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10-01-88/T\OSB09
This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.
Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.
| Tape/disk: | Home » CEEFAX disks » telesoftware4.adl |
| Filename: | 10-01-88/T\OSB09 |
| Read OK: | ✔ |
| File size: | 4673 bytes |
| Load address: | 0000 |
| Exec address: | 0000 |
File contents
OSBITS - An Exploration of the BBC Micro at Machine Level
By Programmer
...........................................................
Part 9: Operating System Calls (III)
And so a 'final' look at the general operating system calls
in the BBC Micro. This is a list of them, together with
their call addresses and their vector addresses. (We'll
come onto vectors in a later module.)
OSCLI FFF7 208
OSBYTE FFF4 20A
OSWORD FFF1 20C
OSWRCH FFEE 20E
OSNEWL FFE7
OSASCI FFE3
OSRDCH FFE0 210
OSFILE FFDD 212
OSARGS FFDA 214
OSBGET FFD7 216
OSBPUT FFD4 218
OSGBPB FFD1 21A
OSFIND FFCE 21C
NVOSWRCH FFCB
NVOSRDCH FFC8
GSREAD FFC5
GSINIT FFC2
OSEVEN FFBF
OSRDRM FFB9
These are all subroutines, to which we JSR and they will RTS
back to us. Many of them pass through a vector, which is to
say they are indirected. This means we can intercept the
routines for our own purposes as we shall see in a later
module. Note that the above list is not exhaustive,
particularly since not all OS routines are documented.
The top batch of routines, down to OSGBPB are what you might
call 'legal' routines on a BBC Micro, which is to say that
Acorn have documented them. As the 'Advanced User Guide'
points out some of the undocumented calls should be used
with caution. In the program in this module I have
cautiously used OSRDRM (or OSRDSC as it is known in the
Master OS) to read information from a sideways ROM to allow
us to print out the title and copyright date.
Let's go through the list from the top, in call address
order.
OSCLI
This is the routine that gets us into the command line
interpreter. Basically that is the part of the operating
system that takes a * (star) command and processes it. If
you have BASIC 2 or later you will have an OSCLI in BASIC
that does the same thing, i.e. OSCLI("HELP") is equivalent
to *HELP.
The line of text you wish to be interpreted (the * command
but without a * at its head) is put in memory and on entry
to the routine X and Y point to that address (X=low byte,
Y=high byte) in the same way they do with OSWORD. The line
of text must finish with a carriage return (13/&0D). It
doesn't matter what is in A.
You can use OSCLI to access some of the other routines in
this list and it may be easier to use OSCLI for this
sometimes. As you might expect the line is checked by the
operating system first. Any commands it doesn't recognise
are then run past sideways ROMS to see if any of them will
pick it up. Finally it is sent to the current filing system
to see if it could be run from disc (for example).
OSBYTE, OSWORD, OSWRCH, OSNEWL, OSASCI, OSRDCH
These I have covered in earlier modules.
The next set of routines are concerned with filing systems,
like disc or tape or ROM or the network. I don't propose to
go into great detail here because the file parameters that
can be saved with a file can be numerous. I suggest you
refer to your filing system user guide or Advanced reference
guide for detailed information on how to lay out parameter
blocks and the like.
OSFILE
This routine is the OS routine equivalent of *SAVE and with
it you read or write a whole file and/or its attributes. A
file's attributes are such things as who can read or write
to it and its load and execution addresses.
To use a file for random access OSFIND, OSARGS, OSBPUT and
OSGBPB are called.
OSFIND
This call is similar to the OPEN commands in BASIC in that
it is used to open and close files and to allocate the file
handle (a number) by which it is recognised. This call must
be issued first to open a file before any of the other
random access filing routines can be used.
OSARGS
This routine reads or writes the attributes of a file. It
could be used to find out where the pointer to the file lies
or see how long the file is.
OSBPUT and OSBGET
These routines put (write) or get (read) a single byte to or
from a file. Where that byte is put depends on the
sequential pointer which can be read or changed using
OSARGS.
