1 <!doctype linuxdoc system>
5 <title>Commodore 128-specific information for cc65
6 <author><url url="mailto:uz@cc65.org" name="Ullrich von Bassewitz">,<newline>
7 <url url="mailto:polluks@sdf.lonestar.org" name="Stefan A. Haubenthal">
11 An overview over the C128 runtime system as it is implemented for the cc65 C
15 <!-- Table of contents -->
18 <!-- Begin the document -->
22 This file contains an overview of the C128 runtime system as it comes with the
23 cc65 C compiler. It describes the memory layout, C128-specific header files,
24 available drivers, and any pitfalls specific to that platform.
26 Please note that C128-specific functions are just mentioned here, they are
27 described in detail in the separate <url url="funcref.html" name="function
28 reference">. Even functions marked as "platform dependent" may be available on
29 more than one platform. Please see the function reference for more
33 <sect>Binary format<p>
35 The standard binary output format generated by the linker for the C128 target
36 is a machine language program with a one line BASIC stub, which calls the
37 machine language part via SYS. This means that a program can be loaded as
38 BASIC program and started with RUN. It is of course possible to change this
39 behaviour by using a modified startup file and linker config.
42 <sect>Memory layout<p>
44 cc65 generated programs with the default setup run with the I/O area and the
45 kernal ROM enabled. Note that this is a non standard memory layout, and that
46 there is no "memory configuration index" for this layout. This means that
47 special care has to be taken when changing the configuration, or calling any
48 code that does this. The memory configuration register at $FF00 should
49 be saved and restored instead of relying on the memory configuration index
50 stored in the zero page.
52 The setup gives a usable memory range of $1C00 - $BFFF. Having
53 just the kernal ROM mapped in means, that kernal entry points may be called
54 directly, but using the BASIC ROM is not possible without additional code.
60 The text screen is located at $400 (as in the standard setup).
63 The C runtime stack is located at $BFFF, and growing downwards.
66 The C heap is located at the end of the program, and grows towards the C
73 <sect>Platform-specific header files<p>
75 Programs containing C128-specific code may use the <tt/c128.h/ or <tt/cbm.h/
76 header files. Using the later may be an option when writing code for more than
77 one CBM platform, since it includes <tt/c128.h/ and declares several functions
78 common to all CBM platforms.
81 <sect1>C128-specific functions<p>
83 The functions listed below are special for the C128. See the <url
84 url="funcref.html" name="function reference"> for declaration and usage.
92 <sect1>C128-specific accelerator functions<p>
94 The functions listed below are accelerator functions for the C128. See the <url
95 url="funcref.html" name="function reference"> for declaration and usage.
107 <sect1>CBM-specific functions<p>
109 Some functions are available for all (or at least most) of the Commodore
110 machines. See the <url url="funcref.html" name="function reference"> for
111 declaration and usage.
141 <sect1>CBM specific CPU functions<p>
143 Some CPU related functions are available for some of the Commodore
144 machines. See the <url url="funcref.html" name="function reference"> for
145 declaration and usage.
154 <sect1>Hardware access<p>
156 The following pseudo variables declared in the <tt/c128.h/ header file do
157 allow access to hardware located in the address space. Some variables are
158 structures, accessing the struct fields will access the chip registers.
163 The <tt/VIC/ structure allows access to the VIC II (the graphics
164 controller). See the <tt/_vic2.h/ header file located in the include
165 directory for the declaration of the structure.
168 The <tt/SID/ structure allows access to the SID (the sound interface
169 device). See the <tt/_sid.h/ header file located in the include directory
170 for the declaration of the structure.
173 The <tt/VDC/ structure allows access to the VDC (the video display
174 controller). See the <tt/_vdc.h/ header file located in the include
175 directory for the declaration of the structure.
177 <tag><tt/CIA1, CIA2/</tag>
178 Access to the two CIA (complex interface adapter) chips is available via
179 the <tt/CIA1/ and <tt/CIA2/ variables. The structure behind these variables
180 is explained in <tt/_6526.h/.
