About everything - how to write a Boot that is 1 sector long (256 bytes).

M.M.A/SPEED SO.                           
                                          
There was such a good printing machine in the world
magazine  "ZX-REVIEW" ..... There was, but whatever it may be
It's unfortunate, but everything came out! And on the ashes
the last  its  circulation,  remained
unpublished article,  written by me
and  Max Vasiliev especially for this
publications.                                  
                                          
And although the following text was typed back in
first  year 1997, he did not lose
that relevance and poignancy. So I decided
include this material in the latest issueBOTH
RON. Don't let the goodness go to waste!             
                                          
Truth   was  one small problems
ka......  Text  articles  written  language
"ZX-REVIEW"  and for readers "ZX-REVIEW".  es-
Basically everything had to be redone. Od-
However,  since the prospect of a complete re-
writings  articles  me  not at all  not
seduced me, I decided to leave everything as it was. 
                                          
  So, let's "grief" for the untimely
the PRESENT that has left usSpectrum
magazine -  "ZX-REVIEW"!                     
                                          
                                          
(C) MAXSOFT / SPEED CO.                   
(C) M.M.A  / SPEED CO.                   
    Samara 1997 a.d.                    
                                          
                                          
       BOOT program in one sector.      
                                          
  Since the first  computers with the system
TR-DOS , appeared  in  our  country,
hackers and programmers never stop solving
great problem of our time: why, how
and  what boot loader should I write??? Those
who  is interested in  question modern
boot-building, I will allow myself to refer to
an article devoted specifically to this topic, which
which  was published in the third issue
Samara  electronic magazine "OBERON".
In  this article, using the example of writing
tion of the boot program, we will consider the issues
implementations  ultra-short  programs on as-
assembler,  a  also  possibility  rational
nal use stabilization procedures
dartnogo ROM  and TR-DOS in similar programs
rammah.                                   
                                          
  It is worth noting that  that attempts to create
there were already ultra-short boot loaders, and
quite  successful. For example boot, write
sled  Shi-soft' in 1992 occupied
two sectors and it worked quite well. I
fundamentally  I'm not talking about the length in bytes,
since in connection with the use
network  media  information  (floppy disks, and
as  consequence, disk   OS, for example
TR-DOS), the concept of program length in bytes,
clearly  is replaced  by the concept of length in
sectors.  And in case your procedure
has  size  260  bytes, and also if
it will  occupy 460 bytes, anyway
when writing to disk the file will be organized
volume in two sectors. Thus, if
your program is closely related to DOS, has
meaning  select its maximum size, multiple
size standard  TR-DOS
sectors and  in  consequences  try  is-
use  every byte (bit) of this volume
memory.                                   
                                          
We  slightly  we've moved away from the topic, let's come back
to  our boots!  Another example of boot-zag
ruzchik in  two sectors -  this is the program
D. Pyankova SMALL VOOT,distributed IN-
FORKOM.  As it is written in the description for this
program: "The main feature is the small
volume  (2 sectors), thereby ensuring
"Fast loading is starting." Quite obvious
but that with a size of one sector loading
will be even faster, and the space  on the disk is like this
boot takes almost no time at all. Vop-
polished exactly this one absolutely seemed
would  crazy idea and two people took up the task at once
Marsky programmer.                     
                                          
Since  the time this idea arose in my
(M.M.A) the head has already passed about one and a half
years Because at that time I wasn't enough
experienced in programming, then simply share
was overwhelmed by the thought of writing such a masterpiece
with other Samara programmers. In re-
As a result,  in tough competition,
single-sector  boot was not just written,
but it’s written so optimally that I’m afraid
readers of "ZX-REVIEW" will no longer be able to do anything
Bo  optimize. Although, if you don't look
listing given below, but try
implement this idea, which is called with
"clean sheet", then perhaps you, dear
dear readers, you will be able to find some new
high, non-standard solutions. Another thing -
changing functional features...  
                                          
