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--- In , "Nigel Johnson" <nw.johnson@i...> wrote: > Stephen, > > Nowadays that is even easier with suprcaps. > > In the pdp-11, a little 6v transformer's output could be used to get the > power-fail information after 1 missing cycle. If transformers are too bulky, a two resistors divider from Live to Neutral will give half mains at the mid point regardless of polarity, a diode and a few more resistors to ground from the midpoint will give a divider that brings it into measurent range. You can use a few caps to galvanically isolate and/or smooth if desired, a bit of smoothing will also keep multi kV mains spikes out of the electronics. (I personally don't like using caps as series impedance, they short too easily). In the past I have used three resistor dividers to ground for safety reasons, (Use a zenner at the mains sections exit point if you wish to limit the output voltage under fault conditions as well as the current). The multi stage divider chain also allows you a shot at the CE marking were you must show that a single component failure remains safe. The dividers should limit the current to ground to below 50uA or so, for safety as well as to stop tripping earth leakage detectors. Of course this will only work if the CPU ground has an earth return. Such circuits can also be useful where you need higher voltages at very low currents for other reasons. Regards, Theo |
flash data storing & realibility
Started by ●April 23, 2004
Reply by ●April 27, 20042004-04-27
Reply by ●April 27, 20042004-04-27
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--- In , "Jordi Costa" <bvjordi@b...> wrote: > Nigel: I remember the old times and the PDP-11, the punched tapes, entering > the start-up code by switches, ... Hi Jordi PDP-11? Young wippersnappers:-) I saw a PDP-1 commissioned, mumble, mumble, must be over thirty years ago. (wasn't involved). I think it had 4k of core, huge it was, of course also fully equipped with punched tape readers etc. After a year or so the teletype was mainly busy printing error codes, just about all of the microswitches that functioned as detectors had failed by then due to the harsh environment. (bit of (lot) sulferic in the air) I scored a small manual, should still be in my library somewhere. Cheers, Theo |
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Reply by ●April 27, 20042004-04-27
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Theo The PDP-1 is not quite dead yet... See: http://www.pdp-1.org/ http://lcs.www.media.mit.edu/groups/el/projects/spacewar/ Steve Russell Nohau At 02:47 PM 4/27/2004, Theo wrote: >--- In , "Jordi Costa" <bvjordi@b...> wrote: > > > Nigel: I remember the old times and the PDP-11, the punched tapes, entering > > the start-up code by switches, ... > >Hi Jordi > >PDP-11? Young wippersnappers:-) I saw a PDP-1 commissioned, mumble, >mumble, must be over thirty years ago. (wasn't involved). >I think it had 4k of core, huge it was, of course also fully equipped with >punched tape readers etc. > >After a year or so the teletype was mainly busy printing error codes, just >about all of the microswitches that functioned as detectors had failed by >then due to the harsh environment. (bit of (lot) sulferic in the air) > >I scored a small manual, should still be in my library somewhere. > >Cheers, > >Theo ************************************************************************* Steve Russell mailto: Senior Software Design Engineer http://www.nohau.com Nohau Corporation phone: (408)866-1820 ext. 1873 51 East Campbell Avenue fax: (408)378-7869 Campbell, CA 95008 ************************************************************************* |
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Reply by ●April 28, 20042004-04-28
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--- In , Steve Russell <stever@n...> wrote: > Theo > > The PDP-1 is not quite dead yet... > > See: > http://www.pdp-1.org/ > http://lcs.www.media.mit.edu/groups/el/projects/spacewar/ Well, well, as I said I wasn't involved with the PDP-1, being a humble electronics engineer and not one of these lofty programmers. I had a broowse on the site and yes, that's it alright, there is a fair amount of nostalgia in computing what? We got involved when Motorola brought out the D2, cut our teeth on that and moved on to Flex, to my utter amazement there is today a flex group building, redesigning and collecting these bits of hardware, more active then this group, the mind boggles. Can't lay my hands on the newsgroup right now (is somewhere hidden in my regular subscriptions) but here is an entry point for those interested. http://www.evenson-consulting.com/swtpc/Downloads.htm The interesting bit is that most of the 6800 software is now public domain and probably will still happely run on the HC12. Good collection of all sorts of basics, compilers, cross assemblers etc, when I have a bit less to do it is going to be investigated:-) The 6809 stuff is ported or being ported to some other chips, unfortunately of course not compatible with HC12. Cheers, Theo |
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Reply by ●April 28, 20042004-04-28
