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F/M\Ctut1
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_22.ADF |
| Filename: | F/M\Ctut1 |
| Read OK: | ✔ |
| File size: | 1218 bytes |
| Load address: | 4D204556 |
| Exec address: | 7574432F |
File contents
USING THE ASSEMBLER 5
~~~~~~~~~~~~~~~~~~~~~
By Richard Dimond
I promised to discuss the making up of screens as I had in mind a program
from EU which I had converted to a completely M/code game and I hope to
publish this in the next issue together with some explanation of what I
have doe.
First, however, are some routines which I have not yet covered and which
can be used to make up screens for simple games.
In my first article I gave a simple routine (uline) for printing a line of
the same character. If we use the 'tab' subroutine also given in that
article we can print horizontal or vertical lines of the same character
anywhere on the screen. Add these two routines to those already entered -
.horiz JSRtab
INX
CPXlimit
BNEhoriz
RTS
.vert JSTtab
INY
CPYlimit
BNEvert
RTS
Add limit=&86 to the variables at line 40. Then to use the routines enter
in the main loop -
For a horizontal line -
LDA# <end col> :STAlimit
LDX# <start col>
LDY# <line>
LDA# <char>
JSR horiz ) or JMPhoriz
RTS )
For a vertical line -
LDA# <end line> :STAlimit
LDX# <column>
LDY# <start line>
LDA# char
JMP vert
Blocks of characters can be printed as in BASIC by entering the data -
EQUS CHR$224+CHR$225+CHR$8+CHR$8+CHR$10+CHR$226+CHR$227
and using the loop -
.comms2 STX addr
STY addr+1
TAX
LDY#0
.clp LDA (addr),Y
JSR oswrch
INY
DEX
BNE clp
RTS
While the loop (cooms) is a little more economical in memory and perhaps
better programming, this loop is easier to use as it avoids the necessity
to reverse all the data. It is used as before -
LDA# <number of commands>
LDX# <data> MOD256
LDY# <data> DIV256
JMP comms2
Windows can be made up using the data -
Text window -
EQUB28:EQUB <left>:EQUB (bottom>:EQUB <right>:EQUB <top>
Graphics window -
EQUB24:EQUW <left>:EQUW <bottom>:EQUW <riht>:EQUW <top>
Double height lettering can be printed with this routine -
.dh STX db: STY db+1
LDA#0:STA &70
.b1 LDY &70:LDA (db),Y
CMP #13:BEQ b3
STA &71:INY:STY &70
LDX #&71:LDY #0
LDA #10:JSR &fff1
LDX #1:LDY #0
.b2 LDA &71,X:STA &CF0,Y
INY:STA &CF0,Y
INY:INX
CPX #9:BNE b2
LDA #254:JSR oswrch
LDA #8:JSR oswrch:LDA #10:JSR oswrch
LDA #255:JSR oswrch
LDA #11:JSR oswrch
JMP b1
.b3 RTS
The variable db=&80 must be added to the variables in line 40. This
will hold the address of the STRING to be printed which must have the CR
character &0D at the end. The routine is used in the same way as the
print routine by -
LDX # <label> MOD256
LDY # <label> DIV256
JMP dh
Note - &70 holds the position in the string of the character being printed
and &71 holds the character. The character codes are then split to &72 to
&79. These are doubled loaded to &CF0 to &CFF for characters 254 and 255.
The routines given so far should enable you to make up screens for simple
games where a clash may be detected by comparing co-ordinates where these
are held at say &74 (x,y) and &76 (x1,y1) -
LDAx:CMPx1:BNE no_clash
LDAx+1:CMPx12+1:BNE no_clash
.clash
<clash routine>
.no_clash RTS
For arcade games of the Reptonm type a map is needed as in BASIC and this
should be entered to a suitabla address for the M/code. The data can be
saved separately with other similar files so they can be looded into the
game.
To load these we use the OS routine OSCLI (&FFF7). This is used for all
* commands. It needs the X and Y registers to be loaded with the address
of the command data as for other routines before being called -
LDX# comm MOD256
LDY# comm DIV256
JMP &FFF7
.comm EQUS "LOAD map <address>"
While it may not be necessary to add the address if it is saved to the
correct address, it can be put in.
I shall be explaining more about maps and other routines next time.
