On Aug 26, 2025, at 10:51 AM, Martin Eberhard via cctalk &lt;cctalk(a)classiccmp.org&gt; wrote: he is putting together with an 11/20. :-) Yes, I'm on this list. I was surprised to see Kim Java show that snippit of my PDP11/20 restoration project. I wasn't even aware that the camera was rolling at that point! So far, the CPU and the extended arithmetic element seem to be working great. I've got my own SRAM board <https://deramp.com/downloads/mfe_archive/005-Documentation%20and%20Code%20by%20Martin/PDP11%20Stuff%20by%20Martin/Unibus%20Boards/Unibus%20RAM0ROM-Bootstrap/> in it. The RX211 is also working great, as is the DL11. I'm in the process of restoring the RK11 disk subsystem (RK03 Diablo drives, external controller). I can now read, write, and format on one of the drives. The other has lots of work to be done. I need to tear both drives apart enough to replace the rotted foam seals for the air-blower interface, and the rubber strip on the front door. I am also considering cleaning and re-lubricating the bearings on the positioner assembly. as they feel a little crunchy. Amazingly, I just bought new air filters for the Diablo drives!

Your quote "to get into the head of those original engineers" is a great sentiment on what the hobby is about. I recall reading about early "steam tractors" - almost trains, before there were any tracks. Monstrous things, I can't recall if they were before steam ship engines - but exploding broilers was a problem (which I view as being akin to "exploding batteries" that we might occasionally deal with today- it happens now and then, as we still haven't perfected the tech {or at least, hadn't 10 years ago}). I'm reading more about those electric powered flying vehicles - with some becoming available around $120K? I think the Joby eVTOL recently did a first public flight between two airports. I've been flying one in MS simulator, neat to see that they might become a reality. The main naysayers of electric-anything vehicles tend to point to cold weather (northern winter) environments. Anyhow, those "personal minicomputers" from 1968-1969 are neat. It's a whole generation of computing that (IMO) is kind of forgotten about - but then again, they cost as much as a house then, so generally only business owners (like supermarket owners) could afford them. I suspect Gomez Addams had a few in their basement :) I've seen some Data General's of that era restored. I'm still trying to see if there are any functional DDP-116 or SEL810B around - but you're right, flip-switch programming is kind of a drag and working teletypes are hard to find these days. You mentioned having your own RAM card, like custom built? Someone recently made an SRAM based replacement RWS for the IBM 5110. Neat stuff, I never yet had the patience (or equipment) for that kind of detailed signal analysis to reverse engineer something like that. -Steve (voidstar / Domesticating the Computer) On Tue, Aug 26, 2025 at 11:26 AM Paul Koning via cctalk < cctalk(a)classiccmp.org&gt; wrote: rack the https://deramp.com/downloads/mfe_archive/005-Documentation%20and%20Code%20b… The Diablo and

I wasn’t around back then ;) But I think the big problem with steam tractors was since they were so heavy they would sink into the fields. I don’t think that was an issue really solved until gas powered tractors came around. Frank cctalk(a)classiccmp.org&gt; wrote: of cctalk(a)classiccmp.org&gt; there as {or some but business stuff, https://deramp.com/downloads/mfe_archive/005-Documentation%20and%20Code%20b… if

I wasn’t around back then ;) But I think the big problem with steam tractors was since they were so heavy they would sink into the fields. I don’t think that was an issue really solved until gas powered tractors came around. Frank > On Aug 26, 2025, at 2:35 PM, Adrian Godwin via cctalk &lt;cctalk(a)classiccmp.org&gt; wrote: > > Exploding boilers seem a lot worse than batteries. They can produce jets of > flame and toxic smoke but not cast iron shrapnel. > > > On Tue, 26 Aug 2025, 19:31 Steve Lewis via cctalk, &lt;cctalk(a)classiccmp.org&gt; > wrote: > >> Your quote "to get into the head of those original engineers" is a great >> sentiment on what the hobby is about. >> >> I recall reading about early "steam tractors" - almost trains, before there >> were any tracks. Monstrous things, I can't recall if they were before >> steam ship engines - but exploding broilers was a problem (which I view as >> being akin to "exploding batteries" that we might occasionally deal with >> today- it happens now and then, as we still haven't perfected the tech {or >> at least, hadn't 10 years ago}). >> >> I'm reading more about those electric powered flying vehicles - with some >> becoming available around $120K? I think the Joby eVTOL recently did a >> first public flight between two airports. I've been flying one in MS >> simulator, neat to see that they might become a reality. The main >> naysayers of electric-anything vehicles tend to point to cold weather >> (northern winter) environments. >> >> >> Anyhow, those "personal minicomputers" from 1968-1969 are neat. It's a >> whole generation of computing that (IMO) is kind of forgotten about - but >> then again, they cost as much as a house then, so generally only business >> owners (like supermarket owners) could afford them. I suspect Gomez >> Addams had a few in their basement :) I've seen some Data General's of >> that era restored. I'm still trying to see if there are any functional >> DDP-116 or SEL810B around - but you're right, flip-switch programming is >> kind of a drag and working teletypes are hard to find these days. >> >> You mentioned having your own RAM card, like custom built? Someone >> recently made an SRAM based replacement RWS for the IBM 5110. Neat stuff, >> I never yet had the patience (or equipment) for that kind of detailed >> signal analysis to reverse engineer something like that. >> >> >> -Steve >> (voidstar / Domesticating the Computer) >> >> >> >> >> >> >> >> >> On Tue, Aug 26, 2025 at 11:26 AM Paul Koning via cctalk < >> cctalk(a)classiccmp.org&gt; wrote: >> >>> >>>> On Aug 26, 2025, at 10:51 AM, Martin Eberhard via cctalk < >>> cctalk(a)classiccmp.org&gt; wrote: >>>>> Interesting for Tesla’s early history, but skip to 49:00 for a nice >> rack >>>> he is putting together with an 11/20. >>>>> https://youtu.be/88KHfX_kPIY >>>>> He also appears to be on the cctalk list. >>>> :-) Yes, I'm on this list. I was surprised to see Kim Java show that >>>> snippit of my PDP11/20 restoration project. I wasn't even aware that >> the >>>> camera was rolling at that point! >>>> >>>> So far, the CPU and the extended arithmetic element seem to be working >>>> great. I've got my own SRAM board >>>> < >> https://deramp.com/downloads/mfe_archive/005-Documentation%20and%20Code%20b… >>>> in it. The RX211 is also working great, as is the DL11. I'm in the >>> process >>>> of restoring the RK11 disk subsystem (RK03 Diablo drives, external >>>> controller). I can now read, write, and format on one of the drives. >> The >>>> other has lots of work to be done. I need to tear both drives apart >>> enough >>>> to replace the rotted foam seals for the air-blower interface, and the >>>> rubber strip on the front door. I am also considering cleaning and >>>> re-lubricating the bearings on the positioner assembly. as they feel a >>>> little crunchy. Amazingly, I just bought new air filters for the >> Diablo >>>> drives! >>> Nice! >>> >>> How do you load software into it? There's always the toggle switches if >>> you have enough patience. Or do you just update the ROM? >>> >>> For that machine, with a full load of memory, you have a bunch of OS >>> options. RT-11/SJ or /FB, DOS-11, RSTS-11. That last option would be >>> amusing: a machine quite similar to yours, with the addition of DECtape >> and >>> another 15 DL11 interfaces, is what my alma mater used for the college >>> timesharing system in 1973-1974. >>> >>> paul >>> >>> >>>