Re: XXDP on PDP-11/03
There are two versions of XXDP+ V2 monitors. The XXDPSM.SYS is needed for cpu's w/o MMU's or don't have more than 28KW. This and XXDPXM.SYS are both on the AK6DN diagnostic image. However, only a few other programs exist on the image. In SIMH the AK6DN image does the same thing. The halt location 100 is near the LTC vector. I turned BEVENT off and it boots successfully. I am not immediately sure why this is necessary. sim> show cpu CPU 11/03, NOEIS, NOFIS, BEVENT disabled, autoconfiguration enabled, idle disabled 56KB sim> show ry RY address=1170-1173, vector=264, BR5, 2 units RY0 512KB, attached to XXDP.RX2, write enabled double density RY1 512KB, not attached, write enabled double density sim> boot ry MEMORY MANAGEMENT UNIT NOT FOUND BOOTING UP XXDP-SM SMALL MONITOR XXDP-SM SMALL MONITOR - XXDP V2.6 REVISION: E0 BOOTED FROM DY0 28KW OF MEMORY NON-UNIBUS SYSTEM RESTART ADDRESS: 152010 TYPE "H" FOR HELP .H ? NOT FOUND: HELP .TXT From a XXDPXM boot. .DIR ENTRY# FILNAM.EXT DATE LENGTH START VERSION 1 XXDPXM.SYS 1-MAR-89 39 67 F.0 2 XXDPSM.SYS 1-MAR-89 29 000136 E.0 3 DRSXM .SYS 1-MAR-89 48 000173 C.0 4 DRSSM .SYS 1-MAR-89 24 000253 G.2 5 DIR .SYS 1-MAR-89 7 000303 D.0 6 DB .SYS 1-MAR-89 2 000312 C.0 7 DD .SYS 1-MAR-89 3 000314 D.0 8 DL .SYS 1-MAR-89 4 000317 D.0 9 DM .SYS 1-MAR-89 4 000323 C.0 10 DR .SYS 1-MAR-89 3 000327 C.0 11 DU .SYS 1-MAR-89 4 000332 E.0 12 DY .SYS 1-MAR-89 3 000336 D.0 13 LP .SYS 1-MAR-89 1 000341 B.0 14 MM .SYS 1-MAR-89 3 000342 C.0 15 MS .SYS 1-MAR-89 4 000345 C.0 16 MU .SYS 1-MAR-89 4 000351 E.0 17 DATE .SYS 1-MAR-89 2 000355 B.0 18 DUSZ .SYS 1-MAR-89 2 000357 C.0 19 ZRXAF0.BIC 1-MAR-89 17 000361 20 ZRXBF0.BIC 1-MAR-89 16 000402 21 ZRXCA0.BIN 1-MAR-89 7 000422 22 ZRXDC0.BIC 1-MAR-89 30 000431 23 ZRXEA2.BIC 1-MAR-89 17 000467 24 ZRXFB0.BIC 1-MAR-89 31 000510 FREE BLOCKS: 629 Jerry On 8/13/19 8:05 PM, Douglas Taylor via cctalk wrote: Recently, I assembled one of the RX02 emulator boards developed by AK6DN. I am using it presently in a BA11-M box with PDP-11/2 cpu (really basic 16 bit system). I put the disk images from github on the SD card (RT11 V5.07 and XXDP not sure what version). The box has a BDV11 bootstrap / terminator board and I use this to boot the RX02 emulator. Works fine when I boot RT11, however I can't boot XXDP - it halts at 000104. Do I need to use a different version of XXDP to run on the PDP-11/03? Doug
Re: Electr* Engineering
in the late 1960s and up thru 1979 UTexas at Arlington Computer Science initially only offered a Masters, and was housed in Industrial Engineering. If you wanted an undergrad degree in "computing" you went thru the math department and got a BA or BS in mathematics with an emphasis in computing. I took a *lot* of CS classes and a couple EE tclasses to build my own CS curriculum on top of my BS-Math. In 1979 when I graduated I could have gotten one of the first BS in Computer Science and Engineering instead of Math. But, I just stoop to taking a 3-unit class for a semester in mechanical drawing which was madnatory for engineering degrees at that time. Has never been a problem, and I enjoyed my math classes. Lee Courtney Lee Courtney On Tue, Aug 13, 2019 at 12:04 PM Yeechang Lee via cctech < cct...@classiccmp.org> wrote: > Adam Thornton says: > > The genealogy of Computer Science departments (and their curricula) > > (at least in the US) is also weird and historically-contingent. > > Basically it seems to have been a tossup at any given school whether > > it came out of the Electr[ical|onic] Engineering department, in > > which case it was memories and logic gates and a bottom-up, > > hardware-focused curriculum, or out of the Mathematics department, > > in which case it was algorithms and complexity analysis and a > > software-focused curriculum. > > Yes, I've noticed the same thing. Example: Harvard's CS department is > originally from the math side, while MIT's is from EE (thus today's > EECS). > > Berkeley = EE > Brown = Math > BYU = Math > Caltech = EE > Columbia = EE > Cornell = Operations research, math > Dartmouth = Math > Illinois = Math > NYU = Both (because Polytechnic developed its own CS program long > before NYU acquired it to regain an engineering school) > Penn = EE > UCLA = OR (probably because of the RAND heritage) > > Caltech until very recently did not formally offer CS degrees; > students received degrees in Engineering and Applied Science, with a > focus on CS (or aeronautics, or civil, or ME). > > Illinois is an example of a track we