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MicroVAX 3900: Add memory details to HELP CPU

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This commit is contained in:
Mark Pizzolato
2022-06-15 12:05:15 -07:00
parent 1a02b4df26
commit 3660b587f6
1 changed files with 16 additions and 0 deletions
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16
VAX/vax_sysdev.c
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@@ -1884,6 +1884,22 @@ fprintf (st, " AUTOGEN (SYS$SYSTEM:MODPARAMS.DAT). If PHYSICALPAGES is specifi
fprintf (st, " it will have to be adjusted before running AUTOGEN to recognize more memory.\n");
fprintf (st, " The default value for PHYSICALPAGES is 1048576, which describes 512MB of RAM.\n\n");
fprintf (st, "Initial memory size is 16MB.\n\n");
fprintf (st, "The real KA655 is limited to 64MB of memory, and the KA655 firmware is\n");
fprintf (st, "coded to this limit. However, the VAX operating systems (VMS, Ultrix,\n");
fprintf (st, "NetBSD) know very little about the hardware details. Instead, they take\n");
fprintf (st, "their memory size information from the Restart Parameter Block (RPB)\n");
fprintf (st, "constructed by the console firmware when it starts. If the firmware sets\n");
fprintf (st, "up an RPB for more than 64MB, the operating systems use the extra memory\n");
fprintf (st, "without requiring source changes.\n\n");
fprintf (st, "If more than 64MB of memory is configured, the simulator implements an 18th\n");
fprintf (st, "CMCTL register. This read-only register gives the size of main memory in MB.\n");
fprintf (st, "The console firmware (ka655x.bin) uses this to set up the RPB. Other parts\n");
fprintf (st, "of the firmware are generally unaware of extended memory; thus, all the\n");
fprintf (st, "diagnostic commands operate only on the first 64MB of memory. However the\n");
fprintf (st, "console SHOW MEM command will display the total amount of memory the simulator\n");
fprintf (st, "is configured with.\n\n");
fprintf (st, "If 64MB or less of memory is configured, the 18th CMCTL register is invisible,\n");
fprintf (st, "and the simulator operates like a real KA655.\n\n");
fprintf (st, "The CPU supports the BOOT command and is the only VAX device to do so. Note\n");
fprintf (st, "that the behavior of the bootstrap depends on the capabilities of the console\n");
fprintf (st, "terminal emulator. If the terminal window supports full VT100 emulation\n");