test-drb May 2007

test-drb@ccmp.vtda.org

235 participants
483 discussions

by john_a_s2004＠hotmail.com

Dear All, Thanks for your helpful reples. On 15 May 2007 at 11:45, Chuck Guzis wrote: >It's entirely possible to fit 10x512 sectors per track using a 765- >type controller, though it's much easier if the IAM is left off and the >space gained used to expand the inter-sector gaps (you can do this with a >uPD 2765-type controller or any of the WD 17xx/27xx controllers. >>I think the Tuscan FDC uses a WD1771 controller... >Nope, the 1771 is restricted to FM only. Maybe a 179x or 1770/1772/1773 though. You're right, it has a FD1791 controller. >It's entirely possible that the drive used to create the diskettes was >somewhat out of alignment. You may have to "unalign" a drive to >successfully read these. This is more common than you might think. Yes, it could be. I tried a different PC last night, same problem as before. Using IMD (Image Disk) utility, and the analyse option, it would show a scrolling display with entries like: 0 7 20 0 for track 0, the 20 meaning that 20 sectors were found up to: 39 5 20 0 for track 39. Using D to read data, I could read track 0 OK, but with higher tracks (especially 10 or higher) then IMD gave errors like: Read error <1> No Addr Mark 2 Read error <2> No Addr Mark 3 etc up to sector 10. I came across this article: http://www.atari-forum.com/viewtopic.php?t=9644&postdays=0&postorder=asc&st… (Google for ["read sector" "splice points"]) which makes the valid point that floppies are often formated on one machine, and written to on another. As I can read track 0, and all the sector marks are found for the other tracks, but I can't read the data part of the sectors for tracks 1 to 39, I am guessing that the drive used to write the data was different to that used to format the floppy and write the system track. The above page talks about 'splice points' where the new data is written over existing data. (Another interesting glossary was found here: http://www.softpres.org/knowledge_base) >You didn't mention if you were using a 48tpi ("360K") drive to read these >or trying to get by on a 96tpi ("720K" or "1.2MB) drive. The former will >usually produce better results. I am using a 48tpi drive, an IBM badged Qumetrak 142 with belt drive ("That is the third worst drive I've dealt with" - Fred Cisin, Oct 2005), also tried a Techmate NPH-502. I have some Tandon TM-100s on various machines, I'll try one of these plus a 96tpi drive for luck. >If the first sector on the track is consistently missing (not always the >lowest-numbered; some systems skew the tracks for better performance), you >might be able to recover it by slowing the drive a bit to allow the first >sector IDAM to move outside of the 765 "blind spot" at the beginning of a >track (although the 765 formats a track with an IAM at the start, it never >reads it). Seems to be every sector past a certan track. BTW the disk is formated with sector skewing, starting from track 0 they are read as: 1 2 3 4 5 6 7 8 9 10 9 10 1 2 3 4 5 6 7 8 7 8 9 10 1 2 3 4 5 6 5 6 7 8 9 10 1 2 3 4 3 4 5 6 7 8 9 10 1 2 1 2 3 4 5 6 7 8 9 10 Luckily I have recently heard from two more Tuscan owners with CP/M boot disks, so hopefully they will have more joy. Regards, John _________________________________________________________________ The next generation of Hotmail is here! http://www.newhotmail.co.uk

18 years

Harwell (was RE: A local computer history group for my area. ..)

by RodSmallwood＠mail.ediconsulting.co.uk

Hi Having had a look at the slides I now have it straight. It was the Alas I saw when at college and the ICL system when I worked just round the corner at RRD. If you had anything to do with Harwell RRD would have been familiar to you. I built experimental rigs and interfaced them to PDP-8's. The science guys would run them whilst the particular reactor (Dido or Pluto) was operating and I would do the maintenance whilst they where on shutdown. Happy Days... I had a office/workshop at one end of a hut with windows on three sides. Taxi to and from work each day and one week in three to a sandwich course. Rod -----Original Message----- From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org] On Behalf Of Roger Holmes Sent: 16 May 2007 23:28 To: cctalk at classiccmp.org Subject: Re: Harwell (was RE: A local computer history group for my area. ..) > > Date: Wed, 16 May 2007 04:13:44 +0100 > From: "Rod Smallwood" <RodSmallwood at mail.ediconsulting.co.uk> > Subject: RE: Harwell (was RE: A local computer history group for my > area . ..) > > Yes slight aberration of the brain. The building was called "The Atlas > Computer Laboratory" but the system was ICL. Maybe it had gone by then, but there are photos on the web of the building when it housed a Ferranti Atlas. Specifically: http://www.chilton-computing.org.uk/gallery/harwell/ slide8.htm or the view the whole collection of photos at http://www.chilton- computing.org.uk/gallery/home.htm > One of my first jobs as a junior engineer (circa 1972) was to > refurbish > 4K core memory stores for an Elliot system. What was involved in refurbishment? > They were about three feet long with a Mullard Core stack in a box in > the middle and plug in cards on either side. > They used early transistors of the OC71 era (Yup -ve supply). I soon > learned all about read, write and sense amplifiers and how the cores > actually worked. My 1301 has five core stores, each of 400(decimal) words x 50 bits (48 data + 2 parity). Three of the stores work perfectly after they have warmed up, but two of the stores are totally dead. We've tried everything, starting with the obvious - looking for a fault in the selection logic, but after replacing the same boards about five times with no effect (especially when the 'scope also says they're working properly), we had to started looking for a fault in each of the stores. But everything there looks OK too, at least measuring voltages they look OK, I don't possess a current probe and I'm not sure if I had one I'd be able to use it. > > As a final test I would put the store back in the system (Elliot > 4100?) > load a very complex FORTRAN program from paper tape ( it worked out > handicaps for large racing yachts based on their dimensions) then a > data > tape. The answer came out on one of two IBM golfball printers (no > keyboards). > > That's what I call classic computing as opposed to a classic computer! > > Rod Smallwood