might call "other" or even > "defense". With government funding the university built its own > computers (including ILLIAC and PLATO), and the group that did so > became the CS department, but the undergraduate CS program began > within the math department. Harvard's and Penn's programs might also > qualify. > > Undergraduate CS degrees are BA (Example: Harvard), BS (Example: > Penn), or both (Example: Columbia). At Penn one must be an engineering > student to major in CS. At Columbia one can major in CS in either the > liberal arts or engineering schools, but with different > curriculums. At Yale there is one undergraduate school, within which > one can receive a BA or BS in CS, with different curriculums. Cornell, > Northwestern, and Berkeley offer CS in their separate liberal arts and > engineering schools; undergraduates receive BA or BS degrees with > identical CS curriculums, with only other requirements differing. > > I've read that medical schools are good at teaching either > pharmacology (drugs), or pathology (diseases); perhaps this is also > because of the expertise/specialty of their early faculty members. > > -- > geo:37.78,-122.416667 > -- Lee Courtney +1-650-704-3934 cell
Re: Electr* Engineering
Adam Thornton says: > The genealogy of Computer Science departments (and their curricula) > (at least in the US) is also weird and historically-contingent. > Basically it seems to have been a tossup at any given school whether > it came out of the Electr[ical|onic] Engineering department, in > which case it was memories and logic gates and a bottom-up, > hardware-focused curriculum, or out of the Mathematics department, > in which case it was algorithms and complexity analysis and a > software-focused curriculum. Yes, I've noticed the same thing. Example: Harvard's CS department is originally from the math side, while MIT's is from EE (thus today's EECS). Berkeley = EE Brown = Math BYU = Math Caltech = EE Columbia = EE Cornell = Operations research, math Dartmouth = Math Illinois = Math NYU = Both (because Polytechnic developed its own CS program long before NYU acquired it to regain an engineering school) Penn = EE UCLA = OR (probably because of the RAND heritage) Caltech until very recently did not formally offer CS degrees; students received degrees in Engineering and Applied Science, with a focus on CS (or aeronautics, or civil, or ME). Illinois is an example of a track we might call "other" or even "defense". With government funding the university built its own computers (including ILLIAC and PLATO), and the group that did so became the CS department, but the undergraduate CS program began within the math department. Harvard's and Penn's programs might also qualify. Undergraduate CS degrees are BA (Example: Harvard), BS (Example: Penn), or both (Example: Columbia). At Penn one must be an engineering student to major in CS. At Columbia one can major in CS in either the liberal arts or engineering schools, but with different curriculums. At Yale there is one undergraduate school, within which one can receive a BA or BS in CS, with different curriculums. Cornell, Northwestern, and Berkeley offer CS in their separate liberal arts and engineering schools; undergraduates receive BA or BS degrees with identical CS curriculums, with only other requirements differing. I've read that medical schools are good at teaching either pharmacology (drugs), or pathology (diseases); perhaps this is also because of the expertise/specialty of their early faculty members. -- geo:37.78,-122.416667
Convergent Technologies NGEN and Datapoint monitor
Good evening, folks... Does anybody know if Datapoint made monitors for Convergent Technologies? In my "near junk" section I have some modules that someone stored in a warehouse next to a carpenter shop and under bombardment from bats and birds. The modules were made by Convergent Technologies and I never did much about them because of their extremely dirty state and also because of the lack of a keyboard. I have: - Two CP-001/8 cpu modules (80186@8MHz, 256KB RAM, 6845 video IC) - Four 5 1/4" dual-floppy modules (each has two Mitsubishi M4853 half-height drives) - One GC-001 graphics controller - Two PS-001 power supplies, one is missing parts and then, a monitor that by the looks and controls is a VC-002 15" to be used with the GC-001, except that it is labeled as: Datapoint Corp. Model 97-1224-001 Serial 934055 Other marks: 53-00355-00 5-84 So, do you guys know if Datapoint made monitors for others? Carlos.