OSGBPB (sometimes known as OS Heebeegeebee!)
This routine is a block version of OSBGET and OSBPUT in that
it reads or writes a group of bytes from or to a file and
can also simultaneously perform some OSARGS functions. It
is particularly useful with Econet where the routeing bytes
sent with every transmitted package will seriously slow a
data transfer if you are only sending bytes one at a time.
You should try reading a View file over Econet and see the
problem (Read not Load, and they've solved the problem with
View 3 I am told). This routine is not implemented with the
cassette filing system.
And so then to the undocumented routines,
NVOSWRCH and NVOSRDCH
These two non-vectored I/O routines, operate exactly like
their vectored equivalents. We will make use of NVOSWRCH in
a later module.
GSINIT and GSREAD
The operating system processes the strings used for some of
its commands (like *KEY) using these two routines, one
initialises the string and the other reads it byte by byte.
OSEVEN
I haven't told you about events yet, they come in a later
module. Suffice it to say that this routine can cause one
and I am rather unsure what it would be useful for.
OSRDRM
With this routine you can read a byte out of a paged ROM.
In the MASTER this routine is called OSRDSC, meaning OS Read
Screen, and has a companion OSWRSC to write to the screen.
It cannot be called from the second processor and is set up
like this:
Y contains the ROM number
&F6 and &F7 (in I/O memory) hold the address of the byte to
be read, low byte first as usual.
On exit the accumulator holds the byte read.
The program in this module, B/osb09, uses OSRDRM to enable
us to build up a list of the headers from the sideways ROMs
in your machine.
I have made an effort to be more disciplined in the code
writing in this module, since it is starting to become
fairly complex. This should make it easier to read, and
easier to modify later.
In lines 130 and 140 I have defined what are called manifest
constants. These are constants I will use within the
program to define certain parameters. Although they could
just as easily be put into statements, like LDA #3 instead
of LDA #number_of_zeros, it may be that they would occur
more than once. Defining them as constants in this way (by,
rather confusingly defining a variable!) avoids any risk of
forgetting to change all the occurrences of one of them. It
is good practice and I shall also be trying to remember to
use manifest constants. (A new years resolution?)
I shall use a couple of bytes of zero page for some
post-indexed indirect addressing. Those bytes are the value
of zp% and zp%+1. zp% is set in line 150 and I am using a
bit of the user space in zero page. In fact anything in
there should be safe because the code saves the contents of
those two bytes on the stack before running and restores
them afterwards. This is done in lines 250-280 and 860-890.
The only possibility of corruption would come from an
interrupt routine which uses those bytes and does not save
and restore properly.
Line 170 is a safeguard and is there for two reasons.
Firstly the OS routine we are going to use, OSRDRM (called
OSRDSC on the Master) will only work in the I/O processor,
otherwise known as an ordinary unexpanded B or B+, or a
Master without a co-processor.
Secondly I intend pinching a page of OS workspace for the
routine and that is in the I/O processor of course. Now in
BASIC 2 there is a means of assembling code with an offset
so you can use ordinary memory whilst assembling for a
special piece of memory. I won't use that here but when I
come onto sideways ROMS I will. (If not before.)
In the code as broadcast I am using page A which is the
RS423 and cassette input buffer. This could cause a problem
if you want to run the finished code from cassette but if
you have no disc filing system then you can use page D (the
Non Maskable Interrupt workspace which is normally only used
by disc filing systems. Other options could be the
equivalent output buffer in page 9, or the user defined
character buffer in page C. Or there is always the bits of
disc filing system space such as page 12 or 13. To change
the position of the code simply change the value of code% in
line 190.
If you have a Master things are a little more difficult.
You are not supposed to use any of the bits of OS workspace
here either and of course the disc workspace is hidden in
private RAM. I suggest you use page B or page C. These are
allocated for ECONET and if you have no econet they should
be useable. If you have econet then why not stay where I
put the code which is in page A. Maybe Acorn will
eventually provide us with some user space in their micros
into which we can put code.
