test-drb

test-drb@ccmp.vtda.org

101090 discussions

4 MB memory unibus/qbus card (was Qbus split I&D?)

by jnc＠mercury.lcs.mit.edu

> From: Mark Kahrs > there are very nice SRAMs available: for example, the Cypress CY62167 > is a 2Mx8 1Mx16 RAM in 48 pin TSOP. So you'd need two ... > (n.b. there is a 4Mx8 but it's only in BGA, so fuggitaboutit). Actually, one 4Mx8 (assuming it's really only 8 bits wide) wouldn't be as easy to work with as two 2Mx8; since most QBUS cycles are 16-bit word, not byte, you'd have to do two memory cycles for each QBUS cycle -> more complexity. Noel

11 years, 4 months

Old NTSC tricks: 240p?

by tsw-cc＠johana.com

A discussion about sync rates on a TV signal. Christian Corti <cc at informatik.uni-stuttgart.de> Wrote: > This has absolutely *nothing* to do with NTSC or PAL (or SECAM or > whatever). NTSC etc. are colour encoding standards and don't describe in > any way how a image signal is generated (fields, syncs, timing). They only > describe how to put colour information into the signal. > Christian Sorry, but this is UNTRUE.? There have been several NTSC standards. The first one defined the signals for standard Black/White TV, it dates from the 1940s.? It defined such things as horizontal sync, vertical sync, field definitions,? and equalizing pulses (among other things).? This version used a horizontal sync rate of 15750Hz, and a vertical sync of 60Hz (field rate).? The later NTSC standard (from the 1950's) added the color definitions (color burst, re-definition of horizontal sync, color phase signals, color sub-carrier, etc.).? This version reduced the sync rates by 0.1%, yielding a horizontal rate of 15734Hz, and a vertical rate of 59.94Hz.? This was needed to make things proper multiples of the color burst rate.? A later definition added stereo audio (related to horizontal sync). If you know things about the signal, you know that there are 4 field types in NTSC color that differ with phase start of color burst, and odd/even field.? I believe that PAL has 8, but I'm not exactly sure. Yes, PAL and SECAM are color definitions.? They are encoded over various underlying TV sync systems.? One can make a SECAM receiver work a PAL signal. Many of the broadcast standards have been dictated by governments.? I believe that the 625/50 standard is "CCIR"? What devices generate is anybodys guess.? What TV sets accept is a crap shoot if it isn't "standard".

11 years, 4 months

Amiga 30th anniversary event kickstarter in July at CHM

by jfoust＠threedee.com

<https://www.kickstarter.com/projects/890300835/amiga-30th-anniversary-in-ca…>https://www.kickstarter.com/projects/890300835/amiga-30th-anniversary-in-ca… - John

11 years, 4 months

PDP-8/E EAE Troubleshooting

by kylevowen＠gmail.com

I've recently been in the midst of repairing an EAE set for the Omnibus. I finally got it working tonight. Surprisingly, unless I was simply reading it wrong, it appears as though the M8340 etch rev. D is in fact compatible with M8341 etch rev. D, despite what the DEC ECO Log suggests. Now, on the other hand, the M8340 does have some ECO changes, but some of these are not cited in the log, perhaps indicating that it was brought up to an equivalent revision E or F, but there are still some big differences particularly involving the inputs to the instruction register. Anyways, here's an album: http://imgur.com/a/QVRLs The TL;DR of it all is I replaced one bad IC. I also ended up making a board that replaces the hard-to-find Signetics N8235 with easy-to-find 7400-series components. A big thanks to all those involved (you know who you are!) in helping get this set functional again, just in time for VCF East and Southeast! Kyle

11 years, 4 months

4 MB memory unibus/qbus card (was Qbus split I&D?)

by mark.kahrs＠gmail.com

This is a classic case of "Great minds run in the same ruts" (sometimes rephrased as gutters...) I've almost designed a 4 MB card twice now. Because I'm a cheapskate, I didn't want to use FRAM. And there are very nice SRAMs available: for example, the Cypress CY62167 is a 2Mx8 1Mx16 RAM in 48 pin TSOP. So you'd need two, that's ~$30 total. (n.b. there is a 4Mx8 but it's only in BGA, so fuggitaboutit). So, you'd only need the bus interface (no, I'm not going there) and the control logic. These SRAM parts are so speedy (45 ns) that cache isn't needed (obviously). Maybe I'll almost design it for the third time!

