Home » Archimedes archive » Archimedes World » AW-1996-08.adf » !6502DEm_6502Dem » Docs/Snapshots
Docs/Snapshots
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/Snapshots |
| Read OK: | ✔ |
| File size: | 0A76 bytes |
| Load address: | 0000 |
| Exec address: | 0000 |
File contents
6502Em: Filetype BBCSnap (&BBC)
===============================
Acorn's filetype &BBC (BBC ROM) has been extended by 6502Em
If the first line of the file is one of the following:
BBC Script
BBC Tapefile
BBC Snapshot
BBC Snapshot101
then it is a new type of file, otherwise it is still
a sideways ROM image (which 6502Em will also load)
BBC Snapshot files are saved out by the emulator, and
contain the complete state of the emulator at the moment
it was saved.
BBC Tapefile files can be accessed from the emulator using
the casette filing system (selected by *TAPE)
BBC Script files are described in 'Scripts'
File format of 'BBC Snapshot101'
--------------------------------
NB if a location is "unused", any information in it will be discarded
when the snapshot is loaded. The information saved out is included for
completeness.
String : "BBC Snapshot101"+CHR$ &0A (ie 16 bytes)
256 bytes (Sheila, &FE00-&FEFF)
Contains the raw values written to memory locations
Word : 6502's Accumulator in top 8 bits
Word : 6502's X register in top 8 bits
Word : 6502's Y register in top 8 bits
Word : 6502's Flags register in bottom 8 bits
Word : 6502's Stack Pointer in top 8 bits
Word : 6502's Program Counter in top 16 bits
Word : unused (Timer 1 mode)
Word : Timer 2 mode (0=no further interrupts)
Word : unused (Timer 3 mode)
Word : Timer 4 mode (0=no further interrupts)
Word : Timer 1 }
Word : Timer 1 latch }
Word : Timer 2 }
Word : Timer 2 latch } NB top two bytes
Word : Timer 3 }
Word : Timer 3 latch }
Word : Timer 4 }
Word : Timer 4 latch }
Word : Counter to vsync } NB bottom two bytes
Word : unused (Latch for above, &9C40) }
Word : unused (time until next interrupt)
Word : unused (timer, used by sound code)
Byte : System VIA's IFR
Byte : System VIA's IER
Byte : User VIA's IFR
Byte : User VIA's IER
Word : unused (arc_screenstart)
Word : unused (tamper)
Word : unused (cursor_tamper)
Word : unused (romsel_on)
Word : Sheila &30 (ROMSEL)
Word }
Word } one byte for each ROM socket - 0=ROM, 1=RAM, 2=unused
Word }
Word }
Word : Sheila &20
Word }
Word }
Word } 6845 CRT's registers
Word } ("register 19" contains contents of addressable latch)
Word }
Word : unused
Word : unused
Word }
Word } Palette Registers
Word }
Word }
Word : unused (palette_on)
Word : ACCCON
Byte : unused (patch_on)
Byte : unused (pal_tamper)