Full boot disassembler with comments
for almost every command you will find in
end of the article. There is also a boot dump there
and notes on code block merging
and  BASIC. We will continue the topic of changes
and  let's see  what  and how you can change
this (basic) version of boot.             
                                          
 In  this  version  control  program
carried out  with  with the help of  SINCLAIR
JOYSTICKand keys "Q", "A", "O", "P". Select
file- "0","ENTER",reading a new directory
ha  -  "SPACE". As you can see, control from
SINCLAIR joystick is somewhat unnecessary and when
If you wish, you can throw it out and insert it
anything else.                          
                                          
For example, a good  effect will give a thickened
font!                                    
                                          
                                          
                                          
                                          
                                          
                                          
                                          
Store additional character set in
memory  -  this is already three sectors (768 bytes),
yes  and  use the creation techniques
fonts usingstandard ROM
font, more than once  described in the ZX-REVIEW, too
you can't  -  too  too much  bytes! Solution
should  be non-standard and at the same time
simple. What if you first print on
everything on the screen in normal font, and then pro-
perform the following operation over the screen:      
                                          
                                          
                                          
                                          
                                          
                                          
                                          
 ORG  30000                      
                                          
      LD HL,#4000                   
In HL - the starting address of the screenLOOP1 LD A, (HL)                     
Open the loop, load the contents into A (HL)
 SRL  A                          
Shift A to the right (or SLA A - to the left)     
      OR (HL)                       
Overlay A onto the original byte on the screen   
      LD (HL),A                     
Place the result on the screen               
      INC  HL                         
Increase the address on the screen by one     
      LD A,H                        
Load to Avalue H,                 
      SR #58                        
and see if it has reached the older one    
attribute area bits (#5800)         
      JR NZ,LOOP1                   
Repeat the cycle if HL < #5800           
      RET   Listing l
                                          
                                          
                                          
                                          
                                          
                                          
In  principle, the procedure on listing l works
is capable, and  occupies only 14 bytes. But
forultra-short boot and that's a lot!
Further improvement of the procedure can be
can be carried out by changing the principles
pa defines the end of the  screen area.
The thickening algorithm itself is already optimal.
                                          
                                          
                                          
                                          
                                          
                                          
                                          
                                          
                                          
 ORG  30000                      
                                          
       LD  HL,#57FF                   
In HL - the very last byte of the screen        
LOOP1  LD  A,(HL) We load the contents into A (HL)                
       RRCA                               
Shift via RRCA (shorter by one byte!)
 OR  (HL)                       
Overlay onto the original                   
       LD  (HL),A                     
Copy back to screen                  
       DEC  HL                         
Reduce HL  *****        
       LD  A,H                        
Check the contents of H at 0               
       OR  A                          
       JR  NZ,LOOP1                   
If HL > #OOFF, then repeat the cycle        
                                          
       RET                                
                                 Listing 2
                                          
                                          
In  in this case, the bytes are counted from the bottom
up", and does not end with #4000, but pro-
goes through the entire ROM (there is, of course, nothing there)
th  does not  change) and  reaches the address
#0100.  Using this method, we save
two more winning bytes and we get the procedure
ru in 12 bytes length.Some  inconvenience  is  that
that while the program "goes" through ROM, tra-
Quite a large number of cycles ticks away
processor  and  the user begins to replace
Let's see how you  thicken the characters. With one
On the other hand, this even  is not bad -  it turns out
very interesting effect but if  it's for you
I really don’t like it,  then  try
the following:                                           
Immediately  after the command DEC HL, marked in
previous listing, type:           
                                          
               BIT   6, N                  
                                          
Checking whether  is installed  or  sixth  bits in
address written  in HL. If installed,
then we continue the cycle, otherwise we exit.      
                                          
