On 12/21/2018 3:07 PM, Paul Koning via cctalk wrote: > > >> On Dec 21, 2018, at 3:06 PM, Bill Degnan via cctalk <cctalk@classiccmp.org> >> wrote: >> >>> >>> >>> >>> My _guess_ is that that probably happened because there is no formal >>> 'model' >>> for that first one (unlike the first -11, which got re-named the -11/20 >>> BITD), and people recently picked that to disambiguate them from all the >>> other -8's. >>> >>> >>> >> The original PDP 11 was sold in two model options, although the numbers did >> not appear on the faceplace, very clearly the model options were called PDP >> 11/10 and PDP 11/20. These are just as legitimate and well defined as the >> 11/05 vs. 11/10 (later version) that followed it except for the one fact of >> the front plate. The fact that the name does not appear on the front panel >> has caused every DEC historian to miss this factoid. Read the first >> brochure, don't take my word for it. >> http://vintagecomputer.net/browse_thread.cfm?id=593 >> >> Momentum prevents change I get it, but it's clear that the model 11/20 and >> 11/10 existed from day one. The problem is that DEC re-used the 11/10 >> model name again a few years later, the other cause for neglecting the >> original 11/10 model. >> >> Bill > > Wow. > > Did that V1 11/10 ever ship? Do any still exist? > > I'm curious about that 1 kW read-only memory. What technology is that > memory? At that size and that date I suspect core rope, but that would be > pretty expensive (due to the labor involved). > > paul > >
It shows up in the pdp11 handbook 1969 inside/1970 on the spine, and pdp11 handbook 2nd edition (also 1969/1970), but has been displaced by the latter 11/10 variant by 1972. Perhaps, since the *only* difference was the memory configuration (near as I can tell), there may have been so few orders (maybe even none?) that they just dropped it. Or maybe a marketing / design team communication misstep. The pdp11 handbook from 1969/1970 identifies the memory attributed to the 11/10 only as read-only core memory with an access time of 500ns (same as the RAM core). It describes the tiny RAM for the 11/10 of 256 words has having a 2us cycle time vs. 1.2us for the 11/20. The handbook also indicates that an 11/20 could do an NPR transfer every 1.2us but an 11/10 could do one ever 1.0us (probably assuming ROM cycle times). As a guess, they may never have sold any (or delivered 11/20's to those who ordered 11/10's).
