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101090 discussions

Differences between the PDP-11/15 and PDP-11/20

by paulp1＠gmail.com

Thanks for posting that the KT-11B documentation is available. Does anyone know if schematics for it were included in the auction? The flip chip board complement for it is in the posted document but nothing else. If the schematics are available, are there plans to get onto bitsavers? Paul Sent from my iPad

10 years, 1 month

X server for original PC (8088/8086)

by cmhanson＠eschatologist.net

Back in the day, did anyone produce an X11 server for DOS-based 8086/8088 systems, say with support for Hercules or CGA graphics? Or was that strictly a 286-or-better thing, given the overall constraints of the 8086 architecture? (There were plenty of mouse-and-window systems for the PC/XT back then, I expect black & white X11 over a serial link would not be *that* bad?) -- Chris

10 years, 1 month

Differences between the PDP-11/15 and PDP-11/20

by jnc＠mercury.lcs.mit.edu

> I'm not sure how the KT11-B works, but my _suspicion_ ... is that it's > not part of the CPU, but a UNIBUS device So, I wuz wrong. The Option Description (part User Manual, with a little bit of Technical Manual thrown in) is now online: http://bitsavers.trailing-edge.com/pdf/dec/pdp11/1120/KT11-B_OD_Apr71.pdf Having looked through it, the KT11-B is a far more impressive beast than I thought: there are -11/20 KA11 CPU processor mods to provide User and Exec mode (i.e. real hardware time-sharing) - there is in fact another cable between the CPU and KT11-B, it did not show up in the pictures, I guess - and the memory mapping is paging, with page tables kept in core. (Just like a junior KI10...) Using the OD, I have prepared a page in the Computer History for it: http://gunkies.org/wiki/KT11-B_Paging_Option which gives (I modestly claim :-) a clear and concise overview of how the whole thing works. (The details are all there in the DEC document, but scattered throughout, in dribs and drabs.) The DEC thing will be a much easier-to-grok read if you've read this first, I reckon. The OD does contains some minor details that aren't in the Wiki page (e.g. you apparently can't modify the CPU's priority in User mode), so if you're really interested in the thing, read the OD too. A couple of observations: First, it does not contain anything like SSR1 in the standard PDP-11 memory management, which records which registers have changed, and by how much, on an instruction which gets a fault. It does record a couple of internal KA11 major state bits: http://gunkies.org/wiki/KA11_CPU which do allow one, after examinging the instruction which faulted (the address of which is provided in a KT11-B register), to work that out (unlike the -11/40, in which some instructions cannot be restarted because the CPU just doesn't keep enough data around). Still, the code to handle faults is going to involve parsing the instruction (like m40.s in V6 UNIX, if anyone cares), to make use of those recorded CPU state bits. Second, for some reason a TRAP instruction in user mode traps to user mode, not kernel! This would be a massive PITA for Unix, which uses the TRAP instruction, for details I won't bore you all with (unless someone cares). Noel

10 years, 1 month

Microvax II hardware not recognized

by dj.taylor4＠comcast.net

I've brought up a MicroVax II and installed VMS 5.5-2 on a SCSI2SD disk and it is fun to work with. (I also installed openvms 7.2 without much drama) The problem I am having is that is has a TK50 tape drive and controller, but it never has shown up in the device list. I even swapped in a different controller. The DHV11 did show up initially but has now disappeared from the device list. Did I do this by removing boards and putting them back in? A RQDX2 board was put back in at a secondary CSR address and that shows up (it is connected to an RX50 which shows up in the device list). Does Autogen recognize new hardware? Doug

