test-drb

test-drb@ccmp.vtda.org

101090 discussions

by jplist2008＠kiwigeek.com

Greetings; My googlefu is failing me and I was wondering if someone might be able to help me identify one of the boot ROMs present in an M9312 bootstrap/term board. The board has three ROMs, an RX01 (042130), an RX02 (042131) and then a mystery code - 043127. The M9312 ROM identification table does not list this ROM code - I suspect it _might_ be for a DSD combined 8" drive and Winchester disk box, but I'm under the impression this would appear as a DU device, and attempting to boot from DU gets an ILL CMD, suggesting otherwise. I tried all of the other possible mnemonics listed in the M9312 manual, so it doesn't appear to piggy-backing on any of those either. My thanks; - JP

9 years, 9 months

Odd memory error in PDP-11/04

by jnc＠mercury.lcs.mit.edu

> From: Ethan Dicks > What's happening now . is when I change one location .. it > echoes across multiple locations... > ... > 1) Depositing any value is echoed 000020 later. > ... > Does this sound like a dodgy CPU, dodgy RAM or both? It could be either. One possible cause of the symptoms you're seeing is that address line A04 on the bus is being held to one value (high or low) by something on the bus, so that whether the CPU tries to set it to 0 or 1, it has no effect. Also, of course, there could be some fault in the CPU, so that when it tries to do something with address 0, it gets 020 (or vice versa). And similarly for the memory. I'd try to write a small (two instruction) loop that sets that address line high/low (e.g.: 5037 CLR @#1020 1020 775 BR .-4 and look and see if that address bit is flickering on/off on the UA11 (it will be on, but dully; constant assertion is bright on, constant de-assertion is full off). If so, the problem is almost certainly in the memory; if not, it could be either. > 2) Setting D10 in location 000000 results in D10 set in all the > locations Sorry, didn't follow that? Did you mean that if you store 02000 in location 0, all other locations now report the 02000 bit set? Noel

9 years, 9 months

vt100 terminfo with padding for an actual vt100?

by fritzm＠fritzm.org

Hi all ? I?m trying to run a real-deal vt100 on a serial port connected to Linux (Xubunto 16.04). I?ve got this working *pretty* well, but it looks like the padding values in the default vt100 terminfo entry are not quite correct ? when running the vt100 at 9600 I still get occasional garbage characters on the screen, and 19200 is a hopeless mess. I did figure out that if the terminfo contains ?xon?, the non-mandatory padding values in the terminfo are disregarded. Removing this, then disabling xon/xoff on both the vt100 and the tty device actually produces *better* results ? apparently the turnaround on xon/xoff isn?t quite fast enough to keep the terminal from being swamped at higher baud rates, and padding actually works better. But tracking down the source for the default vt100 entry turned up a comment that admits that the padding values there are a total guess. :-( So, before I go diving too much further into the terminfo-tweaking-samp, I thought I?d ask if anybody has a good vt100 entry already on hand? (I?d take one for the VT52 as well!) thanks much, ?FritzM.

9 years, 9 months

11/04

by useddec＠gmail.com

Hi Ethan, If you are going to VCF and I go, I'll Try to throw a MS11-JP in the van for you. It's yours for bugging the guy with the H960s one more time. That should save you some chip chasing time. Thanks, Paul

9 years, 9 months

More mystery recycler boards - DEC, Fujitsu(??), Cipher, Emulex

by jnc＠mercury.lcs.mit.edu

> From: Jules Richardson > M8190-AE ; 11/83 CPU > M8190-AB ; 11/83 CPU (or /73??) w/FPU As far as I know, all the M8190's are _basically_ the same: they are the KDJ11-B CPU, which support the PMI memory bus, can operate with a KTJ11-B to provide a UNIBUS, etc. They are the CPU in an 11/83 (with QBUS only backplane) and the 11/84 (with QBUS/UNIBUS backplane). The various models of the M8190 vary in details (e.g. although all have a socket for the FPJ11 floating point accelerator chip, the earlier ones don't work properly with it), including the clock speed (15/18 MHz, etc). The 11/73 uses the KDJ11-A M8192, a completely differente card. Noel