               JR   NZ,LOOP1             
                                          
               RET To understand how this condition works, let me explain:
that all those addresses that may be located
in the  HL register when working with the screen, have
set sixth bit (#40 = %01000000),
a  starting  from  addresses #ЗFFF  (  #3F =
%00111111)  this bit  is reset.  According to this
principle and the detection of the end of the
wound area. We didn't gain any bytes from this.
rali, but it works faster than ver-
this with checking H for 0. But is it possible to
more  save  more? Naturally, you can!
Look in the comments to the boota listing.
Everything there is built on the fact thatsubsequent
the procedure uses the data from the previous one.   
                                          
If before calling the thickening procedure in
register L will contain the number #FF, then
we just need to download the remaining
half register - N.                   
                                          
Put  inListing 2 instead of LD HL,#57FF
command LD  H, #57 and do not forget that in re-
gistre  L should be the number #FF, left-
new from the previous procedure. Here we are
beamed  procedure  in  11  bytes - quite
normal  for our single-sector children-
now.  That's justthe situation with the L register is not -
understandable.  Do I need to download it at all?
If imagine,  that in the L register we can
the moment of starting the procedure is absolutely
random number, then at the end of the work we
simply  we will get non-thickened ones from one to
#FF bytes in the lower third of the screen in the lower
parts of  each  familiarity!  But in ROM
font, as far as I remember, only a comma and
some characters use the bottom line
acquaintances. And since these symbols are named
files  generally  rarely  occur, then
feel free  leave exactly loaded only
register N.                                
                                          
                 ORG  30000            
                 LD      Н,#57            
          LOOP1  LD      A,(HL)           
                 RRCA                     
                 OR      (HL)             
                 LD      (HL),A           
                 DEC     HL               
                 BIT     6,Н              
                 JR      NZ,LOOP1         
                 RET                      
                                          
Вот  она - оптимизированная версия утолще-
ния  всего экрана, которую вы,dear chi-
tatels, you can insert into our one-sector-
new boot instead of additional control
from SINCLAIR - joystick.                  
                                          
Our main goal was to show you how
you need  think  when writing a supercom-
compactcode.  In addition, we want to throw out
power the idea of a single-sector boot on a brain-
howl assault on the entire country. This is in our heads
the idea has already reached its full optimum. But we
We will be very glad if any of the readers
lei will offer something new, interesting, from
whatever you want, as in the famous advertisement,
say: "FRESH...."!                    
                                          
                                          
And  here is  and the bootloader itself is one long
sector:                                           
        ORG     #5D3B                     
                                          
AUTHOR  EQU     #5D52                     
FILE_Р  EQU     #5D52                     
                                          
;BASIC СТРОКА ДЛЯ ЗАПУСКА                 
                                          
   DEFB    #00,#01,#F8,#00,#Е7,#C3,#A7,#3A
                                          
   DEFB    #F9,#C0,#В0,#22,#32,#33,#39,#30
                                          
   DEFB    #35,#22,#3A,#ЕА,#3A,#F7,#22    
                                          
;ИНФОРМАЦИЯ ОБ АВТОРЕ(НЕ МЕНЕЕ 8 СИМВОЛОВ)
                                          
   DEFB    23,11,32,"MAXSOFT'96"          
                                          
                                          
   DEFB    #22         ;КОНЕЦ BASIC-СТРОКИ
   DEFB    #D          ;"СВОБОДНЫЙ" БАЙТ  
                                          
                                          
;1 SECTOR ВООТ                            
;IDEA ВУ М.М.A SOFT/SPEED СО.             
;CODED ВУ MAXSOFT/SPEED СО.               
                                          