10 years, 1 month

6800 CDAT memory diag help

by vintagecomputer＠bettercomputing.net

Thanks Michael!?I did read through those but I'm still getting used to operating the 6800 and am still a bit confused. ?If I want to confine the program to a certain address range, say $0000 to $1111, is the most significant byte of $0000, 0? ?As well as least? ?And then 1 and 1 for the higher address? ?And I'm assuming I set that using the M (addr) command? Thanks!!! Sent from my Samsung device -------- Original message -------- From: Michael Holley <swtpc6800 at comcast.net> Date: 2016-08-20 9:12 PM (GMT-08:00) To: "'General Discussion: On-Topic and Off-Topic Posts'" <cctalk at classiccmp.org> Subject: RE: 6800 CDAT memory diag help Here is the instructions for memory tests, CDAT is on page 3. http://www.swtpc.com/mholley/swtbug/MemoryDiagnostic.pdf The CDAT memory diagnostic can be used to help locate memory problems in a SWTPC 6800 computer system that MEMCON and ROBIT may miss. The program itself resides entirely within the 128 byte SWTBUG? RAM. The program must be loaded in two parts to avoid interfering with the systems push down stack. The contiguous section of memory to be tested is set by loading the most significant byte of the lower memory address into A002, the least significant byte into A003, the most significant byte of the upper memory address in A004 and its least significant byte in A005. The low address must be less than or equal to the upper address. The test starts from the low address and writes a 00 into all memory up to the high address. An FF is then written into the first address and all other locations are checked to be sure they contain 00. If all are OK the FF is replaced with a 00 and an FF is written in the next memory location. This pattern continues until all memory is checked or an error is found. If the computer returns to SWTBUG?, then no errors were found. ?????? NAM??? CDAT-2? ???? *MEM DIAGNOSTIC (JOHN CHRISTENSEN'S) ?????? *MODIFIED FOR MIKBUG AND SWTBUG OPERATION E0E3?????????? CONTRL? EQU??? $E0E3 A002???????????????????????????? ORG??? $A002? A002?????????? LOTEMP? RMB??? 2???????? STARTING ADDRESS? A004?????????? HITEMP? RMB??? 2???????? ENDING ADDRESS Michael Holley -----Original Message----- From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Brad H Sent: Saturday, August 20, 2016 12:49 PM To: General Discussion: On-Topic and Off-Topic Posts Subject: 6800 CDAT memory diag help ??? Hi there, I'm still having some glitches with my 6800 system and would like to do a proper RAM diag.? From reading, it seems like CDAT is the most exhaustive.. but I cannot get it to run.? I can load and then run it.. but it immediately fails at address 8000.? Since I understand this is used for I/O I am wondering how I would adjust CDAT so it ignores that space and does everything else?? Any suggestions would be most appreciated.? I think you can alter the addresses with most and least significant bytes but don't understand quite how. Brad Sent from my Samsung device

10 years, 1 month

6800 CDAT memory diag help

by vintagecomputer＠bettercomputing.net

Hi there, I'm still having some glitches with my 6800 system and would like to do a proper RAM diag. ?From reading, it seems like CDAT is the most exhaustive.. but I cannot get it to run. ?I can load and then run it.. but it immediately fails at address 8000. ?Since I understand this is used for I/O I am wondering how I would adjust CDAT so it ignores that space and does everything else? ?Any suggestions would be most appreciated. ?I think you can alter the addresses with most and least significant bytes but don't understand quite how. Brad Sent from my Samsung device