I should mention that the legal way to do all this is to
reset PAGE or HIMEM and tuck your code away there, but that
negates the benefit of running this little routine from
disc.
I have allocated some space for variables; this is in lines
1950-1980. I could have just put a BRK instruction or
op-code at that address but on this occasion I have used the
EQU functions. BASIC 2 users can replace those with their
built-in EQU pseudo-operators.
One thing to note in passing line 230 is the effect of
putting the OPT pass% on the same line as the bracket. If
you do not the machine will always print out the start
address of the assembly when you assemble. There is no way
you can stop it.
So, into the body of the code.
After saving the zero page workspace we clear the screen and
print out a little title, saying Sideways ROMs. You will
find the wording for the title in line 1940 but beware of
lengthening it by more than a couple of bytes because the
code length is very nearly a whole page (256 bytes). If you
don't want to clear the screen just remove the 'CHR$ 12 +'
from line 1940.
OSBYTE 170 is called next to get the address of the table of
information about the sideways ROMS. This call is one of a
group of OSBYTE calls that can read or write, which is why
we set Y to &FF to define a read. Details in your Advanced
Guide. On exit from this call the X and Y registers hold
the low and high bytes respectively of the origin of the
table. By then transferring these to zp% and zp%+1 (our two
bytes of zero page workspace) we prepare for indexing our
way through the table of 16 bytes in line 440.
Before we do though there is a subroutine which keeps track
of which ROM we are dealing with (from 0 to 15) and prints
its number in Hex (0-F). We use an address called
'romnumber' to store the number currently being processed.
(Hence setting it to zero in line 310. This makes use of
setting X to zero before printing out the heading and saves
a couple of bytes.)
The subroutine is in lines 1060-1180 and makes use of the
trick with binary coded decimal I explained in module 6. Y
is set to the current ROM number during the routine.
In line 440 we read the ROM information byte for the current
ROM. If this is zero then there is not a properly formatted
ROM in that socket so we can ignore it. Hence the code here
BEQs to a label where we have finished with that particular
ROM. If the ROM info byte is not zero we save it and go to
a subroutine at serv_or_lang which checks to see if this ROM
has a service and/or language entry point.
Basically if a ROM has a language entry point it will run as
a language. Examples are VIEW, BASIC, BCPL, ULTRACALC. A
service entry point enables the ROM to react to * commands,
including the one to select itself. Every ROM has a service
entry point except BASIC. The command *BASIC is actually
part of the operating system. Details of all this is in the
Advanced Guides of course.
This subroutine checks to see if bit 6 is set (denoting a
language entry point) or bit 7 (denoting a service entry
point) and prints an L or S accordingly. This check is done
using the BIT operation as described in the last module.
From line 530 is the main section of the routine. Now this
differs from the standard ROM listing routine in that it
prints out all the ROM header. This enables you to see what
the copyright year of your BASIC is for example (I have 3
versions of BBC BASIC in my machine). These headers can be
long and a line length of 70, set in line 130, is fine for
80 column modes. If you want to use the routine in a 40
column mode (like Mode 7) then change line_length to 30.
After setting the counters for zeros and letters printed to
zero we enter the main loop. In the loop we use OSRDRM to
get the bytes from the header one at a time. The header
information we want to read starts at &8009 so we add 9 to
the letter counter and then invoke OSRDRM as described
earlier.
On exit from OSRDRM we have the byte read in the accumulator
and we call a subroutine at address 'test'. This subroutine
checks out the byte, prints it if it is valid, and exits
with the carry flag clear if 3 nulls (zeros) have been
counted from the header and with the character to print in
the accumulator. After 3 nulls there should be no more
human readable information left in the header. This
subroutine starts at line 1670.
Why do I use the carry flag to say that we have finished the
header? Two reasons. I use a flag at all because we cannot
branch directly out of a subroutine without unbalancing the
stack. When you enter a subroutine the microprocessor puts
the return address on the stack ready to be pulled off when
an RTS is reached. If you JMP or BRanch back instead that
address remains on the stack and may corrupt any stack
storage you are using. In this program we are using the
stack for storage during the whole routine.
