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!Spectrum/PCSNAPS/SPECUT~1/SNAPINFO
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 hard disk » apps » Emulators |
| Filename: | !Spectrum/PCSNAPS/SPECUT~1/SNAPINFO |
| Read OK: | ✔ |
| File size: | 156D bytes |
| Load address: | 0000 |
| Exec address: | 0000 |
File contents
.Z80 files
The .Z80 files are a slightly packed Spectrum memory dump format. A .Z80 file
starts off with a 30-byte header-block. In this block, the status of the
emulated Z80 processor at the point at which the Z80-emulator was stopped by
the user is specified. A few extra environmental variables complete the
header.
Byte Length Description
0 1 A register
1 1 F register
2 2 BC register pair (LSB, i.e. C, first)
4 2 HL register pair
6 2 Program counter
8 2 Stack pointer
10 1 Interrupt register
11 1 Refresh register (Bit 7 is not significant!)
12 1 Bit 0 : Bit 7 of the R-register
Bit 1-3: Border colour
Bit 4 : 1=SamRom switched in
Bit 5 : 1=Block of data is 'squeezed'
Bit 6-7: No meaning
13 2 DE register pair
15 2 BC' register pair
17 2 DE' register pair
19 2 HL' register pair
21 1 A' register
22 1 F' register
23 2 IY register (Again LSB first)
25 2 IX register
27 1 Interrupt flipflop, 0=DI, otherwise EI
28 1 IFF2 (not particularly important...)
29 1 Bit 0-1: Interrupt mode (0, 1 or 2)
Bit 2 : 1=Issue 2 emulation
Bit 3 : 1=Double interrupt frequency
Bit 4-5: 1=High video synchronisation
3=Low video synchronisation
0,2=Normal
Bit 6-7: 0=Cursor/Protek/AGF joystick
1=Kempston joystick
2=Sinclair 1 joystick
3=Sinclair 2 joystick
After these 30 bytes, a memory dump of the emulated Spectrum follows,
consisting of the bytes at address 16384 up to 65535. The first versions of
the Spectrum Emulator just dumped the full 48K after the header. These
versions therefore produced .Z80 files that were 49182 bytes (=48K + 30
bytes) in length. The shareware versions of the Emulator all use a slightly
different method of storing the 48K datablock, thereby reducing the size of
the .Z80 files. In effect, the method consists of finding all sequences of
equal bytes, and replacing them by a code of four bytes, "ED ED xx yy" which
tells that byte yy is to repeated xx times. An example will make it clear:
ED 00 44 ED ED 05 00 02 ... (.Z80 file)
is translated back into
ED 00 44 00 00 00 00 00 02 ... (Spec-memory)
Obviously, only sequences of length at least 4 will be coded, for otherwise
there would be no gain in the number of stored bytes. Sequences of 'ED' are
treated separately: the minimum length of an 'ED'-sequence to be coded is 2,
to avoid problems when translating back. And lastly, if a single 'ED' is
encountered, thus an 'ED' followed by a different byte, then this byte
following the 'ED' will not be included in a block. This is done to avoid 'ED
00 00 00 00 00' to be translated into 'ED ED ED 05 00' which would not be
translated back correctly. This particular sequence of bytes will be coded
into 'ED 00 ED ED 04 00'.
The snapshot file format
========================
This format (filetype .SNA) is the format used by the Mirage
Microdriver "Dump" command. It is also used by Peter McGavin's
Spectrum emulator for the Amiga.
Byte offset Contents
0 i register
1 l' register
2 h' register
3 e' register
4 d' register
5 c' register
6 b' register
7 f' register
8 a' register
9 l register
10 h register
11 e register
12 d register
13 c register
14 b register
15 iy low register
16 iy high register
17 ix low register
18 ix high register
19 bit 2 contains iff2
20 r register
21 flags register
22 a register
23 sp low register
24 sp high register
25 interrupt mode (0, 1 or 2)
26 border colour (0..7).
27..49178 48 kbytes ram dump
Since Peter's emulator stores rubbish in byte 26 JPP sets the
border to black if byte 26 is larger than 7.
ARC SPECULATOR
================
Snapshots are 64.25k long!!!! The first 256 bytes hold the processor state
(and other details?). The next 65536 bytes contain a complete image of the
whole spectrum memory map, including the ROM!
