Mercurial > hg > Members > kono > nitros9-code
changeset 2940:824019cd8744
rb1773: Make 48 TPI floppy disks readonly in 96 TPI drives
Deny the disk destroying write with the narrower heads of the 96 tpi drive
when the user has placed a 48 tpi disk in the 96 tpi drive so he can read
it. Double stepping the drive is then done automatically so as to stay in
mechanical synch with the tracks on a 48 tpi disk. But that, until now, did
not make the disk read-only, this patch does that.
Patch by Gene Heskett and Robert Gault.
| author | Robert Gault <robert.gault@att.net> |
|---|---|
| date | Sat, 25 Jan 2014 23:20:06 +0100 |
| parents | 011a5f26e9da |
| children | 4446149f7ea9 |
| files | level1/modules/rb1773.asm |
| diffstat | 1 files changed, 44 insertions(+), 4 deletions(-) [+] |
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--- a/level1/modules/rb1773.asm Sat Jan 25 23:19:38 2014 +0100 +++ b/level1/modules/rb1773.asm Sat Jan 25 23:20:06 2014 +0100 @@ -85,6 +85,17 @@ * * 2009/03/19 Robert Gault * Removed slow down hack from format and write sector but left code just in case. +* +* 2013/12/16 Robert Gault and Gene Heskett +* Added two new flags, flagWP flagFMT, to prevent disk damage by Writes where +* the drive head width does not match the disk track density. +* flagWP <>0 write protects; flagFMT <>0 overrules flagWP so that a Format can +* write to a disk. +* A descriptor that does not match your drive can still cause Writes to disks that +* could possibly cause disk corruption. This cannot be prevented. +* +* When LSN0 is read using a 3.5" drive, most of the checks of density, sides, etc. +* are bypassed as not needed. nam rb1773 ttl Western Digital 1773 Disk Controller Driver @@ -172,6 +183,8 @@ * physlsn rmb 2 PCDOS (512 byte sector) # flag512 rmb 1 PCDOS (512 byte sector) 0=no, 1=yes flagform rmb 1 SCII format flag +flagWP rmb 1 write protection <>0 +flagFMT rmb 1 format flag size equ . fcb DIR.+SHARE.+PEXEC.+PWRIT.+PREAD.+EXEC.+UPDAT. @@ -204,6 +217,8 @@ clr RW.Ctrl clear SCII control register clr flagform,u clear SCII format flag ENDC + clr flagWP,u + clr flagFMT,u ldx V.PORT,u get Base port address lda WD_Data,x get byte at FDC Data register coma complement it to modify it @@ -415,6 +430,10 @@ ldy >lastdrv,u Get drive table ptr back lda <DD.FMT,y Get format for disk in drive ldy 2,s restore path descriptor pointer +* !!!!!!! Most of these tests are pointless with a 3.5" drive RG + ldb <PD.TYP,y Get path's type settings RG + bitb #1 test for 3.5" drive + bne L0128 skip rest of tests if 3.5" drive ldb <PD.DNS,y Get path's density settings bita #FMT.DNS Disk in drive double density? beq L0115 No, all drives can read single, skip ahead @@ -422,8 +441,10 @@ beq erbtyp No, illegal L0115 bita #FMT.TDNS Is new disk 96tpi? beq L011D No, all drives handle 48/135 tpi, so skip ahead + sta flagWP,u set write protection bitb #DNS.DTD Can path dsc. handle 96 tpi? beq erbtyp No, illegal format + clr flagWP,u clear write protection since disk and descriptor match L011D bita #FMT.SIDE Is new disk double sided? beq L0128 No, all drives handle single sided, we're done lda <PD.SID,y Get # sides path dsc. can handle @@ -661,7 +682,15 @@ * CC = carry set on error * B = error code * -Write lbsr Chk512 go adjust LSN for 512 byte sector if needed +Write tst flagFMT,u + bne w3 if a format write normally and clear flags + tst flagWP,u + beq w2 continue if not a mismatch + ldb #E$BTyp + lbra L03E0 report bad type if forced WP +w3 clr flagFMT,u + clr flagWP,u +w2 lbsr Chk512 go adjust LSN for 512 byte sector if needed * Next line was lda #%1001001 which was an error RG lda #%10010001 retry flags for I/O errors (see Disto SCII source) L01C4 pshs x,d preserve LSN, retries @@ -888,10 +917,17 @@ bita #%00000010 ??? (Base 0/1 for sector #?) bne L02CC Skip ahead incb Bump sector # up by 1 +*!!!!!!!!!!!!!!!!!!!!!critical section on double-stepping L02CC stb >DPort+WD_Sect Save into Sector register ldx >lastdrv,u Get last drive table accessed ldb <V.TRAK,x Get current track # on device - lda <DD.FMT,x Get drive format specs; actually disk format specs RG + lda <PD.TYP,y Get drive type + bita #1 3.5" drive + beq L02CCb go if not 3.5" RG + lda ,s recover track # + clr flagWP,u + bra L02E9 +L02CCb lda <DD.FMT,x Get drive format specs; actually disk format specs RG lsra Shift track & bit densities to match PD; bit0 is MF or MFM eora <PD.DNS,y Check for differences with path densities; bit0 is MF MFM, bit1 is 96tpi anda #%00000010 Keep only 96 tpi @@ -901,6 +937,8 @@ beq L02E9 No, continue normally lsla Yes, multiply track # by 2 ('double-step') lslb Multiply current track # by 2 ('double-step') + clr flagWP,u + inc flagWP,u if double-step then prevent future writes L02E9 stb >DPort+WD_Trak Save current track # onto controller * From here to the line before L0307 is for write precomp, but is not used. @@ -1066,7 +1104,7 @@ * fcb $8C *L03E0 ldb #E$Read Read error - orcc #Carry set carry +L03E0 orcc #Carry set carry rts L03E4 bsr L0404 Send command to controller & waste some time @@ -1127,7 +1165,9 @@ ldb #E$UnkSvc return illegal service request error rts -SSWTrk pshs u,y preserve register stack & descriptor +SSWTrk stb flagFMT,u permit unconditional write on format + clr flagWP,u don't protect on a format + pshs u,y preserve register stack & descriptor * Level 2 Code IFGT Level-1