XXDP on PDP-11/03
Recently, I assembled one of the RX02 emulator boards developed by AK6DN. I am using it presently in a BA11-M box with PDP-11/2 cpu (really basic 16 bit system). I put the disk images from github on the SD card (RT11 V5.07 and XXDP not sure what version). The box has a BDV11 bootstrap / terminator board and I use this to boot the RX02 emulator. Works fine when I boot RT11, however I can't boot XXDP - it halts at 000104. Do I need to use a different version of XXDP to run on the PDP-11/03? Doug
Compaq SystemPro XL Service Manual or PSU Schematics
Hello All, Does anyone out there by any chance have the Service Manual for a Compaq SystemPro XL or at least schematics to the PSU? Trying to revive one of these systems and the PSU is not working. TIA! -Ali
Re: ADM-3A question
After hanging vertically for 36 hrs in a hot upstairs room, more goop seeped out from under the keyboard. It now works again. Whew. While running on the bench for burn-in testing, a cursor problem suddenly appeared... it would only move every other keystroke. With the technical description and schematic at hand, it wasn't hard to track down a 74LS193 up/down counter with a blown (floating) LSB output. Confirmed by manually toggling that bit and the cursor would move back and forth one position. Meanwhile I removed the bad chip and put in a DIP socket. Naturally my TTL collection didn't have an 'LS193 so I'm waiting on that. So I have a 24 line, 1 column terminal :) The monitor was occasionally intermittent (no display at all, no HV, +15 and drive signals OK). It seemed to change with movement of the wiring harness from the main board to the monitor, too. I reseated the edge connector on its PCB and it seemed to be fixed - but then the VERTICAL deflection collapsed and tweaking the height adjustment caused increasing loss. The 100 ohm pot to the base of the vertical output transistor had picked that moment to go open. Changed that out and readjusted everything - so far so good after another hour of run time. This ADM-3A could have been unpowered (and in a storage area without climate control) for a very long time. I wonder if that contributed to the failures I'm seeing... hope there aren't any more until I get to use it for a while on my PDP-8/A (or 11/23+). --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus
Re: Electr* Engineering
I can attest to that. ;-) Where I went (CMU) the CS department grew out of the Math department…while I was there the only degree that the CS department granted was PhD. So everyone else majored in something else (EE in my case…which had a bunch of digital stuff but still focused on a lot of theory…differential equations, electromagnetic fields/waves and communications theory) and took CS courses as electives (which focused on data structures, algorithms, etc…e.g. a lot of CS theory). TTFN - Guy > On Aug 12, 2019, at 11:05 PM, Adam Thornton via cctalk > wrote: > > At Rice in the early 90s the department was "Electrical and Computer > Engineering" if my hazy memory serves. > > The genealogy of Computer Science departments (and their curricula) (at least > in the US) is also weird and historically-contingent. Basically it seems to > have been a tossup at any given school whether it came out of the > Electr[ical|onic] Engineering department, in which case it was memories and > logic gates and a bottom-up, hardware-focused curriculum, or out of the > Mathematics department, in which case it was algorithms and complexity > analysis and a software-focused curriculum. > > Adam
IBM 026/029/129 ribbons
Just for reference the following site has ribbons for the subject card punches. https://www.aroundtheoffice.com/IBM-026-Keypunch-Ribbon/productinfo/RP-520-I BM/ I bought some a few years ago. As I understand it he makes a batch every year or so. I don't know but he might like the used reels back to use again. :-) Donald
Re: Electr* Engineering
