Laboratory - ZX-SPECTRUM and operating systems.

<b>Laboratory</b> - ZX-SPECTRUM and operating systems.
(C) 1998 VY Chertkov
Music: THE BEST ITALIAN-'VENICE 'by KENOTRON



    ZX-Spectrum and operating system (OS)



     More recently, asking anyone spektrumyuzeru question: 
"What is an operating system for Why did she want? ", you could 
get the answer: "I do not know!" And it is not surprising, 
since ever existence, on the Spectrum never had OS

fully understood, because it was originally a computer
conceived as a game. As in all such
PC, at the Spectrum instead of the OS was installed BASIC in 
ROM, as This language has the basic features inherent in 
operating systems. But Spectrum BASIC is very primitive, does 
not support disk, press tokenizirovany (very poor syntax), and 
develop it further is extremely difficult. ROM Spectrum is 
built according to the "monitor" - there are no functions 
available to the user devices to service a computer with a 
single interface (in normal computer is called the BIOS or

Kernal). There is only one standard entry point
Monitor (restart) - everything else described in
various literature on the Spectrum - a sub-program monitor, and 
nothing more. Ie, ROM is a "black box" which can not climb. 

     Unlike the computer that Yamaha. Model
MSX-1 is also, like ZX-Spectrum has only BASIC in ROM, but the 
Basic is much steeper than Spectrum and imagined future use

drive. In addition, it is similar to Microsoft BASIC,
but greatly expanded - supports graphics
(Sprites) and sound (AY). In addition to BASIC, the ROM 
contains the system BIOS, and it gives the opportunity to 
develop all the basic software with no loss of compatibility, 
since No one inside these programs does not climb - there are

standard entry point. In general, their own
ROM has every device (RS-232, RTC 'CMOS).
Program tied to any external events (input-output to tape I / O 
RS-232), not synchronized program delays CPU, and based on a 
real time clock, ie on CPU speed correctness of the drivers are 
not independent (compare with the Spectrum). Moreover, the 
functions BIOS available to the user's software - it's just 
wonderful: firstly, there is independence on the equipment, and 
secondly, to write programs much easier, because all low-level 
I / O is already created!


     In the model of MSX-2 was without problems is running 
MSX-DOS, ie, computer worked without the BASIC, though, if 
desired, it can be run on the OS commands. After restarting

computer, in the absence of a system disk in the drive, also 
carried out in BASIC. Ie without OS computer looked like a 
normal MSX-1. But Basic was already a disc - all teams to be 
forwarded from tape to disk (without any RANDOMIZE USR 15619: 
REM :....), although the possibility of working with cassette 
remained. Old tape of the program worked fine from the disk, 
they did not have to be adapted to great difficulty, both on 
the Spectrum in TR-DOS, their had to just copy from tape to 
disk - and all!


     And I said all this to the fact that if Spectrum has been 
designed as a human, then many would problems now did not 
exist. No need to kid ourselves, not even in the hardware 
capabilities of the case, the underlying ideology of the 
computer is outdated! In the form in which there is now a 
Spectrum, it pointless to develop - the next revision will not 
change anything, on the contrary - the car will be even worse. 
Looking for a qualitative change. After all, the Spectrum was 
developed as a cheap gaming computer, but we are now with him 
cope, as a professional machine. Even Clive Sinclair himself by 
1984 had lost interest in him because he was already obsolete, 
but we're still sitting, and that is trying to from him to do 
.... 

    Almost as primitive as the ZX-Spectrum
48, were his competitors - C64 and Atari. But these
firm in time changed his mind and released the brand new 32-bit 
model, having nothing to do with the old 8-bit. 32-bit Spectrum 
QL failed, of course, very sorry ... For the development of the 
new ZX took firm Amstrad, firing again very bad model Sp128 +, 
+2 and +3. They are very not far removed from the Spectrum 48, 
while the price has increased significantly - the sales speak 
for themselves. A after all there was also an opportunity to 
make a good, albeit 8-bit, the new Spectrum. Would take the CPU 
Z-180 or Z-280, which almost fully compatible with the Z80,

at the same time more productive and memory addresses
1MB and 16MB, respectively. Some programs on
These processors would not have gone, but no great loss.
On a new PC can be fitted normal OS
to support the older programs can be done
something like an emulator, though, if you look at it
up to 1985 good games, we can say never happened.
Yes, many things could be done. Instead,
concocted something called Spectrum 128K - apparently developed 
this "after yesterday." What was done in this model - it is 
done hastily and not the best way. In the same wells and the 
memory is addressed more convenient, and there are no such 
restrictions, as Spectrum ...


