test-drb December 2018

test-drb@ccmp.vtda.org

174 participants
203 discussions

Core memory emulator using non volatile ram.

by ggs＠shiresoft.com

FRAM or MRAM. I make extensive use of them in my projects. Everspin has a few (all SMT and 3.3v). As I recall they run ~$20/ea for 4Mb (512K x 8 or 256K x 16). TTFN - Guy > On Dec 15, 2018, at 1:22 AM, Rod G8DGR via cctalk <cctalk at classiccmp.org> wrote: > > I have an idea to produce an MM-8 clone using RAM that acts like core when turned off. > Can anybody suggest a chip that will do this? > > Rod Smallwood > > > Sent from Mail for Windows 10 >

5 years, 5 months

Core memory emulator using non volatile ram.

by jnc＠mercury.lcs.mit.edu

> From: Paul Koning > For that matter, core memory details such as destructive read weren't > visible to the CPU Umm, not quite. If you'd said 'core memory details such as destructive read weren't visible to the _program_', you'd have been 100% correct. But as I suspect you know, just overlooked, most (all?) of the -11 CPU's do use 'read-modify-write' cycles on the bus (DATIP in UNIBUS terms, DATIO in QBUS) where possible precisely for the benefit of core memory with its destructive readout. (And there's some hair for interlocking the multiple CPU's on the -11/74 which I don't recall off the top of my head.) And I have a vague memory of something similar on other early DEC machines; probably some -8 models. Noel

5 years, 5 months

Core memory emulator using non volatile ram.

by paulkoning＠comcast.net

> On Dec 16, 2018, at 10:49 PM, Rod G8DGR via cctech <cctech at classiccmp.org> wrote: > > > I?m trying to make a look and feel reproduction PDP-8/e. > So the memory characteristics need to be as close as possible. > > An original ( and I do have one) and the copy when placed side by side should run in sync. > When executing he same code ? What code I couldn?t care. > > Rod All you need for that to be true is to use the same bus timing as the original. What happens behind the scenes is unimportant. At LCM while restoring their CDC 6500 they built replacement memory modules, which actually mimic not just core memory cycle timing but also core memory waveforms -- which took some fiddling with pulse transformers. But behind the interface logic there's simple modern memory, probably SRAM, I forgot. paul

5 years, 5 months

Core memory emulator using non volatile ram.

by charles.unix.pro＠gmail.com

On Sat, Dec 15, 2018 at 6:15 PM Rod G8DGR via cctalk <cctalk at classiccmp.org> wrote: > All very interesting.. 1201 alarm while I deal will all of the information > Rod > > 1202 coming up... I don't know specifically about the various memory types being bandied about, but I do know that the destructive read behavior of core memory my be required for some architectures; "load and clear" type instructions rely on the suppressing the write-after-read cycle to make the instruction atomic, allowing the implementation of data locking instructions. For some architectures, it may be that any replacement memory would have to support the suppression signal to work correctly. -- Charles

5 years, 5 months

AW: Core memory emulator using non volatile ram.

by gerhard.kreuzer＠liftoff.at

Hi Rod, take some microcontroller and some serial flash memory. With best regards Gerhard -----Urspr?ngliche Nachricht----- Von: cctalk [mailto:cctalk-bounces at classiccmp.org] Im Auftrag von cctalk-request at classiccmp.org Gesendet: Samstag, 15. Dezember 2018 19:00 An: cctalk at classiccmp.org Betreff: cctalk Digest, Vol 51, Issue 15 Send cctalk mailing list submissions to cctalk at classiccmp.org To subscribe or unsubscribe via the World Wide Web, visit http://www.classiccmp.org/mailman/listinfo/cctalk or, via email, send a message with subject or body 'help' to cctalk-request at classiccmp.org You can reach the person managing the list at cctalk-owner at classiccmp.org When replying, please edit your Subject line so it is more specific than "Re: Contents of cctalk digest..."

