Old RPN w/ discrete components and acoustic memory
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03-04-2020, 01:13 PM
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Old RPN w/ discrete components and acoustic memory | |||
03-05-2020, 05:41 AM
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RE: Old RPN w/ discrete components and acoustic memory
(03-04-2020 01:13 PM)ndzied1 Wrote: Maybe it’s been shown before but really cool video. Amazing. Great find! Thoroughly enjoyed it. Jaco Mostert, Elec Eng C47 on DM42, 42S, WP34C&S, 28C, 35S, 32Sii, had 11C; used 67, 85; iOS:42s, Free42, WP31S&34S, HCalc; OSX:WP34C. |
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03-05-2020, 05:44 AM
Post: #3
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RE: Old RPN w/ discrete components and acoustic memory
(03-04-2020 01:13 PM)ndzied1 Wrote: Maybe it’s been shown before but really cool video. 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? Tom L Cui bono? |
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03-05-2020, 06:12 AM
Post: #4
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RE: Old RPN w/ discrete components and acoustic memory
(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. 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 Jaco Mostert, Elec Eng C47 on DM42, 42S, WP34C&S, 28C, 35S, 32Sii, had 11C; used 67, 85; iOS:42s, Free42, WP31S&34S, HCalc; OSX:WP34C. |
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03-06-2020, 01:50 AM
Post: #5
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RE: Old RPN w/ discrete components and acoustic memory
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.
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03-06-2020, 02:04 PM
Post: #6
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RE: Old RPN w/ discrete components and acoustic memory
(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? Tom L Cui bono? |
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03-09-2020, 01:04 PM
Post: #7
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RE: Old RPN w/ discrete components and acoustic memory
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.)
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03-09-2020, 02:41 PM
Post: #8
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RE: Old RPN w/ discrete components and acoustic memory
(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. 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. |
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