test-drb March 2005

test-drb@ccmp.vtda.org

291 participants
840 discussions

by dwight.elvey＠amd.com

>From: "Paul Koning" <pkoning at equallogic.com> > >>>>>> "Jules" == Jules Richardson <julesrichardsonuk at yahoo.co.uk> writes: > > Jules> On Fri, 2005-03-11 at 07:51 +0000, Philip Pemberton wrote: > >> ... > >> Shift register + counter + high speed RAM. Could even do it with > >> an FPGA if you wanted. Buffering an entire track with 8x > >> oversampling is going to be hellishly memory intensive though. > > Jules> Well if worst-case is 1mbps data rate at 300rpm and 8x > Jules> oversample, isn't that (8 * 10240 * 1024) / 5 = 1677722 bits > Jules> of memory maximum needed? > > Jules> (div by 5 because 300rpm gives you a whole track in 1/5 of a > Jules> second) > > Jules> So 256KBytes of RAM should always be enough to buffer a whole > Jules> track, regardless of what physical drive or media you use. > >Even if you want 8 bits per sample, that's still only 1.5 MB, and the >data rate is 7.5 MB/s (since a track is 200 ms by your calculation). > >That's a trivial bandwidth requirement; anything better than antique >DRAM will do the job easily, and the space requirement is tiny, too. > >I'm wondering if you can do this job with a microcontroller similar to >a PIC, running the sampling loop in software. If not quite, it should >be pretty close. > > paul > Hi I've always been looking at using a DSP chip for this job. I did expect to read parts of a track at a time and then reassemble them as condensed data. Chips like the Analog Devices 2181 have some 80Kbytes of onboard RAM. Although, it can't all be used for storage at the same time and some is needed for program space. These chips can be implemented with a real minimum of outside circuits. they even have a serial SPI that can be used to read disk data at higher speeds. These processor run at 30 MIPs plus. They can run some operations, such as data moving to arrays in single cycles, including updating of pointers. They can do as many as 5 operations in a single cycle. The can bootstrap from simple slowspeed EPROM of FLASH. One could easily connect one of these to that USB chip that someone pointer to earlier. Dwight

19 years, 9 months

2 Scrambled PERQs ... Going, ... Going, ... Help!

by brian.russell＠iclway.co.uk

2 Scrambled PERQs - Going, ... Going, . Help! I have two PERQs for disposal, a PERQ-1 and a PERQ-2, here in the UK. I would like to get some data off them before disposal, but am unable to do this on my own as both machines are somewhat 'scrambled'. I am in contact with half a dozen PERQ owners, who have helped with copious advice, and to whom the machines will be going once I have finished with them. The purpose of this posting is twofold. Is there anyone who can make me replacement boot floppies (I have blank discs onto which copies can be made)? Is there anyone who has successfully archived data from a PERQ to a PC who can speed up the rather tedious process of writing RS232 communications software that I have embarked upon? This is an update on a posting I placed on the alt.sys.perq newsgroup before Christmas. I am officially chairman of the Mil-DAP (Military version, Distributed Array Processor) Resurrection Working Party. These two machines were donated to the CCS (Computer Conservation Society) to help in the attempt to resurrect the Mil-DAP. We have succeeded in bringing together the complete set of hardware for the Mil-DAP itself and its PERQ-2 host computer. The DAP and host PERQ have been handed over to The Science Museum, South Kensington, London. The equipment will go to the Science Museum outstation at Wroughton, near Swindon. The Science Museum does not want our two remaining PERQs, as they are not actually a part of the Mil-DAP itself. The PERQ-1 is thought to contain some DAP-specific software, which we intend to copy off onto floppy discs. Copies will then be sent to the Science Museum. After that, we have no further use for the PERQs and we have nowhere to keep them. I would have been unhappy (euphemism!) to see them chucked in the bin. From contacts made thorough alt.sys.perq, I now have homes for the two machines, but I still have a duty to archive the data on them before I can release them. The PERQ-1 is thought to contain some DAP-specific software, which we intend to copy off onto floppy discs (and, if possible, archive onto CD). This is proving to be more difficult than we expected; any advice would be appreciated! Specifically, does anyone have precisely the right software to build boot floppies for either machine so that the hard discs can be fixed? The states of the two machines are: The PERQ-1 is the machine that might have some DAP software on it. I am effectively in the 'forgotten password' situation (except that I never knew the username or password and have tried most of the usual combinations). This is a PERQ-1 T1 with 4k Control Store, portrait monitor and no tablet. (No, we haven't lost the tablet; it was not there when we picked up the machine! We have now found a possible replacement.) The machine is running POS; the top line of the screen reads: "LogIn version 3.10 POS G.666 a-boot". The machine boots up from its 'rigid disc' and gets to the date/time and user/password prompts. After taking advice, I am going to attempt to archive the entire disk at block level before attempting to change things to give me access at file level. The PERQ-2 is a machine that I hoped to use for copying floppy discs, if nothing more. I appear to have damaged the disc, possibly (probably?) by doing a 'Bye Off' instead of just a 'Bye' or 'Bye Wait'. If this is what is wrong, then I have only myself to blame! Whatever, it now only boot up to Diagnostic 157 (Disc Failure) when supplied with its boot disc. Until recently, the machine booted up correctly when supplied with its Boot Floppy; though it has always stopped at Diagnostic 014 (Could not Boot from Either Disc) when attempting to boot from the hard disc alone. This is a PERQ-2 T2 (feature no. = F2361/06, build control serial no. = T2 1619) with landscape monitor and tablet. If there is a friendly PERQ owner out there somewhere with the appropriate boot floppy or engineering tools could you help, please? If so, please reply to this posting or get in contact at the address below. I have a stock of 8-inch floppies, donated by CCS members, which I can post out to anyone able to make me the necessary copies. Brian M. Russell. bmrussell at iclway.co.uk

