From: Paul Koning Sent: Monday, November 23, 2015 11:26 AM >> On Nov 23, 2015, at 1:00 PM, Johnny Billquist <b...@update.uu.se>> wrote:
>> As far as I can tell, disks fall into two groups, as far as massbus control >> is concerned. The RM02, RM03, RM05, RM80 and RP07 is one group. The RP04, >> RP05, RP06 is another. A few register addresses between the groups are the >> same, but the actual register at that address is different. But if I >> remember right, it's registers that have to do with error recovery, so >> potentially not something people would care about in emulation anyway. But >> it still means there are different drivers in the OS for them. [snip] >> And of course, you also have the TM02/TM03 and TM78, which have yet again >> different registers on the massbus. > Yes. And mixing disk and tape on a massbus is something that I don't think > was done on PDP-11s. It certainly could have been done, and it was on VMS > and/or TOPS if I remember right. Two things. 1) There is not such things as "TOPS". The 2 operating systems for the PDP-10 provided by DEC are Tops-10 and TOPS-20. The only thing they have in common is the first 4 letters (modulo case) of the names. They share exactly no code in the monitor ("kernel"), and do not even have the same origins. Tops-10 started as the monitor on the PDP-6, in 1964, and was in continuous development until 1988 (and in maintenance until 1993+), while TOPS-20 began life as the TENEX operating system from BBN c. 1969, licensed for the new KL-10 processor while that was under development. TOPS-20 v1 appeared in 1975. BBN developed a run time package for TENEX called PA1050 which handled a subset of the Tops-10 system calls by merging into user-mode programs and intercepting them; DEC carried on the same mechanism to allow Tops-10 compilers and other utilities to run on the new OS while native versions were developed. 2) Having stated all that, Tops-10 does not allow mixing tapes and disks on a channel, but it does allow mixing disk drive types. TOPS-20 has always allowed mixing tapes and disks on a channel. Rich Rich Alderson Vintage Computing Sr. Systems Engineer Living Computer Museum 2245 1st Avenue S Seattle, WA 98134 mailto:ri...@livingcomputermuseum.org http://www.LivingComputerMuseum.org/