**************************************************************************
00000000 0d 55 53 49 4e 47 20 54 48 45 20 41 53 53 45 4d |.USING THE ASSEM| 00000010 42 4c 45 52 20 35 0d 7e 7e 7e 7e 7e 7e 7e 7e 7e |BLER 5.~~~~~~~~~| 00000020 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 7e 0d 42 79 20 |~~~~~~~~~~~~.By | 00000030 52 69 63 68 61 72 64 20 44 69 6d 6f 6e 64 0d 0d |Richard Dimond..| 00000040 49 1a 20 70 72 6f 6d 69 73 65 64 20 74 6f 20 64 |I. promised to d| 00000050 69 73 63 75 73 73 20 74 68 65 20 6d 61 6b 69 6e |iscuss the makin| 00000060 67 20 75 70 20 6f 66 20 73 63 72 65 65 6e 73 20 |g up of screens | 00000070 61 73 20 49 20 68 61 64 20 69 6e 20 6d 69 6e 64 |as I had in mind| 00000080 20 61 20 70 72 6f 67 72 61 6d 0d 66 72 6f 6d 20 | a program.from | 00000090 45 55 1a 20 77 68 69 63 68 1a 20 49 1a 20 68 61 |EU. which. I. ha| 000000a0 64 20 63 6f 6e 76 65 72 74 65 64 20 74 6f 20 61 |d converted to a| 000000b0 20 63 6f 6d 70 6c 65 74 65 6c 79 20 4d 2f 63 6f | completely M/co| 000000c0 64 65 20 67 61 6d 65 20 61 6e 64 20 49 20 68 6f |de game and I ho| 000000d0 70 65 20 74 6f 0d 70 75 62 6c 69 73 68 20 74 68 |pe to.publish th| 000000e0 69 73 20 69 6e 20 74 68 65 20 6e 65 78 74 1a 20 |is in the next. | 000000f0 69 73 73 75 65 1a 20 74 6f 67 65 74 68 65 72 1a |issue. together.| 00000100 20 77 69 74 68 20 73 6f 6d 65 20 65 78 70 6c 61 | with some expla| 00000110 6e 61 74 69 6f 6e 20 6f 66 20 77 68 61 74 20 49 |nation of what I| 00000120 0d 68 61 76 65 20 64 6f 65 2e 0d 0d 46 69 72 73 |.have doe...Firs| 00000130 74 2c 20 68 6f 77 65 76 65 72 2c 20 61 72 65 20 |t, however, are | 00000140 73 6f 6d 65 20 72 6f 75 74 69 6e 65 73 20 77 68 |some routines wh| 00000150 69 63 68 20 49 20 68 61 76 65 1a 20 6e 6f 74 1a |ich I have. not.| 00000160 20 79 65 74 20 63 6f 76 65 72 65 64 20 61 6e 64 | yet covered and| 00000170 20 77 68 69 63 68 0d 63 61 6e 20 62 65 20 75 73 | which.can be us| 00000180 65 64 20 74 6f 20 6d 61 6b 65 20 75 70 20 73 63 |ed to make up sc| 00000190 72 65 65 6e 73 20 66 6f 72 20 73 69 6d 70 6c 65 |reens for simple| 000001a0 20 67 61 6d 65 73 2e 0d 0d 49 6e 20 6d 79 20 66 | games...In my f| 000001b0 69 72 73 74 20 61 72 74 69 63 6c 65 20 49 20 67 |irst article I g| 000001c0 61 76 65 20 61 20 73 69 6d 70 6c 65 20 72 6f 75 |ave a simple rou| 000001d0 74 69 6e 65 20 28 75 6c 69 6e 65 29 20 66 6f 72 |tine (uline) for| 000001e0 20 70 72 69 6e 74 69 6e 67 20 61 20 6c 69 6e 65 | printing a line| 000001f0 20 6f 66 0d 74 68 65 1a 20 73 61 6d 65 20 63 68 | of.the. same ch| 00000200 61 72 61 63 74 65 72 2e 20 20 49 66 20 77 65 20 |aracter. If we | 00000210 75 73 65 20 74 68 65 20 27 74 61 62 27 20 73 75 |use the 'tab' su| 00000220 62 72 6f 75 74 69 6e 65 20 61 6c 73 6f 1a 20 67 |broutine also. g| 00000230 69 76 65 6e 1a 20 69 6e 1a 20 74 68 61 74 0d 61 |iven. in. that.a| 00000240 72 74 69 63 6c 65 20 77 65 1a 20 63 61 6e 1a 20 |rticle we. can. | 00000250 70 72 69 6e 74 1a 20 68 6f 72 69 7a 6f 6e 74 61 |print. horizonta| 00000260 6c 20 6f 72 20 76 65 72 74 69 63 61 6c 20 6c 69 |l or