Home » Archimedes archive » Micro User » MU 1992-09.adf » ArcFSExtra » Documents/Comp_Mem
Documents/Comp_Mem
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 » Micro User » MU 1992-09.adf » ArcFSExtra |
| Filename: | Documents/Comp_Mem |
| Read OK: | ✔ |
| File size: | 0A2F bytes |
| Load address: | 0000 |
| Exec address: | 0000 |
Duplicates
There is 1 duplicate copy of this file in the archive:
- Archimedes archive » Micro User » MU 1992-08.adf » ArcFSExtra » Documents/Comp_Mem
- Archimedes archive » Micro User » MU 1992-09.adf » ArcFSExtra » Documents/Comp_Mem
File contents
ArcFS 0.50/2.00 Documentation
-----------------------------
Compression formats
-------------------
PC and Spark archives:This version of ArcFS will read crunched, packed, new
format stored objects, squashed and compressed objects.
Objects in a format that ArcFS cannot handle will
give 'Can't handle archive' errors when you attempt
to load them. Archives containing old format stored
objects cannot be opened.
ArcFS archives: This version can read and write stored, packed,
crunched and compressed objects. (As for ArcFS 1.xx)
Memory requirements
-------------------
-----------------------------------------------------------------------------
No. of bits| ArcFS format | Spark / PC formats |Memory requirement
compression| | |
-----------------------------------------------------------------------------12 bits | Crunch 12, Compress 12 | Crunch, Compress 12 | 16K +RDB
13 bits | Crunch 13, Compress 13 | Squash, Compress 13 | 32K +RDB
14 bits | Crunch 14, Compress 14 | Compress 14 | 64K +RDB
15 bits | Crunch 15, Compress 15 | Compress 15 | 128K +RDB
16 bits | Crunch 16, Compress 16 | Compress 16 | 256K +RDB
-----------------------------------------------------------------------------
The above table shows the requirements for free memory in order to load each
of the available formats. Using 16 bit compression formats can cause
problems when trying to load such files on a 1Mbyte machine. ArcFS requires
triple the above requirements when compressing files.
Note that the free memory is required in the relocatable module area. When
copying files on the Risc-OS 2 desktop, all free application memory is
claimed to do the copying. Therefore there must be enough free memory in
module area since it cannot be enlarged automatically.
This problem does not occur on the Risc-OS 3 desktop due to the different
way in which files are copied.
Raw Data Buffer (RDB)
---------------------
When loading and saving files ArcFS uses a buffer to hold compressed data.
The larger the buffer, the fewer times ArcFS has to ask the filing system on
which the archive exists for data (although it is asking for more data each
time).
An RDB of more than 4K on a hard drive or 8K on a floppy drive will probably not give much of an increase in speed. The default is 8K.
N.B. The RDB Size can be set by the *ArcFSRDB command, see the 'Commands'
