test-drb February 2006

test-drb@ccmp.vtda.org

224 participants
452 discussions

by mbbrutman-cctalk＠brutman.com

I revived an old 6Mhz PC AT today by removing the original Western Digital based hard disk controller and replacing it with a newer, generic IDE controller. The large boat-anchor class 5.25" full height hard disk had died, and without a suitable replacement a small IDE drive was chosen. The rest of the machine is original, including the EGA card with the extra memory daughterboard and the full slot monochrome card. While discussing this beast, the topic of putting a CD-ROM on it came up. (I would never do such a thing except for giggles.) The topic of the CD-ROM led to a throughput question - could this old monster even do it? As in, is the ISA bus up to reading from the CD-ROM at a reasonable speed? Well, let's go throught some quick math. 6 million clock cycles per second is a lot, but when you consider that each transation on the bus takes 4 to 5 cycles, and instructions take 4 to 5 cycles (average) on a 80285, the throughput might not be so hot. Forget the CD-ROM and let's just pretend it's an I/O device on the bus, like a fast hard disk. Given a PC AT running at 6Mhz, what can reasonably be expected for bus throughput? (Obviously this depends on the loop and the instructions used.) I would have guess 500K or so per second, but now I'm second guessing myself and I'll actually have to write a small benchmark to try it. When writing to a hard disk, would this machine have used a tight processor loop, or would it have used DMA? Under what circumstances would it use DMA to transfer data to a hard disk? And one last question .. Unlike the PC and XT, the AT BIOS handles hard drives. It didn't blink when I removed the crusty WD based controller and replaced it with a no-name WinBond based controller. Does the new IDE controller really look that much like the old controller that the BIOS can't tell? -Mike

17 years, 5 months

downloading & installing using VMSINSTAL problems

by compoobah＠valleyimplants.com

I am trying to install some layered products on my AXP-VMS machine (VX42 Multia running v7.3-1) and I keep running into the same error. for $@sys$update:vmsinstal (product, tried with CXX065 and AXP_DECWRITE31A) dka0:[install_sets] options n it prints "error reading dka0:[install_sets] AXP_DECWRITE31A.A software block CRC error invalid block size in save set invalid record size in save set invalid record size in save set" several times and then errors out to DCL. I'm getting the sets from vmsone.com, but I do have to launder them through other machines, as Bet doesn't have internet access or a web browser. I've tried Windows at work (high-speed network access), thought it was the Windows bitrot that sometimes occurs, but the "A" saveset of DECWRITE31A doesn't even work when downloaded from a Macintosh (tried with VMSINSTAL and BACKUP). What am I doing wrong, or is it just my cheap equipment (other weirdness- when DECwindows starts it locks up the keyboard - bizarre, don't know if this is a Multia+VMS problem or an issue with the Multia+VMS+SGI keyboard. I'll have to do some testing), What's a good baseline for Alphas in terms of usability with VMS7.3+? the 233MHz LCA seems to be not much faster than a VAXstation 3100/76, and if I do find another Alpha, I don't want to spend a lot on something that creaks along (and I know what the SPEC scores say- but this VX42 is not up where other machines scoring ~100 SPECxx 92 are in basic useability)

17 years, 5 months

classiccmping and cold weather

by chrism3667＠yahoo.com

I had thought lcds get damaged if theyre not allowed to warm up after getting too cold? Dont particularly know, but would think the freezing point of that stuph is much less then h2o. --- cctech-bounces at classiccmp.org <healyzh at aracnet.com> wrote: > At 9:33 PM +0100 2/18/06, lee at geekdot.com wrote: > > > What is the danger related to storing CC gear in extreme cold > >> temperatures? > > > >One thing to keep in mind is that some liquid crystal displays will be > >permanently damaged by freezing. Others will stop working, usually > >turning completely opaque or completely transparent, but will recover > >when they warm up. > > Interesting. Any idea if this would effect the original Game Boy's? > I don't know what it is about them, but I had two of them that lost > lines on the display after they sat unused for a year or two. At the > same time I'm fairly certain neither would have gotten frozen. > > Zane > > > -- > -- > | Zane H. Healy | UNIX Systems Administrator | > | healyzh at aracnet.com (primary) | OpenVMS Enthusiast | > | MONK::HEALYZH (DECnet) | Classic Computer Collector | > +----------------------------------+----------------------------+ > | Empire of the Petal Throne and Traveller Role Playing, | > | PDP-10 Emulation and Zane's Computer Museum. | > | http://www.aracnet.com/~healyzh/ | __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

17 years, 5 months

Slightly OT: Bastard plagiarists

by news＠computercollector.com

Someone copied almost my ENTIRE pda history site onto the web forum at http://tinyurl.com/bhvpv ... Does anyone know what the deal is with this "britishinformation.com" site anyway? The thief who stole my work even included the hyperlinks but they don't work. The site includes a web form for contacting them so I sent a not-so-nice message, but I'm not optimistic about hearing back. Unfortunately I don't see any way to contact the user who posted this. ----------------------------------------- Evan Koblentz's personal homepage: http://www.snarc.net Computer Collector Newsletter: >> http://news.computercollector.com Mid-Atlantic Retro Computing Hobbyists & Museum: >> http://www.marchclub.org >> http://groups.yahoo.com/group/midatlanticretro/

17 years, 6 months

C Compilers for (MS)DOS

by julesrichardsonuk＠yahoo.co.uk

What's the state of play regarding DOS C compilers? I might have a need to do some DOS-based C development work - are there any good-but-free DOS compilers about? I did have Turbo C on tape, but I haven't tried to read those tapes in years and wouldn't hold out much hope of them still being intact... ta Jules

