This post is part of the series on Learning the Data General Nova with simh.
RDOS keeps an open count for each file. That’s not unusual. What is unusual is that it keeps that count on disk. I’m not sure why. Can two Nova CPUs can access the same physical disk concurrently? That would be one reason to keep use counts on disk.
Use counts after a normal start
Let’s start the simulation as above, and then use the LIST command to see some files:
R
list/e
...
BACKUP. 978 D 05/30/85 21:05 05/31/85 [005011] 0
CLI.S0 0 D 12/07/115 11:45 12/07/115 [005015] 1
CLI.SV 11264 SD 05/02/85 20:05 05/31/85 [000206] 0
OVLDR.SV 7168 SD 05/02/85 21:33 05/31/85 [001316] 0
CLI.ER 3584 D 05/02/85 20:05 12/07/115 [000377] 1
ASM.SV 10240 SD 05/01/85 18:59 05/31/85 [001647] 0
ENPAT.SV 3584 SD 05/02/85 21:35 05/31/85 [002053] 0
NSID.SR 793 D 10/20/83 20:44 05/31/85 [002165] 0
CLI.OL 50176 C 05/02/85 20:05 12/07/115 [000235] 1
MCABOOT.SV 5120 SD 05/08/85 10:28 05/31/85 [001127] 0
...
I gave the command as list/e, but it could have been given as LIST/E
just as well. RDOS is case insensitive.
The /E switch tells RDOS to list the dates and use counts for each
file. The last number on each line is the file’s use count.
Shut down improperly
Get the simh prompt using ^e, and then exit simh. This will simulation pulling the plug on the Nova:
R
^e
Simulation stopped, PC: 41741 (MOVZL# 1,1,SNC)
sim> quit
Goodbye
Now start simh/nova. During boot, RDOS will give you a warning indicating that there are non-zero use counts:
NOVA simulator V3.8-1
Filename?
Partition in use - Type C to continue
continue
NOVA RDOS Rev 7.50
Date (m/d/y) ? 12/7/2015
Time (h:m:s) ? 12:24:24
R
Let’s see the counts
R
list/e
...
OVLDR.SV 7168 SD 05/02/85 21:33 05/31/85 [001316] 0
CLI.ER 3584 D 05/02/85 20:05 12/07/115 [000377] 2
ASM.SV 10240 SD 05/01/85 18:59 05/31/85 [001647] 0
ENPAT.SV 3584 SD 05/02/85 21:35 05/31/85 [002053] 0
NSID.SR 793 D 10/20/83 20:44 05/31/85 [002165] 0
CLI.OL 50176 C 05/02/85 20:05 12/07/115 [000235] 2
MCABOOT.SV 5120 SD 05/08/85 10:28 05/31/85 [001127] 0
...
No use count should be greater than 1 right now, so things are not right.
Clearning use counts
Let’s use the CLEAR command to clear the use counts:
R
clear/a/d/v
CLEARED $TTI.
CLEARED $PTP.
CLEARED $PTR.
CLEARED $TTO.
CLEARED $TTP.
CLEARED $TTR.
CLEARED $LPT.
CLEARED SYS.DR
clear/a/d/v clears most files, but not all of them. Most notably:
R
list/e cli.-
CLI.S0 0 D 12/07/115 12:25 12/07/115 [005015] 1
CLI.SV 11264 SD 05/02/85 20:05 05/31/85 [000206] 0
CLI.ER 3584 D 05/02/85 20:05 12/07/115 [000377] 2
CLI.OL 50176 C 05/02/85 20:05 12/07/115 [000235] 2
CLI.CM 131 D 12/14/95 16:20 12/14/95 [005055] 0
We have to name these files explicitly to clear their use counts:
R
CLEAR/V CLI.S0 CLI.ER CLI.OL
CLEARED CLI.S0
CLEARED CLI.ER
CLEARED CLI.OL
R
list/e cli.-
CLI.S0 0 D 12/07/115 12:25 12/07/115 [005015] 0
CLI.SV 11264 SD 05/02/85 20:05 05/31/85 [000206] 0
CLI.ER 3584 D 05/02/85 20:05 12/07/115 [000377] 0
CLI.OL 50176 C 05/02/85 20:05 12/07/115 [000235] 0
CLI.CM 131 D 12/14/95 16:20 12/14/95 [005055] 0
The use counts have been reset, but they are now wrong: Some of the files we’ve cleared the use count on are actually in use (certain of the CLI.- files). The use count is used to prevent modification or deletion of a file that is in use, so as long as we leave those alone, it seems to me that there should be no harm in leaving their use counts incorrect set to 0. I don’t know for sure.
Normal shutdown and restart
A normal shutdown and reboot would return the counts to their normal values, so let’s try it:
release dp0
MASTER DEVICE RELEASED
We then exit simh and reboot (not shown), and see:
NOVA simulator V3.8-1
Filename?
NOVA RDOS Rev 7.50
Date (m/d/y) ? 12/7/2015
Time (h:m:s) ? 12:47:40
R
There was no “PARTITION” warning, which is good. Let’s check those use counts:
R
LIST CLI.ER CLI
...
OVLDR.SV 7168 SD 05/02/85 21:33 05/31/85 [001316] 0
CLI.ER 3584 D 05/02/85 20:05 12/07/115 [000377] 1
ASM.SV 10240 SD 05/01/85 18:59 05/31/85 [001647] 0
ENPAT.SV 3584 SD 05/02/85 21:35 05/31/85 [002053] 0
NSID.SR 793 D 10/20/83 20:44 05/31/85 [002165] 0
CLI.OL 50176 C 05/02/85 20:05 12/07/115 [000235] 1
MCABOOT.SV 5120 SD 05/08/85 10:28 05/31/85 [001127] 0
...
Note: The clear command will need to be issued on every partition and directory that was “initialized” (mounted) at the time the system was improperly shut down. We didn’t have any directories initialized, so didn’t need to do that.
References
RDOS/DOS Command Line Interpreter User’s Manual
- p. 4-17 -
CLEARcommand - p. 4-42 -
LISTcommand