Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!gorodish!guy From: guy%gorodish@Sun.COM (Guy Harris) Newsgroups: comp.arch,comp.unix.wizards,comp.os.minix Subject: Re: pdp-11/55 Message-ID: <30247@sun.uucp> Date: Wed, 7-Oct-87 13:59:18 EDT Article-I.D.: sun.30247 Posted: Wed Oct 7 13:59:18 1987 Date-Received: Sat, 10-Oct-87 08:46:58 EDT References: <1755@ncr-sd.SanDiego.NCR.COM> <275@usl> <29933@sun.uucp> <1806@gryphon.CTS.COM> Sender: news@sun.uucp Lines: 33 Xref: mnetor comp.arch:2540 comp.unix.wizards:4740 comp.os.minix:1827 > Was it a faster 11/45, or an OEM 11/60? No, it was a faster 11/45, according to the PDP-11 04/34/45/55 Processor Handbook: The PDP-11/55 is a bipolar memory based computer designed for greater processor and system performance through the use of a dedicated internal semiconductor memory bus. ... The PDP-11/55 can be expanded up to 248K bytes with the aid of the memory management unit which is an integral part of the central processor. The fast floating point processor operates as an integral part of the central processor... ... The PDP-11/45 has a cycle time of 300 nsec and performs all arithmetic and logical operations required in the system. A Floating Point Processor mounts integrally into the Central Processor as does a Memory Management Unit... So I guess the 11/55 was a "loaded" 11/45, with semiconductor memory (which is not mentioned in the description of the 11/45) and a standard MMU and FPP. By the time the 11/60 came out, the "version - 5" for end-users convention was gone. Early draft versions of the 11/34 manual mentioned an 11/39, but unless they put out a few early ones I don't think they ever put an 11/39 label on that machine. The 11/60 was, indeed, a machine with user-writable microcode; it also had FPP-compatible microcode, so you could execute FPP instructions even if you didn't have an FPP. Unfortunately, it didn't support 22-bit addressing. Guy Harris {ihnp4, decvax, seismo, decwrl, ...}!sun!guy guy@sun.com