18 years

General SCSI+DLT speed questions

by james＠attfield.co.uk

> From: Jim Leonard <trixter at oldskool.org> > > > Don't confuse interface speed vs. actual media speed. > > True, but I didn't have a basis for comparison. I'm hearing that 4MB/s > is indeed slightly above par, so I guess I should be happy . I have several 35/70GB DLT drives on various systems and they all do between 240MB/minute to 400MB/minute depending on the speed of the disk systems (and to some extent CPU's) they are backing up so yours certainly seems in the ball park. You can't go by interface (10MB/s) or bus (132MB/S) speed, it's purely down to the highest rate the drive can stream at and making sure you can feed it data fast enough to keep it in 'streaming' mode. Jim

18 years

Harwell (was RE: A local computer history group for my area. ..)

by RodSmallwood＠mail.ediconsulting.co.uk

>What was involved in refurbishment? Well its 35 years ago but I'll have a go. The store was made up of planes. Each was (I think) 64x64 cores. Wires ran Horizontally and Vertically through each core plus a sense wire that snaked through all the cores diagonally from one corner of the plane to the other. The cores could be magnetized in one direction or the other. It was driven by current pulses of differing magnitude depending on reading or writing. Reads came out on the sense wire as serial pulses of differing polarity to indicate 0 or 1 and you had to write the answer back each time. We had a test bench with power supplies and test boxes to write then read the store. The setting up consisted of setting the shape of the pulse amplifers output to a drawing we had. If it ran the read/write pattern ok for an hour it was a good one. If you had good electronics (ie a working board set and pulses present at the core box input)and no output you checked the date of manufacture of the core box. If it was still in warranty you went to he stores with it and said "Another one to go back to Mullard" and got a new one. If it was out of warranty you threw it out of the last window on the left (That's where the skip was) as you left the building to go and get a new one from the stores. -----Original Message----- From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org] On Behalf Of Roger Holmes Sent: 16 May 2007 23:28 To: cctalk at classiccmp.org Subject: Re: Harwell (was RE: A local computer history group for my area. ..) > > Date: Wed, 16 May 2007 04:13:44 +0100 > From: "Rod Smallwood" <RodSmallwood at mail.ediconsulting.co.uk> > Subject: RE: Harwell (was RE: A local computer history group for my > area . ..) > > Yes slight aberration of the brain. The building was called "The Atlas > Computer Laboratory" but the system was ICL. Maybe it had gone by then, but there are photos on the web of the building when it housed a Ferranti Atlas. Specifically: http://www.chilton-computing.org.uk/gallery/harwell/ slide8.htm or the view the whole collection of photos at http://www.chilton-computing.org.uk/gallery/home.htm > One of my first jobs as a junior engineer (circa 1972) was to > refurbish > 4K core memory stores for an Elliot system. What was involved in refurbishment? > They were about three feet long with a Mullard Core stack in a box in > the middle and plug in cards on either side. > They used early transistors of the OC71 era (Yup -ve supply). I soon > learned all about read, write and sense amplifiers and how the cores > actually worked. My 1301 has five core stores, each of 400(decimal) words x 50 bits (48 data + 2 parity). Three of the stores work perfectly after they have warmed up, but two of the stores are totally dead. We've tried everything, starting with the obvious - looking for a fault in the selection logic, but after replacing the same boards about five times with no effect (especially when the 'scope also says they're working properly), we had to started looking for a fault in each of the stores. But everything there looks OK too, at least measuring voltages they look OK, I don't possess a current probe and I'm not sure if I had one I'd be able to use it. > > As a final test I would put the store back in the system (Elliot > 4100?) > load a very complex FORTRAN program from paper tape ( it worked out > handicaps for large racing yachts based on their dimensions) then a > data > tape. The answer came out on one of two IBM golfball printers (no > keyboards). > > That's what I call classic computing as opposed to a classic computer! > > Rod Smallwood