The carry flag is used because it is easily set or cleared
(SEC or CLC), whereas the overflow flag cannot be directly
affected like this. Also the carry flag is not affected by
a load or save command like the zero flag would be. I have
used it this particular way around to save a couple of bytes
because it will always be clear at line 1750.
During the test subroutine any control codes or bytes over
126 are replaced with spaces.
On exit from test we finish with this ROM if the carry flag
is clear (as per line 680). If not we print the character,
increase the letter counter and check if we are now over our
allotted length. If we are we go on to the next ROM, if not
we look at the next letter.
Line 750 is the address 'rom_finished' where we go when each
ROM has been read. The ROM counter is incremented and we
check to see if we have reached 16 and the end, if not round
we go again.
The routines exit is at line 830 and notice that we restore
the zero page bytes in reverse order. This is because the
stack operates last-in-first-out so you read out in the
reverse order to how you put in.
The rest of the assembler code contains the subroutines and
variable addresses. The final bit of BASIC prints out a
line you can copy with the cursor keys to save the assembled
code. Notice that we set the top 16 bits of a 32 bit
address to tell the filing system that we are in the I/O
processor and want the code to run there.
Here is the output of the routine when I ran it in my
machine. Note that socket 2 is empty and socket F has RAM
in it but that RAM contained only random bytes. Lines 5 and
C have been truncated by me to make them fit here. Also
note that in socket 8 is the DNFS which does not contain a
proper copyright message in its header, hence the gibberish.
(To save you asking, MicroFax is a BBC chip to enable me to
format pages for CEEFAX.)
Sideways Roms
0 ( S) TELETEXT 2.50 (C)BBC 1986
1 (L ) BASIC (C)1981 Acorn
2
3 ( S) TOOLKIT 1.22 (C)1983 Beebug
4 (LS) VIEW A2.1 (C) 1982 Protechnic
5 ( S) Watford Electronics EPSON NLQ ROM V1.0 (C) Watford
6 (LS) MONITOR 2.01 (C)1985 ISMEC
7 (LS) SPELLCHECK II v1.20 (C)1984 BEEBUGSOFT
8 ( S) DFS,NET (C)ROFF '1119E
9 (LS) Ultracalc 2 (C)1984 Topexpress Limited
A (LS) BCPL 7.0 (C) 1982 RICHARDS COMPUTER PRODUCTS LTD.
B (LS) MicroFax 4.4 (C)T.E.Kennington 1985
C ( S) AMX Mouse Support (C)1984 Advanced Memory Systems
D (L ) BASIC (C)1983 Acorn
E (L ) BASIC (C)1982 Acorn
F
I hope you will be wondering why I used subroutines in this
code even though the routines were only called once. My
general rule is to try to write code with these sort of
priorities:
Firstly try to make it as simple and readable as possible.
Hence subroutines and lots of comments. I may have to
modify the program a year or two later.
Secondly any piece of code that is used in more than one
place should be a subroutine. This reduces the size of the
code.
Thirdly subroutines slow down code because of the calling
and putting of return addressed on the stack. So if time is
very critical try to avoid them.
These three things do not always work towards the same end
and there is not usually a single solution to a programming
problem (thank goodness).
And what about a flow chart. Well, to be brutally honest
they are almost impossible to do by telesoftware so I am
unable to send any to you. In fact I rarely flowchart a
complete program myself (which is possibly why trial and
error feature so much in my writing) although if I have a
tricky bit of logic to sort out a flow chart is very useful.
That's all for this module, next time I'll look at errors
and exceptions which become very important as soon as your
programs require people to input into them. Also a brief
overview of the 6502 microprocessor commands, or OPCODES,
which you can use as a reference.