Hi Kevin: Yup. I haven't heard anything about Gana for decades, but Chris is on Facebook... I graduated in 1977... you'll probably also remember Rick Hobson, Jerry Barenholtz, Tom Calvert and Nick Cercone... For those not from SFU - https://www.sfu.ca/computing/about/history.html From: "Kevin McQuiggin" To: "myself" , "cctalk" Sent: Tuesday, August 13, 2019 9:18:53 AM Subject: Re: Electr* Engineering Norman, I recall you! I was at SFU first as a high school student from 1975 then as an undergrad 1977-1981. Elma, Doreen, Ted Sterling, James Weinkam - you’ll remember them! I was a TA as well in the late 1970s and classes were small, especially upper level. 5-6 students per class and we’d TA one another based on our specialities. Mine was system software, OSes, a bit of hardware. It was a great “classic” university eduction, not the big machine it is now. Best wishes, Kevin Remember Gana and Chris Dewhurst? > On Aug 13, 2019, at 8:37 AM, Norman Jaffe via cctalk > wrote: > > Kevin - which university did you go to? > I was in the first class at Simon Fraser University that started in Computing > Science (1974) rather than transferring in from another department... we > often had TAs in one class that were students in the next one, as they had > taken the first class earlier... > > From: "cctalk" > To: "Adam Thornton" , "cctalk" > Sent: Tuesday, August 13, 2019 7:50:15 AM > Subject: Re: Electr* Engineering > > In my school in Canada, the computing science program started about 1974 and > grew out of the math department, but when it was formalized as a department > in 1976-77 the university wisely placed it in a new “Interdisciplinary > Studies” faculty and staffed the school with people from mathematics, > chemistry, physics, and some external engineering folks. > > It worked out very well and the program was recognized shortly as one of the > best in Canada due to recognition of CS’ interdisciplinary nature. > >> On Aug 12, 2019, at 11:05 PM, Adam Thornton via cctalk >> wrote: >> >> At Rice in the early 90s the department was "Electrical and Computer >> Engineering" if my hazy memory serves. >> >> The genealogy of Computer Science departments (and their curricula) (at >> least in the US) is also weird and historically-contingent. Basically it >> seems to have been a tossup at any given school whether it came out of the >> Electr[ical|onic] Engineering department, in which case it was memories and >> logic gates and a bottom-up, hardware-focused curriculum, or out of the >> Mathematics department, in which case it was algorithms and complexity >> analysis and a software-focused curriculum. >> >> Adam
Re: Electr* Engineering
Norman, I recall you! I was at SFU first as a high school student from 1975 then as an undergrad 1977-1981. Elma, Doreen, Ted Sterling, James Weinkam - you’ll remember them! I was a TA as well in the late 1970s and classes were small, especially upper level. 5-6 students per class and we’d TA one another based on our specialities. Mine was system software, OSes, a bit of hardware. It was a great “classic” university eduction, not the big machine it is now. Best wishes, Kevin Remember Gana and Chris Dewhurst? > On Aug 13, 2019, at 8:37 AM, Norman Jaffe via cctalk > wrote: > > Kevin - which university did you go to? > I was in the first class at Simon Fraser University that started in Computing > Science (1974) rather than transferring in from another department... we > often had TAs in one class that were students in the next one, as they had > taken the first class earlier... > > From: "cctalk" > To: "Adam Thornton" , "cctalk" > Sent: Tuesday, August 13, 2019 7:50:15 AM > Subject: Re: Electr* Engineering > > In my school in Canada, the computing science program started about 1974 and > grew out of the math department, but when it was formalized as a department > in 1976-77 the university wisely placed it in a new “Interdisciplinary > Studies” faculty and staffed the school with people from mathematics, > chemistry, physics, and some external engineering folks. > > It worked out very well and the program was recognized shortly as one of the > best in Canada due to recognition of CS’ interdisciplinary nature. > >> On Aug 12, 2019, at 11:05 PM, Adam Thornton via cctalk >> wrote: >> >> At Rice in the early 90s the department was "Electrical and Computer >> Engineering" if my hazy memory serves. >> >> The genealogy of Computer Science departments (and their curricula) (at >> least in the US) is also weird and historically-contingent. Basically it >> seems to have been a tossup at any given school whether it came out of the >> Electr[ical|onic] Engineering department, in which case it was memories and >> logic gates and a bottom-up, hardware-focused curriculum, or out of the >> Mathematics department, in which case it was algorithms and complexity >> analysis and a software-focused curriculum. >> >> Adam
Anyone have a mid-80s Robinson-Nugent connector catalog?
