RT11 sysgen and disk partitions

Jerome H. Fine jhfinexgs2 at compsys.to
Mon Mar 7 22:34:54 CST 2005

 >Vintage Computer Festival wrote:

>>On Mon, 7 Mar 2005, Adrian Graham wrote:
>>Isn't that something to do with using DUX.SYS instead of DU.SYS or am I
>>getting confused with RT11XM and something like RT11SJ? It's been 16 or 17
>>years since I last sysgenned an RT11 box :-\
>What's the difference between RT11XM and RT11SJ?  What do the last two
>letter signify?
Jerome Fine replies:

Names of distributed RT-11 monitors for V04.00 to V05.05 with
V05.06 and V05.07 using RT11SB (Single Background) instead of

UnMapped - Device drivers are dd.SYS
RT11AI  -  Used only for Auto Installation
RT11BL  -  (Base Line) Allows only a Background job (a bit smaller than RT11SJ)
RT11SJ  -  (Single Job) Allows only a Background job
RT11FB  -  (Foreground Background) Allows both a Foreground and Background job

The RT11FB monitor can have system jobs using a SYSGEN.

UnMapped monitors use only the lower 56 KBytes of real physical
memory (there are some exceptions, but normally not for user programs)
with the Resident Monitor using about the top 8 KBytes and the USR
using 4 KBytes (can be SWAPped) just below the LOADed device drivers.
There is lower overhead with an UnMapped monitor and more lower memory
available for user jobs.

Mapped - Device drivers are ddX.SYS
RT11XM  -  (eXtended Memory) Allows both a Foreground and a Background job
           more recent versions also allow system jobs

Mapped monitors allow both the lower 56 KBytes of real physical
memory and extended memory (up to 256 KBytes on V04.00 and 4 MBytes
on V05.0x) as it is available.  The big disadvantage is the reduced
amount of lower (the remainder of the lower 56 KBytes especially with
the USR being NOSWAP) memory for user programs.  The big advantage
is the trivial availability of extended memory for user programs
(which do not need an ISR or the use of the IOPAGE) via the use of
the program VBGEXE which provides the user program with a full
64 KBytes of memory.

Multi-terminal support is always a SYSGENed option.

Any more questions?

I will attempt to discuss disk partitions tomorrow!

Sincerely yours,

Jerome Fine
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