test-drb

test-drb@ccmp.vtda.org

101090 discussions

by snhirsch＠gmail.com

I need to clear some room and would like to give away this system to anyone who wants to drive to Burlington, VT and pick it up: - VT-180 main unit in reasonably clean condition (has DEC logo dust cover and has been covered while in storage. - Keyboard also with DEC logo cover in pristine physical condition - (2) Dual 5.25" external floppy drives - Large box full of system masters, application software and all docs. - All cables for connection of drives to system unit. Caveat: I was given this unit about 8 years ago as what was claimed to be a working system and have never powered it up. Nor am I planning to now. If not claimed by the end of the year, it's going (with a heavy heart) to the local electronics recycler. Steve --

16 years, 5 months

Disc analyser status update -- it works!

by classiccmp＠philpem.me.uk

Quick status update before I go to bed... The analyser is now reading discs. All the buffer data seems valid, and the nifty "so simple I can't believe I didn't think of it first" counter-rollover algorithm proposed by Peter Coghlan seems to work really nicely too. I've dumped track zero from a DOS 1.4MB floppy and (after a quick bit of histogram analysis) it looks like valid MFM data. I'm seeing a big spike at ~2us, a second, smaller, spike at ~3us, and a third, even smaller spike at ~4us. The last spike is only just noticeable on a linear graph scale -- probably due to the large number of 2us "hits" (39,000 in a 90,000 sample acquisition). On a log scale it's a lot more visible. I haven't tried decoding the data yet, but that's next on the list. Writing isn't implemented yet (I need to do a partial-rewrite and redesign of the disc writer state machine) but I'm quite happy with how this has turned out thus far. I'd post screenshots, but console apps don't tend to make very interesting screenshots... (I'd also cross-post this to VCforum, but I'm too tired to remember my password) Cheers, -- Phil. classiccmp at philpem.me.uk http://www.philpem.me.uk/

16 years, 5 months

Disc analyser status update -- it works!

by philpem＠philpem.me.uk

16 years, 5 months

6502 trivia (was Re: Non-fake Apple 1 on ebay)

by ethan.dicks＠gmail.com

On 11/20/09, Brian Lanning <brianlanning at gmail.com> wrote: > On Fri, Nov 20, 2009 at 10:16 AM, Al Kossow <aek at bitsavers.org> wrote: > >> Chuck Peddle told me a couple of months ago that the 6502 was never >> intended to be a general-purpose microprocessor, it was designed to >> be a replacement for hard-wired logic. Well it certainly exceeded those expectations! >> They had a die size target to hit to get to the price point they wanted >> and pulled out things they thought were unnecessary for its use in that >> market. Interesting way to build it - start with a processor... discard things until it fits in a few mm^2... profit! >> In particular, the length of the registers. I had always wondered why they >> built a microprocessor with an 8 bit stack pointer, when the previous 6800 >> design had 16. The first two processors I worked with were the 1802 and the 6502. I do remember the wee stack size was occasionally a problem. It would have been nice to have been able to at least put it somewhere other than $0100, but they probably didn't have enough room for spare transistors to even do that. As a little-brother to the 6800, it still does a pretty good job. I remember wishing for 16-bit registers, but in effect, zero-page is a wad of slow 16-bit registers. > lol Who needs multiply and divide operations anyway? When I used to write commercial games, we used to go to great lengths to calculate screen addresses, etc., with tables and hard-coded multiple routines (times3, times9, done with shifts and adds) since brute-force multiple wasn't an option. > Great info, I never knew that. Interesting to hear the history on it. -ethan

16 years, 5 months

Cromemco Z-2 and IMSAI 8080 at Purdue

by cclist＠sydex.com

Someone over at VCF is worried that these will hit the dumpster. I think that's unlikely, but it might be worth looking into. http://vintage-computer.com/vcforum/showthread.php?p=120672 --Chuck

16 years, 5 months

IC DEC8881

by hachti＠hachti.de

Hi folks, I don't know if it's a fact of certain interest... I found a DEC M841 Omnibus printer interface with a Fairchild "F 7429DC" additionally stamped "DEC8881". As I think the DEC8881 is considered one of the harder to find chips, this could be interesting. I know that many of the DECxxx ICs are pin compatible to standard 74 TTL or Signetics 82 TTL devices so this could be found out by reading the TI data book as well. But I've heard of signal quality, speed and other selection issues making those a DECxxx IC. Perhaps that's a legend? Or at least partially? Best wishes, Philipp :-) p.S.: Here's a picture: http://pdp8.hachti.de?gallery/misc

16 years, 5 months

Indianapolis

by rogpugh＠mac.com

Hi to all across the pond. Are there any places/stores of interest to our hobby in Indianapolis, or is it a bit of a black hole? I am on a business trip there next week from the UK anything worth seeing?? Roger

16 years, 5 months

Unknown IBM S/360s

by wdonzelli＠gmail.com

A old issue of Datamation (Nov 1977, I think - its out in the van right now) had a very short blurb about some upcoming S/360s I have never heard about - models 58 and 7. The 7 intrigues me, being described as a machine smaller than the model 20, which would make it fit somewhere in the minicomputer realm. I doubt these machines ever saw the light of day - likely never even left the back of the napkin at the diner in Poughkeepsie. -- Will

16 years, 5 months

286 to 386 processor upgrades (and the amiga bridgeboard)

by brianlanning＠gmail.com

I just bought a 286 bridge board for the amiga. Much fun awaits... Does anyone know of a stash of 286 to 386 processor upgrades anywhere? I seem to remember a few companies marketing these. Also, iirc, there's a daughter card on the bridge board that covers the 286 socket. Any idea what I can use to widen the gap between the daughter (sandwich) card and the bridge board so that the processor upgrade would fit? Some short ribbon cables might be all it takes. I have an ide caching controller, scsi controller, sound blaster board, and network board ready to plug in. Still need a vga board. I have a 5.25" floppy floating around somewhere, but i'd like to find one of those 5.25" and 3.5" floppy combo drives. Imagine the possibilities :-) What I'd really like to find is one of those isa bus extenders that plug into a passive back plane in another case. With the external scsi tower, that would go a long way toward turning my 2000 into amigazilla. :-) brian

16 years, 5 months

VC-F. (Was Re: Cromemco Z-2 and IMSAI 8080 at Purdue)

by roger.holmes＠microspot.co.uk

> Message: 3 > Date: Thu, 19 Nov 2009 23:19:34 -0500 > From: Bryan Pope <bryan.pope at comcast.net> > Subject: Re: Cromemco Z-2 and IMSAI 8080 at Purdue >> >> >>> Can we just call Erik's web board the VC Forum? >>> >>> >> <smartass> >> >> But then you'll annoy venture capitalists -grin- >> >> </smartass> >> > Tag dutifully taken! :p > > I was hoping the crowd here would automatically know that "VC" mean > "Vintage Computer" and not venture capitalists or umm..., anything > else. Outside of here, VC would of course be fair game. Irrespective of their interests, I think if you mention VC to anyone in the British Commonwealth you'll find they automatically think the abbreviation means Victoria Cross, the highest award for military gallantry. So high that most are awarded posthumously,. Someone with VC after their name gets a lot of respect here. Roger Holmes.

16 years, 5 months

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