vertical li| 00000270 6e 65 73 20 6f 66 20 74 68 65 20 73 61 6d 65 20 |nes of the same | 00000280 63 68 61 72 61 63 74 65 72 0d 61 6e 79 77 68 65 |character.anywhe| 00000290 72 65 20 6f 6e 20 74 68 65 20 73 63 72 65 65 6e |re on the screen| 000002a0 2e 20 20 41 64 64 20 74 68 65 73 65 20 74 77 6f |. Add these two| 000002b0 20 72 6f 75 74 69 6e 65 73 20 74 6f 20 74 68 6f | routines to tho| 000002c0 73 65 20 61 6c 72 65 61 64 79 20 65 6e 74 65 72 |se already enter| 000002d0 65 64 20 2d 0d 0d 20 20 20 2e 68 6f 72 69 7a 20 |ed -.. .horiz | 000002e0 20 4a 53 52 74 61 62 0d 20 20 20 20 20 20 20 20 | JSRtab. | 000002f0 20 20 20 49 4e 58 0d 20 20 20 20 20 20 20 20 20 | INX. | 00000300 20 20 43 50 58 6c 69 6d 69 74 0d 20 20 20 20 20 | CPXlimit. | 00000310 20 20 20 20 20 20 42 4e 45 68 6f 72 69 7a 0d 20 | BNEhoriz. | 00000320 20 20 20 20 20 20 20 20 20 20 52 54 53 0d 0d 20 | RTS.. | 00000330 20 20 2e 76 65 72 74 20 20 20 4a 53 54 74 61 62 | .vert JSTtab| 00000340 0d 20 20 20 20 20 20 20 20 20 20 20 49 4e 59 0d |. INY.| 00000350 20 20 20 20 20 20 20 20 20 20 20 43 50 59 6c 69 | CPYli| 00000360 6d 69 74 0d 20 20 20 20 20 20 20 20 20 20 20 42 |mit. B| 00000370 4e 45 76 65 72 74 0d 20 20 20 20 20 20 20 20 20 |NEvert. | 00000380 20 20 52 54 53 0d 0d 41 64 64 20 6c 69 6d 69 74 | RTS..Add limit| 00000390 3d 26 38 36 20 74 6f 20 74 68 65 20 76 61 72 69 |=&86 to the vari| 000003a0 61 62 6c 65 73 20 61 74 1a 20 6c 69 6e 65 20 34 |ables at. line 4| 000003b0 30 2e 20 54 68 65 6e 20 74 6f 20 75 73 65 20 74 |0. Then to use t| 000003c0 68 65 20 72 6f 75 74 69 6e 65 73 20 65 6e 74 65 |he routines ente| 000003d0 72 0d 69 6e 20 74 68 65 20 6d 61 69 6e 20 6c 6f |r.in the main lo| 000003e0 6f 70 20 2d 0d 0d 46 6f 72 20 61 20 68 6f 72 69 |op -..For a hori| 000003f0 7a 6f 6e 74 61 6c 20 6c 69 6e 65 20 2d 0d 20 20 |zontal line -. | 00000400 20 20 20 20 20 4c 44 41 23 20 3c 65 6e 64 20 63 | LDA# <end c| 00000410 6f 6c 3e 20 3a 53 54 41 6c 69 6d 69 74 0d 20 20 |ol> :STAlimit. | 00000420 20 20 20 20 20 4c 44 58 23 20 3c 73 74 61 72 74 | LDX# <start| 00000430 20 63 6f 6c 3e 0d 20 20 20 20 20 20 20 4c 44 59 | col>. LDY| 00000440 23 20 3c 6c 69 6e 65 3e 0d 20 20 20 20 20 20 20 |# <line>. | 00000450 4c 44 41 23 20 3c 63 68 61 72 3e 0d 20 20 20 20 |LDA# <char>. | 00000460 20 20 20 4a 53 52 20 68 6f 72 69 7a 20 20 20 20 | JSR horiz | 00000470 20 20 20 29 20 20 6f 72 20 4a 4d 50 68 6f 72 69 | ) or JMPhori| 00000480 7a 0d 20 20 20 20 20 20 20 52 54 53 20 20 20 20 |z. RTS | 00000490 20 20 20 20 20 20 20 20 20 29 0d 0d 46 6f 72 20 | )..For | 000004a0 61 20 76 65 72 74 69 63 61 6c 20 6c 69 6e 65 20 |a vertical line | 000004b0 2d 0d 20 20 20 20 20 20 4c 44 41 23 20 3c 65 6e |-. LDA# <en| 000004c0 64 20 6c 69 6e 65 3e 20 3a 53 54 41 6c 69 6d 69 |d line> :STAlimi| 000004d0 74 0d 20 20 20 20 20 20 4c 44 58 23 20 3c 63 6f |t. LDX# <co| 000004e0 6c 75 6d 6e 3e 0d 20 20 20 20 20 20 4c 44 59 23 |lumn>. LDY#| 000004f0 20 3c 73 74 61 72 74 20 6c 69 6e 65 3e 0d 20 20 | <start line>. | 00000500 20 20 20 20 4c 44 41 23 20 63 68 61 72 0d 20 20 | LDA# char. | 00000510 20 20 20 20 4a 4d 50 20 76 65 72 74 0d 0d 42 6c | JMP vert..Bl| 00000520 6f 63 6b 73 20 6f 66 20 63 68 61 72 61 63 74 65 |ocks of characte| 00000530 72 73 20 63 61 6e 20 62 65 20 70 72 69 6e 74 65 |rs can be printe| 00000540 64 20 61 73 20 69 6e 20 42 41 53 49 43 20 62 79 |d as in BASIC by| 00000550 20 65 6e 74 65 72 69 6e 67 20 74 68 65 20 64 61 | entering the da| 00000560 74 61 20 2d 0d 0d 20 20 20 20 20 20 20 45 51 55 |ta -.. EQU| 00000570 53 20 43 48 52 24 32 32 34 2b 43 48 52 24 32 32 |S CHR$224+CHR$22| 00000580 35 2b 43 48 52 24 38 2b 43 48 52 24 38 2b 43 48 |5+CHR$8+CHR$8+CH| 00000590 52 24 31 30 2b 43 48 52 24 32 32 36 2b 43 48 52 |R$10+CHR$226+CHR| 000005a0 24 32 32 37 0d 61 6e 64 20 75 73 69 6e 67 20 74 |$227.and using t| 000005b0 68 65 20 6c 6f 6f 70 20 2d 0d 0d 20 20 20 20 20 |he loop -.. | 000005c0 20 2e 63 6f 6d 6d 73 32 20 20 53 54 58 20 61 64 | .comms2 STX ad| 000005d0 64 72 0d 20 20 20 20 20 20 20 20 20 20 20 20 20 |dr. | 000005e0 20 20 53 54 59 20 61 64 64 72 2b 31 0d 20 20 20 | STY addr+1. | 000005f0 20 20 20 20 20 20 20 20 20 20 20 20 54 41 58 0d | TAX.| 00000600 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 4c | L| 00000610 44 59 23 30 0d 20 20 20 20 20 20 2e 63 6c 70 20 |DY#0. .clp | 00000620 20 20 20 20 4c 44 41 20 28 61 64 64 72 29 2c 59 | LDA (addr),Y| 00000630 0d 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |. | 00000640 4a 53 52 20 6f 73 77 72 63 68 0d 20 20 20 20 20 |JSR oswrch. | 00000650 20 20 20 20 20 20 20 20 20 20 49 4e 59 0d 20 20 | INY. | 00000660 20 20 20 20 20 20 20 20 20 20 20 20 20 44 45 58 | DEX| 00000670 0d 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |. | 00000680 42 4e 45 20 63 6c 70 0d 20 20 20 20 20 20 20 20 |BNE clp. | 00000690 20 20 20 20 20 20 20 52 54 53 0d 0d 57 68 69 6c | RTS..Whil| 000006a0 65 20 74 68 65 20 6c 6f 6f 70 20 28 63 6f 6f 6d |e the loop (coom| 000006b0 73 29 20 69 73 1a 20 61 1a 20 6c 69 74 74 6c 65 |s) is. a. little| 000006c0 20 6d 6f 72 65 20 65 63 6f 6e 6f 6d 69 63 61 6c | more economical| 000006d0 20 69 6e 20 6d 65 6d 6f 72 79 20 61 6e 64 20 70 | in memory and p| 000006e0 65 72 68 61 70 73 0d 62 65 74 74 65 72 20 70 72 |erhaps.better pr| 000006f0 6f 67 72 61 6d 6d 69 6e 67 2c 20 74 68 69 73 20 |ogramming, this | 00000700 6c 6f 6f 70 20 69 73 20 65 61 73 69 65 72 20 74 |loop is easier t| 00000710 6f 1a 20 75 73 65 20 61 73 20 69 74 20 61 76 6f |o. use as it avo| 00000720 69 64 73 20 74 68 65 20 6e 65 63 65 73 73 69 74 |ids the necessit| 00000730 79 0d 74 6f 20 72 65 76 65 72 73 65 20 61 6c 6c |y.to reverse all| 00000740 20 74 68 65 20 64 61 74 61 2e 20 20 49 74 20 69 | the data. It i| 00000750 73 20 75 73 65 64 20 61 73 20 62 65 66 6f 72 65 |s used as before| 00000760 20 2d 0d 0d 20 20 20 20 20 20 20 20 20 20 20 20 | -.. | 00000770 20 20 20 4c 44 41 23 20 3c 6e 75 6d 62 65 72 20 | LDA# <number | 00000780 6f 66 20 63 6f 6d 6d 61 6e 64 73 3e 0d 20 20 20 |of commands>. | 00000790 20 20 20 20 20 20 20 20 20 20 20 20 4c 44 58 23 | LDX#| 000007a0 20 3c 64 61 74 61 3e 20 4d 4f 44 32 35 36 