Post by hydrophilic on Jun 9, 2014 21:50:17 GMT
BASIC 7.80 is a language extension for the Commodore 128. It makes all (well most) of the bitmap commands of v7.0 run on the 80-column (VDC) screen!
I know it is 30 years too late, and since there is already BASIC 8, you may be wondering why? I'll tell you. BASIC 8 syntax is 100% incompatible with BASIC 7. If you want to port a bitmap program from C16, Plus/4, or C128 (40-columns), then you will have a HUGE chore ahead of you, trying to translate the syntax. Also, BASIC 8 will crash if you attempt to use 40-column bitmap graphics. And the kludge BASIC 8 uses to implement new commands means that error trapping is also working differently (I would say "broken").
BASIC 7.80 does not add any new commands. It just makes existing v3.5 and v7.0 bitmap commands work on the VDC:
Download the BASIC 7.80 distribution here. It includes a D64 disk image with program BASIC 7.80; just RUN it. It will auto-boot if in drive 8 when the C128 is turned on. The BASIC 7.80 program is also included as a raw "prg" type file if you like to use hard drive / SD2IEC. It includes a ReadMe file in HTML format that should get you started, so I won't say a lot here, unless you have questions. It also includes the source code, in case you want to see how it works or try to add the missing features...
Things not working:
- Multi-color bitmap modes. The VDC can not display 4 colors in a single cell. You might be able to emulate this with interlace mode.
- Split-screen modes. The VDC has no raster interrupt. Should be possible with synchronized CIA interrupt.
- Sprites. The VDC has no hardware sprites. In bitmap mode, you could (slowly) emulate them in software. More tricky in text mode!
- Some colors. The VDC does not have medium gray or orange. I recommend substition of dark cyan and brown.
The download includes 4 BASIC programs that were rather simply converted from 40-column version. The mandelbrot program should not be tried unless you have SuperCPU or are prepared to let the software run for several hours!! Yes, BASIC 7.80 works fine with SuperCPU.
If you only have 16K VDC RAM, then only monochrome bitmap mode (GRAPHIC 6) is possible. With 64K VDC RAM, either monochrome or "standard" 8x8 color cells is possible (with GRAPHIC 8). A later version (7.81?) should add color for 16K user (at the cost of reduced bitmap size) and non-standard color cells (8x4, 8x2, etc.)
Thanks to Mirkosoft who motivated me to finish this, and also tested it on 64K V-RAM (I only have 16K).