CRC.BG93

Hello, Andrey! Once, Fri Aug 13 1999 00:23, Andrey Chervinsky wrote to All about [CRC.BG93]: AC> Sorry for being intrusive, but could you tell me AC> as the control code is calculated by everyone's favorite VG93 microcircuit. ─ CODE.ZX (500:812/1.25) ────────────────────── ─────────────────────── CODE.ZX Msg : 485 of 1193 Rcv From : Alexander Ageev 2:5030/675.10 Mon 18 Jan 99 12:53 To : Dmitry Lomov Thu 24 Jun 99 00:03 Subj : Re: Mazda ─────────────────── ──────────────────── ──────────────────── ──────────────────── *** Answering a msg posted in area HARDWARE.ZX (HARDWARE.ZX). Hello Dmitry! Thursday January 14 1999 00:16, Dmitry Lomov wrote to Kirill Frolov: KF>> Or maybe you know how 1818VG93 calculates CRC? Tell us! DL> the same as MAC wrote :) I didn’t look into it in detail, I don’t know. DL> has anyone done this? Uncle DARK, you had something DL> is this? AU. === Beginning of crc.txt === ORG #6000 LD HL,TESTHD LD DE,#B230 LD C,4 CALL CRC LD HL,TESTHD LD DE,#E295 LD C,0 CALL CRC RET DW 0 ; IN :HL=DATA; DE=INIT CRC; C=SIZE;OUT :DE=CRC ^^ #B230=HEADER #E295=DATA CRC LD A,D:XOR (HL):LD D,A:INC HL LD B,8 CRC2 SLA E:RL D:JR NC,CRC3 LD A,D:XOR #10:LD D,A LD A,E:XOR #21:LD E,A CRC3 DJNZ CRC2 DEC C:JR NZ,CRC RET ;--------------------------------------- TESTHD DB 0,0,1,1 TESTDT DS 256 === End of crc.txt === Stinger. ───────────────────────вырезать─здесь─────(file: crc)─────────── Всего хорошего. Дмитрий.

Let your enemies, Andrey, die without sons! Fri 13 Aug 1999 at 00:23, Andrey Chervinsky ═> All: AC> Sorry for being intrusive, but could you tell me AC> as the control code is calculated by everyone's favorite VG93 microcircuit. ────[ The Vg_Crc .C file begins here ]─────────────────────── ORG #8000 LD HL,BUFF0,C,#04 XOR A:CALL CRC LD HL,BUFF1,C,#00 LD A,#01:CALL CRC RET BUFF0 DB #00,#00,#01,#01 BUFF1 DS #0100 ;************************************************ ;IN: [HL] =ADDR ; [C]=LENGTH ; [A] =TYPE; 0=HEADER, 1=DATA ; ;OUT: [DE] =CRC ; CRC LD DE,#B230:OR A:JR Z,$+#05 LD DE,#E295 CRC1 LD A,D:XOR (HL):LD D,A INC HL LD B,#08 CRC2 SLA E:RL D:JR NC,CRC3 LD A,D:XOR #10:LD D,A LD A,E:XOR #21:LD E,A CRC3 DJNZ CRC2 DEC C:JR NZ,CRC1 RET ────[ The Vg_Crc .C file ends here ]──────────────────────── [WBR, Oleg. ] [ 05:28 14 August XXXIV A.S. ] 75

Once on 13-08-99 at 00:23:00, I saw an interesting letter, there was Andrey Chervinsky wrote to All. The subject of the letter was CRC.BG93... ...And so I also decided to dent my keyboard. ├┤e└└o, dear Andrey! AC> Hi, All! AC> Sorry for being intrusive, but could you tell me AC> as the control code is calculated by everyone's favorite VG93 microcircuit. Yes to your health... Lecture: The highest noise immunity is cyclic some control codes built on the basis of polynomials. Moreover, The higher the degree of the polynomial, the more reliable the CRC. Test area blocks of fixed length and frames must contain inverted remainder of modulo two division by generator polynomial of the set of bits of the service and information areas, multiplied by X^K, where K is the size of the check area in bits. Since when recording on floppy disks it is used polynomial of 16th degree with a minimum code distance equal to ┌──────────────┐ │X^16+X12+X^5+1│ └──────────────┘ (in accordance with GOST 17422-82). In this case, the length of the block should be no more than 2^15 bits. The same idea applies in hard drives, and even in your favorite PC RAR archiver. Now closer to the point... Bring the programsdemonstrating the method of calculating crc with the VG-93 controller and not only to them... .... LD IX, ARRAY ADDRESS LD DE,ARAY LENGTH CALL CRC16 .... CRC16 LD HL,0 ;INITIAL CONDITIONS LD B,(IX+00) LD C,8 M1 LD A,B XOR H SLA B SLA L JR C,M2 SLA H JR M3 M2 SLA H INC H M3 BIT 7,A JR Z,M4 INC L JR M5 M4 LD A,20 XOR L LD L,A LD A,10 XOR H LD H,A M5 DEC C JR NZ,M1 INC IX LD B,(IX+00) LD C,8 DEC DE LD A,D OR E JR NZ,M1 RET The CRC will be located at the exit in HL! I’ll warn you right away, for the program takes time to work. After all, flop controllers do this it's a hardware issue!!! So if there are brakes, reduce the degree polynomial... ┌═─═─═─═─═─═─═─═─═─═─═─═─═─═─═─═─═┐ ║With the be$t wi$he$ and regards,║ │ Sincerely yours, Yuri. │ ╚─═─═─═─═─═─═─═─═─═─═─═─═─═─═─═─═─╝ (500:812/28.22)