test-drb March 2018

test-drb@ccmp.vtda.org

158 participants
173 discussions

by web＠loomcom.com

Folks, I know someone in North Carolina (not on this list) who just found a small pile of IBM System/36 manuals in three ring binders. These are all already on Bitsavers, and these manuals are in pretty rough shape, but if anyone really really wants them, let me know and I'll pass on your contact information 5360 Vol A1 MIMS "Maintenance Information Manual - General Safety Guide (etc.)" 5360 Vol A2 MIMS "Maintenance Information Manual - CPU & Channel (etc.)" 5360 Vol A3 MIMS "Maintenance Information Manual - Work: Station (etc.)" 5360 Vol B2 MAPS "Maintenance Analysis Procedures" 5360 Vol C1 FLDS "Field Logic Diagram" -Seth -- Seth Morabito web at loomcom.com

6 years, 9 months

PDP11 I/O page memory map

by jnc＠mercury.lcs.mit.edu

> From: Jerry Weiss > Typically execution of the RESET instruction in a user program is > treated as a NOP Yeah, that's not documented in most PDP-11 CPU manuals, either. It's one of the things that makes the PDP-11 impossible to virtualize; only HALT and SPL trap, IIRC. M[TF]P[ID] doesn't, I think, and neither does WAIT or RT[IT], IIRC. Noel

6 years, 9 months

Bug-for-bug compatibility [was RE: SimH DECtape vs. Tops-10 [was RE: Writing emulators [Was: Re: VCF PNW 2018: Pictures!]]]

by RichA＠livingcomputers.org

From: Paul Koning Sent: Monday, February 26, 2018 12:19 PM >> On Feb 26, 2018, at 12:06 PM, Doug Ingraham via cctalk >> <cctalk at classiccmp.org>> wrote: >> The purpose of an emulator is to accurately pretend to be the original >> hardware. It doesn't matter that the original OS runs on a particular >> emulator. If a program can be written that runs on the original hardware >> but fails on the emulator then there is a flaw in that emulator. > That's true. But it is unfortunately also true that creating a bug for bug > accurate model of an existing machine is extremely hard. This is true even in real hardware (or "real" hardware, if you prefer), whether bug-for-bug or simply correct results for corner cases. The XKL Toad-1 System was designed to be a superset clone of the KL-10 based DECSYSTEM-2065 from Digital Equipment Corporation. It implements the full 30-bit extended addressing introduced with TOPS-20 v4, of which the KL-10 provided a 23-bit subset, and provides native support for 10Mbit Ethernet and FASTWIDE differential SCSI2 (both state of the art in 1991 when the design was frozen). As a better DEC-20, the Toad-1 was a success. (We will leave aside the issue of its market failure, which is irrelevant to the story.) Fast forward 20 years, to Living Computer Museum, where a KI-10 based DEC-1070 was undergoing restoration. Diagnostics were needed, so the resident TOPS-20 programmer laid hands on the MAINDEC sources for the KI-10 and proceeded to compile them all and generate paper tapes of the results. All went smashingly well until the multiplication test. The diagnostic source for this test uses a macro to build a set of test values for X**2 where X is a power of 2. Internally, Macro-20 uses the IMULM instruction to build the results. In the KA-10 manual, IMULx of 2**35 * 2**35 is supposed to store the high order part of the result into the 36 bit word addressed by the instruction, and set the overflow bit. On the Toad-1 (and on the Toad-2 prior to our discovery of this bug), a zero is stored instead. Since we compiled the KI-10 diagnostics on the Toad-1, this incorrect result was placed on the diagnostic paper tape, and the KI-10 seemed to fail the diagnostic. Imagine our chagrin when days of trying to correct the problem led to the conclusion that the diagnostic was incorrect. Rich Rich Alderson Vintage Computing Sr. Systems Engineer Living Computers: Museum + Labs 2245 1st Avenue S Seattle, WA 98134 mailto:RichA at LivingComputers.org http://www.LivingComputers.org/

6 years, 9 months

PDP11 I/O page memory map

by jnc＠mercury.lcs.mit.edu

> From: Paul Koning > RTI/RTT are used in the debugger, so they need to work in user mode. > They refuse to raise your privilege level, though. I understand that it has uses, but by specifying the 'failure' mode in User mode (when the contents of the current or previous modes is not User) to be 'ignore', rather than 'trap', that's one more thing that makes the PDP-11 non-virtualizable. (This choice, to ignore, instead of trap, has the same issue in other places where it's done that way, e.g. RESET.) Noel

6 years, 9 months

Is livingcomputers.org down?

by kylevowen＠gmail.com

I'm not able to load Living Computer's website. Anyone else? Kyle

6 years, 9 months

HP 1000 system in Europe

by gerardcjat＠free.fr

NICE system !! I would have love it but hadn't room for it .... too sad :-(( Where did in goes ??? ( Which country, in Europ, I think ? ) Gerard

6 years, 9 months

PDP11 I/O page memory map

by jnc＠mercury.lcs.mit.edu

> From: Charles Dickman > So if the I/O page is completely (all processor modes) unmapped is > there any way to recover besides a power cycle? Does the RESET > instruction disable the MMU? Interesting questions! The CPU manuals don't say, about the RE$ET; I just tried it on the /23 I happen to have next to my desktop, and yes, the RESET instruction does clear bit 0 of SSR0. Noel

6 years, 9 months

VCF East keynotes -- holy moly!

by cctalk＠snarc.net

There will be three awesome keynotes for VCF East this spring. - Friday: our own Bill Dromgoole who'll talk about restoring the VCFed UNIVAC mainframe. - Saturday: Don Eyles (NASA contractor who hacked the Apollo Guidance Computer to save the Apollo 14 mission) - Sunday: Dave Walden, who programmed the IMP at BBN for the ARPANET

6 years, 9 months

PDP11 I/O page memory map

by dj.taylor4＠comcast.net

Is there a document that describes the bank 7 memory page and what addresses are reserved for what?? I think I've seen this before but can't seem to put my hands on it. Another question, bootstrap is reserved for 173000, how many words are allowed there for this?? How do the more complicated bootstraps, e.g. microPDP11-53, accommodate this limitation? Doug

6 years, 9 months

OT: Any tech apprenticeship opportunities in Brisbane, QLD?

by sellam.ismail＠gmail.com

Hello Folks. Forgive me for the intrusion. I know a good soul in Brisbane area in Queensland, Australia who is looking for some sort of apprenticeship in electronics or communications/networking. I thought I would ask here in case this message reaches some of you blokes down there that might be able to point him in a useful direction. He's in his 30s, very sharp and capable, gainfully employed in an entirely unrelated field and looking for a change in his life. Offline responses welcomed. Thanks! Sellam

6 years, 9 months

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test-drb March 2018