Note that the program counter stored value is 256 less than the actual value?
00: = REG A
04: = REG F?
08: = REG B
0C: = REG C
10: = REG D
14: = REG E
18: = REG H
1C: = REG L
20: = PC LO
21: = PC HI -1
28: = SP LO
29: = SC HI
9C: = BORDER COLOUR
A4: = Imode?
BE: = REG I
BF: = IFF ??
EC: = REG A'
ED: = REG F'?
F0: = REG B'
F1: = REG C'
F4: = REG D'
F5: = REG E'
F6: = REG H'
F7: = REG L'
F8: = REG IX LO
F9: = REG IX HI
FC: = REG IY LO
FD: = REG IY HI
??: = Refresh register
00000000 0a 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |. | 00000010 20 20 20 20 20 20 20 20 20 20 20 20 20 2e 5a 38 | .Z8| 00000020 30 20 66 69 6c 65 73 0a 0a 54 68 65 20 2e 5a 38 |0 files..The .Z8| 00000030 30 20 66 69 6c 65 73 20 61 72 65 20 61 20 73 6c |0 files are a sl| 00000040 69 67 68 74 6c 79 20 70 61 63 6b 65 64 20 53 70 |ightly packed Sp| 00000050 65 63 74 72 75 6d 20 6d 65 6d 6f 72 79 20 64 75 |ectrum memory du| 00000060 6d 70 20 66 6f 72 6d 61 74 2e 20 41 20 2e 5a 38 |mp format. A .Z8| 00000070 30 20 66 69 6c 65 0a 73 74 61 72 74 73 20 6f 66 |0 file.starts of| 00000080 66 20 77 69 74 68 20 61 20 33 30 2d 62 79 74 65 |f with a 30-byte| 00000090 20 68 65 61 64 65 72 2d 62 6c 6f 63 6b 2e 20 49 | header-block. I| 000000a0 6e 20 74 68 69 73 20 62 6c 6f 63 6b 2c 20 74 68 |n this block, th| 000000b0 65 20 73 74 61 74 75 73 20 6f 66 20 74 68 65 0a |e status of the.| 000000c0 65 6d 75 6c 61 74 65 64 20 5a 38 30 20 70 72 6f |emulated Z80 pro| 000000d0 63 65 73 73 6f 72 20 61 74 20 74 68 65 20 70 6f |cessor at the po| 000000e0 69 6e 74 20 61 74 20 77 68 69 63 68 20 74 68 65 |int at which the| 000000f0 20 5a 38 30 2d 65 6d 75 6c 61 74 6f 72 20 77 61 | Z80-emulator wa| 00000100 73 20 73 74 6f 70 70 65 64 20 62 79 0a 74 68 65 |s stopped by.the| 00000110 20 75 73 65 72 20 69 73 20 73 70 65 63 69 66 69 | user is specifi| 00000120 65 64 2e 20 41 20 66 65 77 20 65 78 74 72 61 20 |ed. A few extra | 00000130 65 6e 76 69 72 6f 6e 6d 65 6e 74 61 6c 20 76 61 |environmental va| 00000140 72 69 61 62 6c 65 73 20 63 6f 6d 70 6c 65 74 65 |riables complete| 00000150 20 74 68 65 0a 68 65 61 64 65 72 2e 0a 0a 20 20 | the.header... | 00000160 20 20 20 20 20 20 42 79 74 65 20 20 20 20 4c 65 | Byte Le| 00000170 6e 67 74 68 20 20 44 65 73 63 72 69 70 74 69 6f |ngth Descriptio| 00000180 6e 0a 20 20 20 20 20 20 20 20 30 20 20 20 20 20 |n. 0 | 00000190 20 20 31 20 20 20 20 20 20 20 41 20 72 65 67 69 | 1 A regi| 000001a0 73 74 65 72 0a 20 20 20 20 20 20 20 20 31 20 20 |ster. 1 | 000001b0 20 20 20 20 20 31 20 20 20 20 20 20 20 46 20 72 | 1 F r| 000001c0 65 67 69 73 74 65 72 0a 20 20 20 20 20 20 20 20 |egister. | 000001d0 32 20 20 20 20 20 20 20 32 20 20 20 20 20 20 20 |2 2 | 000001e0 42 43 20 72 65 67 69 73 74 65 72 20 70 61 69 72 |BC register pair| 000001f0 20 28 4c 53 42 2c 20 69 2e 65 2e 20 43 2c 20 66 | (LSB, i.e. C, f| 00000200 69 72 73 74 29 0a 20 20 20 20 20 20 20 20 34 20 |irst). 