     Recently, many electronic publications raised questions of 
further development Spectrum, the comparison of different 
models for "Slope", and some places have begun to realize that 
the OS in general, it is necessary. And asking someone whether 
he heard about operating systems, you can get the answer: "Did 
you hear, hear" - referring to the TR-DOS, iS-DOS, CP / M or 
MS-DOS. But, first things first. 

     The fact that the TR-DOS in general is not an operating 
system, written even in the corporate governance (read 
instructions can sometimes be useful) it's just a disk 
interface. When conceived this interface, the main task was to 
approximate it to the cassette, ie, that all operations were as 
much as possible like the similar "cluster". The meaning of the 
interface - just broadcast Cassette I / O to disk. But even 
that turned out pretty poorly - everything needed to redo the 
program, and relatively easy to distilled Only the most simple 
program loader on BASIC. Funny, but when craftsmen recreate 
BETA-DISK for "our" spare parts, apparently for reasons of 
compatibility with the ROM in 1990, the window entrance to the 
TR-DOS was shifted to 256 bytes forward - at the beginning of 
character generator (at address 3C00H on 3D00H). It is easily 
seen by looking at software, "throw" Multiface-128. In the 
"old" BASIC such programs, it happens, stays loader, where it 
is clear that TR-DOS command is invoked like: 



   RANDOMIZE USR 15363: REM: LOAD "file" CODE



     On this basis, it becomes clear why
no one (!!!) program TR-DOS, which came to
us from the West - they just did not work. Another interesting 
fact is that the beta-disk - this is the worst of disk 
interfaces ever created for ZXSpectrum, and he settled down 
with us! And even in an erroneous implementation. What do we 
have a country that survives only in her worst ???.... 

     And, in general, TR-DOS reminds the Monitor Spectrum, ie 
has the same shortcomings. At the same time occupies entire 16K 
- although such a "system" and 2 kilobytes much. Challenges for 
3D13h - it's not BIOS (Ie, primitive, even for BIOS) and much, 
much less DOS. If you're not lamer, you will agree with me. As

and BASIC, ROM TR-DOS to develop practically impossible - to 
begin again the problem (in) compatibility. 



     Another thing iS-DOS - goes for any Spectrum, works pretty 
fast, here are some screaming: "iS-DOS - Best Of The Best !!!!" 
- Not fully understanding the meaning of these words. Although 
she quickly separates file panels, working with 
sub-directories, has external command, etc. In general, creates 
the illusion that your computer is running the OS, but it's 
worth a look in the programmers' manual - as all will become 
clear - it is just a wrapper, empty, You blatantly cheated! No 
OS and No trace. And if you're taking this leadership will come 
to more or less prepared for the programmer Amiga or PC, and 
start him to prove that the iS-DOS the operating system (I'm 
not talking cool) then, at best, he wagged his finger to his 
temple (Or call 03). All that is there - a set of functions for 
drawing windows, text output and input characters from the 
keyboard. File Subsystem (Part Operating system, manage files) 
is missing completely. Also, there is no memory management 
system, what is done - is in its infancy. And if it is compare, 
for example, MS-DOS, then this level of BIOS, ie simple device 
drivers. Yes, and how drivers they are defective: there is no 
clear structure, uniformity of input and output parameters, 
connectivity, custom drivers (like on PC). In normal system, 
all low-level procedures constitute the system BIOS, and to 
connect the extensions (plug-drivers), there exists some 
mechanism in the iS-DOS is a mess. No not that clear, in 
general there is no structure, And it is with the structure and 
begin to write the system .... Before writing the OS, you must 
first work hard to know what it is and how it works. 

     I remember how they told me this system bummer. After 
reading in the advertisement: "... The newest operating 
systems! ... Subdirectories ... just can not believe this is 
unbelievable!" - Of course I was delighted and immediately ran 
to the post office to order the basic kit (in Inforkom, of 
course). Imagine my disappointment when I was at all

it looked - it's just indescribable. So break off! Even 
formatter was not, but, by the way, this basic set, I copied 
the first same day they are even the same utility ARZT (or a 
Doctor, not I remember already, as it was called), such that's 
the case. 

     I certainly have nothing against the authors
this program - they did a great job, but
Unfortunately, all for nothing ....



