SIDin #8 — Catweasel Mk4: a PCI card with two SID sockets (Stefano Tognon, 2005)

Tognon buys Individual Computers' Catweasel Mk4, a PCI floppy-controller card with two sid sockets, fits a 6581 pulled from a dead C64, and gets Simon White's Linux hardsid driver to recognise it — but not yet to play music properly. The article's value for the wiki is what the card is and how the software stack fits together; the sound tests are in the follow-up.

Key claims#

• What it is: "a new PCI card produced by Individual Computers that support 2 sid chips". Tognon's motive: the HardSID card "only supports one sid chip", the HardSID 4 with four is "a dream card"; the Mk4 "with 2 sid chips can be a good solution, as we can add a 6581 and a 8580 in the same card and so listen to all the tunes with the right chip". The card is primarily "a controller that let you to read lot of Amiga and C64 floppy disks and support even the real digital joystick".
• Hardware: bought through Soft3, an Italian Amiga shop; the box holds jumpers, an audio cable "like the CDROM one but with more in/out different terminations", three IDE-like flat cables for floppy drives, two low-profile brackets, a 4-page English/German manual, a CD with the Windows driver and documentation "like real photos of jumper setting for 6581/8580 chips"; "The two sid sockets have gold metal contacts"; the audio goes to the sound card's CD or AUX input (his ISA Sound Blaster 16 Vibra's CD input did not match the cable; the AUX input accepted one of the three plugs); a cut trace and an added wire on the back of the board — "may be this could be a fix after the board production". He fitted the 6581 of a C64 "not working for a dead PLA" into the socket beside the connectors, with the jumper set to 6581 and the other socket's jumper to 8580 for later (commodore-64).
• Software (Linux): White's driver from hardsid.sf.net — the CVS experimental_cmk4 branch plus the latest libsidplay2 "with hardsid builder"; the HEAD branch "did not use the hardware buffer of the card"; "only Linux driver were able to take advantage of this hardware buffer" at the time. Kernel module built with make / make install; the readme's mknod /dev/sid0 c 60 0 … devices are obsolete under udev (kernel 2.6 creates /dev/sid); after loading: /dev/sid, /proc/hardsid (card info; more during playback) and /etc/init.d/hardsid. Fedora Core 3 first took the card for "an ISDN pci modem"; the driver needs the firmware cmk4.fw in /lib/firmware (Fedora) — then HardSID Driver v0.17-dev … Catweasel MK4 card with 6581 as chip 0 detected @ 0xe800 and /proc/hardsid reports "firmware 0.029 / SID type 6581". sidplay2 built from the modules (./bootstrap; ./configure; make; make install) shows a --hardsid option only when a card is detected; other options listed include -fd (dual SID), -ns[0|1] (8580 waveforms), -nf (filter emulation), -s[l|r] stereo.
• First results: sidplay2 ran "50 second of music played in 8 seconds" with no sound; goattracker "(that support MK3 card)" detected the card but gave no sound; the CD line was muted, cables and chip were swapped (the C128's 6581 as a known-good chip) without change. The right branch (experimental) gave sound but "hypersonic" speed; the HEAD branch froze the kernel. White's VICE patch played at the right speed but: "The volume is extremely low", notes "not so in sync", sometimes muted, and "If you move a windows into the desktop the sound goes killed or goes very slow" — reported by Windows users too.
• Conclusion (after 3 months without an answer from Individual Computers): possibly one of "the few early realized that was not tested for DC-DC problem" — a faulty DC-DC converter gives exactly these symptoms per other users; the card stays disconnected for fear of damaging chips. Praise for the driver: it "automatically choose the right sid chip -if available into the card- that is specified into the sid chip model inside the tune", so every program using it gets model selection for free (sid-format). "if you have a MK4 card, go to read what is write into the bottom of it ... interesting..."

Practical takeaways#

• A two-socket card lets one machine carry a 6581 and an 8580 and pick the chip from the .sid model flag — the reason to want two sockets.
• The Linux stack of 2005: hardsid kernel module (+ firmware) → libsidplay2 hardsid builder → sidplay2 / xsidplay / VICE; GoatTracker talks to the Catweasel too.
• Symptoms of a bad card (low volume, dropouts, sound tied to desktop activity) look like driver timing problems; the follow-up separates the two.

Notable quotes#

"we can add a 6581 and a 8580 in the same card and so listen to all the tunes with the right chip"

Relevance to the wiki#

Facts for catweasel (what the card is, sockets, jumpers, driver names and versions); context for s-sidin09-catweasel-6581; a hardware note for commodore-64 and goattracker.

Pages touched#

catweasel · commodore-64 · sid · goattracker · sid-format · sidin