Or some RN 68 pin CLCC sockets, or even a part number for them? I tried buying a 1981 RFN catalog, but they weren't in there. I have a bunch of IMS 80186 slave cards with the CPUs pulled Of course, they didn't keep the caps. RN was bought by 3M and I've been unable to even find a part number for these sockets. I'm hoping not to have to replace the sockets to get these boards working. Pics of what I need are here https://twitter.com/bitsavers/status/1161075014235385857
RE: [EXTERNAL] I need a keypunch (briefly)
Chip - Our museum in Baltimore in 330 miles from you. Our 029 cardpunch worked last time we turned it on! Bob Roswell brosw...@syssrc.com 410-771-5544 ext 4336 https://museum.syssrc.com -Original Message- From: cctalk On Behalf Of cctalk via cctalk Sent: Thursday, August 08, 2019 1:56 PM To: cctalk@classiccmp.org Subject: [EXTERNAL] I need a keypunch (briefly) The Computer Museum of America in Roswell GA (400 miles) has 2 working 029s. Don’t know the condition of the ribbons. Contact Lonnie Simms via i...@computermuseumofamerica.org. Tell him his CA IBM benefactor sent you. I hope you have black cards. If not, let me know. Otherwise you could try http://www.kloth.net/services/cardpunch.php and print the JPEG on heavy stock. Donald Date: Wed, 7 Aug 2019 18:10:32 -0400 From: Chip Davis To: cctalk@classiccmp.org Subject: I need a keypunch (briefly) Message-ID: <5c1abccc-5548-057d-fa0c-0b6be9d0c...@aresti.com> Content-Type: text/plain; charset=utf-8; format=flowed I was referred to this group by dave.g4...@gmail.com who thought you might be able to help me. I need to punch a half-dozen datacards for an award for a retired IBMer. Anyone know where I can find a working 026/029/129 within 300 miles of Raleigh, NC? Many thanks for any pointers. Chip Davis c...@aresti.com +1.919.271.2582
Re: Electr* Engineering
Kevin - which university did you go to? I was in the first class at Simon Fraser University that started in Computing Science (1974) rather than transferring in from another department... we often had TAs in one class that were students in the next one, as they had taken the first class earlier... From: "cctalk" To: "Adam Thornton" , "cctalk" Sent: Tuesday, August 13, 2019 7:50:15 AM Subject: Re: Electr* Engineering In my school in Canada, the computing science program started about 1974 and grew out of the math department, but when it was formalized as a department in 1976-77 the university wisely placed it in a new “Interdisciplinary Studies” faculty and staffed the school with people from mathematics, chemistry, physics, and some external engineering folks. It worked out very well and the program was recognized shortly as one of the best in Canada due to recognition of CS’ interdisciplinary nature. > On Aug 12, 2019, at 11:05 PM, Adam Thornton via cctalk > wrote: > > At Rice in the early 90s the department was "Electrical and Computer > Engineering" if my hazy memory serves. > > The genealogy of Computer Science departments (and their curricula) (at least > in the US) is also weird and historically-contingent. Basically it seems to > have been a tossup at any given school whether it came out of the > Electr[ical|onic] Engineering department, in which case it was memories and > logic gates and a bottom-up, hardware-focused curriculum, or out of the > Mathematics department, in which case it was algorithms and complexity > analysis and a software-focused curriculum. > > Adam
Re: Electr* Engineering
In my school in Canada, the computing science program started about 1974 and grew out of the math department, but when it was formalized as a department in 1976-77 the university wisely placed it in a new “Interdisciplinary Studies” faculty and staffed the school with people from mathematics, chemistry, physics, and some external engineering folks. It worked out very well and the program was recognized shortly as one of the best in Canada due to recognition of CS’ interdisciplinary nature. > On Aug 12, 2019, at 11:05 PM, Adam Thornton via cctalk > wrote: > > At Rice in the early 90s the department was "Electrical and Computer > Engineering" if my hazy memory serves. > > The genealogy of Computer Science departments (and their curricula) (at least > in the US) is also weird and historically-contingent. Basically it seems to > have been a tossup at any given school whether it came out of the > Electr[ical|onic] Engineering department, in which case it was memories and > logic gates and a bottom-up, hardware-focused curriculum, or out of the > Mathematics department, in which case it was algorithms and complexity > analysis and a software-focused curriculum. > > Adam
Re: Electr* Engineering
