Amazing #01 29 сентября 1997

Программирование     TR-DOS

TR-DOS - disable key Break, poll SH 93 at the lack of disk drive head positioning procedure.

Section: Tr-Dos
Text: J. Jury
Music: IRONMAN
Information: Dr.Serg, Mr.Beeper



"Today we will talk
 one of the glitches in TR-DOS "



   So it was written in journal
"ZX-FORMAT", about the glitch, which I
now going to tell you
detail.



   This journal has been described a case
when you start your computer, head
drive directed to trk 159 and tried to move on. Explanation they
given is: (approx)

 - Comrades nick! The problem is not in
Your controller, but in your ROM. So
that change the ROM and everything will work
as it should.


   I'd like to see theirs faces when
this "new ROM" run for about a week. Yes, when to change 
everything as PZU'shku though, would have worked fine, but after

a few days, everything happens for the first time.

   Do not want to upset you, but the whole problem
not in the ROM and floppy drive in your controller! It has 
already been verified and tested several times. Most often this 
"Glitch" found in computers, model "Leningrad2", "Kharkiv", and 
the like, where there is a controller without the ROM, but 
instead the usual 128k worth 512K.


   So comrades PUBLISHER check
the reliability of their materials before
than releasing them into the light!

p.s. Sorry guys!

________________________________________


   I want to write here is about.
Many start working on the assembly
programmers might have noticed that
loading unit sectors with the entry point
15635 (# 3D13 hate HEX - the system!)
stops when you press
BREAK. To avoid this, sufficient
first program to put here such
two lines:


        LD HL, 51697

        LD (23746), HL

and all! That's all suffering with the key
BREAK will be finished - it simply "cease to exist."

  Using the above method
together with the load through # 3D13 - Best
loader, which can only come up with: In - First, it is brief, 
and secondly - Works on all computers nazavisimo version of 
TR-DOS. This method is used and the DREAM MAKERS SOFTWARE, and 
MAX IWAMOTO.


  And: Driesse! Learn to save memory: what to write:


        LD B, LEN

        LD C, 5

because you can instead write:


        LD BC, LEN * 256 5

and assembler will understand and one byte of memory
save ("penny - penny gained").

  Gentlemen programmers! Squeeze, perhaps
hundred, its software products. There is also a peerless thing 
as LZ / PACK or MS_PACK vobschem a lot of them ...




   If you have such materials,
send them to our office and we
must publish them.

Now go to the principal.
________________________________________

Today in section Tr-Dos much as two procedures that will be 
useful to you in many sluchyayah life, namely:



  1. POLL SH 93 AT NO DISC!


  2. PROCEDURE FOR POSITIONING HEAD!



Two of these procedures are provided courtesy of the great 
CODER'om under klikuhoy Dr.Serg. In the subsequent issues this

section will carry it again, and in
application has its Remix Game
"SPACE CR." a MOUSE!!!
So I ask to love and favor.


                *

In order not to complicate your life, to drive
have these procedures in a format ZX-ASM 3



   Poll "VG93" in the absence of a disk!


    Coded and copyright by Dr.SERG,


    (Special for magazine PolyForm)



        ORG # 8000

        DI

        CALL ConDisk

        LD HL, met3

        LD (HL), A
met2 EI

        HALT: DI

        CALL ConDisk

        CP (HL)

        JR NZ, met1

        LD A, # 7f

        IN A, (# fe)

        BIT 0, A

        JR NZ, met2
met1 DS 3

        RET
met3 DB 0

ConDisk PUSH IY

        PUSH IX

        PUSH HL

        PUSH DE

        PUSH BC

        LD (ConDisk1 +1), SP

; Installation for the add. # 5CC2: 3ConDisk1


        LD A, # c3

        LD (# 5cc2), A

        LD HL, ConDisk1

        LD (# 5cc3), HL

; Command "Forced termination"


        LD IX, # 2FC1

        CALL LL7846

; The "Restoration"


        LD A, # 08

        LD BC, # 001F

        LD IX, # 2A53

        CALL LL7846

, Reading the status registers VG93


        LD DE, # 0000

        LD IX, # 2740

        CALL LL7846
ConDisk1 LD SP, 0

        XOR A

Clear the VG93


        LD IX, # 1FF3

        CALL LL7846

; Restore the system registry VG93


        LD IX, # 1FEB

        CALL LL7846

; Command "Forced termination"


        LD IX, # 2FC1

        CALL LL7846

; Installation at - # 5CC2: RET


        LD A, # c9

        LD (# 5cc2), A

        LD A, (# 5CCD)

        AND # 40

        POP BC

        POP DE

        POP HL

        POP IX

        POP IY

        RET
LL7846 PUSH IX

        JP # 3D2F



   The procedure for positioning the head!


    Coded and copyright by Dr.SERG,


    (Special for magazine PolyForm)



VVHOD: w-nom.treka 0-159

       : A = 0 test position 1

                           (0001 1h00)

       : A = 255 not verify 0

  OUTPUT: A = 0 O.K.

        A <> 0 Error,

  BIT 7, a = 1 kom.ne priinyata

  BIT 4, a = 1 osh-ka positioning

  BIT 0, a = 1 kontr.ne ready to receive

  izm.et IX, AF

  Business Registry => (ErrWG)

  When starting the engine pauses

  opred.konstantoy => (DrPause)


        ORG 25000

        LD B, 0; Trk
Posic PUSH BC

        LD IX, posicC

        AND A

        SET 2, (IX +1)

        JR Z, posic3

        RES 2, (ix +1)
posic3 LD IX, posicex

        PUSH IX

And, installation of side


        LD A, B

        SRL A

        LD B, A

        LD IX, # 1feb

        JR NC, posic1

        LD IX, # 1ff6
posic1 CALL Dos2

        LD IX, # 3c30

        CALL Dos2

        BIT 0, A

        jr z, posic4


        ; SH not gotova.preryvanie Kamanda


        LD A,% 11010000

        LD C, # 1f

        LD IX, # 2a53

        JR posic1


        ; Checking motor rotation

        ; And modification konst.zaderzhki

posic4 LD IX, 1

        BIT 7, A

        JR Z, posic5

        LD IX, (DrPause)
posic5 LD (posicp +2), IX

        LD A, B

        LD C, # 7f

        CALL Dos1; installation number trk.
posicC LD A,% 00011100;


        ; Bit 2-way navigation key and check ..


        LD C, # 1f

        CALL Dos1

        CALL Dos1; Track Search

        LD IX, # 3c30; in a, (# 1f)
posic2 CALL Dos2

        BIT 0, A; is the command

        JP NZ, posic2

        BIT 7, A; Emergency exit

        RET NZ; drive worth!

        BIT 4, A: RET NZ; error search

        BIT 3, A: RET NZ; error control.
C; code (if CHECK)

        LD (ErrWG), A

And, a pause, if there was engine start

posicp LD IX, 0
posic6 DEC IX

        LD A, XL

        OR XH

        JR NZ, posic6

        POP BC: RET
posicex LD (ErrWG), a

        POP BC

        RET



        ; Nn transition TR.DOS

        ; For 2A53: OUT (BC), A: RET

Dos1 LD IX, # 2a53; out (c), a: ret
Dos2 PUSH IX

        JP # 3d2f
ErrWG DB 0
DrPause DW # A000

Attention!

These procedures do not work on ROM ver
siey TR-DOS 5.03.

When using these procedures in their own programs, make 
reference to author.


Today all are waiting for your letters of representation
proposition.
________________________________________