Home » Archimedes archive » Archimedes World » AW-1996-08.adf » !6502DEm_6502Dem » Docs/VirtualDFS
Docs/VirtualDFS
This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.
Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.
| Tape/disk: | Home » Archimedes archive » Archimedes World » AW-1996-08.adf » !6502DEm_6502Dem |
| Filename: | Docs/VirtualDFS |
| Read OK: | ✔ |
| File size: | 0AAD bytes |
| Load address: | 0000 |
| Exec address: | 0000 |
File contents
6502Em: The Filing System ========================= The emulator provides a full filing system by means of the VDFS ROM. The following commands can be used to select the Virtual DFS ROM as the current filing system: *DISC *DISC *ADFS *FADFS In addition, the following commands are offered: *Quit (Return to the desktop) *Desktop (Return to the desktop) *Shadow (dummy command) *SRLoad (load image into sideways RAM) *SRWrite (copy memory into sideways RAM) Partial emulation of OSWORD &72 and &7F is performed (reading only!) This allows certain disc protection schemes to work. The DFS filing system structure is fully emulated by noticing when an ADFS directory's name is one letter long. eg if your Currently Selected Directory (CSD) is ADFS::HD.$.BBC.Games.J then: *DIR K will attempt to set the CSD to ADFS::HD.$.BBC.Games.K *DIR J will leave the CSD unaltered *DIR $ will set the CSD to ADFS::HD.$.BBC.Games (to change to the "real" root directory, use *DIR :4.$) *DIR ^ will set the CSD to ADFS::HD.$.BBC.Games eg if your CSD is ADFS::HD.$.BBC.Games then: *DIR $ will leave the CSD unchanged *DIR ^ will set the CSD to ADFS::HD.$.BBC ************************************************************* * If your CSD is set to ADFS::HD.$.BBC.G.L then ambiguity * * can arise, so single letter directories should NOT be * * used within each other. * ************************************************************* Drive numbers within filenames (eg :0.E.Jameson) are ignored so that you can save positions of games onto your hard disc. To specify a drive, use ADFS::0.Jameson *Drive and *Mount are ignored To change drive use *DIR :0, *DIR ADFS::0, *DIR ADFS::HD etc RISC OS's CSD is not changed by the emulator, allowing several incarnations of the emulator to be active. Some filing systems (eg DOSFS) do not support OSGBPB 8, so programs that use it will not work on such filing systems. OSFSC, OSFIND, OSGBPB, OSBPUT, OSBGET, OSARGS, OSFILE are all fully supported. In addition, OSGBPB 9 is partially supported (for the current directory): block?0=number of files to read (number of files read) block!1=address in memory of data block!5=length of data block block!9=sequential