How Amiga 500 RAM Probably Works | Hacker News Reader

How Amiga 500 RAM Probably Works

youtube.com

62 pointsdoener30 comments

I’m skimming over the transcript and this dude is all “well most games didn’t take advantage of anything beyond 512K so what use was it” and, well, we did use the damn things for stuff beyond games back in the day, you know.

Games are the part that’s most interesting for retrocomputing and nostalgia; I played a lot of games on my Amigas, but I also did stuff like “laid out the newsletter for the local Dr Who fan club” and “chatted on BBSs” and “dabbled with art and animation” and all of those things were enhanced by having more than the bare minimum of RAM. Hell, I connected it to the Internet by getting a PPP gateway up on a mainframe at the local university and browsed the Web, that sure was helped by extra RAM.

Exactly - The 512K expansions were by far the most common expansion. I did play games on my Amiga, but far more of my time was spent doing other things with it.

If you make a game for a given platform, it makes sense to target the most common configuration, which in this case was 512k (not 512M btw). Even though RAM expansions eventually became popular, I guess publishers would be hesitant to put a "requires 1M+" sticker on their boxes. But man, 512k seemed like a blessing in those early days, too...

Some games simply used extra ram to hold the contents of, say, disk 2. Reducing disk loading (and swapping!) was a big deal.

If I remember correctly, Dungeon Master was the first game to require 1MB.

k. Not M, right?

Oh right, duh. Fixed, thanks.

Yes.

The Amiga 500 shipped with 500 KB of "chip RAM", so named since it is accessible by all the wonderful custom chips.

Many people opted to install a 512-KB expansion in the "trap door" under the machine. That was "slow RAM".

you could make some changes to the board, and it would all be addressable as 1M chip ram.

of course, the real fun was adding 4M of "fast ram" on the side bus.

That was on amiga 500+ I think, older amiga 500s would not be able to use 1M chip anyhow.

it was a mess, 500 was a 512 or 1MB lottery. https://en.wikipedia.org/wiki/MOS_Technology_Agnus

I had an original non + amiga, and definitely had 1M.

> we did use the damn things for stuff beyond games back in the day, you know.

This. The Amiga's multitasking was amazing back in the mid/late 1980s. My favorite example:

I'm in my dorm room, writing a paper in a non-western-alphabet language[1] on my Amiga. The phone rings. My BBS, running in the background, answers the phone and someone logs in. This all happens with zero impact on my using the computer.

This blew my fellow students' minds. I'd have to show the BBS user's activity for them to believe me. All this on a machine with only floppy disks. I couldn't afford a hard drive until later.

I also wrote solvers for math problems in AmigaBASIC, fancier programs in Modula 2 (I couldn't afford the C compiler), and, of course, played games.

Edited to add [1]

----

[1] There was one PC that supported this. Not having to sign up to use it made getting homework done much easier.

He almost gets it right. The switch doesnt move trapdoor Ram to the other side of the bus buffers, it merely changes how Amiga chipsets see it.

My A500 was tricked out with 3 megs of RAM. 512k onboard + 512k trapdoor + 2 megs on the expansion bus. This was incredible for 1990.

This is very good comedy, and I'm merely an Amiga bystander.

What’s great about this video is that all the jokes have their basis in truth… usually an uncomfortable truth.

I enjoyed the stab at Atari ST far too much - apparently that grudge has lasted well over 30 years.

Is it still uncool to like both? The Atari ST had objectively worse game graphics and sound, but it was better than the Amiga for things like MIDI and DTP.

This might make you smile as an ST fan : https://www.youtube.com/watch?v=qLjgXPDzeZo&t=19s

So many British musicians, including two of my favorites, The KLF and Imogen Heap, were using STs in the 80s and 90s.

No, sure, as a kid who was very much in to techno music the Atari ST was much admired for it's MIDI capabilities. Any actual MIDI gear was very much out of the price range for my parents and for anyone I knew. We had a setup in the music room in school with an Atari ST and a digital sampler though, had lots of fun with it.

My 30 year old grudge has more to with the one rich kid in my school who actually owned an Atari ST. It was slightly more expensive than the Amiga, which he loved to point out.