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--- In , "theobee00" <yahoodump2@o...> wrote: > --- In , Steve Russell <stever@n...> wrote: > > Theo > > > > The PDP-1 is not quite dead yet... > > > > See: > > http://www.pdp-1.org/ > > http://lcs.www.media.mit.edu/groups/el/projects/spacewar/ > > Well, well, as I said I wasn't involved with the PDP-1, being a humble electronics engineer and not one of these lofty programmers. > > I had a broowse on the site and yes, that's it alright, there is a fair amount of nostalgia in computing what? > > We got involved when Motorola brought out the D2, D2! Bloody luxury! I started with the D1 and had to manually convert an old model 35 teletype, stinking of lube old and getting shocks from the 130VDC power supply! |
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Reply by ●April 28, 20042004-04-28
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--- In , "Nigel Johnson" <nw.johnson@i...> wrote: > D2! Bloody luxury! I started with the D1 and had to manually > convert an old model 35 teletype, stinking of lube old and getting > shocks from the 130VDC power supply! Outdone again, I don't think I have ever seen a D1, what did that consist of? But at least we had 240V to keep us awake... Cheers, Theo |
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Reply by ●April 28, 20042004-04-28
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The D1 came as a blank pcb in the pocket of a binder and a bag of parts. It used a multivibrator to generate the baud clock and the monitor bit-boffered through a parallel port. It had three memory chips, 6810 I believe, of 128 bytes each. They used the bit-boffing approach so you could attach something to the ACIA and evaluate it. You had to set up the baud rate clock for the debugger (MIKBUG I think?) by adjusting a pot. The TTY interface was current loop with H11A1 opto isolators. The clock rate was 618.4 kHz to give nice baud rates for the ACIA. The K1100A clock generator was larger than some complete micro eval boards today! And when you tell these young kids how hard we had it, they don't believe you! Nigel Johnson MCSE, MIEEE VE3ID/G4AJQ > -----Original Message----- > From: theobee00 [mailto:] > Sent: Wednesday, April 28, 2004 4:17 PM > To: > Subject: ***[Possible UCE]*** Far off Topic Re: [68HC12] Re: > flash data storing & realibility > --- In , "Nigel Johnson" > <nw.johnson@i...> wrote: > > > D2! Bloody luxury! I started with the D1 and had to manually > > convert an old model 35 teletype, stinking of lube old and getting > > shocks from the 130VDC power supply! > > Outdone again, I don't think I have ever seen a D1, what did > that consist of? > > But at least we had 240V to keep us awake... > > Cheers, > > Theo > > ------------------------ Yahoo! Groups Sponsor > ---------------------~--> Buy Ink Cartridges or Refill Kits > for your HP, Epson, Canon or Lexmark Printer at MyInks.com. > Free s/h on orders $50 or more to the US & Canada. http://www.c1tracking.com/l.asp?cidU11 http://us.click.yahoo.com/mOAaAA/3exGAA/qnsNAA/dN_tlB/TM ---------------------------------~-> --------------------To learn more about Motorola Microcontrollers, please visit http://www.motorola.com/mcu o learn more about Motorola Microcontrollers, please visit http://www.motorola.com/mcu Yahoo! Groups Links |
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Reply by ●April 28, 20042004-04-28
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At 07:31 AM 4/28/04, you wrote: D2! Bloody luxury! I started with the D1 and had to manually >convert an old model 35 teletype, stinking of lube old and getting >shocks from the 130VDC power supply! Right. I had to pound the rocks into sand to make the silicon to make the ICs to make my first computer. Then I had to stay awake for three months straight to program it to add two numbers. And I had to pay them $100 a month for the privilege of working there. But you try and tell kids today that, and they won't believe you. Gary Olmstead Toucan Technology Ventura CA |
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Reply by ●April 28, 20042004-04-28
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--- In , "Nigel Johnson" <nw.johnson@i...> wrote: > The D1 came as a blank pcb in the pocket of a binder and a bag of parts. Yes, so was the D2, lots of bits with a hex keypad and 7seg display. > bit-boffered through a parallel port. It had three memory chips, > 6810 I believe, of 128 bytes each. Yes, that sounds about right, at least I remember having to save up to get another one to put in the expansion socket. Of course programs were written in hex by hand, we didn't have funky things like assemblers or teletypes. Look up instruction, figure out wat it does, write down hex value, calculate branch distance by hand, type in values. It did get expanded bit by bit untill we had a old television showing characters, albeit somewhat wobbly. The first keyboard in use was a homebuild hex keypad, can't remember what my friend said he used for the dome, some sort of stainless steel rice bowl I think, his hand fitted over that and the keys were positioned around the dome. He could type with that and convert Characters to Hex on the fly, seeing that in action at speed confounded the lot of us. > clock rate was 618.4 kHz to give nice baud rates for the ACIA. The > K1100A clock generator was larger than some complete micro eval boards > today! Yes, at the time Motorola was rather proud of their clock generators, small they were not. > And when you tell these young kids how hard we had it, they don't > believe you! Old story, when you start out with "In my day" they lose interest. Son No1 want a quick half a gig expansion memory, he reckons he needs it for his homework probably so he can type faster, I might let him get away with it... Cheers, Theo |
Reply by ●April 28, 20042004-04-28