pointer (0 for first call, -1 when finished) RISC OS errors are passed back into the emulator via BRK. Filing system operations appear instantaneous to the emulator (ie do not run filing system benchmarks within the emulator!) Although the operating system normally appears to be ROM, it can be overwritten by filing system calls (eg *Load) Files that will extend beyond &FFFF will generate an error if you try to load them. (normally files might wrap round back to &0000)
00000000 36 35 30 32 45 6d 3a 20 54 68 65 20 46 69 6c 69 |6502Em: The Fili| 00000010 6e 67 20 53 79 73 74 65 6d 0a 3d 3d 3d 3d 3d 3d |ng System.======| 00000020 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d |================| 00000030 3d 3d 3d 0a 0a 54 68 65 20 65 6d 75 6c 61 74 6f |===..The emulato| 00000040 72 20 70 72 6f 76 69 64 65 73 20 61 20 66 75 6c |r provides a ful| 00000050 6c 20 66 69 6c 69 6e 67 20 73 79 73 74 65 6d 20 |l filing system | 00000060 62 79 20 6d 65 61 6e 73 20 6f 66 20 74 68 65 0a |by means of the.| 00000070 56 44 46 53 20 52 4f 4d 2e 0a 54 68 65 20 66 6f |VDFS ROM..The fo| 00000080 6c 6c 6f 77 69 6e 67 20 63 6f 6d 6d 61 6e 64 73 |llowing commands| 00000090 20 63 61 6e 20 62 65 20 75 73 65 64 20 74 6f 20 | can be used to | 000000a0 73 65 6c 65 63 74 20 74 68 65 20 56 69 72 74 75 |select the Virtu| 000000b0 61 6c 20 44 46 53 0a 52 4f 4d 20 61 73 20 74 68 |al DFS.ROM as th| 000000c0 65 20 63 75 72 72 65 6e 74 20 66 69 6c 69 6e 67 |e current filing| 000000d0 20 73 79 73 74 65 6d 3a 0a 0a 2a 44 49 53 43 0a | system:..*DISC.| 000000e0 2a 44 49 53 43 0a 2a 41 44 46 53 0a 2a 46 41 44 |*DISC.*ADFS.*FAD| 000000f0 46 53 0a 0a 49 6e 20 61 64 64 69 74 69 6f 6e 2c |FS..In addition,| 00000100 20 74 68 65 20 66 6f 6c 6c 6f 77 69 6e 67 20 63 | the following c| 00000110 6f 6d 6d 61 6e 64 73 20 61 72 65 20 6f 66 66 65 |ommands are offe| 00000120 72 65 64 3a 0a 0a 2a 51 75 69 74 20 20 20 20 20 |red:..*Quit | 00000130 20 28 52 65 74 75 72 6e 20 74 6f 20 74 68 65 20 | (Return to the | 00000140 64 65 73 6b 74 6f 70 29 0a 2a 44 65 73 6b 74 6f |desktop).*Deskto| 00000150 70 20 20 20 28 52 65 74 75 72 6e 20 74 6f 20 74 |p (Return to t| 00000160 68 65 20 64 65 73 6b 74 6f 70 29 0a 2a 53 68 61 |he desktop).*Sha| 00000170 64 6f 77 20 20 20 20 28 64 75 6d 6d 79 20 63 6f |dow (dummy co| 00000180 6d 6d 61 6e 64 29 0a 2a 53 52 4c 6f 61 64 20 20 |mmand).*SRLoad | 00000190 20 20 28 6c 6f 61 64 20 69 6d 61 67 65 20 69 6e | (load image in| 000001a0 74 6f 20 73 69 64 65 77 61 79 73 20 52 41 4d 29 |to sideways RAM)| 000001b0 0a 2a 53 52 57 72 69 74 65 20 20 20 28 63 6f 70 |.