4 | 00000210 20 20 20 20 20 20 32 20 20 20 20 20 20 20 48 4c | 2 HL| 00000220 20 72 65 67 69 73 74 65 72 20 70 61 69 72 0a 20 | register pair. | 00000230 20 20 20 20 20 20 20 36 20 20 20 20 20 20 20 32 | 6 2| 00000240 20 20 20 20 20 20 20 50 72 6f 67 72 61 6d 20 63 | Program c| 00000250 6f 75 6e 74 65 72 0a 20 20 20 20 20 20 20 20 38 |ounter. 8| 00000260 20 20 20 20 20 20 20 32 20 20 20 20 20 20 20 53 | 2 S| 00000270 74 61 63 6b 20 70 6f 69 6e 74 65 72 0a 20 20 20 |tack pointer. | 00000280 20 20 20 20 20 31 30 20 20 20 20 20 20 31 20 20 | 10 1 | 00000290 20 20 20 20 20 49 6e 74 65 72 72 75 70 74 20 72 | Interrupt r| 000002a0 65 67 69 73 74 65 72 0a 20 20 20 20 20 20 20 20 |egister. | 000002b0 31 31 20 20 20 20 20 20 31 20 20 20 20 20 20 20 |11 1 | 000002c0 52 65 66 72 65 73 68 20 72 65 67 69 73 74 65 72 |Refresh register| 000002d0 20 28 42 69 74 20 37 20 69 73 20 6e 6f 74 20 73 | (Bit 7 is not s| 000002e0 69 67 6e 69 66 69 63 61 6e 74 21 29 0a 20 20 20 |ignificant!). | 000002f0 20 20 20 20 20 31 32 20 20 20 20 20 20 31 20 20 | 12 1 | 00000300 20 20 20 20 20 42 69 74 20 30 20 20 3a 20 42 69 | Bit 0 : Bi| 00000310 74 20 37 20 6f 66 20 74 68 65 20 52 2d 72 65 67 |t 7 of the R-reg| 00000320 69 73 74 65 72 0a 20 20 20 20 20 20 20 20 20 20 |ister. | 00000330 20 20 20 20 20 20 20 20 20 20 20 20 20 20 42 69 | Bi| 00000340 74 20 31 2d 33 3a 20 42 6f 72 64 65 72 20 63 6f |t 1-3: Border co| 00000350 6c 6f 75 72 0a 20 20 20 20 20 20 20 20 20 20 20 |lour. | 00000360 20 20 20 20 20 20 20 20 20 20 20 20 20 42 69 74 | Bit| 00000370 20 34 20 20 3a 20 31 3d 53 61 6d 52 6f 6d 20 73 | 4 : 1=SamRom s| 00000380 77 69 74 63 68 65 64 20 69 6e 0a 20 20 20 20 20 |witched in. | 00000390 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 000003a0 20 20 20 42 69 74 20 35 20 20 3a 20 31 3d 42 6c | Bit 5 : 1=Bl| 000003b0 6f 63 6b 20 6f 66 20 64 61 74 61 20 69 73 20 27 |ock of data is '| 000003c0 73 71 75 65 65 7a 65 64 27 0a 20 20 20 20 20 20 |squeezed'. | 000003d0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 000003e0 20 20 42 69 74 20 36 2d 37 3a 20 4e 6f 20 6d 65 | Bit 6-7: No me| 000003f0 61 6e 69 6e 67 0a 20 20 20 20 20 20 20 20 31 33 |aning. 