0d 20 | <data> MOD256. | 000007b0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 4c 44 | LD| 000007c0 59 23 20 3c 64 61 74 61 3e 20 44 49 56 32 35 36 |Y# <data> DIV256| 000007d0 0d 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |. | 000007e0 4a 4d 50 20 63 6f 6d 6d 73 32 0d 0d 57 69 6e 64 |JMP comms2..Wind| 000007f0 6f 77 73 20 63 61 6e 20 62 65 20 6d 61 64 65 20 |ows can be made | 00000800 75 70 20 75 73 69 6e 67 20 74 68 65 20 64 61 74 |up using the dat| 00000810 61 20 2d 0d 0d 54 65 78 74 1a 20 77 69 6e 64 6f |a -..Text. windo| 00000820 77 1a 20 2d 0d 0d 1a 20 20 20 45 51 55 42 32 38 |w. -... EQUB28| 00000830 3a 45 51 55 42 1a 20 3c 6c 65 66 74 3e 3a 45 51 |:EQUB. <left>:EQ| 00000840 55 42 1a 20 28 62 6f 74 74 6f 6d 3e 3a 45 51 55 |UB. (bottom>:EQU| 00000850 42 20 3c 72 69 67 68 74 3e 3a 45 51 55 42 20 3c |B <right>:EQUB <| 00000860 74 6f 70 3e 0d 0d 47 72 61 70 68 69 63 73 20 77 |top>..Graphics w| 00000870 69 6e 64 6f 77 20 20 2d 0d 0d 20 20 20 20 45 51 |indow -.. EQ| 00000880 55 42 32 34 3a 45 51 55 57 20 20 3c 6c 65 66 74 |UB24:EQUW <left| 00000890 3e 3a 45 51 55 57 20 3c 62 6f 74 74 6f 6d 3e 3a |>:EQUW <bottom>:| 000008a0 45 51 55 57 20 3c 72 69 68 74 3e 3a 45 51 55 57 |EQUW <riht>:EQUW| 000008b0 20 3c 74 6f 70 3e 0d 0d 44 6f 75 62 6c 65 20 68 | <top>..Double h| 000008c0 65 69 67 68 74 20 6c 65 74 74 65 72 69 6e 67 20 |eight lettering | 000008d0 63 61 6e 20 62 65 20 70 72 69 6e 74 65 64 20 77 |can be printed w| 000008e0 69 74 68 20 74 68 69 73 20 72 6f 75 74 69 6e 65 |ith this routine| 000008f0 20 2d 0d 0d 20 20 20 20 20 20 20 20 2e 64 68 20 | -.. .dh | 00000900 20 20 20 53 54 58 20 64 62 3a 20 53 54 59 20 64 | STX db: STY d| 00000910 62 2b 31 0d 20 20 20 20 20 20 20 20 20 20 20 20 |b+1. | 00000920 20 20 20 4c 44 41 23 30 3a 53 54 41 20 26 37 30 | LDA#0:STA &70| 00000930 0d 20 20 20 20 20 20 20 20 2e 62 31 20 20 20 20 |. .b1 | 00000940 4c 44 59 20 26 37 30 3a 4c 44 41 20 28 64 62 29 |LDY &70:LDA (db)| 00000950 2c 59 0d 20 20 20 20 20 20 20 20 20 20 20 20 20 |,Y. | 00000960 20 20 43 4d 50 20 23 31 33 3a 42 45 51 20 62 33 | CMP #13:BEQ b3| 00000970 0d 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |. | 00000980 53 54 41 20 26 37 31 3a 49 4e 59 3a 53 54 59 20 |STA &71:INY:STY | 00000990 26 37 30 0d 20 20 20 20 20 20 20 20 20 20 20 20 |&70. | 000009a0 20 20 20 4c 44 58 20 23 26 37 31 3a 4c 44 59 20 | LDX #&71:LDY | 000009b0 23 30 0d 20 20 20 20 20 20 20 20 20 20 20 20 20 |#0. | 000009c0 20 20 4c 44 41 20 23 31 30 3a 4a 53 52 20 26 66 | LDA #10:JSR &f| 000009d0 66 66 31 0d 20 20 20 20 20 20 20 20 20 20 20 20 |ff1. | 000009e0 20 20 20 4c 44 58 20 23 31 3a 4c 44 59 20 23 30 | LDX #1:LDY #0| 000009f0 0d 20 20 20 20 20 20 20 20 2e 62 32 20 20 20 20 |. .b2 | 00000a00 4c 44 41 20 26 37 31 2c 58 3a 53 54 41 20 26 43 |LDA &71,X:STA &C| 00000a10 46 30 2c 59 0d 20 20 20 20 20 20 20 20 20 20 20 |F0,Y. | 00000a20 20 20 20 20 49 4e 59 3a 53 54 41 20 26 43 46 30 | INY:STA &CF0| 00000a30 2c 59 0d 20 20 20 20 20 20 20 20 20 20 20 20 20 |,Y. | 00000a40 20 20 49 4e 59 3a 49 4e 58 0d 20 20 