        LD      (IY+#53),#5               
                                          
;SETTING PAPER COLOR IN A CELL (#SC8D)   
;BORDER IS ALREADY INSTALLED FROM BASIC         
                                          
NEW_DISK ;DISC READING
 CALL #D6B ;SCREEN CLEANING   
                                          
;OUTPUT DE=#0000,HL=#50E0,ВС=#1721    
;LOADING THE DISK CATALOG FROM ADDRESS #6801   
                                          
        ADD  HL, BC                     
        LD  BC,#905                   
        PUSH HL CALL    #3D13                     
                                          
                                          
;ПЕЧАТАЕМ ИНФОРМАЦИЮ ОБ АВТОРЕ            
                                          
        LD      DE,AUTHOR                 
        LD      C,#D                      
        CALL    #203C                     
                                          
        LD      A,2                       
                                          
;ОТКРЫВАЕМ ПОТОК ПЕЧАТИ НА ЭКРАН          
                                          
        CALL    #1601                     
        РОР HL                        
        LD      D,Н                       
        LD      Е,L                       
SORT                  ;СОРТИРОВКА КАТАЛОГА
                                          
        LD      ВС,8                      
        DEC     (HL)                      
        JR      Z,NEXT_F   ;СTЁРTЫЙ ФАЙЛ  
        INC     (HL)                      
        JR      Z,END_SORT ;КОНЕЦ КАТАЛОГА
        PUSH    HL                        
                                          
        ADD     HL,ВС                     
        LD      A,(HL)                    
        РОР     HL                        
        СР      "В"        ;ТИП ФАЙЛА     
        JR      NZ,NEXT_F                 
        PUSH    HL                        
        LD      A,#20    ;ПЕЧАТЬ "ПРОБЕЛа"
        RST     #10                      
                                          
МАКЕ_FILE                                 
                                          
        LD      A,(HL)      ;ПЕЧАТЬ       
        RST     #10         ;БУКВЫ        
        LDI                 ;И ЕЁ ПЕРЕНОС 
        JP      РЕ,МАКЕ_FILE              
                                          
                ;(ДЛЯ УПЛОТНЕНИЯ КАТАЛОГА)
                                          
        LD      HL,#70D1   ;СЧЁТЧИК ФАЙЛОВ
        INC     (HL)                      
        LD      A,(HL)                    
                                          
FILE_C                                    
        SUB     3                         
                                          
;ВЫЧИСЛЯЕМ, НАПЕЧАТАНО-ЛИ                 
;ТРИ ИМЕНИ ФАЙЛОВ В ОДНОЙ СТРОКЕ          
                                          
        JR      Z,FILE_C1                 
        JR      NC,FILE_C                 
        LD      A,#20   ;НЕТ,НЕ НАПЕЧАТАНО
        RST     #10     ;-ПЕЧАТЬ "ПРОБЕЛа"
FILE_C1                 ;ДА,НАПЕЧАТАНО    
        LD      A,#20                     
        RST     #10                       
                                          
        РОР     HL                        
NEXT_F                                    
        LD      C,#10  ;ПЕРЕХОДИМ         
        ADD     HL,ВС  ;К СЛЕДУЮЩЕМУ ФАЙЛУ
        JR      SORT                      
END_SORT               ;КОНЕЦ СОРТИРОВКИ  
                                          
                                          
NEW_CUR                ;РЕГИСТР В=0       
                                          
        LD      C,В                       
                                          
;РЕГИСТР С-СЧЁТЧИК ФАЙЛОВ                 
                                          
MOVE_CUR                                  
                                          
        LD      HL,#57F5                  
        LD      DE,#В                     
        XOR     A                         
                                          
;РЕГИСТР A-ВРЕМЕННЫЙ СЧЁТЧИКMOVE_C1                                   
        LD      В,3                       
MOVE_C2                                   
        ADD     HL,DE                     
                                          
;ВЫЧИСЛЯЕМ ПОЗИЦИЮ КУРСОРА                
                                          
                                          
        СР      C                         
        JR      Z,CURSOR                  
        INC     A                         
        DJNZ    MOVE_C2                   
        DEC     HL                        
        JR      MOVE_C1                   
CURSOR                      ;РИСУЕМ КУРСОР
        LD      В,#A                      
        LD      DE,(#70D3)                
        LD      (#70D3),HL                
        LD      A,5                       
CURSOR1                                   
        LD      (DE),A                    
                                          