13| 00000400 20 20 20 20 20 20 32 20 20 20 20 20 20 20 44 45 | 2 DE| 00000410 20 72 65 67 69 73 74 65 72 20 70 61 69 72 0a 20 | register pair. | 00000420 20 20 20 20 20 20 20 31 35 20 20 20 20 20 20 32 | 15 2| 00000430 20 20 20 20 20 20 20 42 43 27 20 72 65 67 69 73 | BC' regis| 00000440 74 65 72 20 70 61 69 72 0a 20 20 20 20 20 20 20 |ter pair. | 00000450 20 31 37 20 20 20 20 20 20 32 20 20 20 20 20 20 | 17 2 | 00000460 20 44 45 27 20 72 65 67 69 73 74 65 72 20 70 61 | DE' register pa| 00000470 69 72 0a 20 20 20 20 20 20 20 20 31 39 20 20 20 |ir. 19 | 00000480 20 20 20 32 20 20 20 20 20 20 20 48 4c 27 20 72 | 2 HL' r| 00000490 65 67 69 73 74 65 72 20 70 61 69 72 0a 20 20 20 |egister pair. | 000004a0 20 20 20 20 20 32 31 20 20 20 20 20 20 31 20 20 | 21 1 | 000004b0 20 20 20 20 20 41 27 20 72 65 67 69 73 74 65 72 | A' register| 000004c0 0a 20 20 20 20 20 20 20 20 32 32 20 20 20 20 20 |. 22 | 000004d0 20 31 20 20 20 20 20 20 20 46 27 20 72 65 67 69 | 1 F' regi| 000004e0 73 74 65 72 0a 20 20 20 20 20 20 20 20 32 33 20 |ster. 23 | 000004f0 20 20 20 20 20 32 20 20 20 20 20 20 20 49 59 20 | 2 IY | 00000500 72 65 67 69 73 74 65 72 20 28 41 67 61 69 6e 20 |register (Again | 00000510 4c 53 42 20 66 69 72 73 74 29 0a 20 20 20 20 20 |LSB first). | 00000520 20 20 20 32 35 20 20 20 20 20 20 32 20 20 20 20 | 25 2 | 00000530 20 20 20 49 58 20 72 65 67 69 73 74 65 72 0a 20 | IX register. | 00000540 20 20 20 20 20 20 20 32 37 20 20 20 20 20 20 31 | 27 1| 00000550 20 20 20 20 20 20 20 49 6e 74 65 72 72 75 70 74 | Interrupt| 00000560 20 66 6c 69 70 66 6c 6f 70 2c 20 30 3d 44 49 2c | flipflop, 0=DI,| 00000570 20 6f 74 68 65 72 77 69 73 65 20 45 49 0a 20 20 | otherwise EI. | 00000580 20 20 20 20 20 20 32 38 20 20 20 20 20 20 31 20 | 28 1 | 00000590 20 20 20 20 20 20 49 46 46 32 20 28 6e 6f 74 20 | IFF2 (not | 000005a0 70 61 72 74 69 63 75 6c 61 72 6c 79 20 69 6d 70 |particularly imp| 000005b0 6f 72 74 61 6e 74 2e 2e 2e 29 0a 20 20 20 20 20 |ortant...). | 000005c0 20 20 20 32 39 20 20 20 20 20 20 31 20 20 20 20 | 29 1 | 000005d0 20 20 20 42 69 74 20 30 2d 31 3a 20 49 6e 74 65 | Bit 0-1: Inte| 000005e0 72 72 75 70 74 20 6d 6f 64 65 20 28 30 2c 20 31 |rrupt mode (0, 1| 000005f0 20 6f 72 20 32 29 0a 20 20 20 20 20 20 20 20 20 | or 2). | 00000600 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 42 | B| 00000610 69 74 20 32 20 20 3a 20 31 3d 49 73 73 75 65 20 |it 2 : 1=Issue | 00000620 32 20 65 6d 75 6c 61 74 69 6f 6e 0a 20 20 20 20 |2 emulation. | 00000630 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 00000640 20 20 20 20 42 69 74 20 33 20 20 3a 20 31 3d 44 | Bit 3 : 1=D| 00000650 6f 75 62 6c 65 20 69 6e 74 65 72 72 75 70 74 20 |ouble interrupt | 00000660 66 72 65 71 75 65 6e 63 79 0a 20 20 20 20 20 20 |frequency. | 00000670 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 00000680 20 20 42 69 74 20 34 2d 35 3a 20 31 3d 48 69 67 | Bit 4-5: 1=Hig| 00000690 68 20 76 69 64 65 6f 20 73 79 6e 63 68 72 6f 6e |h video synchron| 000006a0 69 73 61 74 