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101090 discussions

One of the deeper dives into RISC vs CISC I've seen

by lproven＠gmail.com

Goes a bit over my head but may be of interest: https://userpages.umbc.edu/~vijay/mashey.on.risc.html -- Liam Proven - Profile: https://about.me/liamproven Email: lproven at cix.co.uk - Google Mail/Hangouts/Plus: lproven at gmail.com Twitter/Facebook/Flickr: lproven - Skype/LinkedIn: liamproven UK: +44 7939-087884 - ?R (+ WhatsApp/Telegram/Signal): +420 702 829 053

7 years, 1 month

Anyone have any info on the obscure MX11 PDP-11 option?

by jnc＠mercury.lcs.mit.edu

> From: Al Kossow > Does anyone know where Steve Rothman is? And also Bill Weiske, who's listed as the go-to for the KS11. Noel

7 years, 1 month

Anyone have any info on the obscure MX11 PDP-11 option?

by jnc＠mercury.lcs.mit.edu

> From: Al Kossow > It is in the Dick Best Options and Modules List 197503 Ah, thanks for the pointer; I see it's listed as a "Memory Extension Control" - not sure that tells me much, alas! Interestingly, it's not in the earlier Options and Modules lists, e.g. June '74, but the KS11 is in that earlier list, so the MX11's a later addition. Noel

7 years, 1 month

Anyone have any info on the obscure MX11 PDP-11 option?

by jnc＠mercury.lcs.mit.edu

While I asking on the TUHS list about the KS11, someone mentioned the MX11 Memory Extension Option, described as "enabl[ing] the usage of 128 KW memory (18-bit addressing range) ... developed by the Digital CSS (Computer Special Systems)". I'm not familiar with this, and I couldn't find anything about it. (It's not even in the Spare Modules Handbook, but then again, neither is the KS11 - although the KT11-B is). Some early UNIBUS device address lists (e.g. the '72 "peripherals and interfacing handbook") list up to six, from #1 at 777600-06 to #6 at 777650-56. I can _guess_ what it did, from the description above (e.g. maps an 8KB block, since there can be up to 6), but I was wondering if anyone had any hard data; e.g. memories based on using one BITD, etc, etc. Even a high level description (e.g. 'sat on the UNIBUS between the CPU and extra memory, and mapped a fixed block of low UNIBUS address space to a block controlled by a register') would be an improvement on what we have now, which is basically nothing. Noel

7 years, 1 month

Help with a qic data tape

by danr234＠gmail.com

Someone gave me your info. I have a very important tape I need help with. The tape spooled off the end and I need the belt put back on. Maybe getting the data off the tape too. It?s a 3m dc2120 120Megabyte tape. I?ve tried to do some practice tapes with junk tapes but I?m not confident enough to do it.

7 years, 1 month

unix developed on 11/20 with 20 on panel or machine that just said pdp/11?

by jnc＠mercury.lcs.mit.edu

> From: Steve Malikoff >> According to this page that Dennis Ritchie wrote ... >> https://www.bell-labs.com/usr/dmr/www/picture.html > It states that their 11/20 had a KS-11 memory management unit, was > that mandatory for running v1 Unix on an 11/20? Well, the page does say they had two -11/20's, apparently one with and one without the KS11. Also, ISTR that the source for the -11/20 system has been recovered from a listing and run, and IIRC that didn't have the KS11 stuff in it (but it might be worth checking). Next to nothing is known of the KS11. Dennis' page "Odd Comments and Strange Doings in Unix": https://www.bell-labs.com/usr/dmr/www/odd.html has a story involving it (at the end), and that is all I've ever been able to find out about it (if anyone has anything more, please let me know). My original guess as to its functionality, from that, was that it's not part of the CPU, but a UNIBUS device, which perhaps maps addresses around (and definitely limits user access to I/O page addresses). It might also have mapped part of the UNIBUS space which the -11/20 CPU _can_ see (i.e. in the 0-56KB range) up to higher addresses, where 'extra' memory is configured. However, on re-reading that page, I see it apparently supported some sort of user/kernel mode distinction, which might have require a tie-in to the CPU. (But not necessarily; if there was a flop in the KS11 which stored the 'CPU mode' bit, it might be automatically cleared on all interrupts. Not sure how it would have handled traps, though. I'll have to enquire on the TUHS list. Noel

7 years, 1 month

RK05 indicator lenses?

by mosst＠SDF.ORG

Hi All, I've recently acquired an RK05 that's missing the lenses for its indicator lights. Does anyone know a part number or where I could find replacements? I was hoping there would be a clue in the engineering drawings, but unfortuanetly not. Regards, -Tom mosst at sdf.lonestar.org SDF Public Access UNIX System - http://sdf.lonestar.org

7 years, 1 month

RSS Feeds

by trash80＠internode.on.net

I'm looking for some reliable RSS feeds (I appreciate they seem to be coming rare these days) to do with classic computers, preferably with a TRS-80 flavour but I'm not going to be precious about it. Google didn't seem to produce too many and those it did were either not there anymore or broken or monumentally out of date. If anyone can point me any where I'd be most grateful. Thank you Kevin Parker 0418 815 527

7 years, 1 month

June 22

by sales＠elecplus.com

My warehouse will be open on Sat, Jun 22, from 10-3 for anyone that wants to come scrounge. I am 1 hour from San Antonio, or 2.5 hours from Austin, or 4-5 hours from Houston or Dallas (in decent traffic and weather). Cindy Croxton Electronics Plus 1613 Water Street Kerrville, TX 78028 830-370-3239 cell sales at elecplus.com --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus

7 years, 1 month

unix developed on 11/20 with 20 on panel or machine that just said pdp/11?

by wkt＠tuhs.org

Paul Koning wrote: >> The 1971 Unix Programmer's Manual mentions their 11/20 had 24 KB >> (surely KW?) memory rather than 28KW. > I would assume kW. In the PDP11 world we didn't normally speak of > bytes or kbytes, certainly not for memory and often not elsewhere either. The PDP-11 Unix source: https://github.com/DoctorWkt/unix-jun72/blob/master/pages/e00-01 says: orig = 0 core = orig+40000 / specifies beginning of user's core ecore = core+20000 / specifies end of user's core (4096 words) So: 40000= 16KB for the kernel, 20000= 8KB for the user program. Cheers, Warren

7 years, 1 month

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