Configuring Low Memory VAX/VMS Systems
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Current versions of the simh VAX780 simulator do not allow memory configurations below 8M.

There is a simple workaround for VMS if you want to go lower than the simh limit:

Do a conversational boot, e.g.:

BOOT RQ0/R5:1

At the SYSBOOT> prompt enter your memory limit (in pages of 512 byte) and tell VMS to proceed:

SYSBOOT> SET PHYSICALPAGES 4096
SYSBOOT> CONTINUE

This for example will give you 4096 pages = 2MB of memory.

Mind the absolute VMS minimum requirements:

VMS V1.0: 256KB
VMS V1.6: 256KB
VMS V2.0: 256KB
VMS V3.5: 512KB
VMS V4.2: 1MB
VMS V4.3: 1MB
VMS V4.7: 2MB
VMS V5.4: 2MB