file for more details.
00000000 41 72 63 46 53 20 30 2e 35 30 2f 32 2e 30 30 20 |ArcFS 0.50/2.00 | 00000010 44 6f 63 75 6d 65 6e 74 61 74 69 6f 6e 0a 2d 2d |Documentation.--| 00000020 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------| 00000030 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 0a 0a 43 6f 6d |-----------..Com| 00000040 70 72 65 73 73 69 6f 6e 20 66 6f 72 6d 61 74 73 |pression formats| 00000050 0a 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |.---------------| 00000060 2d 2d 2d 2d 0a 0a 50 43 20 61 6e 64 20 53 70 61 |----..PC and Spa| 00000070 72 6b 20 61 72 63 68 69 76 65 73 3a 54 68 69 73 |rk archives:This| 00000080 20 76 65 72 73 69 6f 6e 20 6f 66 20 41 72 63 46 | version of ArcF| 00000090 53 20 77 69 6c 6c 20 72 65 61 64 20 63 72 75 6e |S will read crun| 000000a0 63 68 65 64 2c 20 70 61 63 6b 65 64 2c 20 6e 65 |ched, packed, ne| 000000b0 77 0a 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |w. | 000000c0 20 20 20 20 20 20 20 20 66 6f 72 6d 61 74 20 73 | format s| 000000d0 74 6f 72 65 64 20 6f 62 6a 65 63 74 73 2c 20 73 |tored objects, s| 000000e0 71 75 61 73 68 65 64 20 61 6e 64 20 63 6f 6d 70 |quashed and comp| 000000f0 72 65 73 73 65 64 20 6f 62 6a 65 63 74 73 2e 0a |ressed objects..| 00000100 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 00000110 20 20 20 20 20 20 4f 62 6a 65 63 74 73 20 69 6e | Objects in| 00000120 20 61 20 66 6f 72 6d 61 74 20 20 74 68 61 74 20 | a format that | 00000130 41 72 63 46 53 20 63 61 6e 6e 6f 74 20 68 61 6e |ArcFS cannot han| 00000140 64 6c 65 20 77 69 6c 6c 0a 20 20 20 20 20 20 20 |dle will. | 00000150 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 67 | g| 00000160 69 76 65 20 27 43 61 6e 27 74 20 68 61 6e 64 6c |ive 'Can't handl| 00000170 65 20 61 72 63 68 69 76 65 27 20 65 72 72 6f 72 |e archive' error| 00000180 73 20 77 68 65 6e 20 20 79 6f 75 20 61 74 74 65 |s when you atte| 00000190 6d 70 74 0a 20 20 20 20 20 20 20 20 20 20 20 20 |mpt. | 000001a0 20 20 20 20 20 20 20 20 20 20 74 6f 20 6c 6f 61 | to loa| 000001b0 64 20 74 68 65 6d 2e 20 41 72 63 68 69 76 65 73 |d them. Archives| 000001c0 20 63 6f 6e 74 61 69 6e 69 6e 67 20 6f 6c 64 20 | containing old | 000001d0 66 6f 72 6d 61 74 20 73 74 6f 72 65 64 0a 20 20 |format stored. | 000001e0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 000001f0 20 20 20 20 6f 62 6a 65 63 74 73 20 63 61 6e 6e | objects cann| 00000200 6f 74 20 62 65 20 6f 70 65 6e 65 64 2e 0a 0a 41 |ot be opened...A| 00000210 72 63 46 53 20 61 72 63 68 69 76 65 73 3a 20 20 |rcFS archives: | 00000220 20 20 20 20 20 54 68 69 73 20 76 65 72 73 69 6f | This versio| 00000230 6e 20 63 61 6e 20 72 65 61 64 20 61 6e 64 20 77 |n can read and w| 00000240 72 69 74 65 20 73 74 6f 72 65 64 2c 20 70 61 63 |rite stored, pac| 00000250 6b 65 64 2c 0a 20 20 20 20 20 20 20 20 20 20 20 |ked,. | 00000260 20 20 20 20 20 20 20 20 20 20 20 63 72 75 6e 63 | crunc| 00000270 68 65 64 20 61 6e 64 20 63 6f 6d 70 72 65 73 73 |hed and compress| 00000280 65 64 20 6f 62 6a 65 63 74 73 2e 20 28 41 73 20 |ed objects. (As | 00000290 66 6f 72 20 41 72 63 46 53 20 31 2e 78 78 29 0a |for ArcFS 1.xx).