00000000 4f 53 42 49 54 53 20 2d 20 41 6e 20 45 78 70 6c |OSBITS - An Expl|
00000010 6f 72 61 74 69 6f 6e 20 6f 66 20 74 68 65 20 42 |oration of the B|
00000020 42 43 20 4d 69 63 72 6f 20 61 74 20 4d 61 63 68 |BC Micro at Mach|
00000030 69 6e 65 20 4c 65 76 65 6c 0d 0d 42 79 20 50 72 |ine Level..By Pr|
00000040 6f 67 72 61 6d 6d 65 72 0d 0d 2e 2e 2e 2e 2e 2e |ogrammer........|
00000050 2e 2e 2e 2e 2e 2e 2e 2e 2e 2e 2e 2e 2e 2e 2e 2e |................|
*
00000080 2e 2e 2e 2e 2e 0d 0d 0d 50 61 72 74 20 39 3a 20 |........Part 9: |
00000090 4f 70 65 72 61 74 69 6e 67 20 53 79 73 74 65 6d |Operating System|
000000a0 20 43 61 6c 6c 73 20 28 49 49 49 29 0d 0d 41 6e | Calls (III)..An|
000000b0 64 20 73 6f 20 61 20 27 66 69 6e 61 6c 27 20 6c |d so a 'final' l|
000000c0 6f 6f 6b 20 61 74 20 74 68 65 20 67 65 6e 65 72 |ook at the gener|
000000d0 61 6c 20 6f 70 65 72 61 74 69 6e 67 20 73 79 73 |al operating sys|
000000e0 74 65 6d 20 63 61 6c 6c 73 0d 69 6e 20 74 68 65 |tem calls.in the|
000000f0 20 42 42 43 20 4d 69 63 72 6f 2e 20 20 54 68 69 | BBC Micro. Thi|
00000100 73 20 69 73 20 61 20 6c 69 73 74 20 6f 66 20 74 |s is a list of t|
00000110 68 65 6d 2c 20 74 6f 67 65 74 68 65 72 20 77 69 |hem, together wi|
00000120 74 68 0d 74 68 65 69 72 20 63 61 6c 6c 20 61 64 |th.their call ad|
00000130 64 72 65 73 73 65 73 20 61 6e 64 20 74 68 65 69 |dresses and thei|
00000140 72 20 76 65 63 74 6f 72 20 61 64 64 72 65 73 73 |r vector address|
00000150 65 73 2e 20 20 28 57 65 27 6c 6c 0d 63 6f 6d 65 |es. (We'll.come|
00000160 20 6f 6e 74 6f 20 76 65 63 74 6f 72 73 20 69 6e | onto vectors in|
00000170 20 61 20 6c 61 74 65 72 20 6d 6f 64 75 6c 65 2e | a later module.|
00000180 29 0d 0d 20 20 20 20 20 20 20 20 20 4f 53 43 4c |).. OSCL|
00000190 49 20 20 20 20 20 20 20 20 20 20 20 20 46 46 46 |I FFF|
000001a0 37 20 20 20 20 20 20 20 20 20 20 20 32 30 38 0d |7 208.|
000001b0 20 20 20 20 20 20 20 20 20 4f 53 42 59 54 45 20 | OSBYTE |
000001c0 20 20 20 20 20 20 20 20 20 20 46 46 46 34 20 20 | FFF4 |
000001d0 20 20 20 20 20 20 20 20 20 32 30 41 0d 20 20 20 | 20A. |
000001e0 20 20 20 20 20 20 4f 53 57 4f 52 44 20 20 20 20 | OSWORD |
000001f0 20 20 20 20 20 20 20 46 46 46 31 20 20 20 20 20 | FFF1 |
00000200 20 20 20 20 20 20 32 30 43 0d 20 20 20 20 20 20 | 20C. |
00000210 20 20 20 4f 53 57 52 43 48 20 20 20 20 20 20 20 | OSWRCH |
00000220 20 20 20 20 46 46 45 45 20 20 20 20 20 20 20 20 | FFEE |
00000230 20 20 20 32 30 45 0d 20 20 20 20 20 20 20 20 20 | 20E. |
00000240 4f 53 4e 45 57 4c 20 20 20 20 20 20 20 20 20 20 |OSNEWL |
