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REFERENCE DISC IMAGES (SSD)

Submitted by Steve Fewell

Here are a few discs that I have made available. The discs are in .SSD format and work
with BeebEM (and probably other BBC emulators that support .SSD format).

Disc 1 contains several maths functions that I have written myself.
The transcendental functions on this disc (i.e. EXP/LOG) are evaluated using power-series expansions
rather than continued-fraction expansions (as in BASIC). The programs are in BASIC not assembly language.
This disc provides a different perspective of these functions and an alternative implementation than the
one used by BBC BASIC 4.
The disk contains the following BASIC programs:
COS - Cosine function
EXP - Exponential function
LN - Natural Logorithmn function
POWER - Evaluation of powers (using LN & EXP)
REAL-FL - Converts from real to Floating (scientific - #.####E##) format
SIN - Sine function
TAN - Tangent function
TRIG & TRIG2 - Graphs showing the trigonometry functions Sine, Cosine, Tangent, Arc Sine, Arc Cosine & Arc Tangent

Disc 2 contains several analysis programs that I have written myself.
These programs have helped me in analysing the BASIC ROM.
The disk contains the following BASIC programs:
FLOAT - Converts between packed Float variables and Real (base 10) values
FLOATH - Converts between packed Float variables and Real (base 10) values,
the variable's exponent (1 byte) and mantissa (4 bytes) are entered in Hexadecimal
SEARCHM - Searches memory between &8000 to &BFFF (The BASIC ROM) for the
assembly language that you type in. I.e. you can type assembly language(i.e.LDA#ASC(">"):JSR &FFEE,
or EQUS"BASIC") and the program will return the locations which contain that informaton.
I used this program extensively when searching for the BASIC4 routine entry points
for a lot of the routines mentioned in THE ADVANCED BASIC ROM USER GUIDE book by Colin Pharo,
where I was only armed with the BASIC2 version of the routine's code.
DISASS - A quick and dirty 6502 disassembler that I used to disassemble the BASIC ROM.
ASSEMNE - A program to extract 6502 OPCODE Mnemonics from the BASIC ROM assembly routine's table.

Another piece of software that I have used extensively is FingerPrint by Dabs Press
This software enables a machine code routine to be monitored instruction by instruction
showing the real-time contents of the registers and flags after each step.
This software is not available from 8bs, as it is copyrighted; however, it may be
available elsewhere on the Internet.


 


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