H8 Bubble Memory Board

[smb...@gmail.com]

The new "bubble Trouble" board:

https://www.youtube.com/watch?v=P_miv4wYzvg

I decided the 8-meg Ramdisk board was too big and too fast, so I went with something smaller and slower. A little bit impractical to build due to the scarcity of 7110AZ bubble memory ICs and their related support chips.

Scott

[glenn.f...@gmail.com]

Very cool scott. I think this may be the first 4-layer H8 board done by a group member? My only recollection of intersecting with bubble memory was a TI silent 700 I used that had some.  Seems like it was a “thing” for a pretty short time…?

 

(There’s quite a pile of H8 boards and JLCPCB boards in the background in that video!)

 

• Glenn

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[smb...@gmail.com]

Interesting, I'm going to have to read up more on the Silent 700,. While I've seen them online, I did not realize they used bubble memory -- was this standard or an option?

It does look like bubble memories were believed to be becoming an upcoming "thing", but they seemed to fizzle out when the HDD and DRAM bang-of-the-buck exploded into what now almost feels like storage and RAM are free these days. Bubble is an interesting technology, and it's surprising these modules are still usable after decades. For a couple years I've had a bubble board in the back my mental "to-do" list, but didn't really come up with a good place to put one until the H8 came along. Trying to fit one on a RC2014, for example, would dwarf the RC2014 in size and add complex power requirements.

I do have a feeling that I'm overtaxing the H8's +18V though, so I have a revision planned that will accommodate a Pololu step-up module.

Scott

[glenn.f...@gmail.com]

It was only on one model: 765.  The bubble memory essentially looked like a paper punch to the remote software so you could save downloaded data and files.

 

If I understood your video you derived the 12V for the bubble via a dc-to-dc converter on the 8V line (so you wouldn’t load down the 18V)?  agree if you can find a polulu step up converter that makes sense…

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[smb...@gmail.com]

I used a good ol' 7812. I did put in a footprint for a DC-DC converter, the same one that Craig Andrews used in his build. Unfortunately, that particular converter is not only expensive, but also seems to have fallen victim of the "supply chain shortage". :( Anyhow, the Polulu boost converter is a third the price, double the amperage, and readily available. The next board will try it out and see if it works.

The next board (which is shipping from China as we speak) will have space for two bubble memories, and features twice the size, twice the speed, and twice the power consumption. The +18V almost certainly won't be able to handle twice the power. The 8080 CPU might not be able to handle twice the speed. Like a floppy controller, this thing is intolerant of the CPU falling persistently behind on reads or writes. It might need Turbo speed on the 8085 or Z80 boards to make double-bubble a reality. It'll be an interesting experiment.

Regarding the four layer board. I've done them before, mostly as a cheat for not wanting to go to the effort to carefully route a complex board. Eagle makes dealing with them relatively straightforward. There's a substantial price increase for 4-layer, though it's not prohibitive. Basically, you turn the inner two layers into power and ground, thus giving yourself excellent power and ground everywhere while also alleviating the need to expend space on the top and bottom layers on power and ground. It's a win-win on everything but cost. As for the bubble board, it's not that it is complex, but it is the case that the handbook says to be very careful on routing, and recommends the 4-layer, especially for multi-bubble boards.

Scott

[Douglas Miller]

I remember drooling over bubble memory in the early days - even before they had stable product. At the time, core memory was still on peoples mind, and the non-volatile nature was still attractive. It was an interesting technology, but I think it was just leap-frogged by "better" technology, like flash and EEPROMs. There were plenty of problems getting quantity and quality to reasonable levels, and then newer technology surpassed it. That happens a lot in our industry, especially for example tape-backup. Seems like every time someone came out with a bigger and better tape technology, harddisk would get larger and less expensive causing the need for larger capacity tape. Tape backup is still used, but it's no longer required for interchange and a lot of sites will employ RAID technology as their primary data retention strategy (with tape serving an archival role).

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[norberto.collado koyado.com]

WOW! Nicely explained. I felt that I was at the University taking a class. Now, I’m ready for the test/quiz.

 

Norberto

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of smb...@gmail.com
Sent: Sunday, June 4, 2023 4:37 PM
To: SEBHC <se...@googlegroups.com>
Subject: [sebhc] H8 Bubble Memory Board

 

The new "bubble Trouble" board:

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[smb...@gmail.com]

The bubble board got a write-up on hackaday: https://hackaday.com/2023/06/09/magnetic-bubble-memory-brought-to-life-on-heathkit.

The double-bubble boards have arrived from China. Probably won't get to them this week, but likely get to try out double-bubble next week. It'll be interesting to see if the H8 can handle the data rate from two bubbles without having to be put into "Turbo" mode.

Scott

[norberto.collado koyado.com]

Very nice and well done, Scott!

 

Norberto

 

From: se...@googlegroups.com <se...@googlegroups.com> on behalf of smb...@gmail.com <smb...@gmail.com>

Date: Saturday, June 10, 2023 at 9:36 AM
To: SEBHC <se...@googlegroups.com>

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[smb...@gmail.com]

Behold, the double-bubble-board:

2MHz is laughably too slow for this board. 4MHz is just not quite enough. It works fine on my 5MHz 8085 or 8MHz Z80. When you double the number of bubbles, you double not only space but also speed. If I had designed it to be interrupt driven, then then it probably could have handled it at lower speeds. I will probably revert back to single-bubble configuration.

Scott

[norberto.collado koyado.com]

Very nice board! As long is faster than a floppy, then it should be fine. 😊

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[Les Bird]