00000250 20 46 46 45 37 0d 20 20 20 20 20 20 20 20 20 4f | FFE7. O|
00000260 53 41 53 43 49 20 20 20 20 20 20 20 20 20 20 20 |SASCI |
00000270 46 46 45 33 0d 20 20 20 20 20 20 20 20 20 4f 53 |FFE3. OS|
00000280 52 44 43 48 20 20 20 20 20 20 20 20 20 20 20 46 |RDCH F|
00000290 46 45 30 20 20 20 20 20 20 20 20 20 20 20 32 31 |FE0 21|
000002a0 30 0d 20 20 20 20 20 20 20 20 20 4f 53 46 49 4c |0. OSFIL|
000002b0 45 20 20 20 20 20 20 20 20 20 20 20 46 46 44 44 |E FFDD|
000002c0 20 20 20 20 20 20 20 20 20 20 20 32 31 32 0d 20 | 212. |
000002d0 20 20 20 20 20 20 20 20 4f 53 41 52 47 53 20 20 | OSARGS |
000002e0 20 20 20 20 20 20 20 20 20 46 46 44 41 20 20 20 | FFDA |
000002f0 20 20 20 20 20 20 20 20 32 31 34 0d 20 20 20 20 | 214. |
00000300 20 20 20 20 20 4f 53 42 47 45 54 20 20 20 20 20 | OSBGET |
00000310 20 20 20 20 20 20 46 46 44 37 20 20 20 20 20 20 | FFD7 |
00000320 20 20 20 20 20 32 31 36 0d 20 20 20 20 20 20 20 | 216. |
00000330 20 20 4f 53 42 50 55 54 20 20 20 20 20 20 20 20 | OSBPUT |
00000340 20 20 20 46 46 44 34 20 20 20 20 20 20 20 20 20 | FFD4 |
00000350 20 20 32 31 38 0d 20 20 20 20 20 20 20 20 20 4f | 218. O|
00000360 53 47 42 50 42 20 20 20 20 20 20 20 20 20 20 20 |SGBPB |
00000370 46 46 44 31 20 20 20 20 20 20 20 20 20 20 20 32 |FFD1 2|
00000380 31 41 0d 20 20 20 20 20 20 20 20 20 4f 53 46 49 |1A. OSFI|
00000390 4e 44 20 20 20 20 20 20 20 20 20 20 20 46 46 43 |ND FFC|
000003a0 45 20 20 20 20 20 20 20 20 20 20 20 32 31 43 0d |E 21C.|
000003b0 0d 20 20 20 20 20 20 20 20 20 4e 56 4f 53 57 52 |. NVOSWR|
000003c0 43 48 20 20 20 20 20 20 20 20 20 46 46 43 42 0d |CH FFCB.|
000003d0 20 20 20 20 20 20 20 20 20 4e 56 4f 53 52 44 43 | NVOSRDC|
000003e0 48 20 20 20 20 20 20 20 20 20 46 46 43 38 0d 20 |H FFC8. |
000003f0 20 20 20 20 20 20 20 20 47 53 52 45 41 44 20 20 | GSREAD |
00000400 20 20 20 20 20 20 20 20 20 46 46 43 35 20 0d 20 | FFC5 . |
00000410 20 20 20 20 20 20 20 20 47 53 49 4e 49 54 20 20 | GSINIT |
00000420 20 20 20 20 20 20 20 20 20 46 46 43 32 0d 20 20 | FFC2. |
00000430 20 20 20 20 20 20 20 4f 53 45 56 45 4e 20 20 20 | OSEVEN |
00000440 20 20 20 20 20 20 20 20 46 46 42 46 0d 20 20 20 | FFBF. |
00000450 20 20 20 20 20 20 4f 53 52 44 52 4d 20 20 20 20 | OSRDRM |
00000460 20 20 20 20 20 20 20 46 46 42 39 0d 0d 54 68 65 | FFB9..The|
00000470 73 65 20 61 72 65 20 61 6c 6c 20 73 75 62 72 6f |se are all subro|
00000480 75 74 69 6e 65 73 2c 20 74 6f 20 77 68 69 63 68 |utines, to which|
00000490 20 77 65 20 4a 53 52 20 61 6e 64 20 74 68 65 79 | we JSR and they|