69 6f 6e 0a 20 20 20 20 20 20 20 20 |isation. | 000006b0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 000006c0 20 20 20 20 20 20 20 20 20 33 3d 4c 6f 77 20 76 | 3=Low v| 000006d0 69 64 65 6f 20 73 79 6e 63 68 72 6f 6e 69 73 61 |ideo synchronisa| 000006e0 74 69 6f 6e 0a 20 20 20 20 20 20 20 20 20 20 20 |tion. | 000006f0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 00000700 20 20 20 20 20 20 30 2c 32 3d 4e 6f 72 6d 61 6c | 0,2=Normal| 00000710 0a 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |. | 00000720 20 20 20 20 20 20 20 20 20 42 69 74 20 36 2d 37 | Bit 6-7| 00000730 3a 20 30 3d 43 75 72 73 6f 72 2f 50 72 6f 74 65 |: 0=Cursor/Prote| 00000740 6b 2f 41 47 46 20 6a 6f 79 73 74 69 63 6b 0a 20 |k/AGF joystick. | 00000750 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | * 00000770 31 3d 4b 65 6d 70 73 74 6f 6e 20 6a 6f 79 73 74 |1=Kempston joyst| 00000780 69 63 6b 0a 20 20 20 20 20 20 20 20 20 20 20 20 |ick. | 00000790 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 000007a0 20 20 20 20 20 32 3d 53 69 6e 63 6c 61 69 72 20 | 2=Sinclair | 000007b0 31 20 6a 6f 79 73 74 69 63 6b 0a 20 20 20 20 20 |1 joystick. | 000007c0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 000007d0 20 20 20 20 20 20 20 20 20 20 20 20 33 3d 53 69 | 3=Si| 000007e0 6e 63 6c 61 69 72 20 32 20 6a 6f 79 73 74 69 63 |nclair 2 joystic| 000007f0 6b 0a 0a 41 66 74 65 72 20 74 68 65 73 65 20 33 |k..After these 3| 00000800 30 20 62 79 74 65 73 2c 20 61 20 6d 65 6d 6f 72 |0 bytes, a memor| 00000810 79 20 64 75 6d 70 20 6f 66 20 74 68 65 20 65 6d |y dump of the em| 00000820 75 6c 61 74 65 64 20 53 70 65 63 74 72 75 6d 20 |ulated Spectrum | 00000830 66 6f 6c 6c 6f 77 73 2c 0a 63 6f 6e 73 69 73 74 |follows,.consist| 00000840 69 6e 67 20 6f 66 20 74 68 65 20 62 79 74 65 73 |ing of the bytes| 00000850 20 61 74 20 61 64 64 72 65 73 73 20 31 36 33 38 | at address 1638| 00000860 34 20 75 70 20 74 6f 20 36 35 35 33 35 2e 20 20 |4 up to 65535. | 00000870 54 68 65 20 66 69 72 73 74 20 76 65 72 73 69 6f |The first versio| 00000880 6e 73 20 6f 66 0a 74 68 65 20 53 70 65 63 74 72 |ns of.the Spectr| 00000890 75 6d 20 45 6d 75 6c 61 74 6f 72 20 6a 75 73 74 |um Emulator just| 000008a0 20 64 75 6d 70 65 64 20 74 68 65 20 66 75 6c 6c | dumped the full| 000008b0 20 20 34 38 4b 20 61 66 74 65 72 20 74 68 65 20 | 48K after the | 000008c0 68 65 61 64 65 72 2e 20 54 68 65 73 65 0a 76 65 |header. These.ve| 000008d0 72 73 69 6f 6e 73 20 74 68 65 72 65 66 6f 72 65 |rsions therefore| 000008e0 20 70 72 6f 64 75 63 65 64 20 2e 5a 38 30 20 20 | produced .Z80 | 000008f0 66 69 6c 65 73 20 74 68 61 74 20 77 65 72 65 20 |files that were | 00000900 34 39 31 38 32 20 62 79 