;СТИРАЕМ СТАРЫЙ КУРСОР                    
                                          
        INC     DE                        
        LD      (HL),#16                  
                                          
;РИСУЕМ НОВЫЙ КУРСОР                      
                                          
                                          
        INC     HL                        
        DJNZ    CURSOR1                   
        LD      HL,#5C08                  
                                          
;ОБНУЛЯЕМ СИСТЕМНУЮ ПЕРЕМЕННУЮ (LAST-KEY) 
                                          
        LD      (HL),В                    
KEYS                      ;ОПРОС КЛАВИШ   
        LD      A,(HL)                    
        СР      " "                       
                                          
;ПРОБЕЛ-ПЕРЕЗAЧИTЫВAНИЕ ДИСКА             
                                          
        JR      Z,NEW_DISK                
        СР      #D                        
;ENTER-ЗАПУСК ПРОГРАММЫ                   
        JR      Z,START_F                 
        СР      "0"                       
                                          
;0-ЗАПУСК ПРОГРАММЫ                       
        JR      Z,START_F                 
                                          
        СР      "7"                       
        JR      Z,L_RIGHT                 
        СР      "6"                       
        JR      Z,L__LEFT                 
        СР      "8"                       
        JR      Z,L__DOWN                 
        СР      "9"                       
        JR      Z,L____UP                 
        OR      #20                       
;ENABLE UPPER CASE FOR LETTERS     
;POLLING LETTER KEYS INDEPENDENT OF     
;MODE "CAPS"                            
        SR  "r"                       
        JR  Z,L_RIGHT                 
        SR  "about"                       
        JR  Z,L__LEFT                 
        SR  "a"                       
        JR  Z,L__DOWN                 
        SR  "q"                       
        JR      NZ,KEYS                   
                                          
                                          
L____UP                     ;КУРСОР ВВЕРХ 
        DEC     C                         
        DEC     C                         
L__LEFT                     ;КУРСОР ВЛЕВО 
        DEC     C                         
        JP      Р,MOVE_CUR                
                                          
;КУРСОР НЕ ДОШЁЛ ДО НАЧАЛА КАТАЛОГА       
                                          
        LD      ВС,(#70D1)                
                                          
;КУРСОР - НА КОНЕЦ КАТАЛОГА               
                                          
        DEC     C                         
        JR      MOVE_CUR                  
L__DOWN                     ;КУРСОР ВНИЗ  
        INC     C                         
        INC     C                         
L_RIGHT                     ;КУРСОР ВПРАВО
        INC     C                         
        LD      A,(#70D1)                 
DEC     A                         
        СР      C                         
        JR      NC,MOVE_CUR               
                                          
;КУРСОР НЕ ДОШЁЛ ДО КОНЦА КАТАЛОГА        
                                          
        JR      NEW_CUR                   
                                          
;КУРСОР - НА НАЧАЛО КАТАЛОГА              
                                          
                                          
START_F                      ;ЗАПУСК ФАЙЛА
                                          
        LD      A,C                       
        INC    A                         
        LD      C,L          ;РЕГИСТР L=8 
        LD      HL,#67F9                  
                                          
;АДРЕС НАЧАЛА КАТАЛОГА МИНУС 8            
                                          
                                          
                                          
ST_F1                                     
        ADD     HL,ВС                     
                                          
;ВЫЧИСЛЯЕМ ПОЗИЦИЮ ИМЕНИ ФАЙЛА В КАТАЛОГЕ 
                                          
        DEC     A                         
        JR      NZ,ST_F1                  
                                          
        LD      DE,FILE_Р                 
                                          
                                          
;ПЕРЕНОСИМ ИМЯ ФАЙЛА В BASIC              
                                          
                                          
        LDIR                              
        JP      #3D03                     
                                          
;ВЫХОДИМ В BASIC С ЗАПУСКОМ ФАЙЛА         
                                          
                                          
                                 Листинг 4
                                          
                                          
 l. НАБРАТь ТЕКСТ ВООТ'A В АССЕМБЛЕРЕ.    
                                          