Byte : unused (lastmode)
Byte : Sheila &FE10
Word : unused (tapecount)
Word : unused (keyaddr)
Word : unused (screenstart_tamper)
Word : unused (screenstart_previous)
Padding up to &210 bytes followed by memory dump
(any size up to &10000, usually &8000 or &C000 bytes)
00000000 36 35 30 32 45 6d 3a 20 46 69 6c 65 74 79 70 65 |6502Em: Filetype|
00000010 20 42 42 43 53 6e 61 70 20 28 26 42 42 43 29 0a | BBCSnap (&BBC).|
00000020 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d |================|
00000030 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 3d 0a |===============.|
00000040 0a 41 63 6f 72 6e 27 73 20 66 69 6c 65 74 79 70 |.Acorn's filetyp|
00000050 65 20 26 42 42 43 20 28 42 42 43 20 52 4f 4d 29 |e &BBC (BBC ROM)|
00000060 20 68 61 73 20 62 65 65 6e 20 65 78 74 65 6e 64 | has been extend|
00000070 65 64 20 62 79 20 36 35 30 32 45 6d 0a 0a 49 66 |ed by 6502Em..If|
00000080 20 74 68 65 20 66 69 72 73 74 20 6c 69 6e 65 20 | the first line |
00000090 6f 66 20 74 68 65 20 66 69 6c 65 20 69 73 20 6f |of the file is o|
000000a0 6e 65 20 6f 66 20 74 68 65 20 66 6f 6c 6c 6f 77 |ne of the follow|
000000b0 69 6e 67 3a 0a 0a 42 42 43 20 53 63 72 69 70 74 |ing:..BBC Script|
000000c0 0a 42 42 43 20 54 61 70 65 66 69 6c 65 0a 42 42 |.BBC Tapefile.BB|
000000d0 43 20 53 6e 61 70 73 68 6f 74 0a 42 42 43 20 53 |C Snapshot.BBC S|
000000e0 6e 61 70 73 68 6f 74 31 30 31 0a 0a 74 68 65 6e |napshot101..then|
000000f0 20 69 74 20 69 73 20 61 20 6e 65 77 20 74 79 70 | it is a new typ|
00000100 65 20 6f 66 20 66 69 6c 65 2c 20 6f 74 68 65 72 |e of file, other|
00000110 77 69 73 65 20 69 74 20 69 73 20 73 74 69 6c 6c |wise it is still|
00000120 0a 61 20 73 69 64 65 77 61 79 73 20 52 4f 4d 20 |.a sideways ROM |
00000130 69 6d 61 67 65 20 28 77 68 69 63 68 20 36 35 30 |image (which 650|
00000140 32 45 6d 20 77 69 6c 6c 20 61 6c 73 6f 20 6c 6f |2Em will also lo|
00000150 61 64 29 0a 0a 42 42 43 20 53 6e 61 70 73 68 6f |ad)..BBC Snapsho|
00000160 74 20 66 69 6c 65 73 20 61 72 65 20 73 61 76 65 |t files are save|
00000170 64 20 6f 75 74 20 62 79 20 74 68 65 20 65 6d 75 |d out by the emu|
00000180 6c 61 74 6f 72 2c 20 61 6e 64 0a 63 6f 6e 74 61 |lator, and.conta|
00000190 69 6e 20 74 68 65 20 63 6f 6d 70 6c 65 74 65 20 |in the complete |
000001a0 73 74 61 74 65 20 6f 66 20 74 68 65 20 65 6d 75 |state of the emu|
000001b0 6c 61 74 6f 72 20 61 74 20 74 68 65 20 6d 6f 6d |lator at the mom|
000001c0 65 6e 74 0a 69 74 20 77 61 73 20 73 61 76 65 64 |ent.it was saved|
000001d0 2e 0a 0a 42 42 43 20 54 61 70 65 66 69 6c 65 20 |...BBC Tapefile |