20 20 20 20 | INY:INX. | 00000a50 20 20 20 20 20 20 20 20 20 43 50 58 20 23 39 3a | CPX #9:| 00000a60 42 4e 45 20 62 32 0d 20 20 20 20 20 20 20 20 20 |BNE b2. | 00000a70 20 20 20 20 20 20 4c 44 41 20 23 32 35 34 3a 4a | LDA #254:J| 00000a80 53 52 20 6f 73 77 72 63 68 0d 20 20 20 20 20 20 |SR oswrch. | 00000a90 20 20 20 20 20 20 20 20 20 4c 44 41 20 23 38 3a | LDA #8:| 00000aa0 4a 53 52 20 6f 73 77 72 63 68 3a 4c 44 41 20 23 |JSR oswrch:LDA #| 00000ab0 31 30 3a 4a 53 52 20 6f 73 77 72 63 68 0d 20 20 |10:JSR oswrch. | 00000ac0 20 20 20 20 20 20 20 20 20 20 20 20 20 4c 44 41 | LDA| 00000ad0 20 23 32 35 35 3a 4a 53 52 20 6f 73 77 72 63 68 | #255:JSR oswrch| 00000ae0 0d 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |. | 00000af0 4c 44 41 20 23 31 31 3a 4a 53 52 20 6f 73 77 72 |LDA #11:JSR oswr| 00000b00 63 68 0d 20 20 20 20 20 20 20 20 20 20 20 20 20 |ch. | 00000b10 20 20 4a 4d 50 20 62 31 0d 20 20 20 20 20 20 20 | JMP b1. | 00000b20 20 20 2e 62 33 20 20 20 52 54 53 0d 0d 54 68 65 | .b3 RTS..The| 00000b30 1a 20 76 61 72 69 61 62 6c 65 1a 20 20 64 62 3d |. variable. db=| 00000b40 26 38 30 1a 20 20 6d 75 73 74 1a 20 62 65 20 61 |&80. must. be a| 00000b50 64 64 65 64 20 74 6f 20 74 68 65 20 76 61 72 69 |dded to the vari| 00000b60 61 62 6c 65 73 20 69 6e 20 6c 69 6e 65 20 34 30 |ables in line 40| 00000b70 2e 20 20 54 68 69 73 0d 77 69 6c 6c 20 68 6f 6c |. This.will hol| 00000b80 64 20 74 68 65 20 61 64 64 72 65 73 73 20 6f 66 |d the address of| 00000b90 1a 20 74 68 65 1a 20 53 54 52 49 4e 47 20 74 6f |. the. STRING to| 00000ba0 20 62 65 20 70 72 69 6e 74 65 64 20 77 68 69 63 | be printed whic| 00000bb0 68 20 6d 75 73 74 20 68 61 76 65 20 74 68 65 20 |h must have the | 00000bc0 43 52 0d 63 68 61 72 61 63 74 65 72 20 26 30 44 |CR.character &0D| 00000bd0 20 61 74 20 74 68 65 20 65 6e 64 2e 20 20 54 68 | at the end. Th| 00000be0 65 20 72 6f 75 74 69 6e 65 1a 20 69 73 1a 20 75 |e routine. is. u| 00000bf0 73 65 64 1a 20 69 6e 1a 20 74 68 65 1a 20 73 61 |sed. in. the. sa| 00000c00 6d 65 20 77 61 79 20 61 73 20 74 68 65 0d 70 72 |me way as the.pr| 00000c10 69 6e 74 20 72 6f 75 74 69 6e 65 20 62 79 20 2d |int routine by -| 00000c20 0d 0d 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |.. | 00000c30 20 4c 44 58 20 23 20 3c 6c 61 62 65 6c 3e 20 4d | LDX # <label> M| 00000c40 4f 44 32 35 36 0d 20 20 20 20 20 20 20 20 20 20 |OD256. | 00000c50 20 20 20 20 20 4c 44 59 20 23 20 3c 6c 61 62 65 | LDY # <labe| 00000c60 6c 3e 20 44 49 56 32 35 36 0d 20 20 20 20 20 20 |l> DIV256. | 00000c70 20 20 20 20 20 20 20 20 20 4a 4d 50 20 64 68 0d | JMP dh.| 00000c80 0d 4e 6f 74 65 20 2d 20 26 37 30 20 68 6f 6c 64 |.Note - &70 hold| 00000c90 73 20 74 68 65 20 70 6f 73 69 74 69 6f 6e 20 69 |s the position i| 00000ca0 6e 20 74 68 65 20 73 74 72 69 6e 67 20 6f 66 20 |n the string of | 00000cb0 74 68 65 20 63 68 61 72 61 63 74 65 72 20 62 65 |the character be| 00000cc0 69 6e 67 20 70 72 69 6e 74 65 64 0d 61 6e 64 20 |ing printed.and | 00000cd0 26 37 31 20 68 6f 6c 64 73 20 74 68 65 20 63 68 |&71 holds the ch| 00000ce0 61 72 61 63 74 65 72 2e 20 20 54 68 65 20 63 68 |aracter. The ch| 00000cf0 61 72 61 63 74 65 72 20 63 6f 64 65 73 20 61 72 |aracter codes ar| 00000d00 65 20 74 68 65 6e 20 73 70 6c 69 74 20 74 6f 20 |e then split to | 00000d10 26 37 32 20 74 6f 0d 26 37 39 2e 20 54 68 65 73 |&72 to.