RIM Loader for SIMH

Discussion:

RIM Loader for SIMH

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Lawrence D'Oliveiro

2009-02-24 20:30:05 UTC

Command sequence for simh-pdp8 to load the RIM loader into its usual
location (save to a file and use simh's "do" command to execute):

d 7756 6032
d 7757 6031
d 7760 5357
d 7761 6036
d 7762 7106
d 7763 7006
d 7764 7510
d 7765 5357
d 7766 7006
d 7767 6031
d 7770 5367
d 7771 6034
d 7772 7420
d 7773 3776
d 7774 3376
d 7775 5356
d 7776 0
d 7777 0

Haven't tested it, but the disassembly looks right:

sim> e -m 7756-7775
7756: KCC
7757: KSF
7760: JMP 7757
7761: KRB
7762: CLL RTL
7763: RTL
7764: SPA
7765: JMP 7757
7766: RTL
7767: KSF
7770: JMP 7767
7771: KRS
7772: SNL
7773: DCA I 7776
7774: DCA 7776
7775: JMP 7756

Don North

2009-02-25 06:13:26 UTC

Permalink

You are aware that SIMH does have a builtin RIM loader, just load
a tape image with the -r switch (or .rim extension) to select it,
otherwise the BIN mode loader is selected.

Post by Lawrence D'Oliveiro
Command sequence for simh-pdp8 to load the RIM loader into its usual
d 7756 6032
d 7757 6031
d 7760 5357
d 7761 6036
d 7762 7106
d 7763 7006
d 7764 7510
d 7765 5357
d 7766 7006
d 7767 6031
d 7770 5367
d 7771 6034
d 7772 7420
d 7773 3776
d 7774 3376
d 7775 5356
d 7776 0
d 7777 0
sim> e -m 7756-7775
7756: KCC
7757: KSF
7760: JMP 7757
7761: KRB
7762: CLL RTL
7763: RTL
7764: SPA
7765: JMP 7757
7766: RTL
7767: KSF
7770: JMP 7767
7771: KRS
7772: SNL
7773: DCA I 7776
7774: DCA 7776
7775: JMP 7756

cjl

2009-03-05 08:52:06 UTC

Permalink

If a binary file is suitably formatted, it can be loaded in either BIN
or RIM format. All that is needed is an extra origin setting at the
end. If the file is created as a BIN file, the "data" for the out-of-
bounds last origin becomes the file checksum that BIN requires.

In essence, the source file just has to have origin settings in front
of each and every word. This trick has appeared in more than a few
source files from the diagnostics group. [I forget which file I first
saw it used in; literally every other source line in the file was an
origin setting redundant to where it already was, etc.] [In essence,
use ""*." statements in front of each and every code-generating source
line.]

The P?S/8 BIN utility has /R options to handle RIM format. In
actuality, it does the above so the dual compatibility is present.
You never know when you have the BIN loader and not the RIM loader.
Perhaps the RIM loader is for the wrong hardware [say low-speed
instead of high-speed] while the standard BIN loader uses the switch
register to choose between hardware types, thus can never be the wrong
choice.

Thus, P?S/8 binary files can be punched to either the low or high-
speed punch. Specifying /R at the time outputs the "enhanced" RIM
format as described; the resulting paper-tape can be loaded with any
of the standard loaders.

The RIM loader has no checksumming, so it's all cross-your-fingers.
The BIN loader can complain about a detected checksum error. Thus, if
the paper-tape is in this format, you can use the BIN loader to
confirm the tape has a chance of being read in later via a RIM loader,
etc.

cjl

Post by Don North
You are aware that SIMH does have a builtin RIM loader, just load
a tape image with the -r switch (or .rim extension) to select it,
otherwise the BIN mode loader is selected.

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