000004a0 20 77 69 6c 6c 20 52 54 53 0d 62 61 63 6b 20 74 | will RTS.back t|
000004b0 6f 20 75 73 2e 20 20 4d 61 6e 79 20 6f 66 20 74 |o us. Many of t|
000004c0 68 65 6d 20 70 61 73 73 20 74 68 72 6f 75 67 68 |hem pass through|
000004d0 20 61 20 76 65 63 74 6f 72 2c 20 77 68 69 63 68 | a vector, which|
000004e0 20 69 73 20 74 6f 0d 73 61 79 20 74 68 65 79 20 | is to.say they |
000004f0 61 72 65 20 69 6e 64 69 72 65 63 74 65 64 2e 20 |are indirected. |
00000500 20 54 68 69 73 20 6d 65 61 6e 73 20 77 65 20 63 | This means we c|
00000510 61 6e 20 69 6e 74 65 72 63 65 70 74 20 74 68 65 |an intercept the|
00000520 0d 72 6f 75 74 69 6e 65 73 20 66 6f 72 20 6f 75 |.routines for ou|
00000530 72 20 6f 77 6e 20 70 75 72 70 6f 73 65 73 20 61 |r own purposes a|
00000540 73 20 77 65 20 73 68 61 6c 6c 20 73 65 65 20 69 |s we shall see i|
00000550 6e 20 61 20 6c 61 74 65 72 0d 6d 6f 64 75 6c 65 |n a later.module|
00000560 2e 20 20 4e 6f 74 65 20 74 68 61 74 20 74 68 65 |. Note that the|
00000570 20 61 62 6f 76 65 20 6c 69 73 74 20 69 73 20 6e | above list is n|
00000580 6f 74 20 65 78 68 61 75 73 74 69 76 65 2c 0d 70 |ot exhaustive,.p|
00000590 61 72 74 69 63 75 6c 61 72 6c 79 20 73 69 6e 63 |articularly sinc|
000005a0 65 20 6e 6f 74 20 61 6c 6c 20 4f 53 20 72 6f 75 |e not all OS rou|
000005b0 74 69 6e 65 73 20 61 72 65 20 64 6f 63 75 6d 65 |tines are docume|
000005c0 6e 74 65 64 2e 0d 0d 54 68 65 20 74 6f 70 20 62 |nted...The top b|
000005d0 61 74 63 68 20 6f 66 20 72 6f 75 74 69 6e 65 73 |atch of routines|
000005e0 2c 20 64 6f 77 6e 20 74 6f 20 4f 53 47 42 50 42 |, down to OSGBPB|
000005f0 20 61 72 65 20 77 68 61 74 20 79 6f 75 20 6d 69 | are what you mi|
00000600 67 68 74 0d 63 61 6c 6c 20 27 6c 65 67 61 6c 27 |ght.call 'legal'|
00000610 20 72 6f 75 74 69 6e 65 73 20 6f 6e 20 61 20 42 | routines on a B|
00000620 42 43 20 4d 69 63 72 6f 2c 20 77 68 69 63 68 20 |BC Micro, which |
00000630 69 73 20 74 6f 20 73 61 79 20 74 68 61 74 0d 41 |is to say that.A|
00000640 63 6f 72 6e 20 68 61 76 65 20 64 6f 63 75 6d 65 |corn have docume|
00000650 6e 74 65 64 20 74 68 65 6d 2e 20 20 41 73 20 74 |nted them. As t|
00000660 68 65 20 27 41 64 76 61 6e 63 65 64 20 55 73 65 |he 'Advanced Use|
00000670 72 20 47 75 69 64 65 27 0d 70 6f 69 6e 74 73 20 |r Guide'.points |
00000680 6f 75 74 20 73 6f 6d 65 20 6f 66 20 74 68 65 20 |out some of the |
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10-01-88/T\OSB09.m1
10-01-88/T\OSB09.m2
10-01-88/T\OSB09.m4
10-01-88/T\OSB09.m5
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