Energy #05 29 мая 1997

TR-DOS

TR-DOS - The work of the ports of TR-DOS'a.

                 TR-DOS



                  Docent / LGN '& Spectre / LGN


    In this issue we discover ENERGY
a new section dedicated to small
ruses, which facilitate the difficult
life of the encoder. The first of these articles
little deploy theme begun in
ZX-FORMAT'e # 5 "TR-DOS programmers.
ZX-FORMAT in the face of Max Petrov us very
described in detail how to write a turbo-loader;
Echo told how to avoid trouble
when working with VG'shkoy; well and we will discuss
work with the ports of TR-DOS'a. There is
several ways to work with ports
TR-DOS'a:


    - On some computers (eg

    PROFI) can be put on VG'shku

    direct access


    - In some ROM (TR-DOS) at

    # 3C30 stitched command codes


             IN A, (# 1F)

             RET


    - In TR-DOS v5.03 at # 09E7 is

    similar combination


    Pull all the port # 1F explained by the fact
that the remaining ports to read is not so important
(Except port # 7F course). And the port # 1F
Reads a byte error occurred when
the disc. A small digression: from
entry in the ports are no problems, so
as at # 2A53 stitched:


             OUT (C), A

             RET


    Now, about reading, the first and
the best known way to read from the port # 1F
Rodionov mentioned in his book, "TR-DOS
for users and programmers, "he
Despite its flaws (some spoil
registers, spoil the contents of the port
sectors, etc.) is still active
applied. A more detailed description
this method, see above
book. We will tell you two more:


      # 3EF3 IN H, (C)

      # 3EF5 IN A, (# FF)

             AND # C0

             JR Z, # 3EF5

             EI

             RET M

             DI

             IN A, (# 7F)

             JR # 3EF5


    This method works on all
computers, using it can be read
the contents of any register VG'shki. For
that in BC Specifies the port number and H
get the value read, the main
that during this procedure
came to signal the end of execution
team.

    And the second:


      # 3FE5 IN A, (# FF)

             AND # C0

             JR Z, # 3FE5

             RET M

      # 3FEC INI

             JR # 3FE5


    This procedure is used TR-DOS'om
to read the data, but we can
use it for reading information from
any port. Application: HL asking
address of where to place the result of the operation,
and the BC port number. It needs to run with
Address # 3FEC. Conditions of performance
similar to the previous one. Corresponding bits
to read information can be found in
All the same book Rodionova of TR-DOS'e.
If you are interested we can mention
the address of # 2099, resulting from the use
This procedure will be the state flag
ZERO: if there was not one mistake then
to Z, well, and if NZ - DISK ERROR!!! When
This error is any situation (no
disk read / write error, etc.)
Now calling the procedure:


        PUSH BC; save BC and HL

        PUSH HL; IN

        LD HL, CONTIN; A, (# 1F)

        PUSH HL;

        LD HL, METKA; AND # 7F

        PUSH HL;

        LD B, 1; OR A

        PUSH BC;

        LD HL, # 2099; RET Z

        PUSH HL

        JP # 3D2F
METKA DB # 01
CONTIN DI

        POP HL; continued

        POP BC

 Note: after is EI.


    At the end of articles may add
in order to avoid problems with your computer
"Byte-01 and to health
our turbo-loader'ov on your hard drive
The authors of this paper used the standard
entry point to the TR-DOS - # 3D13, and the errors
caught by # 5CC2. How to catch
errors through # 5CC2 look at ART
STUDIO. And maybe we'll write about it
article.