18 years

The Last of The Line

by bqt＠softjar.se

"Rod Smallwood" <RodSmallwood at mail.ediconsulting.co.uk> skrev: > Well I think I understand the list. > But for clarity's sake here's the problem again. > > 1. I have a number of PDP-11/94's > 2. The first three slots are Quad Qbus > 3. The missing KDJ11-EB would have been in slot one > 4. Slot two has a M9714 ALT PWR FOR KDJ11-E in it. > 5 Slot three is empty. > 6. Slot four is a Unibus slot and has a M8191 KTJ11-B Unibus controller > in it > 7 Slot five has a M7547 TUK50-BB Tape controller in it. > 8. Slot's Six,seven and eight are empty > 9. Slot nine has a M9302 (UNIBUS TERMINATOR) at one end and a M9713 > (MIN. LOAD MODULE) at the other. > > "Your mission Mr Phelps (Should you accept it) is to replace the missing > KDJ11-EB with the lowest cost plug in alternative that will run" > > The winner gets (for the cost of the shipping) a 11/94 system unit box > as described above. Sorry, but your options are very few. The first three slots of that backplane are not Q-bus, but a special adaptation of it for the PMI memory and nothing else. You cannot use Q-bus memory on it, and no other Q-bus options either (atleast according to the manuals, I haven't tried in real life. I could check out if any signals differ, if it were real important). Second, the Unibus adapter required some special signals from the CPU-board as well. Your options are basically the 11/8x and 11/9x CPU boards. No others will originate the signals for the Unibus adapter required. Memory wise only PMI memory boards will do. For an 11/94, all memory are on the CPU board, so for those, the two PMI slots should always be empty. To make the power supply happy, you normally have some bus loads on them. If you go for the 11/84 instead, you also need to find PMI memory boards. That's the CPU/memory part of your system. You then need to configure the Unibus correctly, which means you need unibus grant cards in theright place of all empty slots. You probably also want some disk controller in that system. Johnny -- Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt at softjar.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol

18 years

Vintage Computer Festival - OT

by velocite＠gmail.com

I am writing an educational book about the invention of the videotape machine and subsequent evolution of nonlinear edit systems on desktop computers. In order to background the reader properly, I am including material on the development of not only the GUI by companies like Xerox but also microprocessors and PC's by companies and people like MOS, Motorola, DG, Intel, Faggin, De Castro, Chuck Peddle and Bill Mensche. I have tried without luck to contact Mr Peddle and wish to do so. I believe Mr Peddle will be attending, Vintage Computer Festival East 4.0 this June Maybe you are too? http://www.vintage.org/2007/east/ If you are going I am looking to convey my interest in making contact with him, to make sure the facts in my book are fair and accurate. I would love to attend but I am in Sydney, Australia. I am more than happy to give fair credit in the published work to ClassicCMP. Thanks John velocite (at) gmail dot com

18 years

A local computer history group for my area . . .

by dgreelish＠mac.com

Hi everyone, I have just started up a user group in my area to get together once a month and enjoy old computers and the history, etc. I plan to give a short presentation each meeting, bring a few systems, have some retro gaming available and basic refreshments. I'm calling it what I once called a "club" I started years ago - The Historical Computer Society. It will take many meetings and some time, but I hope it can grow and become a true non-profit group on it's own standing with elected officers, etc. - a user group. I have arranged for the space in the public library near my house, every third Saturday, from 2pm - 3:30pm, starting with next Saturday, May 19th. Here's the library, in Fruit Cove, FL, just south of Jacksonville: http://www.sjcpls.org/Branches/BartramTrail.aspx If you're not too far and interested, please let me know. Best, David David Greelish classiccomputing.com The Classic Computing Podcast Home of Computer History Nostalgia Stan Veit's History of the Personal Computer Audio Book Podcast

18 years

Com-tran Ten

by rborsuk＠colourfull.com

Does anyone know what a Com-tran Ten is? I have a set of prints (over 30 pages) I pulled from my filing cabinet (while looking for Mac info for Teo and Jeff) which say they are a reprint by permission of Digiac Corporation. I tried doing some goggling but to no avail. Any ideas (or links)? Rob Rob Borsuk email: rborsuk at colourfull.com Colourfull Creations Web: http://www.colourfull.com

18 years

Harwell (was RE: A local computer history group for my area . ..)

