Sunday, October 21, 2018

a few more words on cgfourteen

A customer asked me if he’ll ever gets a chance to watch HD movies on an emulated SPARC machine. At first, I was going to say never ever, but then I looked at the specs of some ancient adapters and got surprised.  The SGI machines were commonly known for good graphics, but it never occurred to me that Sun machines were really powerful as well.
The cgfourteen (cg14) adapter could show Full-HD (1920x1080) pictures back in 1993!
Since the manufacturers sometimes claim just the theoretic abilities of the chipset, I wanted to check that the software has been really aware of such graphic modes in early nineties.
So, I gave a spin to the old cgfourteen patch from Bob Breuer. And here we go.
SPARCstation 20 OBP supports 1920x1080
Overall the cgfourteen adapter was really powerful. Michael Lorenz who added the hardware acceleration support for cgfourteen to NetBSD, wrote “SX has plenty of registers (128 - eight of them have special functions, the rest is free for all) and every instruction takes a count to operate on several subsequent registers or memory locations (ALU ops can use up to 16, memory accesses up to 32). SX supports some parallelism too - the ALUs can do up to two 16bit multiplications and two other arithmetic or logical ops per clock cycle (32bit multiplications use both ALUs).

The bad news is that Bob’s patch doesn’t implement the SX rendering engine. Also, the Solaris (or rather OpenWindows) driver is very much bound to sun4m SRMMU, so it won’t work on sun4u machines.

Would really like to have the emulation of a graphic card which would be better than cgthree, and ideally would work on both sun4m and sun4u machines, but it’s not easy.

Right now, I’m choosing between cgsix and creator ffb, but none of them has public documentation.

P.S. A funny fact about the Solaris SX driver: there are lots of symbols which have the word “SPAM” in a name. It can spamify and unspamify.  It’s really hard to google what it could mean back in nineties. “M” is probably for “Memory”.