000001e0 66 69 6c 65 73 20 63 61 6e 20 62 65 20 61 63 63 |files can be acc|
000001f0 65 73 73 65 64 20 66 72 6f 6d 20 74 68 65 20 65 |essed from the e|
00000200 6d 75 6c 61 74 6f 72 20 75 73 69 6e 67 0a 74 68 |mulator using.th|
00000210 65 20 63 61 73 65 74 74 65 20 66 69 6c 69 6e 67 |e casette filing|
00000220 20 73 79 73 74 65 6d 20 28 73 65 6c 65 63 74 65 | system (selecte|
00000230 64 20 62 79 20 2a 54 41 50 45 29 0a 0a 42 42 43 |d by *TAPE)..BBC|
00000240 20 53 63 72 69 70 74 20 66 69 6c 65 73 20 61 72 | Script files ar|
00000250 65 20 64 65 73 63 72 69 62 65 64 20 69 6e 20 27 |e described in '|
00000260 53 63 72 69 70 74 73 27 0a 0a 46 69 6c 65 20 66 |Scripts'..File f|
00000270 6f 72 6d 61 74 20 6f 66 20 27 42 42 43 20 53 6e |ormat of 'BBC Sn|
00000280 61 70 73 68 6f 74 31 30 31 27 0a 2d 2d 2d 2d 2d |apshot101'.-----|
00000290 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d |----------------|
000002a0 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 2d 0a 0a 4e 42 20 |-----------..NB |
000002b0 69 66 20 61 20 6c 6f 63 61 74 69 6f 6e 20 69 73 |if a location is|
000002c0 20 22 75 6e 75 73 65 64 22 2c 20 61 6e 79 20 69 | "unused", any i|
000002d0 6e 66 6f 72 6d 61 74 69 6f 6e 20 69 6e 20 69 74 |nformation in it|
000002e0 20 77 69 6c 6c 20 62 65 20 64 69 73 63 61 72 64 | will be discard|
000002f0 65 64 0a 77 68 65 6e 20 74 68 65 20 73 6e 61 70 |ed.when the snap|
00000300 73 68 6f 74 20 69 73 20 6c 6f 61 64 65 64 2e 20 |shot is loaded. |
00000310 54 68 65 20 69 6e 66 6f 72 6d 61 74 69 6f 6e 20 |The information |
00000320 73 61 76 65 64 20 6f 75 74 20 69 73 20 69 6e 63 |saved out is inc|
00000330 6c 75 64 65 64 20 66 6f 72 0a 63 6f 6d 70 6c 65 |luded for.comple|
00000340 74 65 6e 65 73 73 2e 0a 0a 53 74 72 69 6e 67 20 |teness...String |
00000350 3a 20 22 42 42 43 20 53 6e 61 70 73 68 6f 74 31 |: "BBC Snapshot1|
00000360 30 31 22 2b 43 48 52 24 20 26 30 41 20 28 69 65 |01"+CHR$ &0A (ie|
00000370 20 31 36 20 62 79 74 65 73 29 0a 0a 32 35 36 20 | 16 bytes)..256 |
00000380 62 79 74 65 73 20 28 53 68 65 69 6c 61 2c 20 26 |bytes (Sheila, &|
00000390 46 45 30 30 2d 26 46 45 46 46 29 0a 43 6f 6e 74 |FE00-&FEFF).Cont|
000003a0 61 69 6e 73 20 74 68 65 20 72 61 77 20 76 61 6c |ains the raw val|
000003b0 75 65 73 20 77 72 69 74 74 65 6e 20 74 6f 20 6d |ues written to m|
000003c0 65 6d 6f 72 79 20 6c 6f 63 61 74 69 6f 6e 73 0a |emory locations.|
000003d0 0a 57 6f 72 64 20 3a 20 36 35 30 32 27 73 20 41 |.Word : 6502's A|
000003e0 63 63 75 6d 75 6c 61 74 6f 72 20 69 6e 20 74 6f |ccumulator in to|
000003f0 70 20 38 20 62 69 74 73 0a 57 6f 72 64 20 3a 20 |p 8 bits.Word : |