> On Aug 13, 2019, at 2:05 AM, Adam Thornton via cctalk > wrote: > > At Rice in the early 90s the department was "Electrical and Computer > Engineering" if my hazy memory serves. > > The genealogy of Computer Science departments (and their curricula) (at least > in the US) is also weird and historically-contingent. Basically it seems to > have been a tossup at any given school whether it came out of the > Electr[ical|onic] Engineering department, in which case it was memories and > logic gates and a bottom-up, hardware-focused curriculum, or out of the > Mathematics department, in which case it was algorithms and complexity > analysis and a software-focused curriculum. That was true in other countries as well. Sometimes different terms were used to show differences in focus, like "Computing science" or "Informatics". Early computer people, not surprisingly, had backgrounds from all over the science and engineering world. Several of the early Dutch computer designers were physicists with very little EE knowledge (and it showed...). For that matter, the famous Dutch computer scientist E.W. Dijkstra got his Ph.D. from the Department of Mathematics and Physics. The curriculum differences came a bit later, I think. At the very beginning you had to deal with the circuits and logic, no matter your background. Again, looking at the Dutch case, the Amsterdam computers came out of the "Mathematical Center" (an applied math institution) -- but they still assembled relays and tubes into complete computer systems, while working on algorithms. paul
Re: Electr* Engineering
On 8/13/19 2:05 AM, Adam Thornton via cctalk wrote: > At Rice in the early 90s the department was "Electrical and Computer > Engineering" if my hazy memory serves. > > The genealogy of Computer Science departments (and their curricula) (at least > in the US) is also weird and historically-contingent. Basically it seems to > have been a tossup at any given school whether it came out of the > Electr[ical|onic] Engineering department, in which case it was memories and > logic gates and a bottom-up, hardware-focused curriculum, or out of the > Mathematics department, in which case it was algorithms and complexity > analysis and a software-focused curriculum. In the early 80's West Point had "Geography and Computer Science". CS has always been the red headed step child. bill
Re: Pertec Interface Cable Length
On 8/12/19 8:16 AM, Nigel Johnson via cctalk wrote: > Another consideration with the TC02 is the small buffer. I don't know > what tape speed your drive runs at, but we lost a lot of sales to Dilog > because of buffer overflow on some of the faster CDC dirves. When we > came out with the TC03, it had a larger buffer to handle this. The Qualstar drive is a *slow* drive. 50 ips in 1600 PE mode and a whopping 12.5 IPS in 6250 GCR mode. Transfer rate in either is about 80KB/sec. Qualstar doesn't have a mechanical buffer (spring arms or vacuum column) like most drives; it's all handled by the reel servos. It's wonder that it works at all.I doubt that it will overwhelm a PDP11. It probably doesn't overwhelm an IBM PC XT. The SCSI version of the drive does have a 256KB buffer, but I'm uncertain what the Pertec interface model has. --Chuck
Electr* Engineering
At Rice in the early 90s the department was "Electrical and Computer Engineering" if my hazy memory serves. The genealogy of Computer Science departments (and their curricula) (at least in the US) is also weird and historically-contingent. Basically it seems to have been a tossup at any given school whether it came out of the Electr[ical|onic] Engineering department, in which case it was memories and logic gates and a bottom-up, hardware-focused curriculum, or out of the Mathematics department, in which case it was algorithms and complexity analysis and a software-focused curriculum. Adam
Re: Pertec Interface Cable Length
On 08/11/2019 08:00 PM, Douglas Taylor via cctech wrote: This is where the electrical engineer could help. How do you determine how long a cable the 74LS240 can drive? Well, there are several considerations. First, it takes some current to charge up the cable capacitance. More current charges the capacitance faster, but also creates faster edges which cause more crosstalk. Then, the data rate needs to be considered. Mag tape data rates are not that high. So, for 1600 BPI at 45 IPS, the data rate is 72 K bytes/second, or about 14 us per byte. Twisted-pair cable should have a little less capacitance, and it is supposed to reduce crosstalk, so should work better. The most serious problem is when many data lines switch at the same time, it may contaminate the clock pulses and cause bytes to be dropped or added. With the low data rates involved, proper delays to allow ringing to settle on the data lines and prevent short crosstalk pulses from affecting the clocks should make the system very tolerant of cable issues. But, maybe some engineers didn't really optimize their logic for these problems. Jon
Re: Pertec Interface Cable Length
