- vcf-midatlantic - lists.vcfed.org

Altair bootloader
by Mike Loewen 25 Mar '17

25 Mar '17

Our Josh Bensadon received a mention on Hackaday for his 14-byte bootloader for the Altair 8800: https://just8bits.blogspot.co.uk/2017/03/doing-it-in-less-than-bill-gates.h… Mike Loewen mloewen(a)cpumagic.scol.pa.us Old Technology http://q7.neurotica.com/Oldtech/

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Online hangout for Enigma fans?
by Evan Koblentz 25 Mar '17

25 Mar '17

I want to let the Enigma community know about Tom P.'s talk+class at VCF East. Where do Enigma people congregate online? ________________________________ Evan Koblentz, director Vintage Computer Federation a 501(c)(3) educational non-profit evan(a)vcfed.org (646) 546-9999 www.vcfed.org facebook.com/vcfederation twitter.com/vcfederation instagram.com/vcfederation

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Looking for Tarbell DD controller
by Richard Cini 25 Mar '17

25 Mar '17

All – I still can’t get my Cromemco 16FDC to work properly with the hacked-together Gazelle I have – the individual parts seem to work but not the whole. By chance, does someone have a spare/extra Tarbell DD controller that they would part with? Or I’d even maybe I could send my 16FDC to someone with a working Cromemco system who can test it for me. It would also be helpful if I could get a picture of the floppy controller and CPU Support cards in the Gazelle that VCFMA has in-stock. I pinged Jim privately but I haven’t heard back. Please let me know off-list if you can help. Thanks! Rich -- Rich Cini http://www.classiccmp.org/cini http://www.classiccmp.org/altair32 All –

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"PC Radio Show" interview link
by Evan Koblentz 24 Mar '17

24 Mar '17

Here's the podcast link for my recent interview on the WBAI "PC Radio Show": http://pcradioshow2.org/2017/pcrs_2017_march22_128kbps.mp3 I'm on from about 5:30-16:30 in the program. Special thanks to friend-of-VCFed Hank Kee for making it happen. Then next Wednesday evening I'll be on 2600's "Off the Hook" show on the same station, with VCFed friends Bernie S., Emmanuel Goldstein, and Kyle Drosdick.

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Sat. night VCF East dinner
by Evan Koblentz 24 Mar '17

24 Mar '17

Everyone, Tickets for the Saturday night VCF East dinner will be $33 (plus cash bar). Just so you all know, we are not making any money on that. The ticket price is exactly our cost. Last year we charged less and lost money. Dinner will be at the same place as last year: Clancy's Tavern, 25 South Main St., Neptune City, NJ 07753. Same menu too, including the (mmmm) VCFed logo ice cream cake. We will sell tickets at the show. First we'll go to exhibitors, vendors, speakers, etc., and then to everyone else. Cash, PayPal, credit cards are all accepted. ________________________________ Evan Koblentz, director Vintage Computer Federation a 501(c)3 educational non-profit evan(a)vcfed.org (646) 546-9999 www.vcfed.org facebook.com/vcfederation twitter.com/vcfederation instagram.com/vcfederation

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MARCHIAN invasion of Trenton
by Herb Johnson 24 Mar '17

24 Mar '17

I attended the TCF and saw talks by Frank OBrien (Apollo Guidance Computer), Neil Cherry (Home Automation / Internet of Things) and Evan and Jeff's robotics presentation. The TCF "flea market" was flea-sized to be sure. But good people brought vintage computing things, proportionally it was a large piece of a small pie. One of my friend bought an SGI Octane 2 (newer model) , a SGI Indigo 2 High Impact and a BeBox ($1000) were also offered. Ther were even a few 360K floppy drives and diskettes for sale. I bought, from another vendor of many things vintage, another TI 99/4A, with transformer and TV interface, to test the TI I bought not long ago - both worked by the way. A book vendor had many vintage computing books, some VERY vintage (my era); from his father's collection so he said. Neil's talk was most informative, despite his protests as posted here. The key concept from it, in my opinion, was "MQTT", which is a message-based protocol between sensors and controllers - "publishers and subscribers" in the lexicon. The widespread adoption of a messaging protocol is a signifigant step - akin to TCP/IP for networking, my impression. The rest of the talk was about things talking with things to do things. Neil, practice this phrase: "details of implementation or scope are beyond the limited time I have available today. Contact me afterwards and I can give you references. Thank you." Evan is correct, in his reportage that I said his and Jeff's robotics talk was more technically informative, than my discussion with a student and faculty-member of their $40K demonstration robot. I could not get those persons, to describe the programming interface to their tower of plastic and motors. Evan showed a BASIC program with peeks and pokes. The 20th century won that "battle of the 'bots". Am I a judge? I worked on robotic system interfaces to minicomputers in 1975. Frank always gives an entertaining talk, and he's a published expert on the Apollo Guidance Computer. He claims the DSKY human interface designed in the early 1960's, presaged personal and embedded-computer human interfaces to come. It may be fun to confirm that claim, the interface has a design history. But "success has many parents..." I have photos, to answer another post, which I'll put on a Web page in due course; a link will be posted here. I'll point to other photoed sites or sources, if their publishers give me Web links and permission for use of selected photos. Those who are photographed should contact me and name themselves. Herb Johnson retrotechnology.com -- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net

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Re: What limited the C64's CPU to ~ 1 MHz? , Vol 17, Issue 23
by SVCatITC＠aol.com 24 Mar '17

