Although this blog is being written in Czech language, I’ll make an excuse and write this article in English, as it could be interesting for wider audience.

Martin8bity asked me to make a comparison article on SID and the newest ARMSID, the C64 SID sound chip replacemet based on an ARM processor developed by Nobomi. So I pulled my old 6581 based breadbox and a 8580R5 „C“ out of the shelf and started recording randomly chosen SID tunes. Well, not so much randomly chosen, I recorded those ones where I awaited possible sound glitches and irregularities. Then I replaced the regular SID in my C64C with the newest ARMSID with fw 2.8 I got from Martin at Forever party and recorded same tunes and sounds again in both 6581 and 8580 variants. I only set the 6581 emulation of my ARMSID to sound as close as my original 6581 C64 by adjusting filter settings in the settings program supplied with the ARMSID.


First I recorded not the SID sound itself, but how SID and ARMSID interfere with silence and C64 internals. There were always audible interferences on the original SID chips but I was curious how ARMSID behaves in this. I used a BASIC – 1541U menu – BASIC scheme, so in the first part of all 4 audio files there is BASIC, then I pressed the Menu button of the 1541U-II and then I pressed it again to return to BASIC. You can hear the changes clearly on original SIDs, the 6581 and 8580 differs a bit. On the ARMSID, there are audible interferences present as well, but more silent and identical for 6581 and 8580 settings. The recordings are amplified to +20dB to hear the interferencing clearly. The audio out was over standard A/V DIN plug on the back of the C64 in all cases.

Interferences: 6581 8580 AS6581 AS8580


Next, I focused on classic musics. I chose Commando as an example. I also sampled some in-game sounds. I think Rob Hubbard didn’t use sophisticated SID technics much so the musics sound almost identical on all the SIDs, as well as the sound fx.

Commando main tune: 6581 8580 AS6581 AS8580
Commando sound fx: 6581 8580 AS6581 AS8580

Notice that the 5th sound in the sample sounds different than on the original chips. This is something ARMSID fw author could focus on in the future, but it isn’t a major issue at all.

Robocop 3

The second classic tunes‘ representative is Jeroen Tel and his notorious Robocop 3 tune. As a bonus I recorded the 4th submusic as well. There is no ARMSID 8580 version recorded as it was identical to the real 8580 version and the tune is written for 6581 SID primarily.

Robocop 3 subtune #1: 6581 8580 AS6581
Robocop 3 subtune #4: 6581 8580 AS6581

Bionic Commando & LED Storm

Tim Follin squeezed out of the SID chip a bit more so here are examples of Bionic Commando and LED Storm title tunes. The second one always differed on the old vs new SID.

Binonic Commado: 6581 8580 AS6581 AS8580
LED Storm: 6581 8580 AS6581 AS8580


In this game with music by Markus Schneider is a subtune #8 with use of only one SID channel due to use in a game section where the other channels are used for sound fx. There’s a spectacular bass tone which sounds different on various SIDs.

Platou: 6581 8580 AS6581 AS8580

Note the „more sythetic“ sound of the bass sound in 6581 and AS6581 samples. The original SID sounds a little bit more vivid.

Southern & Trible Speed Tune

I categorize this songs because they use twice as fast player routine than usually, i.e. 100Hz, resp. 150Hz instead of standard 50Hz. That allows the composer to get a twice as softer time „grid“ for making instruments so unusual new sounds can be made using this magic. Southern is composed by Taki/Natural Beat and Trible Speed Tune is MSK’s work. Sounthern isn’t included in the AS6581 form because it’s composed specially for the 8580 type of SID and sounds awful on the old SID. Notice the length of the bass sound in Trible Speed Tune on the old/new SID.

Southern: 6581 8580 AS8580
Trible Speed Tune: 6581 8580 AS6581 AS8580

64 Forever & Make Some Noise

These two songs are special as they use so called speech, i.e. synth based vocals. Both are composed for the 8580 SIDs only, so I included the 6581 versions just for having a listen. 64 Forever composed by Linus, Make Some Noise is by Jammer.

64 Forever: 8580 AS8580
Make Some Noise: 6581 8580 AS6581 AS8580


Thanks att for poiting me to this song by Markus Müller from 1991. It seems to sound very different on each SID, even on the ARMSID it’s different. On the original 6581 there is a lot of resonance. On the AS6581 there’s no resonance in filtered channels and the sound is pretty softer as well as on the AS8580. Let’s compare:

Mechanicus: 6581 8580 AS6581 AS8580

C64 48KHz HiFi Digi Player 2

On request there is a comparison of a sampled song of Elvis Costello „Welcome to the Working Week“, original 8580 SID and ARMSID with 8580 emulation. I didn’t bother with 6581’s because the author of the player complains on miserable quality on the old SIDs. At the first listen, I haven’t noticed any SID vs ARMSID difference!

C64 48KHz HiFi Digi Player 2: 8580 AS8580


Believe me or not, but I think the current version of ARMSID can handle more or less all SID’s features and anomalies. I haven’t noticed any major glitch or issue when listening to various SID tunes and SID sounds. That doesn’t approve me to say absolutely ideal verdict on the ARMSID, but I can’t find any issue that could be mentioned reasonably. In general, it sounds less vivid and is more silent than the originals, some sounds may still sound different. Normal listener doesn’t notice that, musicians and long-time-SID-listeners usually do. That means the ARMSID is nearly perfect SID replacement with extras like an option of switching the SID model on the fly and fiddling with the filter settings. The firmware is easily upgradable so there is a hope it could sound even more perfect in the future. Gorgeous and marvellous, futuristic, awesome!

You can find more tech info about the device here at the author’s website. The eshop where ARMSID can be ordered is here. There is a possibility that some of the Czech demoscene freaks could sell a few pieces at the upcoming Revision party in Germany during the Easter. But it isn’t confirmed, yet.

Last edit: 22-05-2019

Kategorie Počítače, Info