egz@druky.UUCP (BonnellDS) (06/23/84)
About a week ago a request was made for information on UNIX and UNIX like operating systems for the PDP 11/23 or 11/23+. I would like to recommend the UNIX lookalike operating system marketed by Venturcom, VENIX/11. I have used this operating system on several 11/23 systems, and have not been disappointed with the performance or abilities of VENIX/11. VENIX/11 is a mixture of V6, V7 and Berkley UNIX. The filesystems are formated in the V6 style, with inodes of 32 bytes each instead of the V7 style of 64 bytes each. This difference is only of concern at boot time, file transfers can be handled by 'tar' or some other utility that uses it's own file format. VENIX/11 has it's kernel code re-written from 'C' source to PDP11 assembler. This has the advantage of producing a small (56KB) and fast kernel, but source is not available from Venturcom. I have seen several schemes used to 'overlay' the various sections of standard V7 UNIX on an 11/23. They all have performed poorly in terms of execution speed and certain versions had trouble with the memory management, causing very strange crashes! VENIX/11 allows the user to 'lock' I/O intensive processes in memory for 'real time' performance. The utilities provided with VENIX/11 are fairly complete. The 'vi' editor is not available, since 'vi' requires a lot of memory space for data and the 11/23 does not have separate I and D space. The screen editor supplied with VENIX/11 is called 'ice'. This is a simple editor that expects a VT-52 type terminal. The source for 'ice' is part of the VENIX/11 distribution package, so modifications could be made for use with other terminals. Source is provided for a large range of standard DEC peripherals, RL/RK disk drives, DL and DZ serial boards, etc. Source is also provided for c.c (device switch table) and l.s (interrupt vectors). Since the person who requested this information mentioned that the system would be used at home, I would recommend investigating using VENIX/11 with a non DEC standard disk system. I have source for a disk driver that is based upon the Data Technologies SASI interface and ST-506 disk controllers for the LSI 11. A 20 MB disk subsystem could be constructed for about $1800. The DTC boards are available from Shugart through Hamilton Avnet. I paid $550 for the set that I am currently using. Certain of the utility programs that are dependant on the filesystem layout have names that are different from V7. As an example, 'fsck' on V7 expects V7 filesystems (not V6) and uses the kernel file '\unix' for info of the filesystems to be checked. The VENIX/11 version of this utility is called 'fcheck', and uses the kernel file '/venix'. I consider these minor variations on the utility names to be only a minor inconvienience. It does make it clear which utilities have been changed, however. While the VENIX/11 package can be purchased directly from Venturcom, the price is in the $2000 range. Cambridge Digital was willing to sell the package to my former employers for around $1200. This price may or may not be discounted because of the purchase of the hardware along with VENIX/11. Of course, the above thoughts are purely my own and do not reflect the feelings of my current or past employers in any way. Some of the words I have used that cannot be found in a dictionary, and all of the words in uppercase, are trademarks of assorted companies. Douglas Bonnell "the problem's plain to see, too much technology"
guy@rlgvax.UUCP (06/25/84)
> Certain of the utility programs that are dependant on the filesystem > layout have names that are different from V7. As an example, 'fsck' on V7 > expects V7 filesystems (not V6) and uses the kernel file '\unix' for info > of the filesystems to be checked. The VENIX/11 version of this utility is > called 'fcheck', and uses the kernel file '/venix'. I consider these minor > variations on the utility names to be only a minor inconvienience. It does > make it clear which utilities have been changed, however. Actually, "fcheck" was a program that came with PWB/UNIX - a V6 descendant - written by Hal Pierson, formerly of BTL and now of CCI Office Systems Group; Ted Kowalski modified it for the V7 filesystem to make "fsck" (just wanted to give credit where credit was due!). "fsck" does some checks which "fcheck" didn't do, so unless Venturcom put those checks into their "fcheck" it won't quite catch as many problems as "fsck" does. (Be warned; PWB/UNIX changed the V6 file system not to support doubly-indirect blocks (which cut the maximum file size to 1MB, a "feature" propagated in the V7-based USG versions which enforce this by setting the file size limit to 1MB. Bleah!), but "fcheck" supports the original V6 file system. If you try to use "fcheck" on a system with 8 singly-indirect blocks, change it.) Also, the "lost+found" directory for putting orphaned file into was an "fsck" "innovation" (actually, the DEC Files-11 equivalents of "fsck" have done it for ages). The name of the kernel executable image changes every time somebody ports UNIX, so that's par for the course (it's been called "/xenix", "/perpos", "/vmunix", and probably at least 10 other things). Guy Harris {seismo,ihnp4,allegra}!rlgvax!guy