&79. Thes| 00000d20 65 20 61 72 65 20 64 6f 75 62 6c 65 64 20 6c 6f |e are doubled lo| 00000d30 61 64 65 64 20 74 6f 20 26 43 46 30 20 74 6f 20 |aded to &CF0 to | 00000d40 26 43 46 46 20 66 6f 72 20 63 68 61 72 61 63 74 |&CFF for charact| 00000d50 65 72 73 20 32 35 34 20 61 6e 64 20 32 35 35 2e |ers 254 and 255.| 00000d60 0d 0d 54 68 65 20 72 6f 75 74 69 6e 65 73 20 67 |..The routines g| 00000d70 69 76 65 6e 20 73 6f 20 66 61 72 1a 20 73 68 6f |iven so far. sho| 00000d80 75 6c 64 20 65 6e 61 62 6c 65 20 79 6f 75 20 74 |uld enable you t| 00000d90 6f 20 6d 61 6b 65 20 75 70 20 73 63 72 65 65 6e |o make up screen| 00000da0 73 20 66 6f 72 20 73 69 6d 70 6c 65 0d 67 61 6d |s for simple.gam| 00000db0 65 73 20 77 68 65 72 65 20 61 20 63 6c 61 73 68 |es where a clash| 00000dc0 20 6d 61 79 20 62 65 1a 20 64 65 74 65 63 74 65 | may be. detecte| 00000dd0 64 20 62 79 20 63 6f 6d 70 61 72 69 6e 67 20 63 |d by comparing c| 00000de0 6f 2d 6f 72 64 69 6e 61 74 65 73 20 77 68 65 72 |o-ordinates wher| 00000df0 65 20 74 68 65 73 65 0d 61 72 65 20 68 65 6c 64 |e these.are held| 00000e00 20 61 74 20 73 61 79 20 26 37 34 20 28 78 2c 79 | at say &74 (x,y| 00000e10 29 20 61 6e 64 20 26 37 36 20 28 78 31 2c 79 31 |) and &76 (x1,y1| 00000e20 29 20 2d 0d 0d 20 20 20 20 20 20 20 20 20 20 20 |) -.. | 00000e30 20 20 20 20 4c 44 41 78 3a 43 4d 50 78 31 3a 42 | LDAx:CMPx1:B| 00000e40 4e 45 20 6e 6f 5f 63 6c 61 73 68 0d 20 20 20 20 |NE no_clash. | 00000e50 20 20 20 20 20 20 20 20 20 20 20 4c 44 41 78 2b | LDAx+| 00000e60 31 3a 43 4d 50 78 31 32 2b 31 3a 42 4e 45 20 6e |1:CMPx12+1:BNE n| 00000e70 6f 5f 63 6c 61 73 68 0d 20 20 20 20 20 20 20 20 |o_clash. | 00000e80 20 20 20 20 20 20 20 2e 63 6c 61 73 68 0d 20 20 | .clash. | 00000e90 20 20 20 20 20 20 20 20 20 20 20 20 20 3c 63 6c | <cl| 00000ea0 61 73 68 20 72 6f 75 74 69 6e 65 3e 0d 20 20 20 |ash routine>. | 00000eb0 20 20 20 20 20 20 20 20 20 20 20 20 2e 6e 6f 5f | .no_| 00000ec0 63 6c 61 73 68 20 52 54 53 0d 0d 46 6f 72 20 61 |clash RTS..For a| 00000ed0 72 63 61 64 65 20 67 61 6d 65 73 1a 20 6f 66 20 |rcade games. of | 00000ee0 74 68 65 20 52 65 70 74 6f 6e 6d 20 74 79 70 65 |the Reptonm type| 00000ef0 20 61 20 6d 61 70 20 69 73 20 6e 65 65 64 65 64 | a map is needed| 00000f00 20 61 73 20 69 6e 20 42 41 53 49 43 20 61 6e 64 | as in BASIC and| 00000f10 20 74 68 69 73 0d 73 68 6f 75 6c 64 20 62 65 20 | this.should be | 00000f20 65 6e 74 65 72 65 64 20 74 6f 1a 20 61 1a 20 73 |entered to. a. s| 00000f30 75 69 74 61 62 6c 61 20 61 64 64 72 65 73 73 20 |uitabla address | 00000f40 66 6f 72 20 74 68 65 20 4d 2f 63 6f 64 65 2e 20 |for the M/code. | 00000f50 20 54 68 65 20 64 61 74 61 20 63 61 6e 20 62 65 | The data can be| 00000f60 0d 73 61 76 65 64 20 73 65 70 61 72 61 74 65 6c |.saved separatel| 00000f70 