5 years, 5 months

remove bad yelpMATERIAL INGEST. adams associates COMPUTER CHARACTERISTICS QUARTERLY 1963

by couryhouse＠aol.com

How to Remove Bad Yelp Reviews (and Report Fake Yelp Reviews)MATERIAL INGEST? ?ADAMS ASSOCIATES? ?COMPUTER CHARACTERISTICS QUARTERLY 1963 ? HAVE ONE? A? LITTLE? CUTE? LOOKS? AS? ?NEW POCKET? GUIDE? ? I? ?SEE ONE IN GOOGLE? SCANNED? ?FROM? 67? SO DO NOT KNOW THIS? NEEDS TO BE? OR? ? ALSO? A? EAI? POCKET? CALENDAR? APPOINTMENT? REMINDER? BUT? ? AS? NEW? NO? FASCINATING NOTES? ALAS.. ? ALSO A? 67 STOCK HOLDERS AGENDA? SHEET.? PURPLE? ? DITTO? ?REPRODUCED. ? ? ?

5 years, 5 months

HUNTING EXISTENCE OF NCR 304 COMPUTER PCB BOARD PIX IS THERE ONE OF THESE EVEN LEFT?

by couryhouse＠aol.com

HUNTING EXISTENCE OF NCR 304 COMPUTER PCB?BOARD PIX IS THERE ONE OF THESE EVEN LEFT?

5 years, 5 months

ok but we did get some cool EAI stuff... sometimes I kist stuff as this in case there is similare interest or needs

by couryhouse＠aol.com

MATERIAL INGEST ADAMS ASSOCIATES COMPUTER CHARACTERISTICS QUARTERLY 1963 HAVE ONE A LITTLE CUTE LOOKS AS NEW POCKET GUIDE I SEE ONE IN ?GOOGLE SCANNED FROM 67 SO DO NOT KNOW THIS NEEDS TO BE OR? ?ALSO A EAI POCKET CALENDAR APPOINTMENT REMINDER BUT AS NEW NO ?FASCINATING NOTES ALAS.. ?ALSO A 67 EAI STOCK HOLDERS AGENDA SHEET. PURPLE DITTO REPRODUCED.

5 years, 5 months

Core memory emulator using non volatile ram.

by elson＠pico-systems.com

On 12/15/2018 11:19 PM, Rod G8DGR via cctech wrote: > > > However I began to think would it be possible to create a close copy of an 8/e out of modern parts. > > > Finally the big one ? Omnibus and the connectors its made from. A 3D printing candidate? > I?m going to autopsy a busted connector and see how they are constructed inside. Yup, this will be a problem. A couple decades ago, there was a very common technology, press-fit backplanes. You made a PC board with all the interconnect on it (power + signals) and pressed-in contact fingers. Then, connector housings were pressed onto the contacts. I don't know if anybody still makes these contacts. It would be hugely expensive to have custom ones made, but if they are still being made they might not be too bad. I'm not sure 3D-printed housings would be strong enough for this, but maybe if ABS they would. Of course, there might actually still be somebody making clones of the DEC connectors. They used basically the same design for PDP-8, PDP-11, KL10, VAX, etc. Certainly, there were people cloning them back in the 1980's. Winchester made the official ones for DEC. > Objectives > The basic board set as original. M8300, M8310, M8320 etc. > Same form factor > Plug compatible ? but board contents can differ from original Well, this could all be done with one FPGA, but if you want to do each PC board separately, a modest CPLD or small FPGA would certainly do each board's functionality. Jon

5 years, 5 months

8-Update

by pbirkel＠gmail.com

>-----Original Message----- >-From: cctalk [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Rod G8DGR via cctalk >-Sent: Sunday, December 16, 2018 2:36 AM >-To: General Discussion: On-Topic and Off-Topic Posts >-Subject: 8-Update > >Sheesh!! >Well what a response. >This stems from my (so far) successful major over haul of my PDP-8/e. >I found one failed 7474 and one failed 8881 ? replaced and now working. >I think I have the rim loader toggled in and will attempt to send a paper tape image from Hyperterm >Strangely I do have at least three genuine complete 4k memory sets. > >The eightstoration will continue. > >However I began to think would it be possible to create a close copy of an 8/e out of modern parts. >As you all know I make front panels so that?s not a problem. >I did manage to copy my (distorted) bezel in resin. >A friend has been able to 3D print toggle switch leavers that fit and work. >... Could you (or your fried) tell us more about "A friend has been able to 3D print toggle switch leavers that fit and work"? I have need to do the same :-<. And I don't have a 3D printer, either. paul

5 years, 5 months

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test-drb December 2018