TR-DOS
ZXNet echo conference «real.speccy»
* Forwarded from CODE.ZX by Kirill Frolov (2:5030/827.2).
* Originally by: Kirill Frolov (500:812/9.8), 11 Nov 99 23:57.
* Originally to: All.
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Immediately click on RESET, All !
Well, I figured out how to issue auxiliary commands
and what glitches there are. You can live without reading register 1F; readiness is always read through
FF.
At the same time I learned that the DX command cannot be given to the VGshka. She then
goes into meditation, does not give out INTRQ... We need D0, really
an immediate interruption.
But as for recording sector readings, it couldn’t be worse. :-(
I dug up this in TR-DOS:
3F4B 3ED0 LD A, 0xD0
3F4D D31F OUT (0x1F), A
3F4F 78 LD A, B
3F50 E601 AND 0x01
3F52 C2E73E JP NZ, 0x3EE7
3F55 DB3F IN A, (0x3F)
3F57 B7 OR A
3F58 2005 JR NZ, 0x3F5F
3F5A DB5F IN A, (0x5F)
3F5C FE0A CP 0x0A
3F5E C8 RET Z
So that if there is an error when reading sector 10 on track 0
TR-DOS doesn’t care about it. Moreover, _SIDE NUMBER IS NOT CHECKED_!
And this means that sector 10 itself.the first file on the disk may
be read with an error or not read at all! =%-()
The conclusion is quite logical - 3d13 Mazda. But no turboloaders
can save you here, they either ignore errors altogether, since they cannot
read register 1F, or they use this buggy program
in TR-DOS.
But I just wanted to create a program for reading-writing
sectors with error detection and without using system variables
TR-DOS. I came to the conclusion that this is simply impossible without reading register
1F.
We need to fix TR-DOS, this time... It's a terrible glitch. :-(
It will definitely work in iS-DOS on 640kb disks,
in MOA CP/M, in TR-DOS itself, when reading MS-DOS 800kb disks...
Kirill Frolov. [ZX]
-+- Fid0Ed v1.60
+ Origin: I am Absolute Monarch and the stars obey me... (500:812/9.8)
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Immediately click on RESET, All !
Kirill Frolov [ZX]