19 years, 9 months

Format of '.tap' files on bitsavers ...

by john_sambrook＠yahoo.com

Hi Eric, Thank you for your help. I've had a look at your utilities link and I'm going to give them a try. Best, John Sambrook --- Eric Smith <eric at brouhaha.com> wrote: > John Sambrook wrote: > > Anyone know the format of ".tap" files found on > > www.bitsavers.org/bits/... ? > > It's John Wilson's tape image file format. > > A data record consists of a four byte record length, the data, > then another copy of the record length. The record length is stored > in little-endian byte order. > > A tape mark is fourbytes of zeros. > > There are no extra padding bytes to force any alignment. > > Bob Subnik's SIMH tape image file format is similar except that it > uses 16-bit alignment. SIMH comes with utilities to convert the > formats. > > There are also some simple tape image utilities at: > http://www.brouhaha.com/~eric/software/tapeutils/ > > Eric > > __________________________________ Do you Yahoo!? Yahoo! Mail - Easier than ever with enhanced search. Learn more. http://info.mail.yahoo.com/mail_250

19 years, 9 months

Mac memory needed

by rcini＠optonline.net

All: I'm looking for at least 4 pieces (and up to 8) of 16mb, 70ns, non-parity FPM 30-pin SIMMs for a Mac IIci. The Apple part is APL30P16, but any matched set of four or eight will do. Please contact off-list. Thanks. Rich Rich Cini Collector of classic computers Build Master for the Altair32 Emulation Project Web site: http://highgate.comm.sfu.ca/~rcini/classiccmp/ /************************************************************/

19 years, 9 months

Seeking Motorola S38FC012PIO2 ($$$ Bounty! $$$)

by wmaddox＠pacbell.net

--- "Dwight K. Elvey" <dwight.elvey at amd.com> wrote: > Also, have you removed the chip and put some > contact > enhancer on it?? ( You know, some silicon grease ) > Dwight I imagine that some DeOxit or similar would be good, but silicon grease? I thought that was for *thermal* conductivity only. --Bill

