Re: Core memory emulator using non volatile ram.

[allison via cctech]

On 12/15/2018 01:01 PM, Guy Sotomayor Jr via cctech wrote:
> 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  
>> 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
>>
>>
My call on this is that cmos static ram 4Bit wide does the job well I
have 32K of it in my PDP-8 to
get past possible failure of hard to find and get core.  A Panasonic
BR-1 lithium cell has enough
capacity at the measured drain for about 6-7 years and the Dallas power
management chip
makes it a non hack.  Flash, EEprom and Magnetic FRAM and MRAM) types
have many unacceptable
properties for a random access read write memory.  It makes no
difference to the PDP8(ILEFMA)
that read is not destructive as it will write back as needed anyway.

There is a design on the 'net for using CMOS ram in a straight forward
buildable array for Omnibus
with battery back up that is fine.  Don;t get wraped around the axle
about RMW as any sufficiently
fast ram can do that without wearout.  And compared to core it doesn't
take much speed.

EEprom and Flash work fine for read mostly disks or disk simulators.

Allison

Re: Researching IBM rare equipment from 50s to 80s

[Randy Dawson via cctech]

I worked with an ex-IBMer who told me about this thing.

It was nick-named "The Noodle Snatcher" - with a puff of air it wiggled the mag 
tape and wrapped it around a drum for read/write.

It had a nasty habit of mis-handling the tape.

He told me that during a sales presentation  to a customer, this happened, it 
wrinkled the tape wrapped it around the drum, and then put the crumpled tape 
back in the holder.

The IBM salesman, without missing a beat, said, "and when it finds BAD data..."

From: cctech  on behalf of Jay Jaeger via cctech 

Sent: Friday, December 14, 2018 1:04 PM
To: cctech@classiccmp.org
Subject: Re: Researching IBM rare equipment from 50s to 80s

On 12/14/2018 4:41 AM, Peter Van Peborgh via cctech wrote:
> Fellow geeks of more mature vintage,
>
> Do any of you guys know whether it is possible to find out to whom any IBM
> equipment was sold back in the day? (Still chasing IBM 2321 Data Cell - I
> never learn!)
>
> Many thanks,
>
> peter
>

Well, if your intention is to actually find one, can't help.

I do know that Wisconsin DOT had one back in the day, on an IBM 360/50,
but it was gone before I started work there.  I think that I have a
large negative of the beastie lying around somewhere.  No, it is not
stuffed anywhere.  Indeed the building that formerly housed it (and was
home for me during my career) was razed just this year.

In general, even if IBM still had such records, I am sure that they
would not release them, and doubt that they would be indexed in fine
detail such that you could find customers of any particular machine type
(unless they fed them to Watson ;) ).  Leased units would have been
turned back into IBM.  Purchased units would have been mostly traded in
and scrapped.

A Google Search found these instances of customer units (there may well
be more - I stopped after a few pages)

http://www.columbia.edu/cu/computinghistory/datacell.html

https://www.facebook.com/HealthManagementTechnology/photos/ibm-2321-data-cell-drive/132475567020/

https://commons.wikimedia.org/wiki/File:IBM2321DataCellAtUMich.jpg




JRJ