*SRWrite (cop| 000001c0 79 20 6d 65 6d 6f 72 79 20 69 6e 74 6f 20 73 69 |y memory into si| 000001d0 64 65 77 61 79 73 20 52 41 4d 29 0a 0a 50 61 72 |deways RAM)..Par| 000001e0 74 69 61 6c 20 65 6d 75 6c 61 74 69 6f 6e 20 6f |tial emulation o| 000001f0 66 20 4f 53 57 4f 52 44 20 26 37 32 20 61 6e 64 |f OSWORD &72 and| 00000200 20 26 37 46 20 69 73 20 70 65 72 66 6f 72 6d 65 | &7F is performe| 00000210 64 0a 28 72 65 61 64 69 6e 67 20 6f 6e 6c 79 21 |d.(reading only!| 00000220 29 0a 54 68 69 73 20 61 6c 6c 6f 77 73 20 63 65 |).This allows ce| 00000230 72 74 61 69 6e 20 64 69 73 63 20 70 72 6f 74 65 |rtain disc prote| 00000240 63 74 69 6f 6e 20 73 63 68 65 6d 65 73 20 74 6f |ction schemes to| 00000250 20 77 6f 72 6b 2e 0a 0a 0a 54 68 65 20 44 46 53 | work....The DFS| 00000260 20 66 69 6c 69 6e 67 20 73 79 73 74 65 6d 20 73 | filing system s| 00000270 74 72 75 63 74 75 72 65 20 69 73 20 66 75 6c 6c |tructure is full| 00000280 79 20 65 6d 75 6c 61 74 65 64 0a 62 79 20 6e 6f |y emulated.by no| 00000290 74 69 63 69 6e 67 20 77 68 65 6e 20 61 6e 20 41 |ticing when an A| 000002a0 44 46 53 20 64 69 72 65 63 74 6f 72 79 27 73 20 |DFS directory's | 000002b0 6e 61 6d 65 20 69 73 20 6f 6e 65 0a 6c 65 74 74 |name is one.lett| 000002c0 65 72 20 6c 6f 6e 67 2e 0a 0a 65 67 20 69 66 20 |er long...eg if | 000002d0 79 6f 75 72 20 43 75 72 72 65 6e 74 6c 79 20 53 |your Currently S| 000002e0 65 6c 65 63 74 65 64 20 44 69 72 65 63 74 6f 72 |elected Director| 000002f0 79 20 28 43 53 44 29 0a 69 73 20 41 44 46 53 3a |y (CSD).is ADFS:| 00000300 3a 48 44 2e 24 2e 42 42 43 2e 47 61 6d 65 73 2e |:HD.$.BBC.Games.| 00000310 4a 20 74 68 65 6e 3a 0a 0a 2a 44 49 52 20 4b 20 |J then:..*DIR K | 00000320 77 69 6c 6c 20 61 74 74 65 6d 70 74 20 74 6f 20 |will attempt to | 00000330 73 65 74 20 74 68 65 20 43 53 44 20 74 6f 20 41 |set the CSD to A| 00000340 44 46 53 3a 3a 48 44 2e 24 2e 42 42 43 2e 47 61 |DFS::HD.$.BBC.Ga| 00000350 6d 65 73 2e 4b 0a 0a 2a 44 49 52 20 4a 20 77 69 |mes.K..*DIR J wi| 00000360 6c 6c 20 6c 65 61 76 65 20 74 68 65 20 43 53 44 |ll leave the CSD| 00000370 20 75 6e 61 6c 74 65 72 65 64 0a 0a 2a 44 49 52 | unaltered..*DIR| 00000380 20 24 20 77 69 6c 6c 20 73 65 74 20 74 68 65 20 | $ will set the | 00000390 43 53 44 20 74 6f 20 41 44 46 53 3a 3a 48 44 2e |CSD to ADFS::HD.| 000003a0 24 2e 42 42 43 2e 47 61 6d 65 73 0a 28 74 6f 20 |$.BBC.Games.(to | 000003b0 63 68 61 6e 67 65 20 74 6f 20 74 68 65 20 22 72 |change to the "r| 000003c0 65 61 6c 22 20 72 6f 6f 74 20 64 69 72 65 63 74 |eal" root direct| 000003d0 6f 72 79 2c 20 75 73 65 20 2a 44 49 52 20 3a 34 |ory, use *DIR :4| 000003e0 2e 24 29 0a 0a 2a 44 49 52 20 5e 20 77 69 6c 6c |.$)..