00000400 36 35 30 32 27 73 20 58 20 72 65 67 69 73 74 65 |6502's X registe|
00000410 72 20 69 6e 20 74 6f 70 20 38 20 62 69 74 73 0a |r in top 8 bits.|
00000420 57 6f 72 64 20 3a 20 36 35 30 32 27 73 20 59 20 |Word : 6502's Y |
00000430 72 65 67 69 73 74 65 72 20 69 6e 20 74 6f 70 20 |register in top |
00000440 38 20 62 69 74 73 0a 57 6f 72 64 20 3a 20 36 35 |8 bits.Word : 65|
00000450 30 32 27 73 20 46 6c 61 67 73 20 72 65 67 69 73 |02's Flags regis|
00000460 74 65 72 20 69 6e 20 62 6f 74 74 6f 6d 20 38 20 |ter in bottom 8 |
00000470 62 69 74 73 0a 57 6f 72 64 20 3a 20 36 35 30 32 |bits.Word : 6502|
00000480 27 73 20 53 74 61 63 6b 20 50 6f 69 6e 74 65 72 |'s Stack Pointer|
00000490 20 69 6e 20 74 6f 70 20 38 20 62 69 74 73 0a 57 | in top 8 bits.W|
000004a0 6f 72 64 20 3a 20 36 35 30 32 27 73 20 50 72 6f |ord : 6502's Pro|
000004b0 67 72 61 6d 20 43 6f 75 6e 74 65 72 20 69 6e 20 |gram Counter in |
000004c0 74 6f 70 20 31 36 20 62 69 74 73 0a 57 6f 72 64 |top 16 bits.Word|
000004d0 20 3a 20 75 6e 75 73 65 64 20 28 54 69 6d 65 72 | : unused (Timer|
000004e0 20 31 20 6d 6f 64 65 29 0a 57 6f 72 64 20 3a 20 | 1 mode).Word : |
000004f0 54 69 6d 65 72 20 32 20 6d 6f 64 65 20 28 30 3d |Timer 2 mode (0=|
00000500 6e 6f 20 66 75 72 74 68 65 72 20 69 6e 74 65 72 |no further inter|
00000510 72 75 70 74 73 29 0a 57 6f 72 64 20 3a 20 75 6e |rupts).Word : un|
00000520 75 73 65 64 20 28 54 69 6d 65 72 20 33 20 6d 6f |used (Timer 3 mo|
00000530 64 65 29 0a 57 6f 72 64 20 3a 20 54 69 6d 65 72 |de).Word : Timer|
00000540 20 34 20 6d 6f 64 65 20 28 30 3d 6e 6f 20 66 75 | 4 mode (0=no fu|
00000550 72 74 68 65 72 20 69 6e 74 65 72 72 75 70 74 73 |rther interrupts|
00000560 29 0a 57 6f 72 64 20 3a 20 54 69 6d 65 72 20 31 |).Word : Timer 1|
00000570 20 20 20 20 20 20 20 20 20 20 7d 0a 57 6f 72 64 | }.Word|
00000580 20 3a 20 54 69 6d 65 72 20 31 20 6c 61 74 63 68 | : Timer 1 latch|
00000590 20 20 20 20 7d 0a 57 6f 72 64 20 3a 20 54 69 6d | }.Word : Tim|
000005a0 65 72 20 32 20 20 20 20 20 20 20 20 20 20 7d 0a |er 2 }.|
000005b0 57 6f 72 64 20 3a 20 54 69 6d 65 72 20 32 20 6c |Word : Timer 2 l|
000005c0 61 74 63 68 20 20 20 20 7d 20 4e 42 20 74 6f 70 |atch } NB top|
000005d0 20 74 77 6f 20 62 79 74 65 73 0a 57 6f 72 64 20 | two bytes.Word |
000005e0 3a 20 54 69 6d 65 72 20 33 20 20 20 20 20 20 20 |: Timer 3 |
000005f0 20 20 20 7d 0a 57 6f 72 64 20 3a 20 54 69 6d 65 | }.Word : Time|
00000600 72 20 33 20 6c 61 74 63 68 20 20 20 20 7d 0a 57 |r 3 latch }.W|
00000610 6f 72 64 20 3a 20 54 69 6d 65 72 20 34 20 20 20 |ord : Timer 4 |
00000620 20 20 20 20 20 20 20 7d 0a 57 6f 72 64 20 3a 20 | }.Word : |
