Home » Personal collection » Acorn ADFS disks » Electron_User_Group » EUG_29.ADF » P/+SNAP1
P/+SNAP1
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 » Personal collection » Acorn ADFS disks » Electron_User_Group » EUG_29.ADF |
| Filename: | P/+SNAP1 |
| Read OK: | ✔ |
| File size: | 048E bytes |
| Load address: | 0000 |
| Exec address: | FFFFFFFF |
File contents
SUBJECT - MEMORY SNAPSHOT Mark Bellis followed my advice of using the interrupt line on the 1MHz bus to swipe the unpacked code from commercial games. Being painstakingly slow,he avoided tape use at the expense of having to page in the DFS (which overwrites about 2k of memory). The result being,that those 2k were missing,which is the reason for my rom. This is a rom image,called SNAPIT which will not only save your main memory to disk direct,but also the memory that was behind the DFS workspace. How it works - well,I could be here all day explaining every opcode,but basically,on receiving an IRQ the rom copies the DFS workspace (well,it's actually the bottom 8k of memory) into itself (hence it can only be used in sideways RAM and not blown onto EPROM) then saves as per Mark's original code did then downloads its 8k buffer to disk too. The result is a 32k disk image of the BBC fresh and ready to disassemble or whatever you might want to do with it. The software uses no vectors,so I can't envisage any software it wont snap to disk.Tell me if otherwise. It is loaded using a generic loader no matter which machine you have. Robert Sprowson.
00000000 53 55 42 4a 45 43 54 20 2d 20 4d 45 4d 4f 52 59 |SUBJECT - MEMORY| 00000010 20 53 4e 41 50 53 48 4f 54 0d 0d 4d 61 72 6b 20 | SNAPSHOT..Mark | 00000020 42 65 6c 6c 69 73 20 66 6f 6c 6c 6f 77 65 64 20 |Bellis followed | 00000030 6d 79 20 61 64 76 69 63 65 20 6f 66 0d 75 73 69 |my advice of.usi| 00000040 6e 67 20 74 68 65 20 69 6e 74 65 72 72 75 70 74 |ng the interrupt| 00000050 20 6c 69 6e 65 20 6f 6e 20 74 68 65 0d 31 4d 48 | line on the.1MH| 00000060 7a 20 62 75 73 20 74 6f 20 73 77 69 70 65 20 74 |z bus to swipe t| 00000070 68 65 20 75 6e 70 61 63 6b 65 64 0d 63 6f 64 65 |he unpacked.code| 00000080 20 66 72 6f 6d 20 63 6f 6d 6d 65 72 63 69 61 6c | from commercial| 00000090 20 67 61 6d 65 73 2e 0d 0d 42 65 69 6e 67 20 70 | games...Being p| 000000a0 61 69 6e 73 74 61 6b 69 6e 67 6c 79 20 73 6c 6f |ainstakingly slo| 000000b0 77 2c 68 65 20 61 76 6f 69 64 65 64 0d 74 61 70 |w,he avoided.tap| 000000c0 65 20 75 73 65 20 61 74 20 74 68 65 20 65 78 70 |e use at the exp| 000000d0 65 6e 73 65 20 6f 66 20 68 61 76 69 6e 67 20 74 |ense of having t| 000000e0 6f 0d 70 61 67 65 20 69 6e 20 74 68 65 20 44 46 |o.page in the DF| 000000f0 53 20 28 77 68 69 63 68 20 6f 76 65 72 77 72 69 |S (which overwri| 00000100 74 65 73 20 61 62 6f 75 74 0d 32 6b 20 6f 66 20 |tes about.2k of | 00000110 6d 65 6d 6f 72 79 29 2e 0d 0d 54 68 65 20 72 65 |memory)...The re| 00000120 73 75 6c 74 20 62 65 69 6e 67 2c 74 68 61 74 20 |sult being,that | 00000130 74 68 6f 73 65 20 32 6b 20 77 65 72 65 20 0d 6d |those 2k were .m| 00000140 69 73 73 69 6e 67 2c 77 68 69 63 68 20 69 73 20 |issing,which is | 00000150 74 68 65 20 72 65 61 73 6f 6e 20 66 6f 72 20 6d |the reason for m| 00000160 79 20 72 6f 6d 2e 0d 0d 54 68 69 73 20 69 73 20 |y rom...This is | 00000170 61 20 72 6f 6d 20 69 6d 61 67 65 2c 63 61 6c 6c |a rom image,call| 00000180 65 64 20 53 4e 41 50 49 54 20 77 68 69 63 68 0d |ed SNAPIT which.