79 20 77 69 74 68 20 6f 74 68 65 72 20 73 69 6d |y with other sim| 00000f80 69 6c 61 72 20 66 69 6c 65 73 1a 20 73 6f 1a 20 |ilar files. so. | 00000f90 74 68 65 79 20 63 61 6e 20 62 65 20 6c 6f 6f 64 |they can be lood| 00000fa0 65 64 20 69 6e 74 6f 20 74 68 65 0d 67 61 6d 65 |ed into the.game| 00000fb0 2e 20 20 0d 0d 54 6f 20 6c 6f 61 64 20 74 68 65 |. ..To load the| 00000fc0 73 65 20 77 65 20 75 73 65 20 74 68 65 20 4f 53 |se we use the OS| 00000fd0 20 72 6f 75 74 69 6e 65 1a 20 4f 53 43 4c 49 1a | routine. OSCLI.| 00000fe0 20 28 26 46 46 46 37 29 2e 20 20 54 68 69 73 20 | (&FFF7). This | 00000ff0 69 73 20 75 73 65 64 20 66 6f 72 20 61 6c 6c 20 |is used for all | 00001000 0d 2a 20 63 6f 6d 6d 61 6e 64 73 2e 20 20 49 74 |.* commands. It| 00001010 20 6e 65 65 64 73 20 74 68 65 20 58 20 61 6e 64 | needs the X and| 00001020 20 59 20 72 65 67 69 73 74 65 72 73 20 74 6f 1a | Y registers to.| 00001030 20 62 65 20 6c 6f 61 64 65 64 20 77 69 74 68 20 | be loaded with | 00001040 74 68 65 20 61 64 64 72 65 73 73 0d 6f 66 20 74 |the address.of t| 00001050 68 65 20 63 6f 6d 6d 61 6e 64 20 64 61 74 61 20 |he command data | 00001060 61 73 20 66 6f 72 20 6f 74 68 65 72 20 72 6f 75 |as for other rou| 00001070 74 69 6e 65 73 20 62 65 66 6f 72 65 20 62 65 69 |tines before bei| 00001080 6e 67 20 63 61 6c 6c 65 64 20 2d 0d 0d 20 20 20 |ng called -.. | 00001090 20 20 20 20 20 20 20 20 20 20 20 20 20 20 4c 44 | LD| 000010a0 58 23 20 63 6f 6d 6d 20 4d 4f 44 32 35 36 0d 20 |X# comm MOD256. | 000010b0 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | | 000010c0 4c 44 59 23 20 63 6f 6d 6d 20 44 49 56 32 35 36 |LDY# comm DIV256| 000010d0 0d 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 |. | 000010e0 20 20 4a 4d 50 20 26 46 46 46 37 0d 20 20 20 20 | JMP &FFF7. | 000010f0 20 20 20 20 2e 63 6f 6d 6d 20 20 20 20 45 51 55 | .comm EQU| 00001100 53 20 22 4c 4f 41 44 20 6d 61 70 20 3c 61 64 64 |S "LOAD map <add| 00001110 72 65 73 73 3e 22 0d 0d 57 68 69 6c 65 20 69 74 |ress>"..While it| 00001120 20 6d 61 79 20 6e 6f 74 20 62 65 20 6e 65 63 65 | may not be nece| 00001130 73 73 61 72 79 20 74 6f 20 61 64 64 20 74 68 65 |ssary to add the| 00001140 20 61 64 64 72 65 73 73 20 69 66 1a 20 69 74 1a | address if. it.| 00001150 20 69 73 1a 20 73 61 76 65 64 1a 20 74 6f 20 74 | is. saved. to t| 00001160 68 65 0d 63 6f 72 72 65 63 74 20 61 64 64 72 65 |he.correct addre| 00001170 73 73 2c 20 69 74 20 63 61 6e 20 62 65 20 70 75 |ss, it can be pu| 00001180 74 20 69 6e 2e 0d 0d 49 20 73 68 61 6c 6c 20 62 |t in...I shall b| 00001190 65 20 65 78 70 6c 61 69 6e 69 6e 67 20 6d 6f 72 |e explaining mor| 000011a0 65 20 61 62 6f 75 74 20 6d 61 70 73 20 61 6e 64 |e about maps and| 000011b0 20 6f 74 68 65 72 20 72 6f 75 74 69 6e 65 73 20 | other routines | 000011c0 6e 65 78 74 20 74 69 6d 65 2e 0d 0d 2a 2a 2a 2a |next time...****| 000011d0 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a 2a |****************| * 00001210 2a 2a 2a 2a 2a 2a 0d 0d |******..| 00001218
F/M\Ctut1.m0
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.