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+--- Thread: Old RPN w/ discrete components and acoustic memory (/thread-14603.html)
Old RPN w/ discrete components and acoustic memory - ndzied1 - 03-04-2020 01:13 PM
Maybe it’s been shown before but really cool video.
https://youtu.be/2BIx2x-Q2fE
RE: Old RPN w/ discrete components and acoustic memory - Jaco@cocoon-creations.com - 03-05-2020 05:41 AM
(03-04-2020 01:13 PM)ndzied1 Wrote: Maybe it’s been shown before but really cool video.
https://youtu.be/2BIx2x-Q2fE
Amazing. Great find! Thoroughly enjoyed it.
RE: Old RPN w/ discrete components and acoustic memory - toml_12953 - 03-05-2020 05:44 AM
(03-04-2020 01:13 PM)ndzied1 Wrote: Maybe it’s been shown before but really cool video.
https://youtu.be/2BIx2x-Q2fE
I still don't really get acoustic memory. How does it store the information for more than a few milliseconds as the pulse goes around the loop to the end?
RE: Old RPN w/ discrete components and acoustic memory - Jaco@cocoon-creations.com - 03-05-2020 06:12 AM
(03-05-2020 05:44 AM)toml_12953 Wrote:(03-04-2020 01:13 PM)ndzied1 Wrote: Maybe it’s been shown before but really cool video.
https://youtu.be/2BIx2x-Q2fE
I still don't really get acoustic memory. How does it store the information for more than a few milliseconds as the pulse goes around the loop to the end?
The way I understand it, is that it gets sent around again once picked up by the sensor on the end. This video attempts to show both ends:
https://youtu.be/N9cUbYII5RY
RE: Old RPN w/ discrete components and acoustic memory - cruff - 03-06-2020 01:50 AM
If you've ever read a description of how the magnetic bubble memory operated, the design is similar in that the contents of the loop need to be regenerated continuously. At the point (in time) there a specific data bit falls off the end is where you read the value or write a new value.
RE: Old RPN w/ discrete components and acoustic memory - toml_12953 - 03-06-2020 02:04 PM
(03-06-2020 01:50 AM)cruff Wrote: If you've ever read a description of how the magnetic bubble memory operated, the design is similar in that the contents of the loop need to be regenerated continuously. At the point (in time) there a specific data bit falls off the end is where you read the value or write a new value.
So that's what the fan is for? To blow all of those bits that fell off the end out of the machine?
RE: Old RPN w/ discrete components and acoustic memory - Dave Britten - 03-09-2020 01:04 PM
The funny thing is that the program memory in the HP 65 is very conceptually similar, except that it's a very long shift register rather than a mechanical/acoustic device. Technically, the 65 doesn't have "RAM" in that regard, since it isn't "random access", and there are no absolute addresses. It just reads/inserts/swaps bits as they pass by the window. (I imagine there's a bit more to it to allow the calculator to do things like inserting and swapping steps for moving the program pointers around, but that's the general idea.)
RE: Old RPN w/ discrete components and acoustic memory - Paul Berger (Canada) - 03-09-2020 02:41 PM
(03-05-2020 05:44 AM)toml_12953 Wrote:(03-04-2020 01:13 PM)ndzied1 Wrote: Maybe it’s been shown before but really cool video.
https://youtu.be/2BIx2x-Q2fE
I still don't really get acoustic memory. How does it store the information for more than a few milliseconds as the pulse goes around the loop to the end?
Many years ago I used to service a proof machine that had delay line memory and that machine had a solid state shift register in between the two ends of the delay line that you would insert and retrieve data from, but since it is a continuous stream of bits that you cannot stop, you need to know when a unit of data is aligned in the solid state register and insert or retrieve data before the shift register advances.
I also took a call on a test scoring machine one time that used delay line memory to hold the correct answers that where compared to the students answer sheets.
Paul.