00000630 54 69 6d 65 72 20 34 20 6c 61 74 63 68 20 20 20 |Timer 4 latch |
00000640 20 7d 0a 57 6f 72 64 20 3a 20 43 6f 75 6e 74 65 | }.Word : Counte|
00000650 72 20 74 6f 20 76 73 79 6e 63 20 20 20 20 20 20 |r to vsync |
00000660 20 20 20 20 20 20 20 20 20 20 20 20 7d 20 20 4e | } N|
00000670 42 20 62 6f 74 74 6f 6d 20 74 77 6f 20 62 79 74 |B bottom two byt|
00000680 65 73 0a 57 6f 72 64 20 3a 20 75 6e 75 73 65 64 |es.Word : unused|
00000690 20 28 4c 61 74 63 68 20 66 6f 72 20 61 62 6f 76 | (Latch for abov|
000006a0 65 2c 20 26 39 43 34 30 29 20 20 20 7d 0a 57 6f |e, &9C40) }.Wo|
000006b0 72 64 20 3a 20 75 6e 75 73 65 64 20 28 74 69 6d |rd : unused (tim|
000006c0 65 20 75 6e 74 69 6c 20 6e 65 78 74 20 69 6e 74 |e until next int|
000006d0 65 72 72 75 70 74 29 0a 57 6f 72 64 20 3a 20 75 |errupt).Word : u|
000006e0 6e 75 73 65 64 20 28 74 69 6d 65 72 2c 20 75 73 |nused (timer, us|
000006f0 65 64 20 62 79 20 73 6f 75 6e 64 20 63 6f 64 65 |ed by sound code|
00000700 29 0a 42 79 74 65 20 3a 20 53 79 73 74 65 6d 20 |).Byte : System |
00000710 56 49 41 27 73 20 49 46 52 0a 42 79 74 65 20 3a |VIA's IFR.Byte :|
00000720 20 53 79 73 74 65 6d 20 56 49 41 27 73 20 49 45 | System VIA's IE|
00000730 52 0a 42 79 74 65 20 3a 20 55 73 65 72 20 56 49 |R.Byte : User VI|
00000740 41 27 73 20 49 46 52 0a 42 79 74 65 20 3a 20 55 |A's IFR.Byte : U|
00000750 73 65 72 20 56 49 41 27 73 20 49 45 52 0a 57 6f |ser VIA's IER.Wo|
00000760 72 64 20 3a 20 75 6e 75 73 65 64 20 28 61 72 63 |rd : unused (arc|
00000770 5f 73 63 72 65 65 6e 73 74 61 72 74 29 0a 57 6f |_screenstart).Wo|
00000780 72 64 20 3a 20 75 6e 75 73 65 64 20 28 74 61 6d |rd : unused (tam|
00000790 70 65 72 29 0a 57 6f 72 64 20 3a 20 75 6e 75 73 |per).Word : unus|
000007a0 65 64 20 28 63 75 72 73 6f 72 5f 74 61 6d 70 65 |ed (cursor_tampe|
000007b0 72 29 0a 57 6f 72 64 20 3a 20 75 6e 75 73 65 64 |r).Word : unused|
000007c0 20 28 72 6f 6d 73 65 6c 5f 6f 6e 29 0a 57 6f 72 | (romsel_on).Wor|
000007d0 64 20 3a 20 53 68 65 69 6c 61 20 26 33 30 20 28 |d : Sheila &30 (|
000007e0 52 4f 4d 53 45 4c 29 0a 57 6f 72 64 20 7d 20 0a |ROMSEL).Word } .|
000007f0 57 6f 72 64 20 7d 20 6f 6e 65 20 62 79 74 65 20 |Word } one byte |
00000800 66 6f 72 20 65 61 63 68 20 52 4f 4d 20 73 6f 63 |for each ROM soc|
00000810 6b 65 74 20 2d 20 30 3d 52 4f 4d 2c 20 31 3d 52 |ket - 0=ROM, 1=R|
00000820 41 4d 2c 20 32 3d 75 6e 75 73 65 64 0a 57 6f 72 |AM, 2=unused.Wor|
00000830 64 20 7d 0a 57 6f 72 64 20 7d 0a 57 6f 72 64 20 |d }.Word }.Word |
00000840 3a 20 53 68 65 69 6c 61 20 26 32 30 0a 57 6f 72 |: Sheila &20.Wor|
