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J.B. Langston
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@@ -40,7 +40,53 @@ Modernized sources:
- [Makefile](Makefile) is a GNU makefile that will build the supermon64.prg binary
using the above sources.
## Instructions
## Background
After working my way through Jim Butterfield's excellent book using his equally excellent monitor,
I wanted to find some real assembly code to study, and the software I had just been using seemed
like a natural place to start. I started looking for the sources online but for a piece of
public domain software, it wasn't as easy as to find as you'd think.
I found [this thread](http://comp.sys.cbm.narkive.com/KUAL6oqM/attn-jim-butterfiled-i-m-looking-for-supermon-64-source-code)
on comp.sys.cbm where someone asked for the sources and Jim Butterfield himself responded but
didn't have easy access to the sources. One person pointed to this
[modified version](http://www.ffd2.com/fridge/programs/supermon.s)
but I wanted the original. Someone else mentioned a file called SPRMON64.SDA at a now-defunct FTP
site. I googled for the filename and found what is apparently the last remaining copy on the internet
on a [gopher proxy](https://gopherproxy.meulie.net/sdf.org/1/users/rogertwo/prgs/cbm/c64/programming/).
I downloaded it and found that it contains what appear to be the original source and binaries
for the updated 1.2 version. Since it doesn't seem to have an official home and it's
continued availability on the internet seemed precarious, I decided to give it one on GitHub.
I have modernized the source code so it can be built using the
[64tass](https://sourceforge.net/projects/tass64/) cross-assembler. The original source
(included on the D64 image) was almost completely uncommented and used a few outdated constructs
that were unsupported by 64tass. I converted these to the equivalent modern constructs, indented the
code, and then worked my way through the code line-by-line until I understood it all, commenting
it as I went along.
As Jim noted in his usenet posting, the provided sources don't produce the final Supermon 64 binary:
>I should note that, since Supermon+64 is relocatable code, the source
does not assemble into the final binary file. It may seem crude, but
I follow this procedure: (1) The source is carefully structured so
that there are no "dispersed addresses" such as might be created with
something like LDA #>VECTOR .. LDY #<VECTOR - every relocatable
address is two adjacent bytes; (2) I assemble the source TWICE, to
two different page addresses; the only difference in the binaries will
be the high-order bytes of the relocatable addresses; (3) a small
post-processing program blends the two binaries into a relocatable
package, adding a Basic driver to complete the bundle.
Neither the sources for the relocator nor the post-processing program Jim refers to were included
in the self-dissolving archive, so I disassembled the original supermon64.prg binary and
reconstructed the relocator stub from that. I also wrote a simple python script that builds a
relocatable binary according to Jim's instructions above. I have confirmed that the
binary produced by assembling `supermon64.asm` and `relocator.asm` and then combining them using
`build.py` is identical to the original binary `supermon64.prg` provided in the archive.
## Usage Instructions
SUPERMON+ is a new version of 'SUPERMON'. The reason for the new
version is to provide identical commands to those of the built-in
@@ -336,52 +382,6 @@ be on your machine. Be sure to note the SYS command which links SUPERMON
to the Commodore. It may be used to reconnect the monitor if it is
accidentally disconnected by use of the run-stop/restore keys.
## Background
After working my way through Jim Butterfield's excellent book using his equally excellent monitor,
I wanted to find some real assembly code to study, and the software I had just been using seemed
like a natural place to start. I started looking for the sources online but for a piece of
public domain software, it wasn't as easy as to find as you'd think.
I found [this thread](http://comp.sys.cbm.narkive.com/KUAL6oqM/attn-jim-butterfiled-i-m-looking-for-supermon-64-source-code)
on comp.sys.cbm where someone asked for the sources and Jim Butterfield himself responded but
didn't have easy access to the sources. One person pointed to this
[modified version](http://www.ffd2.com/fridge/programs/supermon.s)
but I wanted the original. Someone else mentioned a file called SPRMON64.SDA at a now-defunct FTP
site. I googled for the filename and found what is apparently the last remaining copy on the internet
on a [gopher proxy](https://gopherproxy.meulie.net/sdf.org/1/users/rogertwo/prgs/cbm/c64/programming/).
I downloaded it and found that it contains what appear to be the original source and binaries
for the updated 1.2 version. Since it doesn't seem to have an official home and it's
continued availability on the internet seemed precarious, I decided to give it one on GitHub.
I have modernized the source code so it can be built using the
[64tass](https://sourceforge.net/projects/tass64/) cross-assembler. The original source
(included on the D64 image) was almost completely uncommented and used a few outdated constructs
that were unsupported by 64tass. I converted these to the equivalent modern constructs, indented the
code, and then worked my way through the code line-by-line until I understood it all, commenting
it as I went along.
As Jim noted in his usenet posting, the provided sources don't produce the final Supermon 64 binary:
>I should note that, since Supermon+64 is relocatable code, the source
does not assemble into the final binary file. It may seem crude, but
I follow this procedure: (1) The source is carefully structured so
that there are no "dispersed addresses" such as might be created with
something like LDA #>VECTOR .. LDY #<VECTOR - every relocatable
address is two adjacent bytes; (2) I assemble the source TWICE, to
two different page addresses; the only difference in the binaries will
be the high-order bytes of the relocatable addresses; (3) a small
post-processing program blends the two binaries into a relocatable
package, adding a Basic driver to complete the bundle.
Neither the sources for the relocator nor the post-processing program Jim refers to were included
in the self-dissolving archive, so I disassembled the original supermon64.prg binary and
reconstructed the relocator stub from that. I also wrote a simple python script that builds a
relocatable binary according to Jim's instructions above. I have confirmed that the
binary produced by assembling `supermon64.asm` and `relocator.asm` and then combining them using
`build.py` is identical to the original binary `supermon64.prg` provided in the archive.
## License
To the best of my knowledge, this software is in the public domain. I claim no ownership.