I had a $50 MIDI interface box on my Amiga. It would’ve been nice to have it built-in, but it was one of the cheaper things to add.

Sure, but like I said, actual MIDI controllable gear was not cheap.

Right, but doesn’t that apply to using an ST, too? You didn’t get a discount on synths based on which OS you were using.

midi interface was one thing, but what really sold ST as a music computer was 640x400 72Hz 12 inch mono monitor. Sharp picture, no headache inducing interlace.

I had both, and thought the "rivalry" was just a bit of fun ...

A large portion of the games were developed for both systems simultaneously, often without the Amiga version taking advantage of the machine's better capabilities. Some games had better music on the Atari ST, but largely because of the abilities of the composers.

Honestly both the Amiga and ST were excellent computers. Judging by the A1000 I'd even say the ST was the better machine, considering the price.

The reason so many people who had an Amiga are (still) salty over the ST is that lots of games were ported straight from the ST without taking any advantage of the extra power of the Amiga besides audio. While the publishers are to blame here, the ST is the easy target.

Had the ST not existed, those games would have likely targeted the Amiga hardware first and foremost, and been far better as a result (proper scrolling, higher framerates, more and better colors, etc.). But again, the ST is not to blame for that.

Similar thing happened to MSX and Amstrad CPC owners with ZX Spectrum ports. These days all these machines have healthy homebrew scenes that show how nice the hardware really is. I still can't believe Dread and Metro Siege are real Amiga games. And Dread has an ST port, and that's a good thing.

Ex Amiga and Atari ST programmer. C Compiler, games, BBS doors, databases, and a few other things published.

There were many games that worked beyond 512K, Prince of Persia being a notable one, and I think DungeonMaster by FTL being another. I started on the A500 but eventually acquired an Amiga workstation with 8MB RAM, a 68030 CPU and a 120MB HDD that was an absolutely stunning development system for the time. I also had a couple of A500s on the desk, in various configurations, to make sure the code I wrote would work on other machines. And a dedicated A2000 running the BBS with a 1GB HDD. I'd code on the x30 equipped Amiga, and download via parallel cable to the A500 for testing.

The interesting thing about Amiga RAM layout was that there was Chip RAM and Fast RAM and RAM. Chip RAM was accessible by both CPU and dedicated video/sound chips. I am going to get a bit fuzzy on the remembered details, but the CPU accessed the RAM on the rising clock and the chips accessed the RAM on the falling clock - I'd have to verify if that was the correct way around. Fast RAM on the Zorro bus or in the Sidecar was only accessible by CPU, so it had full bandwidth access. I recall the trapdoor RAM expansions was often slower, not just because of the shared bus but also many manufacturers just used the cheapest/slowest RAM they could source.

I recall the ECS could access RAM up to 1MB, maybe even more, it's been 30+ years. I wrote functions to detect if the computer had Fast RAM installed and if so, relocate the code above 512KB for a speed boost, and also, in the case of a compiler, put a small "RAM disk" above 512KB to cache data.

Original Atari ST was interesting for other reasons beyond the chipset of the Amiga, mainly the peripheral support, the not worrying about RAM layout, the higher resolution displays (oh my god those high rez grey scale displays). Also I could wire up my ST to my Yamaha DX7 and run Cubase. My first ST development system was the 260 ST with the ROM BIOS on a dongle on the left hand side, which I had to send back (the entire machine) to Atari for replacement when they finally released the 520 ST to developers. Years later I was kicking myself for having sent the machine back because there was less than 1,000 of the 260 ST developer units made and it was a piece of history. And then through a strange confluence of events, almost 25 years later, I was wandering around WeirdStuff several years before it closed and there, on the shelf, for ten bucks, was the 260 ST with my initials on it.

I liked programming the Atari ST for "just get on with it", in that it was you, the CPU, and the display output, and it was a pretty straight line between the two. On the Amiga, you often had to think in "parallel" parts and timings, so it was a different mindset. It wasn't harder or easier, it was just different. I enjoyed developing for both for different reasons.

The humour in this is excellent!

Reply on news.ycombinator.com