Path: utzoo!attcan!utgpu!watmath!att!tsdiag!scr1!pechter From: pechter@scr1.UUCP (Bill Pechter) Newsgroups: comp.arch Subject: Re: DECSYSTEM 20 Message-ID: <441@scr1.UUCP> Date: 31 Jul 89 14:40:05 GMT References: <3256@wpi.wpi.edu> <443@anasaz.UUCP> <3893@phri.UUCP> <433@scr1.UUCP> <976@mplvax.EDU> Reply-To: pechter@scr1.UUCP (Bill Pechter) Organization: CONCURRENT COMPUTER,OCEANPORT NJ Lines: 28 Summary:register address via Unibus In article <976@mplvax.EDU> cdl@mplvax.ucsd.edu.UUCP (Carl Lowenstein) writes: >Some of the medium-early 11's (11/10 and 11/05 specifically) >had a register set that was addressable on the bus by a program. >Others of earlier and later vintage did not. > I believe every 11 had the registers addressable on the bus via a program... Includeing the 11/70. The trick was knowing the addressing space (memory management). a >Of course, all *Real* PDP-11's can read and load their >register set through the front panel lights and switches. >Nowadays, the lights and switches must cost more than >the CPU chip, so they don't make them like that. I remember and love the front panels -- especially the DecDatasystem 570 version of the 11/70 (or the unreleased 11/74 type where the 11/05 type short switches were used. Bill -- Bill Pechter -- Home - 103 Governors Road, Lakewood, NJ 08701 (201)370-0709 Work -- Concurrent Computer Corp., 2 Crescent Pl, MS 172, Oceanport,NJ 07757 Phone -- (201)870-4780 Usenet . . . rutgers!pedsga!tsdiag!scr1!pechter ** MS-DOS is CP/M on steroids, bigger bulkier and not much better **