6502 EMULATOR EHBASIC MAC OS
6502 EMULATOR EHBASIC SERIAL
6502 EMULATOR EHBASIC CODE
6502 EMULATOR EHBASIC SERIES

The list (msbasic.lst) file is not copied and is overwritten when the next platform is built. After each platform is built, the resulting bin and lbl files are copied to the tmp directory. I changed the original make.shВ build script to enable a detailed assembly listing of each variant of BASIC.Д«y default, the script builds for all the platforms. This is again a jmp to the actual warm start routine. The warm start entry point is 3 bytes after the start of the binary image. This is a jmp to the actual cold start entry point. The BASIC entry point is now at the start of the BASIC binary image. To make this change, I added the following to the header.s file: I used the same approach with my port of Enhanced BASIC.

On the other hand, the RC2014 Z80 MS BASIC puts the cold start entry point at the start of the binary image.

6502 EMULATOR EHBASIC CODE

Every time after making a code change, I had to look in the osi.lbl file to find the address of the COLD_START routine.

There is no fixed entry point to MS BASIC. Now that I had everything building and actually running, the next step was to make it all easier to use. I added an OSI build condition to the INLINAIM routine to check for a backspace character. The last functional fix was in inline.sВ to enable the use of the backspace key for editing. When I have time, I'll dig into this a little further. What worked was a change in osi_iscntc.s to call MONISCNTC as a subroutine vs a jmp. I tried porting over Grant Searle's implementation of the ISCNTC routine but that didn't work either. We call the non-blocking check_input BIOS API at $ff06 and if there is a keypress, check if it is $03.Дefining MONISCNTC itself did not enable the use of CTRL-C to break a program. This is a routine to check if CTRL-C has been pressed while a BASIC program is running. While I was doing that, I added a definition for MONISCNTC. To fix the problem, I added the following:ДЄnd of course I needed to actually write the LOAD/SAVE routines, which were easy to do (!!):

6502 EMULATOR EHBASIC SERIES

This was pulled into the build process in a series of conditional compile statements in the loadsave.s file. In the more customized versions of MS BASIC, a _loadsave.s file was used to define the LOAD and SAVE routines. The next errors I hit were the undefined functions: LOAD and SAVE. feature force_range was undefined in the version of cc65 that I am using. Unlike EhBASIC, the OSI build of MS BASIC fits under 8KB, so you can change the size from $2400 to $2000ДЄfter setting up osi.cfg and defines_osi.c, I ran an initial build and hit an error. For example, if you are replacing EhBASIC on a 6502 RC2014 system, you can set the value to $c100 (current EhBASIC start address). If you are planning to burn the BASIC image into ROM, you will need to set this value to the start address of where the image will be sitting. BASROM is set to $5000 which is in RAM: I load the binary to RAM for testing. The osi.cfg file defines where in memory the BASIC will reside.

6502 EMULATOR EHBASIC SERIAL

Remember that the $300 page is used by the Monitor/Debugger.ДЇinally, the serial input/output routines ( MONRDKEY and MONCOUT) point to the BIOS entry points. RAMSTART2В is set to the beginning of usable RAM at $400. To get the 'latest/greatest', I used CONFIG_2A to build for MS BASIC 2. The original OSI BASIC was based on MS BASIC 1. So back to 6-digit floating point instead. I started off using CONFIG_SMALL := 0 to use 9-digit floating point but found it to be very slow. You will also customize for your hardware and BIOS entry points here. The first level change is in the defines_osi.s file where you can enable or disable features. I decided to use the Ohio Scientific (OSI) configuration as the starting point for the adaptation. My fork of the MS BASIC source code is on GitHub here. If you haven't seen it yet, I had previously also described the port of Lee Davison's Enhanced BASIC in this article. To recap, you probably want to look at this archeological analysisВ of MS BASIC for the 6502. Today, I'll go through the details of the source code modifications to build a version of MS BASIC for the 6502 RC2014 system.

6502 EMULATOR EHBASIC MAC OS

My last articleВ covered building the cc65 cross-compiler for use with Mac OS X.

6502 emulator ehbasic