74 65 73 20 28 3d 34 38 |49182 bytes (=48| 00000910 4b 20 2b 20 33 30 0a 62 79 74 65 73 29 20 69 6e |K + 30.bytes) in| 00000920 20 6c 65 6e 67 74 68 2e 20 54 68 65 20 20 73 68 | length. The sh| 00000930 61 72 65 77 61 72 65 20 76 65 72 73 69 6f 6e 73 |areware versions| 00000940 20 6f 66 20 74 68 65 20 45 6d 75 6c 61 74 6f 72 | of the Emulator| 00000950 20 61 6c 6c 20 75 73 65 20 61 20 73 6c 69 67 68 | all use a sligh| 00000960 74 6c 79 0a 64 69 66 66 65 72 65 6e 74 20 20 6d |tly.different m| 00000970 65 74 68 6f 64 20 6f 66 20 73 74 6f 72 69 6e 67 |ethod of storing| 00000980 20 74 68 65 20 34 38 4b 20 64 61 74 61 62 6c 6f | the 48K datablo| 00000990 63 6b 2c 20 74 68 65 72 65 62 79 20 72 65 64 75 |ck, thereby redu| 000009a0 63 69 6e 67 20 74 68 65 20 73 69 7a 65 20 20 6f |cing the size o| 000009b0 66 0a 74 68 65 20 2e 5a 38 30 20 66 69 6c 65 73 |f.the .Z80 files| 000009c0 2e 20 49 6e 20 65 66 66 65 63 74 2c 20 74 68 65 |. In effect, the| 000009d0 20 6d 65 74 68 6f 64 20 63 6f 6e 73 69 73 74 73 | method consists| 000009e0 20 6f 66 20 66 69 6e 64 69 6e 67 20 61 6c 6c 20 | of finding all | 000009f0 20 73 65 71 75 65 6e 63 65 73 20 6f 66 0a 65 71 | sequences of.eq| 00000a00 75 61 6c 20 62 79 74 65 73 2c 20 61 6e 64 20 72 |ual bytes, and r| 00000a10 65 70 6c 61 63 69 6e 67 20 74 68 65 6d 20 62 79 |eplacing them by| 00000a20 20 61 20 63 6f 64 65 20 6f 66 20 66 6f 75 72 20 | a code of four | 00000a30 20 62 79 74 65 73 2c 20 22 45 44 20 45 44 20 78 | bytes, "ED ED x| 00000a40 78 20 79 79 22 20 77 68 69 63 68 0a 74 65 6c 6c |x yy" which.tell| 00000a50 73 20 74 68 61 74 20 62 79 74 65 20 79 79 20 69 |s that byte yy i| 00000a60 73 20 74 6f 20 72 65 70 65 61 74 65 64 20 78 78 |s to repeated xx| 00000a70 20 20 74 69 6d 65 73 2e 20 41 6e 20 65 78 61 6d | times. An exam| 00000a80 70 6c 65 20 77 69 6c 6c 20 6d 61 6b 65 20 69 74 |ple will make it| 00000a90 20 63 6c 65 61 72 3a 0a 0a 20 20 20 20 20 20 20 | clear:.. | 00000aa0 20 20 20 20 20 20 20 20 20 45 44 20 30 30 20 34 | ED 00 4| 00000ab0 34 20 45 44 20 45 44 20 30 35 20 30 30 20 30 32 |4 ED ED 05 00 02| 00000ac0 20 2e 2e 2e 20 20 20 20 20 20 20 20 20 20 20 20 | ... | 00000ad0 20 28 2e 5a 38 30 20 66 69 6c 65 29 0a 0a 20 20 | (.Z80 file).. | 00000ae0 20 20 20 20 20 20 69 73 20 74 72 61 6e 73 6c 61 | is transla| 00000af0 74 65 64 20 62 61 63 6b 20 69 6e 74 6f 0a 0a 20 |ted back into.. | 00000b00 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 45 | E| 00000b10 44 20 30 30 20 34 34 20 30 30 20 30 30 20 30 30 |D 00 44 00 00 00| 00000b20 20 30 30 20 30 30 20 30 32 20 2e 2e 2e 20 20 20 | 00 00 02 ... | 00000b30 20 20 20 20 20 20 20 28 53 70 65 63 2d 6d 65 6d | (Spec-mem| 00000b40 6f 72 79 29 0a 0a 