9 years, 9 months

Y Combinator is restoring one of Alan Kay's Xerox Alto machines

by curiousmarc3＠gmail.com

Ken's in-depth blog post to go with the previous video http://www.righto.com/2016/07/restoring-y-combinators-xerox-alto-day_11.html > On Jul 5, 2016, at 2:46 PM, Curious Marc <curiousmarc3 at gmail.com> wrote: > > Video from yesterday?s work on the Diablo cartridge disc: > https://youtu.be/PR5LkQugBE0 > Should be up in a few minutes. > We were tickled pink to have official representation from PARC (former Xerox Parc) at the session. > Marc > > Ken?s new post on the monitor repair to go with my previous video. > http://www.righto.com/2016/07/restoring-y-combinators-xerox-alto-day.html > Al Kossow got us a new CRT tube, so we are probably going to try that this week-end. > Marc > > > Latest entry from Ken Shirriff, trying out BCPL (ancestor of C). On the emulator, not yet on the real machine: > http://www.righto.com/2016/06/hello-world-in-bcpl-language-on-xerox.html > > Marc > > There are only two entries right now: > http://www.righto.com/2016/06/y-combinators-xerox-alto-restoring.html > http://www.righto.com/2016/06/restoring-y-combinators-xerox-alto-day.html > Marc > >

9 years, 9 months

The huge lot that had the NIB 8" floppies is now on ebay

by jnc＠mercury.lcs.mit.edu

> From: Jason Howe > Some pretty interested stuff comes up on ebay occasionally which I > might not have seen otherswise. Exactamundo. > when folks just dump an ebay item number rather than a full link, those > posts should die Why? It's a tiny bit more work to use them (prepend the number with the string "http://www.ebay.com/itm/", and away you go), so one can't just click and go, but are people really that unwilling to go to the slightest effort? Noel

9 years, 9 months

Components available

by COURYHOUSE＠aol.com

In a message dated 9/6/2016 11:55:46 P.M. US Mountain Standard Time, pontus at Update.UU.SE writes: On Tue, Sep 06, 2016 at 06:16:23PM -0700, Al Kossow wrote: > > I walked out of the donations meeting with the other curators today > who thought it was a piece of s**t and didn't want to take it, calling > it a 'dumpster fire' > Wow, what an attitude.. I don't know much about Unicomps but should lesser know machines but unusual machines be preserved as well? /P Right on... All machines are part of the overall history, true, some more significant than others but... ALL have a place. Good thing about lists like this is someone can be found to adopt some of these systems. Ed#

9 years, 9 months

Why V.32bis modems are 14400 bps rather than 19200 bps (was Re: vt100 terminfo with padding for an actual vt100?)

by spacewar＠gmail.com

On Tue, Sep 6, 2016 at 5:18 PM, Eric Christopherson <echristopherson at gmail.com> wrote: > Is this why modems went to 14400 instead of 19200? No, that was because the V.32 modulation was easily extended to 12000 and 14400 bps by slightly expanding the QAM signal constellation, requiring a little better SNR on the line, but keeping other parameters the same and increasing the constellation size enough to get 19200 bps was not expected to work within available SNR on most POTS lines. That didn't stop some vendors from offering 19200 as a proprietary extension to V.32bis. It's known unofficially as V.32ter, but was never actually ratified as an ITU-T V-series recommendation. V.32 at 9600bps uses 1800Hz carrier, 2400 baud, and 32 carrier states (constellation points) using one trellis coding bit for 4 data bits, so effectively 4 data bits per baud, and 2400 * 4 = 9600 bps. V.32bis at 14400bps uses the same carrier and baud rate, and 128 carrier states (constellation points), with slightly more complex trellis coding, so effectively 6 data bits per baud, and 2400 * 6 = 14400 bps. (There's also a fallback to 12000 bps) V.32 and V.32bis are synchronous modulation, and when used with V.42 error control and a normal serial port configuration of 8N1, the modem effectively removes the start and stop bits (20% overhead on the serial port), though framing is added so that the throughput doesn't go up by that full amount. This is noticeable when running such a modem with a higher serial port baud rate (requiring flow control). For instance, a V.32 9600bps modem without V.42 would be able to transfer 960 characters per second, but with V.42 and a higher serial port rate with flow control, can exceed that. V.42bis compression can further improve the throughput provided that the data is compressible. To go beyond 14400 bps with conventional modulation and typical POTS line SNR requires more complex techniques, used in V.34 for up to 33600 bps. Abandoning conventional modulation and introducing a direct dependency on the PCM line code used within the PSTN allows up to 56000 bps PCM downstream and 33600 bps using V.34 modulation upstream (V.90), or 56000 bps PCM downstream and 48000 bps PCM upstream (V.92)

9 years, 9 months

Complete DisplayWriter on eBay

by cctalk＠ibm51xx.net

Well, looks like the seller cancelled the bids and suddenly item is no longer available. Would like to believe it is a mistake but we all know better... -Ali

9 years, 9 months

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