24 Mar '17

Hi Dan, John; Newbe here....... Thanks for the enlightenment on legacy high speed chip design. Boy does this bring back memories! Back in the early 80's, had a similar problem designing a quiet 5mHz main clock, with dividers, to run test fixture registers, on component hardware from production runs. (Working in the test fixture / model shop.) In a macro sense, like your 'micro' illustration, I had harmonic splash all over the fixture and DUT circuits..... Way too noisy for testing the low level analog circuits on the hybrid DUT PC board. I finally ended up taking the main clock components off the main breadboard (oscillator and the like), and enclosing them in a total metal capacitor enclosure (forget the alloy) with ceramic feedthroughs for power and clock out. With the total metal shield around the 'heartbeat'..... quieted everything down. We all, in the normal thoughts in our brains, think only digital when we are in front of such devices, however, when you are designing main 'heartbeats' in these things, you have to think 'analog' and design around the analog component of the rudimentary signals before moving on to 'clocking' signals and gate chasing around the PC board. In devices that have an analog component (Data Acquisition), have seen guard circuit PC traces totally circling around the 'heartbeat' circuits, for shielding. So like the 12 items you identified in rudimentary CPU design, when you are at that level, one must think basic analog and physics for high speed design and compensate for all the parasitic effects. As you noted, they all had trade-offs. It comes down to best bang for the buck! Thank you so much for the refresher course! Bill Inderrieden ----------- Original Message ------------- Message: 15 Date: Thu, 23 Mar 2017 11:01:04 -0400 From: Dan Roganti <ragooman(a)gmail.com> To: vcf-midatlantic <vcf-midatlantic(a)lists.vintagecomputerfederation.org> Subject: Re: [vcf-midatlantic] What limited the C64's CPU to ~ 1 MHz? Message-ID: <CADo=F9Eai8W_OvDosnWSm1vq9tbF+yQHKcB179t5cEBg05HzLA(a)mail.gmail.com> Content-Type: text/plain; charset=UTF-8 On Thu, Mar 23, 2017 at 8:47 AM, John Heritage via vcf-midatlantic < vcf-midatlantic(a)lists.vintagecomputerfederation.org> wrote: >> Does anyone know the reason why the C64 only ran at ~1 MHz? Was it to >> keep RAM costs or system cost as low as possible or was there a different >> engineering reason? >> >> (The Atari and BBC machines managed higher clocks, but were very expensive >> compared to the C= devices, although the 1977 Atari 2600 managed ~1.19 MHz >> out of it's 6507 (6502 with low pin count/less addressing).. > The various clock circuits inside the different home computers was the > least of their problems. All of those different combinations used between > the various home computers were just methods they found to minimize their > Bill of Materials - because every penny was crucial to their bottom line > when making thousands of them in the consumer market. > There were still real and significant design challenges present in the > early VLSI designs of the 1970s to make these faster. But they slowly > marched on and made improvements every year to where we had the 8086 > running at 5mhz and 68000 running at 8mhz already by 1979. This list below > is just some of design problems and they are all interrelated. Making trade > offs between each of these was a constant battle. This list is mostly > ordered by significance, but some of this could be a matter of opinion. > 1. BJT, NMOS, PMOS, or CMOS logic families contribute to speed, > eg. depletion-load NMOS is faster than BJT > 2. Miller Effect [capacitance] prsent even on the silicon die > 3. VLSI design geometries were limited to about 5um > 4. Clock distribution across the silicon die [eg, too much clock skew] > 5. Higher Clock speed required more power dissipation > 6. Negative Bias voltage was a burden to compensate for Miller Effect > [eg. 8080 ] > 7. Lead Inductance present even on the silicon die > 8. Slew Rate, > eg, ECL being faster ran on smaller voltages, slew rate was less, > giving faster clock speed > 9. TTL signals are above the noise floor > eg, ECL being faster was below noise floor, ie power is negative voltage > 10. TTL operate in saturation for logic signals, [eg. ECL being faster > operate in Linear region] > 11. Square wave logic signals have more odd numbered harmonics > than a linear analog device, reducing the possible bandwidth > 12. Pin Capacitance limited not only the driver characteristics but also > the frequency bandwidth

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The Atlantic : How Aristotle Created the Computer
by Herb Johnson 23 Mar '17

23 Mar '17

The cited article is a surprisingly through and generally correct presentation of the formal history of logic, computation and computing theory. This article, is how academics and historians look at "computing", and doesn't really have much new from my glance. It's a good tutorial, I think. I'm not sure why The Atlantic published it in the recent issue, what event or circumstance prompted it - I read very quickly to scope out the article. The author apparently is an "angel investor" and former/current? computing financial whiz. Of course, the title argument is merely a draw to read the article, "success has many parents". Herb -- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT retrotechnology DOT info

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Museum updates
by Evan Koblentz 23 Mar '17

23 Mar '17

Tony brought some of his employees to the museum today to replace our center door with a regular section of wall. They'll continue working on it tomorrow and finish Monday. Not having the unnecessary door there means they're won't be an ugly brown blob behind George, and also that we'll have more room for a timeline exhibit in the hallway (probably this summer). Adam and I are going to be at the museum all weekend to finish other projects in time for VCF East. Getting the tablets all done, completing the modern history exhibit, and a ton of minor things nobody will notice but will collectively be an improvement. Jeff B. and others are also expected.

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What limited the C64's CPU to ~ 1 MHz?
by John Heritage 23 Mar '17

23 Mar '17

Does anyone know the reason why the C64 only ran at ~1 MHz? Was it to keep RAM costs or system cost as low as possible or was there a different engineering reason? (The Atari and BBC machines managed higher clocks, but were very expensive compared to the C= devices, although the 1977 Atari 2600 managed ~1.19 MHz out of it's 6507 (6502 with low pin count/less addressing)..

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