On 8/12/19 8:11 AM, Douglas Taylor via cctech wrote: > The bad news is that the cable lengths must be short to use the Qualstar > 1260 with a PDP11, the good news is that I can lift and carry the tape > drive! For many of us in this hobby that it is extremely important. > > After looking at pictures of the 1260 on the internet I see that it was > designed to be used with a PC and the interface cable was 62 pins and > quite short. Someone mentioned earlier that it was a cheap tape drive > that didn't meet the Pertec standard and I'm finding out what exactly > that meant. > > It is nice to have a reel to reel tape drive and watch it work. If you needed to cobble something up suitable for long cable driving, you could work up the correct pertec driver interface to sit between the Qualstar interface board and the cable and install it in the 1260 case--there's plenty of room without the SCSI interface PCB. The big problem with the 1260 is that it doesn't move the tape fast enough for reliable operation at the 6250 GCR setting; operation at 1600 PE is just passable. But it's a drive that's portable and that is an advantage, especially to us older folk. Another possible option would be to replace the Qualstar LS240 drivers with TI 74BCT756 open-collector drivers (same pinout) with 64 ma drive capability. That probably would be the harder option, as it would entail removing the soldered-in LS240s. FWIW, Chuck
Re: Pertec Interface Cable Length
Another consideration with the TC02 is the small buffer. I don't know what tape speed your drive runs at, but we lost a lot of sales to Dilog because of buffer overflow on some of the faster CDC dirves. When we came out with the TC03, it had a larger buffer to handle this. cheers, Nigel Johnson On 12/08/2019 11:13, Jon Elson via cctech wrote: On 08/11/2019 08:00 PM, Douglas Taylor via cctech wrote: This is where the electrical engineer could help. How do you determine how long a cable the 74LS240 can drive? Well, there are several considerations. First, it takes some current to charge up the cable capacitance. More current charges the capacitance faster, but also creates faster edges which cause more crosstalk. Then, the data rate needs to be considered. Mag tape data rates are not that high. So, for 1600 BPI at 45 IPS, the data rate is 72 K bytes/second, or about 14 us per byte. Twisted-pair cable should have a little less capacitance, and it is supposed to reduce crosstalk, so should work better. The most serious problem is when many data lines switch at the same time, it may contaminate the clock pulses and cause bytes to be dropped or added. With the low data rates involved, proper delays to allow ringing to settle on the data lines and prevent short crosstalk pulses from affecting the clocks should make the system very tolerant of cable issues. But, maybe some engineers didn't really optimize their logic for these problems. Jon -- Nigel Johnson MSc., MIEEE VE3ID/G4AJQ/VA3MCU Amateur Radio, the origin of the open-source concept! You can reach me by voice on Skype: TILBURY2591 If time travel ever will be possible, it already is. Ask me again yesterday This e-mail is not and cannot, by its nature, be confidential. En route from me to you, it will pass across the public Internet, easily readable by any number of system administrators along the way. Nigel Johnson Please consider the environment when deciding if you really need to print this message
Re: Pertec Interface Cable Length
On 8/12/2019 1:25 AM, Chuck Guzis via cctech wrote: On 8/11/19 8:51 PM, Douglas Taylor via cctech wrote: The TC02 is an Emulex TS11 emulation for pertec interface tape drives. The J1 and J2 are sort of standard terminology, don't know why. Ah, the *Emulex* TC02. You had me going there--DEC also has a DECtape controller called the TC02. Looking at the TC02, there are 374s to latch data coming from the Qualstar and use the termination packs, but there are also 7438s driving the lines from the TC02 to the Qualstar. Those have no terminators. The TC02 reference manual says that you get run lines up to 30 feet long between the TC02 and formatter. My point is that the driver technology for the Qualstar (i.e. read data and status) is inappropriate for long cable runs. The spec calls for 48 ma OC drivers. --Chuck , The bad news is that the cable lengths must be short to use the Qualstar 1260 with a PDP11, the good news is that I can lift and carry the tape drive! For many of us in this hobby that it is extremely important. After looking at pictures of the 1260 on the internet I see that it was designed to be used with a PC and the interface cable was 62 pins and quite short. Someone mentioned earlier that it was a cheap tape drive that didn't meet the Pertec standard and I'm finding out what exactly that meant. It is nice to have a reel to reel tape drive and watch it work. Doug