*DIR ^ will| 000003f0 20 73 65 74 20 74 68 65 20 43 53 44 20 74 6f 20 | set the CSD to | 00000400 41 44 46 53 3a 3a 48 44 2e 24 2e 42 42 43 2e 47 |ADFS::HD.$.BBC.G| 00000410 61 6d 65 73 0a 0a 65 67 20 69 66 20 79 6f 75 72 |ames..eg if your| 00000420 20 43 53 44 20 69 73 20 41 44 46 53 3a 3a 48 44 | CSD is ADFS::HD| 00000430 2e 24 2e 42 42 43 2e 47 61 6d 65 73 20 74 68 65 |.$.BBC.Games the| 00000440 6e 3a 0a 0a 2a 44 49 52 20 24 20 77 69 6c 6c 20 |n:..*DIR $ will | 00000450 6c 65 61 76 65 20 74 68 65 20 43 53 44 20 75 6e |leave the CSD un| 00000460 63 68 61 6e 67 65 64 0a 0a 2a 44 49 52 20 5e 20 |changed..*DIR ^ | 00000470 77 69 6c 6c 20 73 65 74 20 74 68 65 20 43 53 44 |will set the CSD| 00000480 20 74 6f 20 41 44 46 53 3a 3a 48 44 2e 24 2e 42 | to ADFS::HD.$.B| 00000490 42 43 0a 0a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a |BC..************| 000004a0 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a |****************| * 000004d0 2a 0a 2a 20 20 49 66 20 79 6f 75 72 20 43 53 44 |*.* If your CSD| 000004e0 20 69 73 20 73 65 74 20 74 6f 20 41 44 46 53 3a | is set to ADFS:| 000004f0 3a 48 44 2e 24 2e 42 42 43 2e 47 2e 4c 20 74 68 |:HD.$.BBC.G.L th| 00000500 65 6e 20 61 6d 62 69 67 75 69 74 79 20 20 2a 0a |en ambiguity *.| 00000510 2a 20 20 63 61 6e 20 61 72 69 73 65 2c 20 73 6f |* can arise, so| 00000520 20 73 69 6e 67 6c 65 20 6c 65 74 74 65 72 20 64 | single letter d| 00000530 69 72 65 63 74 6f 72 69 65 73 20 73 68 6f 75 6c |irectories shoul| 00000540 64 20 4e 4f 54 20 62 65 20 20 20 20 2a 0a 2a 20 |d NOT be *.* | 00000550 20 75 73 65 64 20 77 69 74 68 69 6e 20 65 61 63 | used within eac| 00000560 68 20 6f 74 68 65 72 2e 20 20 20 20 20 20 20 20 |h other. | 00000570 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 00000580 20 20 20 20 20 20 20 20 20 20 2a 0a 2a 2a 2a 2a | *.****| 00000590 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a |****************| * 000005c0 2a 2a 2a 2a 2a 2a 2a 2a 2a 0a 0a 44 72 69 76 65 |*********..Drive| 000005d0 20 6e 75 6d 62 65 72 73 20 77 69 74 68 69 6e 20 | numbers within | 000005e0 66 69 6c 65 6e 61 6d 65 73 20 28 65 67 20 3a 30 |filenames (eg :0| 000005f0 2e 45 2e 4a 61 6d 65 73 6f 6e 29 20 61 72 65 20 |.E.Jameson) are | 00000600 69 67 6e 6f 72 65 64 0a 73 6f 20 74 68 61 74 20 |ignored.so that | 00000610 79 6f 75 20 63 61 6e 20 73 61 76 65 20 70 6f 73 |you can save pos| 00000620 69 74 69 6f 6e 73 20 6f 66 20 67 61 6d 65 73 20 |itions of games | 00000630 6f 6e 74 6f 20 79 6f 75 72 20 68 61 72 64 20 64 |onto your hard d| 00000640 69 73 63 2e 0a 54 6f 20 73 70 65 63 69 66 79 20 |isc..To specify | 00000650 61 20 64 72 69 76 65 2c 20 75 73 65 20 41 44 46 |a drive, use ADF| 00000660 53 3a 3a 30 2e 4a 61 6d 65 73 6f 6e 0a 0a 2a 44 |S::0.Jameson..