     Now we discuss the system CP / M. Many
(Not all, of course), who saw the CP / M to the pros, why
is convinced that CP / M - is the actual panel file shells 
CopyK, although it is certainly not the case. Interesting, but 
similarly judged and the MS-DOS shell to Norton Commander. 
Seeing how slow CopyK, many will say: "CP / M - this shit!". 
But it all that CopyK - it's just a program running

under CP / M - and the fact that she ugly napisanz does not 
mean that the CP / M system is bad. It just means that CopyK - 
brake program! And CopyK we must pay tribute, in a time when it 
was written (92-93g), on the Spectrum nothing (!!!) this was 
not observed, although generally it and now the situation has 
not changed much. 

     OS CP / M - is an add-on equipment
computer, the intermediary between programs and devices. At the 
disposal of the programmer is a set of functions, which greatly 
simplifies writing programs. Those who disketiroval game in 
TR-DOS, they will not believe how easy it is to work with 
files, even in standard CP / M (on the extended versions, I do 
not say). System provides ease and convenience working with 
file structures. Program, working through the CP / M, will work 
on a floppy disk, a screw or electronic drive - to work on 
another device, it should just go copy and do not need to redo 
it. Complex manipulation sectors, tracks, teams controller - all

it takes the OS. You do a direct solution of the problem, 
rather than recreate some parts of the OS at each program (as 
is well known, qualified in all different programmers ...). 



          * TO BE CONTINUED *



fragments of the OS at each program (as is well known, 
qualified in all different programmers ...). 



          * TO BE CONTINUED *



vobodnoy from the intro of

    - Why?

    - I do not know!



(C) 1998 VY Chertkov
Music: SPECIAL COMPOS 'by KENOTRON'96



     ZX-Spectrum and operating system (OS)

                  (Continued)



     Now for the visual comparison of the systems. The point
that "see" the operating system can not, ie
because this is just a set of functions - is not a program such 
as musical demonstrations - which draws chtoto on the screen to 
the music - it's not something ... System can only be assessed 
on their abilities (Both existing and possible future).

Although, like it is! The magazine ZX-Format N4 Nemo, 
reflecting on the Spectrum, gave a comparison of existing 
systems to ZX. We compared the CP / M, iS-DOS, TR-DOS and MagOS 
(!). Nemo, not stupid like a man, a good article says, but he 
thought of comparing CP / M with MagOS? It's like comparing a 
scooter with a "nine". After all, people are not very versed in 
this, after reading the article have thought that the program 
MagOS on Scorpio - is a system comparable to the level of CP / 
M. The same just wild! And indeed, in this series CP / M - is

the only operating system, so I do not understand how they can 
be compared. 

     Despite all that, in comparing these systems
won, what do you think, what? Yes, all right,
iS-DOS! In CP / M, it appears, and the interface is not (I 
wonder how it all works then?), And segmented, and "long" 
files. You are wrong, all it is, why it can not not be. The 
only thing the human Nemo - subfolders in the usual CP / M 
actually no, but there are areas of the user - USER'y. I agree 
that working in the command line is not very convenient, but no 
one did not make work exclusively in it (you're in MS-DOS too

both work?) - writes the file wrapper, and all
becomes very cool! The main thing that has not considered Nemo:
CP / M - is a real OS, and as a consequence, is able to develop 
and improve (example - system DOS 4.0 (the pros) is compatible 
with CP / M and supports subdirectories). I certainly 
understand that iS-DOS was created in his native city for Nemo, 
but all well, you can not be because of this so biased.


     Reading the various journals and newspapers,
I noticed an interesting trend: Many agree that the OS Spectrum 
is needed, but everyone wants to create its own system 
(naturally, VERY BEST), which has nothing in common with the 
previously existing ones. Since, in their opinion, all the old 
system - bullshit. As a rule, these people already have 
achieved some success: created several dem (And possibly very 
steep), intruh, disketirovali a variety of programs, etc. But, 
I dare say if you've written at least 50 superkrutyh demo, it 
is not means that you create at least one operating

system (the opposite way, too true). Yet the process of writing 
the demos and the OS is slightly different. Many simply do not 
understand how difficult to develop an operating system from 
scratch. After all, you must fully think through the system, 
for example: 

 1 How it will interact with the programs

   external devices and their own

   components;


 2 How to be organized by an external memory (in the form

   files or otherwise);


 3 How the system will allocate memory, includ
   le extension; ie, how it will manage the PA
   myatyu;


 4 If the system will manage the files, it will be

   whether to use any of the existing

   filesystems (ekstentnaya CP / M, FAT, NTFS,

   HPFS or another) or will be developed Sauveur
   Shannon new file system.


