Assembler - Secrets of the TR-DOS: the methods of distribution presence drives.

             TR-DOS



            (C) TimeKeeper / MHCG



  Opening this column, I would like
would be to start to say a few words
about why this is and for whom. The fact that a conversation on 
this subject was already quite a lot and

it may seem that nothing new here for you can imagine,
So, once I hasten to assure you that there are still
enough problems and puzzles
that joint efforts can
try to solve. Yes and no
All that has been published or
someone said about the TR-DOS
was correct and understandable. I have already
quite a long time trying to write
driver disk to complete the interception of disk errors,
but could not find all the necessary data. Even in
famous ZX-Revue I have not found
answers to my
issues, and listings of drivers that I tried to recruit,
was often a lot of mistakes
or they simply did not fit me. By the way, once I started,
I'd tell a few "gentle"
of articles from the ZX-Revue. Interesting there, of course, 
very much, but here's Listings leave much to be

desired. Driver disk, which is in this issue
magazine, has been recruited precisely because
Revyushki, but it otassemblirovat
in its original form and is not
failed. Part Subprogramme just
missing, and part was napisana wrong. I only narrowly failed to 
bring the driver to working condition. In connection with the

this occasion I had the
the impression that the listings
programs are printed without any
what a preliminary check on the performance. But
this is the issue of professionalism, and perhaps we'll come 
back to it, but in another again ...


 The first thing I wanted to write - it's how you can determine
availability of disk drives. Not the presence or absence of a 
floppy disk in drive, namely the existence of the drive. You 
ask why? Well, this is at your discretion. I used this 
verification in Hard Core ver 3.01 full, to

know how many panels can be printed, two or one, and just 
recently included in the fashion insert in the program test

computer, so that's there then
You can adapt this procedure:



        ORG # 8000

        ENT

        XOR A

        CALL TEST

        LD (DRV_0), A

        LD A, 1

        CALL TEST

        LD (DRV_1), A

        LD A, 2

        CALL TEST

        LD (DRV_2), A

        LD A, 3

        CALL TEST

        LD (DRV_3), A

        RET
TEST OR # 3C

        LD C, # FF

        LD HL, # 1FF3

        CALL DOS

        LD A, # 08

        LD HL, # 2FC3

        CALL DOS

        LD IY, 10000

, The number of matched IY
; Empirically.
, (The maximum time of movement; of drive heads from the 
village; glaciers on track zero) 

AGAIN LD HL, # 1FDD

        CALL DOS

        LD A, (# 5CD7)

        CP # 50

        RET NZ

        DEC IY

        LD A, LY

        OR HY

        JR NZ, AGAIN

        RET
DOS PUSH HL

        JP # 3D2F
DRV_0 DEFB 0
DRV_1 DEFB 0
DRV_2 DEFB 0
DRV_3 DEFB 0



  Generally speaking, the controller
There is a special tool for
definition of "readiness" to drive, but I have this tool
triggered only when the drive is inserted floppy disk. A 
reduced the procedure correctly determines whether the drive is 
not regardless of whether there is in it

floppy disk or not.


  How it works: when we send the controller command output
on the zero track, he tries to
receive from the drive confirmation operation is performed.
(Signal 'head in the initial state' - 2_oy bit port # 1F)
If the drive is connected and the head is at the zero path
the controller immediately generates
this signal, and if the drive
No, the controller receives
confirmation from the drive and not
will issue a confirmation signal, indicating that
team has not been completed. Naturally, testing should be 
carried out at off turbo mode if you have it. 


  After starting the program will
in turn the LED
drives. To test each
have spent approximately
1 / 25 seconds if the drive
connected, and about 1 / 2 otherwise, so that during 
verification, before going on to the next drive, it would be 
nice display a message like: "wait, test drive number

N ", so that the user did not think that the program hung.


  After testing, the corresponding variable is entered
toe, if the device is not detected or # 28 with a positive
result.


  At this opredelyalki about everything.
Maybe next time I'll show you how to determine
drive parameters: number of sides, paths, velocity heads, and 
perhaps even firm, to produce this model. :-))