-----Original Message----- From: Megan &lt;mbg(a)world.std.comTo: classiccmp(a)classiccmp.org &lt;classiccmp(a)classiccmp.orgDate: Saturday, February 12, 2000 9:28 PM Subject: Re: RX01 Bootstrap Loader <snip>>Taken with what you mentioned elsewhere in the message, I suspect that That's right. You can set the vector to anything you want (well, almost) and XXDP will boot and talk to the console - no matter the kind. M9312 will talk to a single interrupt teletype card as it too does PIO. I find that out every time I pull out a DL11-W and the vectors get messed up because the dip switches brush against another board. DEC *must* have done something for customers who did not wish to upgrade their old KL11s (M780 cards). After going through tech notes and FCOs I found that DEC switched from M780 -> M782 -> M7821 . Since a DL11-B,C,E, or -W can not be installed in the PDP-11/20 (because no +15V) a decision was made to add a G8000 module that would filter the 8V lamp voltage and use it as +15, add a couple of wires.. and a DL11 with EIA could work. As a result of RT11, DEC produced a new interrupt module M7820 (old one was M782). The new module handled two interrupts. :-) I just found a box of them :-) and the PDP-11/20 just booted RT11-V3.0B!!! and.. I just tried to boot RT11-V4.00 . Boots okay but there is not enough memory to run Basic. Those MM11-Es are a dogs breakfast. I can live with tuning 4K of core memory in a PDP-8 but tuning a bunch of core sets in a pdp-11!??!?! Yuck. executing "Show All" returns the mini is a "PDP-11/15,20 Processor".. after that it says "no device 012056". Guess I have to sysgen a 30b and a 4 for the 11/20s. Thanks for the help... I am happy that the PDP-11/20s will continue to use the initial KL11 board set but I will contact you off list so that maybe the original M782 module can be used. john PDP-8 and other rare mini computers http://www.pdp8.com > Megan Gentry > Former RT-11 Developer >+--------------------------------+-------------------------------------+ >| Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com | >| Unix Support Engineering Group | (home): mbg!world.std.com | >| Compaq Computer Corporation | addresses need '@' in place of '!' | >| 110 Spitbrook Rd. ZK03-2/T43 | URL: http://world.std.com/~mbg/ | >| Nashua, NH 03062 | "pdp-11 programmer - some assembler | >| (603) 884 1055 | required." - mbg | >+--------------------------------+-------------------------------------+