00000850 64 20 7d 0a 57 6f 72 64 20 7d 0a 57 6f 72 64 20 |d }.Word }.Word |
00000860 7d 20 20 36 38 34 35 20 43 52 54 27 73 20 72 65 |} 6845 CRT's re|
00000870 67 69 73 74 65 72 73 0a 57 6f 72 64 20 7d 20 20 |gisters.Word } |
00000880 28 22 72 65 67 69 73 74 65 72 20 31 39 22 20 63 |("register 19" c|
00000890 6f 6e 74 61 69 6e 73 20 63 6f 6e 74 65 6e 74 73 |ontains contents|
000008a0 20 6f 66 20 61 64 64 72 65 73 73 61 62 6c 65 20 | of addressable |
000008b0 6c 61 74 63 68 29 0a 57 6f 72 64 20 7d 0a 57 6f |latch).Word }.Wo|
000008c0 72 64 20 3a 20 75 6e 75 73 65 64 0a 57 6f 72 64 |rd : unused.Word|
000008d0 20 3a 20 75 6e 75 73 65 64 0a 57 6f 72 64 20 7d | : unused.Word }|
000008e0 20 0a 57 6f 72 64 20 7d 20 50 61 6c 65 74 74 65 | .Word } Palette|
000008f0 20 52 65 67 69 73 74 65 72 73 0a 57 6f 72 64 20 | Registers.Word |
00000900 7d 0a 57 6f 72 64 20 7d 0a 57 6f 72 64 20 3a 20 |}.Word }.Word : |
00000910 75 6e 75 73 65 64 20 28 70 61 6c 65 74 74 65 5f |unused (palette_|
00000920 6f 6e 29 0a 57 6f 72 64 20 3a 20 41 43 43 43 4f |on).Word : ACCCO|
00000930 4e 0a 42 79 74 65 20 3a 20 75 6e 75 73 65 64 20 |N.Byte : unused |
00000940 28 70 61 74 63 68 5f 6f 6e 29 0a 42 79 74 65 20 |(patch_on).Byte |
00000950 3a 20 75 6e 75 73 65 64 20 28 70 61 6c 5f 74 61 |: unused (pal_ta|
00000960 6d 70 65 72 29 0a 42 79 74 65 20 3a 20 75 6e 75 |mper).Byte : unu|
00000970 73 65 64 20 28 6c 61 73 74 6d 6f 64 65 29 0a 42 |sed (lastmode).B|
00000980 79 74 65 20 3a 20 53 68 65 69 6c 61 20 26 46 45 |yte : Sheila &FE|
00000990 31 30 0a 57 6f 72 64 20 3a 20 75 6e 75 73 65 64 |10.Word : unused|
000009a0 20 28 74 61 70 65 63 6f 75 6e 74 29 0a 57 6f 72 | (tapecount).Wor|
000009b0 64 20 3a 20 75 6e 75 73 65 64 20 28 6b 65 79 61 |d : unused (keya|
000009c0 64 64 72 29 0a 57 6f 72 64 20 3a 20 75 6e 75 73 |ddr).Word : unus|
000009d0 65 64 20 28 73 63 72 65 65 6e 73 74 61 72 74 5f |ed (screenstart_|
000009e0 74 61 6d 70 65 72 29 0a 57 6f 72 64 20 3a 20 75 |tamper).Word : u|
000009f0 6e 75 73 65 64 20 28 73 63 72 65 65 6e 73 74 61 |nused (screensta|
00000a00 72 74 5f 70 72 65 76 69 6f 75 73 29 0a 0a 50 61 |rt_previous)..Pa|
00000a10 64 64 69 6e 67 20 75 70 20 74 6f 20 26 32 31 30 |dding up to &210|
00000a20 20 62 79 74 65 73 20 66 6f 6c 6c 6f 77 65 64 20 | bytes followed |
00000a30 62 79 20 6d 65 6d 6f 72 79 20 64 75 6d 70 0a 28 |by memory dump.(|
00000a40 61 6e 79 20 73 69 7a 65 20 75 70 20 74 6f 20 26 |any size up to &|
00000a50 31 30 30 30 30 2c 20 75 73 75 61 6c 6c 79 20 26 |10000, usually &|
00000a60 38 30 30 30 20 6f 72 20 26 43 30 30 30 20 62 79 |8000 or &C000 by|
00000a70 74 65 73 29 0a 0a |tes)..|
00000a76 
.