17 years, 6 months

sexy PDP-11/44 panel (was: Re: Original 11/74 front panel)

by henk.gooijen＠oce.com

Without thinking much about it, I'd say that mounting any real blinkenlight console on a 11/44 is *not* trivial! Of course, grabbing UNIBUS address- and data-lines and wiring that to the lights is trivial, but to get all panel functions (LOAD ADDR, DEP, EXAM, etc). working on an 11/44 is more work. I guess there are more people on the list who have a boring PDP-11/44 with a dull panel, that would like to make the /44 more sexy with an 'appropriate' panel. The "upgrade" is, of course, done in such a way that it can be undone ... I (we) do not have a /74 panel :-( , but I'd like to hear what approach you are thinking of, Don. Hmm, you could do it like I did as add-on to SIMH. Hardware with some intelligence reads the front panel and translates the switches to messages in ODT syntax which are send to the 11/44 monitor program ... - Henk, PA8PDP. > -----Original Message----- > From: cctalk-bounces at classiccmp.org > [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Don North > Sent: vrijdag 10 februari 2006 21:07 > To: On-Topic and Off-Topic Posts > Subject: Re: Original 11/74 front panel > > Actually I was thinking of making a replacement/alternate > front panel for my 11/44 using the 11/74 panel. > Add real blinking lights/switches connected up to the real > UNIBUS/memorybus. > > The 11/44 panel is *way* too spartan looking, and the 11/74 > panel would fit just perfectly on the front of the box. This message and attachment(s) are intended solely for the use of the addressee and may contain information that is privileged, confidential or otherwise exempt from disclosure under applicable law. If you are not the intended recipient or agent thereof responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, or copying of this communication is strictly prohibited. If you have received this communication in error, please notify the sender immediately by telephone and with a "reply" message. Thank you for your cooperation.

17 years, 6 months

Vaxstations in London

by williams.dan＠gmail.com

Due to impending job change/move I need to slim down my collection there will be quite a few machines. Some of the bigger stuff I need to put on ebay as I really need the money. I will be putting a 4000/500 with 9 dssi drives and a 4000/700 with 12 dssi drives on ebay towards the end of the month. I have gone through some machines there will be more : Vaxstation 3100/30 12mb unknown drive Vaxstation 3100/76 2xRZ74 16mb Floppy Vaxstation 3100/30 2gb drive 8mb Floppy Vaxstation 3100/40 3x100mb drive 32mb ram missing front flap Microvax 3100 16mb 2xRz25 3.2gb Vaxstation 3100/76 floppy 16mb 500mb drive Vax storage expansion box no drives but possible with the cable if I can find it. These are all free to pick up from Soho London. Dan

17 years, 6 months

PDP-11 Integer Divide Instruction "Div", To: General Discussion: On-Topic and Off-Topic Post

by bqt＠update.uu.se

"Jerome H. Fine" <jhfinedp3k at compsys.to> wrote: > Hi All, > > I have noticed what may be an interesting result when I use the > PDP-11 Integer Divide Instruction "Div". Since I have noticed > at least one individual who worked on the microcode for the > PDP-11, perhaps there is an explicit "Yes / No" answer to my > question: Since this actually have nothing to do with the microcode, and actually is nothing specific with the PDP-11 DIV instruction, just about anyone should be able to answer definitely. > If I divide 196612 by 3 - i.e. "Div (R2),R0" where R0 = 3, R1 = 4, (R2) = 3 > the result (in addition to the condition bits) is R0 = 1, R1 = 1 which is > exactly correct if the quotient is regarded as a 32 bit result with R0 being > the low order 16 bits of that result and the high order 32 bits are somewhere > else - probably inaccessible as far as programming is concerned, but easily > obtained by: > Mov R1-(SP) ; Save low order 16 bits of dividend > Mov R0,R1 ; Divide high order 16 bits > Clr R0 ; of dividend > Div (R2),R0 ; by the divisor > Mov R0,R3 ; Save high order 16 bits of quotient > Mov R1,R0 ; Divide the remainder > Mov (SP)+,R1 ; of the dividend > Div (R2),R0 ; by the divisor > i.e. R3 now contains the high order 16 bits of the 32 bit quotient > with R0 holding the low order 16 bits of the 32 bit quotient What you have implemented here, as well as described, is the exact way you should have been taught how to do division on paper in elementary school. Yes, that algorithm is valid, and can be extended to arbitrary sizes, as long as you remember the full method. > Can anyone confirm what I have found in practice? Certainly. It's basic math, the way it's taught in elementary school. That was atleast the first way I was taught how do do divides on big numbers on paper. > Even better would be a method of retrieving the high > order 16 bits of the quotient in a manner which takes > fewer instructions and without a second divide instruction! I doubt you'll find it. Johnny -- Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt at update.uu.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol

17 years, 6 months

Xenix 286?

by doc＠mdrconsult.com

I'm looking for something Unix-ey to run on this 80286 system. It has 640KB RAM, and uses prorietary memory modules, so even Minix is going to be an extremely tight fit. Mostly out of curiosity, I'd like to try Xenix on it. Does anyone have install images I could "evaluate"? Xenix 286 was apparenly (judging by some BIOS parameters) a supported OS on this Compaq. Doc

17 years, 6 months

Teletype 31?

by CPUMECH＠aol.com

Heard of a 28, 23, 33, but no 31.

17 years, 6 months

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test-drb February 2006