182 <tag><tt/COLOR_RAM/</tag>
183 A character array that mirrors the color RAM of the C128 at $D800.
189 <sect>Loadable drivers<p>
191 The names in the parentheses denote the symbols to be used for static linking of the drivers.
194 <sect1>Graphics drivers<p>
196 The default drivers, <tt/tgi_stddrv (tgi_static_stddrv)/, point to <tt/c128-vdc.tgi (c128_vdc_tgi)/.
198 Note: The graphics drivers for the VDC are incompatible with the extended
199 memory drivers using the VDC memory!
203 <tag><tt/c128-hi.tgi (c128_hi_tgi)/</tag>
204 This driver features a resolution of 320×200 with two colors and an
205 adjustable palette (that means that the two colors can be chosen out of a
206 palette of the 16 VIC colors). Unlike BASIC 7.0, this driver puts its
207 graphics data into the RAM behind the ROMs.
209 <tag><tt/c128-vdc.tgi (c128_vdc_tgi)/</tag>
210 This driver was written by Maciej Witkowiak. It uses the 80-column display,
211 and features a resolution of 640×200 with two colors and an adjustable
212 palette (that means that the two colors can be chosen out of the 16 VDC
215 <tag><tt/c128-vdc2.tgi (c128_vdc2_tgi)/</tag>
216 This driver was written by Maciej Witkowiak. This driver uses the 80-column
217 display, and features a resolution of 640×480 with two colors and an
218 adjustable palette (that means that the two colors can be chosen out of the
219 16 VDC colors). The driver requires 64KB VDC RAM.
223 Note: The colors are translated from the definitions in the headers to correct
224 VDC values; so, please use definitions or VIC color numbers only. Colors
225 <tt/GRAY3/ and <tt/BROWN/ are missing on the VDC; and, are translated to the
226 two colors missing from the VIC palette.
229 <sect1>Extended memory drivers<p>
233 <tag><tt/c128-efnram.emd (c128_efnram_emd)/</tag>
234 Extended memory driver for the C128 External Function RAM.
235 Written and contributed by Marco van den Heuvel.
237 <tag><tt/c128-georam.emd (c128_georam_emd)/</tag>
238 A driver for the GeoRam cartridge. The driver will always assume 2048 pages
239 of 256 bytes each. There are no checks, so if your program knows better,
242 <tag><tt/c128-ifnram.emd (c128_ifnram_emd)/</tag>
243 Extended memory driver for the C128 Internal Function RAM.
244 Written and contributed by Marco van den Heuvel.
246 <tag><tt/c128-ram.emd (c128_ram_emd)/</tag>
247 An extended memory driver for the RAM in page 1. The common memory area is
248 excluded, so this driver supports 251 pages of 256 bytes each.
250 <tag><tt/c128-ram2.emd (c128_ram2_emd)/</tag>
251 An extended memory driver for the RAM in pages 1-3. The common memory area
252 is excluded, so this driver supports up to 731 pages of 256 bytes each. The
253 driver can be used as a full replacement for <tt/c128-ram.emd/, because RAM
254 in pages 2+3 is autodetected, but it's larger and there are not many
255 machines with RAM in banks 2+3, so it has been made a separate driver. The
256 additional code was contributed by Marco van den Heuvel.
258 <tag><tt/c128-ramcart.emd (c128_ramcart_emd)/</tag>
259 A driver for the RamCart 64/128 written and contributed by Maciej Witkowiak.
260 Will test the hardware for the available RAM.
262 <tag><tt/c128-reu.emd (c128_reu_emd)/</tag>
263 A driver for the CBM REUs. The driver will test the connected REU to find
264 out how much RAM is present.
266 <tag><tt/c128-vdc.emd (c128_vdc_emd)/</tag>
267 A driver for the VDC memory of the C128, written and contributed by Maciej
268 Witkowiak. Autodetects the amount of memory available (16 or 64K), and offers
269 64 or 256 pages of 256 bytes each. Note: This driver is incompatible with
270 any of the graphics drivers using the VDC!