4f 62 76 69 6f 75 73 6c 79 2c |ory)..Obviously,| 00000b50 20 6f 6e 6c 79 20 73 65 71 75 65 6e 63 65 73 20 | only sequences | 00000b60 6f 66 20 6c 65 6e 67 74 68 20 61 74 20 6c 65 61 |of length at lea| 00000b70 73 74 20 34 20 77 69 6c 6c 20 62 65 20 63 6f 64 |st 4 will be cod| 00000b80 65 64 2c 20 66 6f 72 20 6f 74 68 65 72 77 69 73 |ed, for otherwis| 00000b90 65 0a 74 68 65 72 65 20 77 6f 75 6c 64 20 62 65 |e.there would be| 00000ba0 20 6e 6f 20 67 61 69 6e 20 69 6e 20 74 68 65 20 | no gain in the | 00000bb0 6e 75 6d 62 65 72 20 6f 66 20 73 74 6f 72 65 64 |number of stored| 00000bc0 20 62 79 74 65 73 2e 20 53 65 71 75 65 6e 63 65 | bytes. Sequence| 00000bd0 73 20 6f 66 20 27 45 44 27 20 61 72 65 0a 74 72 |s of 'ED' are.tr| 00000be0 65 61 74 65 64 20 73 65 70 61 72 61 74 65 6c 79 |eated separately| 00000bf0 3a 20 74 68 65 20 6d 69 6e 69 6d 75 6d 20 6c 65 |: the minimum le| 00000c00 6e 67 74 68 20 6f 66 20 61 6e 20 27 45 44 27 2d |ngth of an 'ED'-| 00000c10 73 65 71 75 65 6e 63 65 20 74 6f 20 62 65 20 63 |sequence to be c| 00000c20 6f 64 65 64 20 69 73 20 32 2c 0a 74 6f 20 61 76 |oded is 2,.to av| 00000c30 6f 69 64 20 70 72 6f 62 6c 65 6d 73 20 77 68 65 |oid problems whe| 00000c40 6e 20 74 72 61 6e 73 6c 61 74 69 6e 67 20 62 61 |n translating ba| 00000c50 63 6b 2e 20 41 6e 64 20 6c 61 73 74 6c 79 2c 20 |ck. And lastly, | 00000c60 69 66 20 61 20 73 69 6e 67 6c 65 20 27 45 44 27 |if a single 'ED'| 00000c70 20 69 73 0a 65 6e 63 6f 75 6e 74 65 72 65 64 2c | is.encountered,| 00000c80 20 74 68 75 73 20 61 6e 20 27 45 44 27 20 66 6f | thus an 'ED' fo| 00000c90 6c 6c 6f 77 65 64 20 62 79 20 61 20 64 69 66 66 |llowed by a diff| 00000ca0 65 72 65 6e 74 20 62 79 74 65 2c 20 74 68 65 6e |erent byte, then| 00000cb0 20 74 68 69 73 20 62 79 74 65 0a 66 6f 6c 6c 6f | this byte.follo| 00000cc0 77 69 6e 67 20 74 68 65 20 27 45 44 27 20 77 69 |wing the 'ED' wi| 00000cd0 6c 6c 20 6e 6f 74 20 62 65 20 69 6e 63 6c 75 64 |ll not be includ| 00000ce0 65 64 20 69 6e 20 61 20 62 6c 6f 63 6b 2e 20 54 |ed in a block. T| 00000cf0 68 69 73 20 69 73 20 64 6f 6e 65 20 74 6f 20 61 |his is done to a| 00000d00 76 6f 69 64 20 27 45 44 0a 30 30 20 30 30 20 30 |void 'ED.00 00 0| 00000d10 30 20 30 30 20 30 30 27 20 74 6f 20 62 65 20 74 |0 00 00' to be t| 00000d20 72 61 6e 73 6c 61 74 65 64 20 69 6e 74 6f 20 27 |ranslated into '| 00000d30 45 44 20 45 44 20 45 44 20 30 35 20 30 30 27 20 |ED ED ED 05 00' | 00000d40 77 68 69 63 68 20 77 6f 75 6c 64 20 6e 6f 74 20 |which would not | 00000d50 62 65 0a 74 72 61 6e 73 6c 61 74 65 64 20 62 61 |be.translated ba| 00000d60 63 6b 20 63 6f 72 72 65 63 74 6c 79 2e 20 54 68 |ck correctly. 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