| 000002a0 0a 4d 65 6d 6f 72 79 20 72 65 71 75 69 72 65 6d |.Memory requirem| 000002b0 65 6e 74 73 0a 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |ents.-----------| 000002c0 2d 2d 2d 2d 2d 2d 2d 2d 0a 0a 2d 2d 2d 2d 2d 2d |--------..------| 000002d0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------| * 00000310 2d 2d 2d 2d 2d 2d 2d 0a 4e 6f 2e 20 6f 66 20 62 |-------.No. of b| 00000320 69 74 73 7c 20 41 72 63 46 53 20 66 6f 72 6d 61 |its| ArcFS forma| 00000330 74 20 20 20 20 20 20 20 20 20 20 20 7c 20 53 70 |t | Sp| 00000340 61 72 6b 20 2f 20 50 43 20 66 6f 72 6d 61 74 73 |ark / PC formats| 00000350 20 20 7c 4d 65 6d 6f 72 79 20 72 65 71 75 69 72 | |Memory requir| 00000360 65 6d 65 6e 74 0a 63 6f 6d 70 72 65 73 73 69 6f |ement.compressio| 00000370 6e 7c 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |n| | 00000380 20 20 20 20 20 20 20 20 20 20 7c 20 20 20 20 20 | | | 00000390 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 000003a0 7c 0a 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d ||.--------------| 000003b0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------| * 000003e0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 31 |---------------1| 000003f0 32 20 62 69 74 73 20 20 20 20 7c 20 43 72 75 6e |2 bits | Crun| 00000400 63 68 20 31 32 2c 20 43 6f 6d 70 72 65 73 73 20 |ch 12, Compress | 00000410 31 32 20 7c 20 43 72 75 6e 63 68 2c 20 43 6f 6d |12 | Crunch, Com| 00000420 70 72 65 73 73 20 31 32 20 7c 20 31 36 4b 20 20 |press 12 | 16K | 00000430 2b 52 44 42 0a 31 33 20 62 69 74 73 20 20 20 20 |+RDB.13 bits | 00000440 7c 20 43 72 75 6e 63 68 20 31 33 2c 20 43 6f 6d || Crunch 13, Com| 00000450 70 72 65 73 73 20 31 33 20 7c 20 53 71 75 61 73 |press 13 | Squas| 00000460 68 2c 20 43 6f 6d 70 72 65 73 73 20 31 33 20 7c |h, Compress 13 || 00000470 20 33 32 4b 20 20 2b 52 44 42 0a 31 34 20 62 69 | 32K +RDB.14 bi| 00000480 74 73 20 20 20 20 7c 20 43 72 75 6e 63 68 20 31 |ts | Crunch 1| 00000490 34 2c 20 43 6f 6d 70 72 65 73 73 20 31 34 20 7c |4, Compress 14 || 000004a0 20 43 6f 6d 70 72 65 73 73 20 31 34 20 20 20 20 | Compress 14 | 000004b0 20 20 20 20 20 7c 20 36 34 4b 20 20 2b 52 44 42 | | 64K +RDB| 000004c0 0a 31 35 20 62 69 74 73 20 20 20 20 7c 20 43 72 |.15 bits | Cr| 000004d0 75 6e 63 68 20 31 35 2c 20 43 6f 6d 70 72 65 73 |unch 15, Compres| 000004e0 73 20 31 35 20 7c 20 43 6f 6d 70 72 65 73 73 20 |s 15 | Compress | 000004f0 31 35 20 20 20 20 20 20 20 20 20 7c 20 31 32 38 |15 | 128| 00000500 4b 20 2b 52 44 42 0a 31 36 20 62 69 74 73 20 20 |K +RDB.16 bits | 00000510 20 20 7c 20 43 72 75 6e 63 68 20 31 36 2c 20 43 | | Crunch 16, C| 00000520 6f 6d 70 72 65 73 73 20 31 36 20 7c 20 43 6f 6d |ompress 16 | Com| 00000530 70 72 65 73 73 20 31 36 20 20 20 20 20 20 20 20 |press 16 | 00000540 20 7c 20 32 35 36 4b 20 2b 52 44 42 0a 2d 2d 2d | | 256K +RDB.