core memory
in [Design]
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From: John Larkin on 5 Dec 2009 13:51 Testing some FTP stuff, threw up some test files... ftp://jjlarkin.lmi.net/Core_304bits.jpg ftp://jjlarkin.lmi.net/Core_4K.jpg ftp://jjlarkin.lmi.net/Core_4Kdetail.jpg John
From: Jan Panteltje on 5 Dec 2009 14:03 On a sunny day (Sat, 05 Dec 2009 10:51:36 -0800) it happened John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in <kqalh59i8jsogn1t6p3ghuaop5c137qtoj(a)4ax.com>: >Testing some FTP stuff, threw up some test files... > >ftp://jjlarkin.lmi.net/Core_304bits.jpg 16 bits x 19?? >ftp://jjlarkin.lmi.net/Core_4K.jpg Amazing.. >ftp://jjlarkin.lmi.net/Core_4Kdetail.jpg Must have been expensive. >John > > >
From: ChrisQ on 5 Dec 2009 14:18 Jan Panteltje wrote: > On a sunny day (Sat, 05 Dec 2009 10:51:36 -0800) it happened John Larkin > <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in > <kqalh59i8jsogn1t6p3ghuaop5c137qtoj(a)4ax.com>: > >> Testing some FTP stuff, threw up some test files... >> >> ftp://jjlarkin.lmi.net/Core_304bits.jpg > > 16 bits x 19?? > > >> ftp://jjlarkin.lmi.net/Core_4K.jpg > > Amazing.. > > >> ftp://jjlarkin.lmi.net/Core_4Kdetail.jpg > > Must have been expensive. > > >> John >> >> >> Don't recognise either of those as to manufacturer, but the last machine that I had with core was an early pdp11/05, which eventually got shipped back to the us. Ok, quiz time: how does core memory work ?. (and no cheating via google etc :-)... Regards, Chris
From: Jan Panteltje on 5 Dec 2009 14:50 On a sunny day (Sat, 05 Dec 2009 19:18:45 +0000) it happened ChrisQ <meru(a)devnull.com> wrote in <qmySm.123940$yM2.60574(a)newsfe10.ams2>: >Jan Panteltje wrote: >> On a sunny day (Sat, 05 Dec 2009 10:51:36 -0800) it happened John Larkin >> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in >> <kqalh59i8jsogn1t6p3ghuaop5c137qtoj(a)4ax.com>: >> >>> Testing some FTP stuff, threw up some test files... >>> >>> ftp://jjlarkin.lmi.net/Core_304bits.jpg >> >> 16 bits x 19?? >> >> >>> ftp://jjlarkin.lmi.net/Core_4K.jpg >> >> Amazing.. >> >> >>> ftp://jjlarkin.lmi.net/Core_4Kdetail.jpg >> >> Must have been expensive. >> >> >>> John >>> >>> >>> > >Don't recognise either of those as to manufacturer, but the last machine >that I had with core was an early pdp11/05, which eventually got shipped >back to the us. > >Ok, quiz time: how does core memory work ?. (and no cheating via google >etc :-)... OK, without cheating, I have never used core memory so... XY wires, magnetize one core at X,Y. There is also a read wire, mabe use a lower power to address the one you want to read, and then the read wire will give a signal depending on the magnetisation of that specific core.. Or maybe use full power to address, and then write back a 1 if it was a 1, and a 0 if it was a 0, so opposite magenetisation for 0 and 1. Not sure. Something like that. Am watching a weid kung fu movie, so ... >Regards, > >Chris >
From: Andrew Holme on 5 Dec 2009 16:18
"ChrisQ" <meru(a)devnull.com> wrote in message news:qmySm.123940$yM2.60574(a)newsfe10.ams2... > Jan Panteltje wrote: >> On a sunny day (Sat, 05 Dec 2009 10:51:36 -0800) it happened John Larkin >> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote in >> <kqalh59i8jsogn1t6p3ghuaop5c137qtoj(a)4ax.com>: >> >>> Testing some FTP stuff, threw up some test files... >>> >>> ftp://jjlarkin.lmi.net/Core_304bits.jpg >> >> 16 bits x 19?? >> >> >>> ftp://jjlarkin.lmi.net/Core_4K.jpg >> >> Amazing.. >> >> >>> ftp://jjlarkin.lmi.net/Core_4Kdetail.jpg >> >> Must have been expensive. >> >> >>> John >>> >>> >>> > > Don't recognise either of those as to manufacturer, but the last machine > that I had with core was an early pdp11/05, which eventually got shipped > back to the us. > > Ok, quiz time: how does core memory work ?. (and no cheating via google > etc :-)... > > Regards, > > Chris The cores have hysteresis. You can't flip the direction of magnetisation unless the current in the wires exceeds a certain threshold. You put half the required current down an X wire and half down a Y wire. Only one core at the X,Y intersection gets flipped. When you flip a core, you get a pulse induced in the read wire. This means you have to do a destructive read. If you write a 1 and get a big pulse back then you know it must have been a 0 before. If it was already a 1, you only get a tiny pulse. Every read must be followed by a write to restore the previous state. See my core memory page for 'scope captures of actual read pulses: http://www.holmea.demon.co.uk/Core/Flipper.htm |