*D| 00000670 72 69 76 65 20 61 6e 64 20 2a 4d 6f 75 6e 74 20 |rive and *Mount | 00000680 61 72 65 20 69 67 6e 6f 72 65 64 0a 54 6f 20 63 |are ignored.To c| 00000690 68 61 6e 67 65 20 64 72 69 76 65 20 75 73 65 20 |hange drive use | 000006a0 2a 44 49 52 20 3a 30 2c 20 2a 44 49 52 20 41 44 |*DIR :0, *DIR AD| 000006b0 46 53 3a 3a 30 2c 20 2a 44 49 52 20 41 44 46 53 |FS::0, *DIR ADFS| 000006c0 3a 3a 48 44 20 65 74 63 0a 0a 52 49 53 43 20 4f |::HD etc..RISC O| 000006d0 53 27 73 20 43 53 44 20 69 73 20 6e 6f 74 20 63 |S's CSD is not c| 000006e0 68 61 6e 67 65 64 20 62 79 20 74 68 65 20 65 6d |hanged by the em| 000006f0 75 6c 61 74 6f 72 2c 20 61 6c 6c 6f 77 69 6e 67 |ulator, allowing| 00000700 0a 73 65 76 65 72 61 6c 20 69 6e 63 61 72 6e 61 |.several incarna| 00000710 74 69 6f 6e 73 20 6f 66 20 74 68 65 20 65 6d 75 |tions of the emu| 00000720 6c 61 74 6f 72 20 74 6f 20 62 65 20 61 63 74 69 |lator to be acti| 00000730 76 65 2e 0a 0a 53 6f 6d 65 20 66 69 6c 69 6e 67 |ve...Some filing| 00000740 20 73 79 73 74 65 6d 73 20 28 65 67 20 44 4f 53 | systems (eg DOS| 00000750 46 53 29 20 64 6f 20 6e 6f 74 20 73 75 70 70 6f |FS) do not suppo| 00000760 72 74 20 4f 53 47 42 50 42 20 38 2c 0a 73 6f 20 |rt OSGBPB 8,.so | 00000770 70 72 6f 67 72 61 6d 73 20 74 68 61 74 20 75 73 |programs that us| 00000780 65 20 69 74 20 77 69 6c 6c 20 6e 6f 74 20 77 6f |e it will not wo| 00000790 72 6b 20 6f 6e 20 73 75 63 68 20 66 69 6c 69 6e |rk on such filin| 000007a0 67 20 73 79 73 74 65 6d 73 2e 0a 0a 4f 53 46 53 |g systems...OSFS| 000007b0 43 2c 20 4f 53 46 49 4e 44 2c 20 4f 53 47 42 50 |C, OSFIND, OSGBP| 000007c0 42 2c 20 4f 53 42 50 55 54 2c 20 4f 53 42 47 45 |B, OSBPUT, OSBGE| 000007d0 54 2c 20 4f 53 41 52 47 53 2c 20 4f 53 46 49 4c |T, OSARGS, OSFIL| 000007e0 45 0a 61 72 65 20 61 6c 6c 20 66 75 6c 6c 79 20 |E.are all fully | 000007f0 73 75 70 70 6f 72 74 65 64 2e 0a 0a 49 6e 20 61 |supported...In a| 00000800 64 64 69 74 69 6f 6e 2c 20 4f 53 47 42 50 42 20 |ddition, OSGBPB | 00000810 39 20 69 73 20 70 61 72 74 69 61 6c 6c 79 20 73 |9 is partially s| 00000820 75 70 70 6f 72 74 65 64 20 28 66 6f 72 20 74 68 |upported (for th| 00000830 65 0a 63 75 72 72 65 6e 74 20 64 69 72 65 63 74 |e.current direct| 00000840 6f 72 79 29 3a 0a 0a 62 6c 6f 63 6b 3f 30 3d 6e |ory):..block?0=n| 00000850 75 6d 62 65 72 20 6f 66 20 66 69 6c 65 73 20 74 |umber of files t| 00000860 6f 20 72 65 61 64 20 28 6e 75 6d 62 65 72 20 6f |o read (number o| 00000870 66 20 66 69 6c 65 73 20 72 65 61 64 29 0a 62 6c |f files read).bl| 00000880 6f 63 6b 21 31 3d 61 64 64 72 65 73 73 20 69 6e |ock!1=address in| 00000890 20 6d 65 6d 6f 72 79 20 6f 66 20 64 61 74 61 0a | memory of data.