11 years, 4 months

IBM 5100 Restoration in progress

by marc.verdiell＠gmail.com

>Christian Corti <cc at informatik.uni-stuttgart.de> wrote: >Ehm, you did have a look at our web site, don't you? >http://computermuseum.informatik.uni-stuttgart.de/dev_en/ibm_5110/technik/e n/5110.html Wow, nice! Highly informative site.

11 years, 4 months

VCFMW 10 Hotel Rooms

by barythrin＠gmail.com

Jay.. think of the children! ..and wives...and other non octal folk and how long it will take to explain the shirt! ;-) <div>-------- Original message --------</div><div>From: Jay West <jwest at classiccmp.org> </div><div>Date:03/17/2015 1:33 PM (GMT-06:00) </div><div>To: "'General Discussion: On-Topic and Off-Topic Posts'" <cctalk at classiccmp.org> </div><div>Subject: RE: VCFMW 10 Hotel Rooms </div><div> </div> ...Defcon alread did the hexidecimal thing with their 10th being "0A." 012 because Octal is where it's at ;)

11 years, 4 months

Old NTSC tricks: 240p?

by kspt.tor＠gmail.com

On 18 March 2015 at 19:18, tony duell <ard at p850ug1.demon.co.uk> wrote: > Not part of the _video_ signal, but part of the overall signal : IIRC continental Europe (mostly?) put the sound > carrier 5.5 MHz way from the video carrier, but the UK had a 6MHz offset. > > -tony SECAM comes in two variants, one with a 5.5MHz sound carrier offset and another with a 6.5MHz offset. The Russians apparently use a variant of the latter - many years ago I visited a family living close to the Russian border and they used to tune in to Russian TV on their black&white TV. But they had a hard time getting picture and sound at the same time, IIRC it was either one or the other. They would tune to sound or video depending on what was on - there are some great classical music programmes so presumably that's when they tuned to sound only. As for NTSC - 'never twice same color' - that sounds cumbersome, what we learned in (TV repair!) school was 'Never The Same Colour' :-) (PAL means Phase Alternating Line, except for the lines/frequency differences it is really just NTSC but with the phase of the colour subcarrier alternating every other line. Thus automatically cancelling out transmission phase errors which would otherwise change the colour. That's all really: NTSC with automatic colour phase error cancellation.) -Tor

11 years, 4 months

BASIC Week 4 starts on Saturday

by fozztexx＠fozztexx.com

BASIC Week 4 starts on RetroBattlestations on Saturday, March 21st. The program this time around is a Space War inspired turn based game with simple graphics, so it doesn't need a fast computer. This will be the 4th BASIC Week we've done on RetroBattlestations, the previous two used ASCII graphics, and the first one used simple vector graphics. The challenge is about getting out old computers and doing something with them, in the spirit of the old type-in magazine listings. Usually there a lot of ports to various platforms, although the past programs have been a lot smaller. This will be the largest one yet and might be almost too big to actually type in. While the contest is more about having fun with your old computers, there are prizes. At the end of the week I randomly select five winners and send them their choice of two retro themed vinyl stickers: http://imgur.com/a/iAS5T So far the only versions of the program are for an Apple II and the original HP 3000 which used terminal graphics. If anyone would like to contribute a another port, that would be awesome! The program is on github, you can find the link here: http://redd.it/2yi2d2 -- Follow me on twitter: @FozzTexx Check out my blog: http://insentricity.com

11 years, 4 months

Recovering Leading Edge Word Processor (LEWP) docs?

by tony.aiuto＠gmail.com

I recovered a bunch of old floppies for a friend of mine. Her documents are >from the 1980s, but all in LEWP format. Alas, I could not recover the disk with the binary on it. :-(. I am hoping someone has a copy of the binary or a pointer to the file format so I can write my own converter. I can't find either

11 years, 4 months

Jump to page:

2026

2025

2024

2023

2022

2021

2020

2019

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

2000

1999

1998

1997

test-drb