19 years, 9 months

MicroVAX II - TK50 problem

by pete＠dunnington.u-net.com

On Mar 11 2005, 23:39, Witchy wrote: > > > No. It's only the RQDX1 that has the "must be last on the bus" > > problem, and only then if what's below it uses DMA and interrupts. > > RQDX2 and RQDX3 have no such limitation. You won't find an RQDX1 in a > > MicroVAX II because it is not compatible with the MicroVAX II > > processor. > > I know of the incompatibility but I'm surprised at the RQDX3 not having > the limitation - every single microPDP and qbus uVAX I used, installed or > watched Failed Circus maintain had to have the disk controller last on the > bus; the only exception to this was if you had the RQDXE extender for > external drives. Even the machines I've got here now are built like that. The RQDX2 and RQDX3 definitely don't have the limitation. It's in the manuals, and also in Micronotes. I've seen lots of PDP-11s where the RQDX is not the last device, and my MicroVAX-II came with its RQDX3 further up, as well. If you have an RQC25 (then you have my commiserations) it usually goes below the RQDX, as does a KDA50 or a DRV11, according to Micronote 041. And of course if you have two RQDX2/3 controllers, one after the other, both work. That's not true of an RQDX1 (you can only have one). In general, the main reason for the order of things on the QBus has to do with interrupt priority and latency. For example, a DL serial interface can't deal with being too far down the bus, so it usually goes right after the memory; similar rules apply to a DEQNA. However, a DHV11 or a DHQ11 is a bit better, so it can go further down. Tape controllers are often less tolerant than disks, especially if they're supposed to be operated in streaming mode, so they usually go higher up. As I mentioned, even DEC's notes show a config with an RQDX3 further up. However, one of the FS memos says "This device may have to be placed as the last device in the CPU box because of cabling requirements." Also, there is a performance issue with the RQDX2 in systems using lots of block-mode DMA, because while the RQDX2 is doing a block transfer, it holds the bus for longer than is desirable and blocks BDMR while doing so (it does pass it the rest of the time, and an RQDX3 doesn't block BDMR at all). So it should be below things that have problems with latency, like Ethernet or DECnet controllers. However, an RQC25 is even worse in that respect, and it does block transfers in pairs! What's recommended by Field Circus, what's "supported" by DEC, and what works, are three different things! -- Pete Peter Turnbull Network Manager University of York

19 years, 9 months

Atari 1040ST

by leeedavison＠yahoo.co.uk

Free to a good home, or even a bad one. Atari 1040ST, mouse, monitor and possibly some manuals and software. Possibly another similar Atari for parts. Untested - I was given it and it's sat in it's box ever since. This is in the UK. Email me directly if you're interested. This goes to the tip in a week if no one wants it. Lee. . Send instant messages to your online friends http://uk.messenger.yahoo.com

19 years, 9 months

Name that cap...

by wh.sudbrink＠verizon.net

Hi all, I'd like to get a 5 1/4 inch floppy working on my Ohio Scientific C1P-MF. Since I only have one OSI 5 1/4 inch drive available, on my C4P-MF, I want to get another working. OSI relied on the drive unit to provide data separation, relatively easy to find on 8 inchers but seems to be pretty tough to find on a 5 1/4. There is an old article describing how to build a suitable data separator circuit available on a couple of sites on the web. Seems pretty simple, just uses two chips a couple of resistors and a cap. The problem is, I can't read the cap value. The best image I can find is here: http://www.technology.niagarac.on.ca/people/mcsele/images/SA400Disk1.jpg You want to look at "Figure #3". I've used several different image processing programs, but I can't get the scribble next to the cap legible. I've looked at the data sheet for the chip, but I don't know enough for an obvious value to jump out at me. Part of the accompanying text says: "The RC time constant is adjusted to give an output pulse width on pin#1 of the 74LS121 of 5.5 ls." I assume "ls" is an oddball abbreviation for microsecond? Alternatively, does anybody have an MPI B51 or B52 with data separator available for trade, or another design for a data separator? Thanks, Bill

19 years, 9 months

OT Troubleshooting: Old computers with modern parts

by leeedavison＠yahoo.co.uk

> The lack of a punch has kept me from doing a PDP/8 in a > CPLD as well as not knowing of where to get ferromagnetic? > ram. I want real non-voiltile memory. Go to http://www.ramtron.com they do the ferromagnetic RAM. A year ago they were offering free samples and may still be doing so. FRAM is very similar to core in that a read is destructive and you have to do a write after read but this is all done transparently by the device. Lee. . Send instant messages to your online friends http://uk.messenger.yahoo.com

19 years, 9 months

selling off my entire lot

by James＠jdfogg.com

> To all, I have taken a position with a new company and will > be closing down my warehouse. Any one interested in my entire > inventory or at least the board inventory (4000 + DEC and > VAX) please let me know. I am in Melbourne, FL and all are > welcome to come visit, or call me at 321-768-0006. THANK YOU > ALL for your past support. Do you have any kind of a list? Do you have any complete systems you are parting with? I'm particularly interested in Data General systems.

19 years, 9 months

← Newer
1
...
42
43
44
45
46
47
48
...
84
Older →

Jump to page:

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

2000

1999

1998

1997

test-drb March 2005