 2. ВЫЙТИ В BASIC. СТЕРЕТь ВСЕ BASIC-СТРО-
 KI RELATING TO  ASSEMBLER AND CREATE
 OWN LINE LENGTH 248 BYTES, I.E. KO-
 MANDA PRINT RACK 23869 MUST SHOW
 248.IN THIS WAY, IT IS UNDESIRABLE TO USE
 EDITOR'S BASIC 128.              
                                          
 3. RETURN  B ASSEMBLER AND  PRODUCE
 ASSEMBLY.                      
                                          
 4. EXIT BASIC AND SAVE BASIC-PROG 
 FRAME : RANDOMIZE USR 15619:REM:SAVE"1SBOOT"LINE 1
                                          
                                          
                                          
     Regarding improvements and changes.     
                                          
In the basic version of the boot, given in lis-
tuhre 4.available 1 free byte. Its use
use for additional services
possibilities practically  unreal. But
really try to print the files
not in three columns, but in two, and then new and
new  freed  bytes will open  you
opportunity for more and more new bells and whistles
within the same one sector dis-
kovy space.In general, if it turns out that we have completed
accurately optimized the idea of single-sector
boot's and readers  will not be able to find
even an extra byte, we propose to arrange
competition for the most convenient and powerful seven-sec
tory  loader. This boot is very convenient
that that  can be  located in unusable
used sectors of the zero track. In this
case  it turns out that boot does not take
not a single sector on the disk.               
                                          
K  the same as if   in one/two-sector
boot loaders are only about providing
baking the minimum service, then in boot
seven sectors longyou can use
and auto-reading of discs and beautiful effects
you  in the background (stars, snow) and much more
other.                                   
                                          
Р.S. And most importantly, remember: “Any procedure
can  be further optimized to such an extent.
that it will consist of one command
NOP  and  and do everything. what from her
required."                               
                                          
                                          
                                          
                                          
                                          
                                          
                                          
This was such a good article..... However,
since  we publish it electronically, and
not   paper  magazine, there is  possibility
make your life a little lighten !              
                                          
In the  appendix to the magazine you will find two
to to use of the "single-sector-
new boot:                             
                                          
       1SBOOT_М (version by MAXSOFT)       
                                          
                    and                     
                                          
     1SBOOT_Р (version by POLTERGEIST)     
                                          
The version from MAXSOFT was described in detail
in  read  by you article,  and version from
POLTERGEISTA about  too mostly but with
other functional features. K
In addition, this version several
before  and  therefore  programmed  not-
many  otherwise. How? You'll figure it out for yourself when
disassemble!                         
                                          
Well  and  for  most  inquisitive minds, on disk
written  two  files  in editor format
ZX-WORD:                                  
                                          
  1S_boot+. (listing with comments)  
                                          
                    and                     
                                          
  1S_boot-. (listing without comments) 
                                          
The first  file is convenient for converting to
assemblers  with  editor  for 64 characters in
line  and  with support for Russian font
alternative  encoding.  An example is:
th assembler  is version of ALASM4X8,
in  then  time like TASM x.xx although it supports
lives  64  characters in a line, but "bummer-
appears" in Russian comments.           
                                          
                                          
For all those who do not use ALASM,
intendedsecond listing. It lacks
There are comments in Russian and lengthy
per line does not exceed 42 characters.       
                                          
This file can be directly loaded into
TASM 2.0,  and with  using the option  Import
Tasm2.0  and  in  assemblers  TASM 3.XX, TASM
4.0 (XLD), TASM 4.XX (RST#7).             
                                          
How to convert text  to  other types
assemblers I I hope you  will understand
yourself.                                     
                                          
                  Good luck!                  
                                          
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MUSIC VU: VISUAL/MS/XTM