by roger.holmes＠microspot.co.uk

> > Date: Wed, 16 May 2007 04:13:44 +0100 > From: "Rod Smallwood" <RodSmallwood at mail.ediconsulting.co.uk> > Subject: RE: Harwell (was RE: A local computer history group for my > area . ..) > > Yes slight aberration of the brain. The building was called "The Atlas > Computer Laboratory" but the system was ICL. Maybe it had gone by then, but there are photos on the web of the building when it housed a Ferranti Atlas. Specifically: http://www.chilton-computing.org.uk/gallery/harwell/ slide8.htm or the view the whole collection of photos at http://www.chilton- computing.org.uk/gallery/home.htm > One of my first jobs as a junior engineer (circa 1972) was to > refurbish > 4K core memory stores for an Elliot system. What was involved in refurbishment? > They were about three feet long with a Mullard Core stack in a box in > the middle and plug in cards on either side. > They used early transistors of the OC71 era (Yup -ve supply). I soon > learned all about read, write and sense amplifiers and how the cores > actually worked. My 1301 has five core stores, each of 400(decimal) words x 50 bits (48 data + 2 parity). Three of the stores work perfectly after they have warmed up, but two of the stores are totally dead. We've tried everything, starting with the obvious - looking for a fault in the selection logic, but after replacing the same boards about five times with no effect (especially when the 'scope also says they're working properly), we had to started looking for a fault in each of the stores. But everything there looks OK too, at least measuring voltages they look OK, I don't possess a current probe and I'm not sure if I had one I'd be able to use it. > > As a final test I would put the store back in the system (Elliot > 4100?) > load a very complex FORTRAN program from paper tape ( it worked out > handicaps for large racing yachts based on their dimensions) then a > data > tape. The answer came out on one of two IBM golfball printers (no > keyboards). > > That's what I call classic computing as opposed to a classic computer! > > Rod Smallwood

18 years

Computer stuff 1970's ish at Lucas Birmingham Gt King St

by roger.holmes＠microspot.co.uk

> Date: Wed, 16 May 2007 09:43:27 +0100 > From: "Rod Smallwood" <RodSmallwood at mail.ediconsulting.co.uk> > Subject: RE: Computer stuff 1970's ish at Lucas Birmingham Gt King St > > Very Interesting!!! > > 1. The console terminal is a Creed Model 75 Teleprinter ie > Baudot Telex code not ASCII > This may be a Bletchley Park legacy. > The later electronic BP systems were designed to break > teleprinter codes and hence the > high speed tape readers and terminals were for telex code. > You can just see the M75 reader/punch above the operators > hand. > > 2. To the left of the operator are two high speed paper tape > readers. Are these the 1000 character per second model or the 300 character per second model? I presume they are the slower 300 cps units as the 1000 cps Elliott version on my ICT 1301 needs a powered tape un- roller to feed it. It can still stop between characters even at that speed, but I understand from my old boss when I worked at Elliott's Rochester works that the older Elliott readers did not have the stop on character facility, so that our software always put four null characters after every carriage return line feed pair, and the reading software would always read a line of input at full speed before doing any heavy processing which might take longer than a character time. > > 3. You can see the holes in the top of the desk where the tape > went after the reader > > 4. The tape rewinder is on the corner of the other desk. > > 5. The two boxes on the right are the storage cases for the high > speed readers or could be tape punches. They are the acoustic cases for Teletype BRPE paper tape punches. 100 characters per second. You had to raise the cover to load new rolls of tape into the unit, then press the feed button on top of the unit as you pulled on the tape until it started feeding itself. Then you closed the cover and when it was ready the computer started punching and the tape fed out of the chrome lined hole on the left hand side. It looks like it fed into the two holes in the desk to the left of these units. My ICT 1301 has had one of these grafted onto it in the 1970s using a Vero board full of TTL logic which is housed within the paper tape reader cabinet. Interest interface between the plus 5 volt logic levels of TTL and the minus 6.3 volt logic levels of the discrete germanium transistor logic of the 1301. A slight cheat - the TTL ground is actually at -5 volts and the TTL's VCC is connected to the 1301's 0 volt earth level. This also means a TTL '1' is a 1301 '0' and vice-versa. The 1301 to TTL signals work fine with no special circuitry, but the TTL to 1301 need a transistor (GET872) to work correctly. > > 6. The row of horizontal drawers on the right of the desk are > for rewound paper tapes. > > 7. The row of cabinets under the window is the electronics. > > 8. You needed a whole cabinet to hold 16K of core + PSU > > 9. The desk to the left appears to have some punched cards on > it. But they look a bit big. > > 10. The drawers in the desk to the left look like card storage. > > 11. The desk to the left could be a punched card station but I > have > never seen one so am unsure.

18 years

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test-drb May 2007