275 <sect1>Joystick drivers<p>
277 The default drivers, <tt/joy_stddrv (joy_static_stddrv)/, point to <tt/c128-stdjoy.joy (c128_stdjoy_joy)/.
281 <tag><tt/c128-ptvjoy.joy (c128_ptvjoy_joy)/</tag>
282 Driver for the Protovision 4-player adapter originally written by Groepaz
283 for the C64, and converted for the C128 by Uz. See <url
284 url="http://www.protovision-online.de/hardw/4_player.php?language=en"
285 name="Protovision shop"> for prices and building instructions. Up to four
286 joysticks are supported.
288 <tag><tt/c128-stdjoy.joy (c128_stdjoy_joy)/</tag>
289 Supports up to two joysticks connected to the standard joysticks ports of
296 <sect1>Mouse drivers<p>
298 The default drivers, <tt/mouse_stddrv (mouse_static_stddrv)/, point to <tt/c128-1351.mou (c128_1351_mou)/.
302 <tag><tt/c128-1351.mou (c128_1351_mou)/</tag>
303 Supports a standard mouse connected to port #0 of the C128.
305 <tag><tt/c128-inkwell.mou (c128_inkwell_mou)/</tag>
306 Supports the Inkwell Systems lightpens, connected to port #0 of the
307 C128. It can read both the one-button 170-C and the two-button 184-C pens.
308 (It can read other lightpens and light-guns that send their button signal to
309 the joystick left-button pin or the paddle Y [up/down] pin.) It works on
310 only the 40-column screen.
312 <tag><tt/c128-joy.mou (c128_joy_mou)/</tag>
313 Supports a mouse emulated by a standard joystick, e.g. 1350 mouse, in port
316 <tag><tt/c128-pot.mou (c128_pot_mou)/</tag>
317 Supports a potentiometer device, e.g. Koala Pad, connected to port #1 of
323 <sect1>RS232 device drivers<p>
327 <tag><tt/c128-swlink.ser (c128_swlink_ser)/</tag>
328 Driver for the SwiftLink cartridge. Supports up to 38400 BPS, hardware flow
329 control (RTS/CTS), and interrupt-driven receives. Note that, because of the
330 peculiarities of the 6551 chip, together with the use of the NMI, transmits
331 are not interrupt driven; and, the transceiver blocks if the receiver asserts
332 flow control because of a full buffer.
334 The driver uses the RS232 variables and buffers of the kernal (buffers at
335 $C00 and $D00).
348 <sect1>Passing arguments to the program<p>
350 Command-line arguments can be passed to <tt/main()/. Since this is not
351 supported directly by BASIC, the following syntax was chosen:
354 RUN:REM ARG1 " ARG2 IS QUOTED" ARG3 "" ARG5
358 <item>Arguments are separated by spaces.
359 <item>Arguments may be quoted.
360 <item>Leading and trailing spaces around an argument are ignored. Spaces within
361 a quoted argument are allowed.
362 <item>The first argument passed to <tt/main()/ is the program name.
363 <item>A maximum number of 10 arguments (including the program name) are
368 <sect1>Program return code<p>
370 The program return code (low byte) is passed back to BASIC by use of the
376 The runtime for the C128 uses routines marked as <tt/.INTERRUPTOR/ for
377 interrupt handlers. Such routines must be written as simple machine language
378 subroutines and will be called automatically by the interrupt handler code
379 when they are linked into a program. See the discussion of the <tt/.CONDES/
380 feature in the <url url="ca65.html" name="assembler manual">.
386 This software is provided 'as-is', without any expressed or implied
387 warranty. In no event will the authors be held liable for any damages
388 arising from the use of this software.
390 Permission is granted to anyone to use this software for any purpose,
391 including commercial applications, and to alter it and redistribute it
392 freely, subject to the following restrictions:
395 <item> The origin of this software must not be misrepresented; you must not
396 claim that you wrote the original software. If you use this software
397 in a product, an acknowledgment in the product documentation would be
398 appreciated but is not required.
399 <item> Altered source versions must be plainly marked as such, and must not
400 be misrepresented as being the original software.
401 <item> This notice may not be removed or altered from any source