Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!mcsun!unido!tools!fl From: fl@tools.uucp (Frank Lancaster) Newsgroups: comp.sys.acorn Subject: Re: ARM3 spec changes; R260 <-> SPARC Message-ID: Date: 31 May 91 08:04:19 GMT References: <10615@castle.ed.ac.uk> <7333@acorn.co.uk> Sender: news@tools.UUCP Distribution: comp Organization: TooLs GmbH, Bonn, Germany Lines: 76 In-reply-to: asmith@acorn.co.uk's message of 29 May 91 07:52:07 GMT Our R260 runs at 26Mhz. RiscIX does 16000-19500 Dhrystones depending on screen mode. RISC OS about the same. My old A440 with 30Mhz ARM3 did 17800 Dhrystones in Mode 0. Mode 21 is much faster on the R260 (nearly the same as Mode 20), you can actually use it in RiscIX. Compared with a SPARC SLC (costs something around 10000-12000 DM in Germany), the Dhrystones are about the same. But programmes like TeX and METAFONT run at least twice as fast on the SLC! I think this is mainly due to the small cache size on the ARM3. The SLC also has a FPU, but it isn't that fast (a Sparc Station 2 does about 7-8 MFLOPS, a SLC 1-2). A few points concerning the R260 as a UNIX workstation: 1. I don't like preinstalled UNIX systems on hard disc with NO backup supplied. What are you supposed to do if you accidently remove the kernel!? I quickly copied the kernel to floppy disc, and tested booting from floppy disc. That works, but you still have to specify where your swap space is and it has to be on a hard disc (at least I didn't find out if you could specify a floppy disc as swap space). 2. Next I wanted to reconfigure the hard disc with a larger RISC OS section, as we develope both UNIX and RISC OS software. Hmm, a programme is supplied to do this, but of course it destroys all data on your hard disc! So you either need a second hard disc (we didn't have a spare one) or you have to boot discless without hard disc. 3. Booting without hard disc via ethernet. Well, this wasn't easy. The R260 isn't supplied with all software required for a discless boot. But using the *boot command with the undocumented parameter et0(0,0) as root device revealed that after loading the kernel from floppy disc the systems tries to boot over ethernet. Well, we configured one of our SPARC Stations as server and installed all the RISCIX files on it, set up a swap partition on the SPARC, and rebooted the R260. It worked! You still have to load the kernel from floppy disc but now you can reconfigure your hard disc and reinstall the RISCIX system (backed-up on a remote tape device, you go bananas when backing up to floppy disc) 4. Next I wanted to reconfigure the kernel. On SUN systems you can relink the kernel after changing and compiling the parameter files, so you can remove unused device drivers etc. On the R260, as supplied, you can't relink the kernel. Well, we love adb (the standard UNIX debugger) and started patching the kernel (more file buffers, yummy!) This is all undocumented, the contents of the (available at extra cost) programmers reference manuals aren't even listed anywhere ("Man muss die Katze im Sack kaufen"). 5. On RISC OS I use a module to improve the screen modes on my multisync monitor (less flicker, larger picture). Alas, reconfiguring the screen modes is again undocumented. But debugging the kernel is fun, and we discovered a variable called video_mode which points to the VIDC paramter table for the current screen mode. The rest is easy, calculate the parameters for the VIDC, patch the VIDC tables, and reboot! Now I don't have to twiddle the position controls on my multisync anymore when switching screen modes and the picture doesn't flicker as much as it used to. 6. I hope that Acorn will supply the OpenLook GUI with their next UNIX release, as Motif is quite horrible and the twm window manager is also configured most horrible (green borders, half wide title bars!) We've started porting the XView OpenLook package. The OpenLook window manager works with slight problems, but looks quite nice in colour. The filemgr programme looks far better than the IXI desktop. After all this criticism, you may think that I hate this machine. But no, I actually quite like it. Its the fastest Archimedes around with the best operating system on it. Only it could be a lot better... Switching between RISCIX and RISC OS doesn't take long, booting UNIX without disc checks takes about 1min. GNU emacs is supplied, but not the newest version. Networking with SUNs works without any problem, overall performance of UNIX is quite okay, not much swapping and disc access is fast. Well, this was intended as only a short message about processing speed, but I hope my experiences were of some interest. Frank Lancaster