| 000008a0 62 6c 6f 63 6b 21 35 3d 6c 65 6e 67 74 68 20 6f |block!5=length o| 000008b0 66 20 64 61 74 61 20 62 6c 6f 63 6b 0a 62 6c 6f |f data block.blo| 000008c0 63 6b 21 39 3d 73 65 71 75 65 6e 74 69 61 6c 20 |ck!9=sequential | 000008d0 70 6f 69 6e 74 65 72 20 28 30 20 66 6f 72 20 66 |pointer (0 for f| 000008e0 69 72 73 74 20 63 61 6c 6c 2c 20 2d 31 20 77 68 |irst call, -1 wh| 000008f0 65 6e 20 66 69 6e 69 73 68 65 64 29 0a 0a 52 49 |en finished)..RI| 00000900 53 43 20 4f 53 20 65 72 72 6f 72 73 20 61 72 65 |SC OS errors are| 00000910 20 70 61 73 73 65 64 20 62 61 63 6b 20 69 6e 74 | passed back int| 00000920 6f 20 74 68 65 20 65 6d 75 6c 61 74 6f 72 20 76 |o the emulator v| 00000930 69 61 20 42 52 4b 2e 0a 0a 46 69 6c 69 6e 67 20 |ia BRK...Filing | 00000940 73 79 73 74 65 6d 20 6f 70 65 72 61 74 69 6f 6e |system operation| 00000950 73 20 61 70 70 65 61 72 20 69 6e 73 74 61 6e 74 |s appear instant| 00000960 61 6e 65 6f 75 73 20 74 6f 20 74 68 65 20 65 6d |aneous to the em| 00000970 75 6c 61 74 6f 72 0a 28 69 65 20 64 6f 20 6e 6f |ulator.(ie do no| 00000980 74 20 72 75 6e 20 66 69 6c 69 6e 67 20 73 79 73 |t run filing sys| 00000990 74 65 6d 20 62 65 6e 63 68 6d 61 72 6b 73 20 77 |tem benchmarks w| 000009a0 69 74 68 69 6e 20 74 68 65 20 65 6d 75 6c 61 74 |ithin the emulat| 000009b0 6f 72 21 29 0a 0a 41 6c 74 68 6f 75 67 68 20 74 |or!)..Although t| 000009c0 68 65 20 6f 70 65 72 61 74 69 6e 67 20 73 79 73 |he operating sys| 000009d0 74 65 6d 20 6e 6f 72 6d 61 6c 6c 79 20 61 70 70 |tem normally app| 000009e0 65 61 72 73 20 74 6f 20 62 65 20 52 4f 4d 2c 0a |ears to be ROM,.| 000009f0 69 74 20 63 61 6e 20 62 65 20 6f 76 65 72 77 72 |it can be overwr| 00000a00 69 74 74 65 6e 20 62 79 20 66 69 6c 69 6e 67 20 |itten by filing | 00000a10 73 79 73 74 65 6d 20 63 61 6c 6c 73 20 28 65 67 |system calls (eg| 00000a20 20 2a 4c 6f 61 64 29 0a 0a 46 69 6c 65 73 20 74 | *Load)..Files t| 00000a30 68 61 74 20 77 69 6c 6c 20 65 78 74 65 6e 64 20 |hat will extend | 00000a40 62 65 79 6f 6e 64 20 26 46 46 46 46 20 77 69 6c |beyond &FFFF wil| 00000a50 6c 20 67 65 6e 65 72 61 74 65 20 61 6e 20 65 72 |l generate an er| 00000a60 72 6f 72 0a 69 66 20 79 6f 75 20 74 72 79 20 74 |ror.if you try t| 00000a70 6f 20 6c 6f 61 64 20 74 68 65 6d 2e 0a 28 6e 6f |o load them..(no| 00000a80 72 6d 61 6c 6c 79 20 66 69 6c 65 73 20 6d 69 67 |rmally files mig| 00000a90 68 74 20 77 72 61 70 20 72 6f 75 6e 64 20 62 61 |ht wrap round ba| 00000aa0 63 6b 20 74 6f 20 26 30 30 30 30 29 0a |ck to &0000).| 00000aad
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