cc65/doc/osi.sgml

<!doctype linuxdoc system>

<article>

<title>Ohio Scientific-specific information for cc65
<author>
<url url="mailto:stephan.muehlstrasser@web.de" name="Stephan M&uuml;hlstrasser"><newline>
<date>2015-02-04

<abstract>
An overview over the Ohio Scientific runtime system as it is implemented for the cc65 C
compiler.
</abstract>

<!-- Table of contents -->
<toc>

<!-- Begin the document -->

<sect>Overview<p>

This file contains an overview of the Ohio Scientific runtime system as it comes with the
cc65 C compiler. It describes the memory layout, Ohio Scientific-specific header files,
and any pitfalls specific to that platform.

Please note that Ohio Scientific-specific functions are just mentioned here, they are
described in detail in the separate <url url="funcref.html" name="function
reference">. Even functions marked as "platform dependent" may be available on
more than one platform. Please see the function reference for more
information.

<sect>Targets<p>

Currently the target "osic1p" is implemented. This works for the Ohio Scientific
Challenger 1P machine.

<sect>Binary format<p>

The standard binary output format generated by the linker for the osic1p target
is a machine language program.<p>

For uploading into a real machine over the serial port or into an emulator a
program must be converted to a text file that is understood by the 65V PROM
monitor. For this purpose the srec_cat program from the
<url url="http://srecord.sourceforge.net/" name="SRecord">
tool collection can be used.

Care must be taken that the -offset and -execution-start-address options for the srec_cat
program correspond to the start address of the executable.

Example for converting an executable "hello" that was built for the default
start address &dollar;0200 to an uploadable file "hello.c1p":

<tscreen>
srec_cat hello -binary -offset 0x200 -o hello.c1p -Ohio_Scientific -execution-start-address=0x200
</tscreen>

<sect>Memory layout<p>

By default programs compiled for the osic1p target are configured for 32 kB RAM.
The RAM size can be configured via the symbol __HIMEM__.

Special locations:

<descrip>
  <tag/Program start address/
  The default start address is &dollar;0200. The start address is configurable
  via the compiler option --start-addr.

  <tag/Stack/
  The C runtime stack is located at the top of RAM and growing downwards.
  The size is configurable via the symbol __STACKSIZE__. The default
  stack size is &dollar;0400.

  <tag/Heap/
  The C heap is located at the end of the program and grows towards the C
  runtime stack.

  <tag/Video RAM/
  The 1 kB video RAM is located at &dollar;D000. On the monitor only a subset
  of the available video RAM is visible. The address of the upper left corner
  of the visible area is &dollar;D085 and corresponds to conio cursor
  position (0, 0).

</descrip><p>

Example for building a program with start address &dollar;0300, stack size
&dollar;0200 and RAM size &dollar;2000:

<tscreen>
cl65 --start-addr 0x300 -Wl -D,__HIMEM__=$2000,-D,__STACKSIZE__=$0200 -t osic1p hello.c
</tscreen>

<sect>Linker configurations<p>

The ld65 linker comes with a default config file "osic1p.cfg" for the Ohio Scientific
Challenger 1P, which is implicitly used via <tt/-t osic1p/. The
osic1p package comes with additional secondary linker config files, which are
used via <tt/-t osic1p -C &lt;configfile&gt;/.

<sect1>default config file (<tt/osic1p.cfg/)<p>

The default configuration is tailored to C programs.

<sect1><tt/osic1p-asm.cfg/<p>

This configuration is made for assembler programmers who don't need a special
setup.

To use this config file, assemble with <tt/-t osic1p/ and link with
<tt/-C osic1p-asm.cfg/. The former will make sure that correct runtime library
is used, while the latter supplies the actual config. When using <tt/cl65/,
use both command line options.

Sample command line for <tt/cl65/:

<tscreen><verb>
cl65 -o program -t osic1p -C osic1p-asm.cfg source.s
</verb></tscreen>

<sect>Platform-specific header files<p>

Programs containing Ohio Scientific-specific code may use the <tt/osic1p.h/ 
header file. 

<sect1>Ohio Scientific-specific functions<p>

There are currently no special Ohio Scientific functions.

<sect1>Hardware access<p>

There is no specific support for direct hardware access.

<sect>Loadable drivers<p>

There are no loadable drivers available.

<sect>Limitations<p>

<sect1>conio implementation<p>

The conio implementation is complete except for the kbhit() function. A
call to cgetc() always blocks until a character is entered.

<sect1>stdio implementation<p>

There is no support for stdio at the moment.

<sect>Other hints<p>

<sect1>Passing arguments to the program<p>

There is currently no support for passing arguments to a program.

<sect1>Program return code<p>

The program return code currently has no effect. When the main() function
finishes, the boot prompt is shown again.

<sect>License<p>

This software is provided 'as-is', without any expressed or implied
warranty.  In no event will the authors be held liable for any damages
arising from the use of this software.

Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:

<enum>
<item>	The origin of this software must not be misrepresented; you must not
	claim that you wrote the original software. If you use this software
	in a product, an acknowledgment in the product documentation would be
	appreciated but is not required.
<item>	Altered source versions must be plainly marked as such, and must not
	be misrepresented as being the original software.
<item>	This notice may not be removed or altered from any source
	distribution.
</enum>

</article>