as the timing problem being fixed).

[Overdoc]

I'd say it goes like this:

Fat Agnus - Commodore part# 8371 : can access 512k of ram
Fatter Agnus - Commodore part# 8372A: can access 1MB of ram
Super-Fat Agnus - Commodore part# 8375 : can access 2MB of ram ( this is the Agnus ECS machines like the A-500+ and A-600 have ! )

Normal Denise - 8362
Super Denise - 8373 ( this is the ECS Denise in A-500+ & A-600 )

Upgrading the Agnus will give you the ability to have more chipram, like e.g using a A501 ramexpansion as chipram instead of slowram, but will not let you do extra hires screens afaik.

For the hires mode you will need the Super-Denise, and I think also at least a 1MB Agnus chip to be able to display a super hires screen.

[trydowave]

Originally Posted by Overdoc

later Kick 1.3 Amigas had the 8372A 1MB-Fat Agnus.

This surprises me. I always thought it was just A500s with 512 kb chip ram? The batman pack etc

then i thought the first 1mb chip ram amgia was the A500+ ?

IF thats not the case; which ocs amigas had these 1mb chips? Fatter Angus or whatever its called?

Were they released in a pack here in the UK? I brought one of the later ones, Screen Gems with KS 1.3 and im pretty sure it was 512 kb chip ram only.

P.s. I just realised how old this post is

[Megalomaniac]

I think he meant that the later A500s had potential to support 1Mb chip RAM from new, not that they came with it. A500s came with the A501 upgrade for about its last six months.

Did ECS in itself cause many incompatibilities? I know Double Dragon 2 didn't work on ECS, as opposed to because of Kickstart 2, was that a one-off? Did anyone have problems with (say) Lotus or Italy 1990 (which have that same kind of garbled-screen fault on A500+s) on a later 1.3 A500?

[pandy71]

A500 rev 6 usually have 1MB Agnus and standard Denise - normally on PCB 512KiB of CHIP RAM but after adding 512KiB SlowRAM you could rewire PCB to be 1MiB of CHIP (also on those boards seem RAM was visible in shadow area - can be addressed as SLow and as CHIP). ECS means new bits AND new registers - 1MiB Agnus could have only bits to extend addressable CHIP range (i never verified this on my Amiga motherboard).

[alexh]

My 1990 Flight of Fantasy A500 was half ECS. It had Kickstart 2.04 and 1MB Agnus and standard Denise, 512KB ChipRAM on the motherboard and a reseller fitted A501 512KB slo-RAM which appeared as ChipRAM. (I believe this to be true because the game Lionheart on this computer needed to use "FakeFast" program to work. Perhaps this is not an accurate deduction?)

It was "incompatible" with lots of stuff... but that was just KS2.04. I fitted a KS ROM switcher and mainly used mine in KS1.3

[trydowave]

Originally Posted by Megalomaniac

Did ECS in itself cause many incompatibilities? I know Double Dragon 2 didn't work on ECS, as opposed to because of Kickstart 2, was that a one-off? Did anyone have problems with (say) Lotus or Italy 1990 (which have that same kind of garbled-screen fault on A500+s) on a later 1.3 A500?

I had a few games that had this problems (cant remember which ones but im sure Lotus was one of them. Maybe LedStorm too. Been a while.

I had an A500 and later on my Mum brought an A600. Relokick sorted out any issue i had. I think i had a fixed version of DD2 as well.

[trydowave]

Originally Posted by alexh

My 1990 Flight of Fantasy A500 was half ECS. It had Kickstart 2.04 and 1MB Agnus but no ECS denise.

This is interesting . One of the reason i ask is the new Wonderboy game (u can see it over at indie retro news) is said to run on all amigas (well.. maybe not the 1000) as long as it has 1mb chip and another 1mb of chip or slow ram installed.

Does that mean your amiga could, with the right expansion, could run that game?

Also. Flights of Fantasy was the pack my friend owned before I got my Screen Gems. Flights of Fantasy being far superior, but thats besides the point.

Does that mean my Screen Gems Amiga has a 1mb Agnus?

Cheers

[alexh]

Originally Posted by trydowave

Does that mean my Screen Gems Amiga has a 1mb Agnus?

Almost certainly.

[zipper]

Yes, my rev 6, bought 1991 had a 1 MB Agnus but came configured 0.5 + 0.5 with trapdoor expansion. Later I modified it to 1 MB Chip.