| 00000190 77 69 6c 6c 20 6e 6f 74 20 6f 6e 6c 79 20 73 61 |will not only sa| 000001a0 76 65 20 79 6f 75 72 20 6d 61 69 6e 20 6d 65 6d |ve your main mem| 000001b0 6f 72 79 20 74 6f 0d 64 69 73 6b 20 64 69 72 65 |ory to.disk dire| 000001c0 63 74 2c 62 75 74 20 61 6c 73 6f 20 74 68 65 20 |ct,but also the | 000001d0 6d 65 6d 6f 72 79 20 74 68 61 74 0d 77 61 73 20 |memory that.was | 000001e0 62 65 68 69 6e 64 20 74 68 65 20 44 46 53 20 77 |behind the DFS w| 000001f0 6f 72 6b 73 70 61 63 65 2e 0d 0d 48 6f 77 20 69 |orkspace...How i| 00000200 74 20 77 6f 72 6b 73 20 2d 20 77 65 6c 6c 2c 49 |t works - well,I| 00000210 20 63 6f 75 6c 64 20 62 65 20 68 65 72 65 20 61 | could be here a| 00000220 6c 6c 0d 64 61 79 20 65 78 70 6c 61 69 6e 69 6e |ll.day explainin| 00000230 67 20 65 76 65 72 79 20 6f 70 63 6f 64 65 2c 62 |g every opcode,b| 00000240 75 74 20 0d 62 61 73 69 63 61 6c 6c 79 2c 6f 6e |ut .basically,on| 00000250 20 72 65 63 65 69 76 69 6e 67 20 61 6e 20 49 52 | receiving an IR| 00000260 51 20 74 68 65 20 72 6f 6d 0d 63 6f 70 69 65 73 |Q the rom.copies| 00000270 20 74 68 65 20 44 46 53 20 77 6f 72 6b 73 70 61 | the DFS workspa| 00000280 63 65 20 28 77 65 6c 6c 2c 69 74 27 73 0d 61 63 |ce (well,it's.ac| 00000290 74 75 61 6c 6c 79 20 74 68 65 20 62 6f 74 74 6f |tually the botto| 000002a0 6d 20 38 6b 20 6f 66 20 6d 65 6d 6f 72 79 29 20 |m 8k of memory) | 000002b0 69 6e 74 6f 0d 69 74 73 65 6c 66 20 28 68 65 6e |into.itself (hen| 000002c0 63 65 20 69 74 20 63 61 6e 20 6f 6e 6c 79 20 62 |ce it can only b| 000002d0 65 20 75 73 65 64 20 69 6e 0d 73 69 64 65 77 61 |e used in.sidewa| 000002e0 79 73 20 52 41 4d 20 61 6e 64 20 6e 6f 74 20 62 |ys RAM and not b| 000002f0 6c 6f 77 6e 20 6f 6e 74 6f 20 45 50 52 4f 4d 29 |lown onto EPROM)| 00000300 0d 74 68 65 6e 20 73 61 76 65 73 20 61 73 20 70 |.then saves as p| 00000310 65 72 20 4d 61 72 6b 27 73 20 6f 72 69 67 69 6e |er Mark's origin| 00000320 61 6c 20 63 6f 64 65 0d 64 69 64 20 74 68 65 6e |al code.did then| 00000330 20 64 6f 77 6e 6c 6f 61 64 73 20 69 74 73 20 38 | downloads its 8| 00000340 6b 20 62 75 66 66 65 72 20 74 6f 20 0d 64 69 73 |k buffer to .dis| 00000350 6b 20 74 6f 6f 2e 0d 0d 54 68 65 20 72 65 73 75 |k too...The resu| 00000360 6c 74 20 69 73 20 61 20 33 32 6b 20 64 69 73 6b |lt is a 32k disk| 00000370 20 69 6d 61 67 65 20 6f 66 0d 74 68 65 20 42 42 | image of.the BB| 00000380 43 20 66 72 65 73 68 20 61 6e 64 20 72 65 61 64 |C fresh and read| 00000390 79 20 74 6f 20 64 69 73 61 73 73 65 6d 62 6c 65 |y to disassemble| 000003a0 0d 6f 72 20 77 68 61 74 65 76 65 72 20 79 6f 75 |.or whatever you| 000003b0 20 6d 69 67 68 74 20 77 61 6e 74 20 74 6f 20 64 | might want to d| 000003c0 6f 20 77 69 74 68 0d 69 74 2e 0d 0d 54 68 65 20 |o with.it...The | 000003d0 73 6f 66 74 77 61 72 65 20 75 73 65 73 20 6e 6f |software uses no| 000003e0 20 76 65 63 74 6f 72 73 2c 73 6f 20 49 20 0d 63 | vectors,so I .c| 000003f0 61 6e 27 74 20 65 6e 76 69 73 61 67 65 20 61 6e |an't envisage an| 00000400 79 20 73 6f 66 74 77 61 72 65 20 69 74 20 77 6f |y software it wo| 00000410 6e 74 0d 73 6e 61 70 20 74 6f 20 64 69 73 6b 2e |nt.snap to disk.| 00000420 54 65 6c 6c 20 6d 65 20 69 66 20 6f 74 68 65 72 |Tell me if other| 00000430 77 69 73 65 2e 0d 0d 49 74 20 69 73 20 6c 6f 61 |wise...It is loa| 00000440 64 65 64 20 75 73 69 6e 67 20 61 20 67 65 6e 65 |ded using a gene| 00000450 72 69 63 20 6c 6f 61 64 65 72 0d 6e 6f 20 6d 61 |ric loader.no ma| 00000460 74 74 65 72 20 77 68 69 63 68 20 6d 61 63 68 69 |tter which machi| 00000470 6e 65 20 79 6f 75 20 68 61 76 65 2e 0d 0d 52 6f |ne you have...Ro| 00000480 62 65 72 74 20 53 70 72 6f 77 73 6f 6e 2e |bert Sprowson.| 0000048e
P/+SNAP1.m0
P/+SNAP1.m1
P/+SNAP1.m2
P/+SNAP1.m4
P/+SNAP1.m5
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