---| 00000550 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------| * 00000590 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 0a 0a 54 68 65 20 |----------..The | 000005a0 61 62 6f 76 65 20 74 61 62 6c 65 20 73 68 6f 77 |above table show| 000005b0 73 20 74 68 65 20 72 65 71 75 69 72 65 6d 65 6e |s the requiremen| 000005c0 74 73 20 66 6f 72 20 66 72 65 65 20 6d 65 6d 6f |ts for free memo| 000005d0 72 79 20 69 6e 20 6f 72 64 65 72 20 74 6f 20 6c |ry in order to l| 000005e0 6f 61 64 20 65 61 63 68 0a 6f 66 20 74 68 65 20 |oad each.of the | 000005f0 61 76 61 69 6c 61 62 6c 65 20 66 6f 72 6d 61 74 |available format| 00000600 73 2e 20 55 73 69 6e 67 20 31 36 20 62 69 74 20 |s. Using 16 bit | 00000610 63 6f 6d 70 72 65 73 73 69 6f 6e 20 66 6f 72 6d |compression form| 00000620 61 74 73 20 63 61 6e 20 63 61 75 73 65 0a 70 72 |ats can cause.pr| 00000630 6f 62 6c 65 6d 73 20 77 68 65 6e 20 74 72 79 69 |oblems when tryi| 00000640 6e 67 20 74 6f 20 6c 6f 61 64 20 73 75 63 68 20 |ng to load such | 00000650 66 69 6c 65 73 20 6f 6e 20 61 20 31 4d 62 79 74 |files on a 1Mbyt| 00000660 65 20 6d 61 63 68 69 6e 65 2e 20 41 72 63 46 53 |e machine. ArcFS| 00000670 20 72 65 71 75 69 72 65 73 0a 74 72 69 70 6c 65 | requires.triple| 00000680 20 74 68 65 20 61 62 6f 76 65 20 72 65 71 75 69 | the above requi| 00000690 72 65 6d 65 6e 74 73 20 77 68 65 6e 20 63 6f 6d |rements when com| 000006a0 70 72 65 73 73 69 6e 67 20 66 69 6c 65 73 2e 0a |pressing files..| 000006b0 0a 4e 6f 74 65 20 74 68 61 74 20 74 68 65 20 66 |.Note that the f| 000006c0 72 65 65 20 6d 65 6d 6f 72 79 20 69 73 20 72 65 |ree memory is re| 000006d0 71 75 69 72 65 64 20 69 6e 20 74 68 65 20 72 65 |quired in the re| 000006e0 6c 6f 63 61 74 61 62 6c 65 20 6d 6f 64 75 6c 65 |locatable module| 000006f0 20 61 72 65 61 2e 20 57 68 65 6e 0a 63 6f 70 79 | area. When.copy| 00000700 69 6e 67 20 66 69 6c 65 73 20 6f 6e 20 74 68 65 |ing files on the| 00000710 20 52 69 73 63 2d 4f 53 20 32 20 64 65 73 6b 74 | Risc-OS 2 deskt| 00000720 6f 70 2c 20 61 6c 6c 20 66 72 65 65 20 61 70 70 |op, all free app| 00000730 6c 69 63 61 74 69 6f 6e 20 6d 65 6d 6f 72 79 20 |lication memory | 00000740 69 73 0a 63 6c 61 69 6d 65 64 20 74 6f 20 64 6f |is.claimed to do| 00000750 20 74 68 65 20 63 6f 70 79 69 6e 67 2e 20 54 68 | the copying. Th| 00000760 65 72 65 66 6f 72 65 20 74 68 65 72 65 20 6d 75 |erefore there mu| 00000770 73 74 20 62 65 20 65 6e 6f 75 67 68 20 66 72 65 |st be enough fre| 00000780 65 20 6d 65 6d 6f 72 79 20 69 6e 0a 6d 6f 64 75 |e memory in.modu| 00000790 6c 65 20 61 72 65 61 20 73 69 6e 63 65 20 69 74 |le area since it| 000007a0 20 63 61 6e 6e 6f 74 20 62 65 20 65 6e 6c 61 72 | cannot be enlar| 000007b0 67 65 64 20 61 75 74 6f 6d 61 74 69 63 61 6c 6c |ged automaticall| 000007c0 79 2e 0a 54 68 69 73 20 70 72 6f 62 6c 65 6d 20 |y..This problem | 000007d0 64 6f 65 73 20 6e 6f 74 20 6f 63 63 75 72 20 6f |does not occur o| 000007e0 6e 20 74 68 65 20 52 69 73 63 2d 4f 53 20 33 20 |n the Risc-OS 3 | 000007f0 64 65 73 6b 74 6f 70 20 64 75 65 20 74 6f 20 74 |desktop due to t| 00000800 68 65 20 64 69 66 66 65 72 65 6e 74 0a 77 61 79 |he different.way| 00000810 20 69 6e 20 77 68 69 63 68 20 66 69 6c 65 73 20 | in which files | 00000820 61 72 65 20 63 6f 70 69 65 64 2e 0a 0a 52 61 77 |are copied...Raw| 00000830 20 44 61 74 61 20 42 75 66 66 65 72 20 28 52 44 | Data Buffer (RD| 00000840 42 29 0a 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |B).-------------| 00000850 2d 2d 2d 2d 2d 2d 2d 2d 0a 0a 57 68 65 6e 20 6c |--------..When l| 00000860 6f 61 64 69 6e 67 20 61 6e 64 20 73 61 76 69 6e |oading and savin| 00000870 67 20 66 69 6c 65 73 20 41 72 63 46 53 20 75 73 |g files ArcFS us| 00000880 65 73 20 61 20 62 75 66 66 65 72 20 74 6f 20 68 |es a buffer to h| 00000890 6f 6c 64 20 63 6f 6d 70 72 65 73 73 65 64 20 64 |old compressed d| 000008a0 61 74 61 2e 0a 54 68 65 20 6c 61 72 67 65 72 20 |ata..The larger | 000008b0 74 68 65 20 62 75 66 66 65 72 2c 20 74 68 65 20 |the buffer, the | 000008c0 66 65 77 65 72 20 74 69 6d 65 73 20 41 72 63 46 |fewer times ArcF| 000008d0 53 20 68 61 73 20 74 6f 20 61 73 6b 20 74 68 65 |S has to ask the| 000008e0 20 66 69 6c 69 6e 67 20 73 79 73 74 65 6d 20 6f | filing system o| 000008f0 6e 0a 77 68 69 63 68 20 74 68 65 20 61 72 63 68 |n.which the arch| 00000900 69 76 65 20 65 78 69 73 74 73 20 66 6f 72 20 64 |ive exists for d| 00000910 61 74 61 20 28 61 6c 74 68 6f 75 67 68 20 69 74 |ata (although it| 00000920 20 69 73 20 61 73 6b 69 6e 67 20 66 6f 72 20 6d | is asking for m| 00000930 6f 72 65 20 64 61 74 61 20 65 61 63 68 0a 74 69 |ore data each.ti| 00000940 6d 65 29 2e 0a 0a 41 6e 20 52 44 42 20 6f 66 20 |me)...An RDB of | 00000950 6d 6f 72 65 20 74 68 61 6e 20 34 4b 20 6f 6e 20 |more than 4K on | 00000960 61 20 68 61 72 64 20 64 72 69 76 65 20 6f 72 20 |a hard drive or | 00000970 38 4b 20 6f 6e 20 61 20 66 6c 6f 70 70 79 20 64 |8K on a floppy d| 00000980 72 69 76 65 20 77 69 6c 6c 20 70 72 6f 62 61 62 |rive will probab| 00000990 6c 79 20 6e 6f 74 20 67 69 76 65 20 6d 75 63 68 |ly not give much| 000009a0 20 6f 66 20 61 6e 20 69 6e 63 72 65 61 73 65 20 | of an increase | 000009b0 69 6e 20 73 70 65 65 64 2e 20 54 68 65 20 64 65 |in speed. The de| 000009c0 66 61 75 6c 74 20 69 73 20 38 4b 2e 0a 0a 4e 2e |fault is 8K...N.| 000009d0 42 2e 20 54 68 65 20 52 44 42 20 53 69 7a 65 20 |B. The RDB Size | 000009e0 63 61 6e 20 62 65 20 73 65 74 20 62 79 20 74 68 |can be set by th| 000009f0 65 20 2a 41 72 63 46 53 52 44 42 20 63 6f 6d 6d |e *ArcFSRDB comm| 00000a00 61 6e 64 2c 20 73 65 65 20 74 68 65 20 27 43 6f |and, see the 'Co| 00000a10 6d 6d 61 6e 64 73 27 0a 66 69 6c 65 20 66 6f 72 |mmands'.file for| 00000a20 20 6d 6f 72 65 20 64 65 74 61 69 6c 73 2e 0a | more details..| 00000a2f
.