10 years, 1 month

Have Calcomp 565 plotter - looking for pen mechanism

by COURYHOUSE＠aol.com

I have same problem here we have the large size calcomp early plotter that actually has an ibm tag on it! it came to us with a hp 3000 series 3 with a parallel interface board for the 3000... I used to enjoy playing with it. back in the days when museum was in a suite next to computer exchange inc in phx things were really openly displayed and I suspect years ago some early collector stole the pun box having little pens and the solenoid head thing. I used to have a spare solenoid only but do not know where it ended up... the little fitted wood box was cool though! In a message dated 8/19/2016 9:51:37 P.M. US Mountain Standard Time, pete at petelancashire.com writes: Unless you are willing to make you own, they are very, very rare. Two have shown up on Ebay in the past 3 maybe 4 years that I'm aware of. I was lucky I got one that due to its description I was either the only bidder or close to it. The one that sold recently went for a lot more, $500 or more. My suggestion decide what your willing to pay and keep your eyes open, If you in an area that would have been where the plotters would have been used, start asking around. Someones grandfather took one home or something like that and it will be in a garage sale for $1. So put some ad on Craigslist with pretty much nothing other then some good photos, the owner will not have a clue what your talking about. Start asking around, etc etc etc. good luck -pete On Fri, Aug 19, 2016 at 7:13 PM, Jack Rubin <j at ckrubin.us> wrote: > I returned from the recent VCF-West with one more item off my ever-shorter > "must have" list - I am the new owner of a very nice Calcomp 565 drum > plotter. Even better, I was able to find the perfect shipping container for > it at Weird Stuff! > > Photos here - http://tinyurl.com/calcomp565 . > > The only problem, unfortunately a major one, is that it is completely > lacking the pen mechanism. This is actually a multi-part assembly that > threads into the carriage on the front rails of the plotter and lifts the > pen up and down in response to z-axis commands from the controller. It is a > solenoid that uses the pen as the core and was thus supplied in many > configurations depending on the kind of pen used. I'd be happy with any > bits of any configuration if you might have an idea where to find such > items. > > BTW, I'm well aware (and deeply envious!) of the fine work done by Tom > Mikulic who recreated the entire mechanism from scratch - > http://tomislavmikulic.com/proj-565.html . > > Thanks for any help you can provide, > Jack > > >

10 years, 1 month

Have Calcomp 565 plotter - looking for pen mechanism

by j＠ckrubin.us

I returned from the recent VCF-West with one more item off my ever-shorter "must have" list - I am the new owner of a very nice Calcomp 565 drum plotter. Even better, I was able to find the perfect shipping container for it at Weird Stuff! Photos here - http://tinyurl.com/calcomp565 . The only problem, unfortunately a major one, is that it is completely lacking the pen mechanism. This is actually a multi-part assembly that threads into the carriage on the front rails of the plotter and lifts the pen up and down in response to z-axis commands from the controller. It is a solenoid that uses the pen as the core and was thus supplied in many configurations depending on the kind of pen used. I'd be happy with any bits of any configuration if you might have an idea where to find such items. BTW, I'm well aware (and deeply envious!) of the fine work done by Tom Mikulic who recreated the entire mechanism from scratch - http://tomislavmikulic.com/proj-565.html . Thanks for any help you can provide, Jack

10 years, 1 month

DEC Indicator Panels page

by jnc＠mercury.lcs.mit.edu

> From: Mike Ross >> It seems to be always near the CPU ... there are only a few >> possibilities: BA15 (paper tape controller), DW15A (bus converter), >> KE15 (extended arithmetic), MM15-A and MK15-A (memory). It might also >> be a BD15 ... since that was listed as having an insert for it. It turns out the KE15 registers are available on the main console, with a setting on the rotary 'select registers to display' switch. > I'm not aware of any memory indicator panels associated with > any pdp-15 configuration I was just being complete/thorough... :-) > Bingo! > BA15 & TC15 (and many other pics) Oooh, thanks ever so much for turning that up!!! So that mystery panel seems to be a general panel, more associated with the but one quadrant is the KT15 memory management, one is the KA15 priority interrupt system, and there's general CPU/system stuff throughout (memory parity, power fail, instruction register). I'm not sure what it's formal name might be (I don't think it can be BA15, given all the CPU stuff that's in it). Very odd that the User's Handbook doesn't cover it when it covers the KT15, the KA15, etc, etc; the print set might be informative (now that I can see what's on that panel). Noel

10 years, 1 month

Microvax II hardware not recognized

by jnc＠mercury.lcs.mit.edu

> From: Paul Koning > A lot of Unibus/Qbus devices have "floating CSRs" which means they > don't have fixed address assignments. Instead, the correct address is > based on a set of rules, which puts devices in an ordered list and > assigns addresses in sequence. .. If you get the address wrong, the > system will see the device as the wrong type What about if you have a series of devices (A, B, C, D, E), assigned addresses in the correct order, and then you remove C from the system; will the software stop probing for more devices when it gets to C (ie. D and E, although still plugged in, will not be seen)? Noel

10 years, 1 month

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