 5 What status will be launched programs
   we have: serial or parallel processes,

   substituted modules or something else.


 6 In what form will be a dialogue with users
   Telem: as a command line, menu, or the Picts
   gram.



     In this list I bring the first thing that came to
mind, it has a lot left out! In addition, the program
control external devices (drivers) should
written by a man, at least a little knowledgeable in
hardware (preferably - good). Take for example
keyboard driver. Some may say: "No
could not be easier, and will, of course, wrong. What I have 
seen enough in the same demah and email. magazines like crooked 
interviewed key! here and unrepaired chatter, zavivisimost 
speed replay (Repeat) and the delay before the first repetition 
of the clock frequency of CPU and other defects. When Reed's 
software keyboard, and he know does not know that there is such 
a thing as a "bounce" keys (one must understand the physics of 
the phenomenon). Wrote calmly program, they had to work fine, 
but only with him. At the other company - is continuous glitch. 
Or another example - the procedure for loading the unit with a 
tape recorder (the same 1366 or # 0556) how many people 
understand thoroughly ee? A because it was the most simple 
examples, but there is still extended memory (also there is not 
so simple as it may shown), mouse, disks (it is not very 
difficult) other devices ... The device driver should be the 
absolutely correct no matter from which, as it was his duty - 
that's why it is written. Leave podprogrammki, anyhow, if only 
work is not difficult. Modules that work well not only on the 
machine of the author and do in any circumstances, create a 
much more complicated, but still, and they must occupy as 
little memory and run as fast as possible. 



     To develop and implement a new operating system can
leave year 2-3, not counting time spent on
testing, error correction, etc. In addition,
a completely new system, there will be no assemblers
no debugger, no programming language of high
level - nothing at all. The question is, who and why
Such a system is needed, whether it is 10 times steeper than 
MSDOS, Windows NT or AmigaOS? 

     For example, when creating MS-DOS, the authors do not
steel puzzle, but simply took as a basis for CP / M
and improve it. Almost all software from the CP / M was easily 
moved to a new OS (was even a special utility that allows you 
to translate the source code i8080 assembler code for a 
processor i8086). New systems for an 8-bit computers, which 
appeared after the establishment of CP / M, as a rule, have 
been with it compatible. That is, the system is a CP / M + 
"something else" at the discretion of the developer. Because 
creating a compatible system, not need to worry about the 
underlying software, as it already created: there is a steep 
and assemblers, and debuggers, and Languages Vysk level. 
Thus, to create a completely new system for an 8-bit computer 
that is not compatible with CP / M, totally meaningless. 



     There is one very important point. Case
that absolutely all of the programs for the ZX-Spectrum
were created, given that the OS on your computer
no. From this, in particular, that appears
any OS, it run the program for the Spectrum
will not (remember iS-DOS). All prog for ZX written on "naked" 
computer, using all available memory. The program is running 
any OS, in some way limited: they using only the available 
memory, to perform certain actions cause the operating system, 
after completion of the work through to the OS, but do not 
reset memory, etc. Thus, the conclusion suggests itself: 
Spectrum and any operating system are incompatible! The 
situation would seem hopeless, but still I see solution.


     Let's start with the fact that the interface TR-DOS - it is
non-standard device, it does not support any
one western Spectrum emulator for the PC, although supported by 
virtually the entire periphery, ever existed on the ZX. 
Standard is the same as It is strange - the tape recorder, or 
rather, in emulators these are images of tapes - tap-files. 
These files are "understood" any emulator, in addition, it at 
any time you can write on this tape and upload to the This 
Spectrum ... That is to say, the first time, not in favor of 
TR-DOS. 

     It's no secret that the programs normally transferred from 
the tape in TR-DOS, there is little, each can find at least a 
little, but a glitch (that blocks marred, the picture, then use 
a different disc does not want to boot, it does not 
"understand" one-sided disk drive, then upload the disk does 
not work). A program on the tape is quite normal to work, 
without no problem ... Not only does the West program

come up all the broken, when moving to TR-DOS are
once more maimed. It is not often that the program is "purely" 
moved - now in one problem or the other. And this is the second 
time. Thus, in the long run, you can opt out of the interface 
TR-DOS, returning "back to the tape" - but at a new level!