Fishtank by Stuart Gascoigne The graphics for Fishtank were designed using 'The Advanced Art Studio' by Rainbird. You can use it to modify the fishtank screen if you wish. The palette file for the fishtank is included to make life easier, although the program doesn't use this, (i.e. the inks are preset to the same values in the program). The title screen and tank are held in compressed format. The program CRUNCH converts to this format. The fishes in the fishtank are also created with AAS. They are drawn using the same palette, and saved as window files. You can create your own fish using AAS, define a window around it and save it to a file. Normally, the window should just enclose the fish. If you add extra lines of background to the top or bottom of the fish, you will slow it down. If you add extra pixels of background to the right or left of the fish, it will appear to turn early. The background for the fishes must be plain ink 0, anything else is assumed to be part of the fish. Note that the fishes should point rightwards (unless you want them to swim backwards!). Each fish window must conform to the following limits - a maximum of &6b0 bytes in length - not more than 96 pixels in height - not more than 40 bytes (80 pixels) in width. There must be a maximum of 16kbytes of fishes in total. You can add your fish(es) to the default set by calling it FISH-x.WIN, where x is the next letter in sequence, and poking location &3680 with (the ASCII value of x) - 64 (,i.e. the number of fishes). As provided, there are 10 fishes, and there is room for up to 15. Thanks to Sam Farr for the mutant ninja terrapin, mermaid and submarine. My version of Advanced Art Studio is 2.4, compatability with other versions is unknown. The Hisoft GENA assembler is used throughout and sources are included.

;fishtank, by stuart gascoigne ;the cheapest fishtank on the market ;idea pinched from J Raphael B Salgado's "Aquarium" ;on a ibm pc ;screen is assumed to be not rolled and not scrolled ;it makes the calculations a lot easier FISHSZ:equ #6b0 ;maximum length of a fish MAXYSZ:equ 96 ;max height of fish window MAXXSZ:equ 40 ;max width of fish window FISH1:equ #100 ;address of fish MASK1:equ FISH1+FISHSZ ;address of mask FISH2:equ MASK1+FISHSZ ;fish moved 1 pixel MASK2:equ FISH2+FISHSZ ;mask for fish 2 FISH1B:equ MASK2+FISHSZ ;backwards fish 1 MASK1B:equ FISH1B+FISHSZ FISH2B:equ MASK1B+FISHSZ ;backwards fish 2 MASK2B:equ FISH2B+FISHSZ TEMPFI:equ #4000 ;fishes read into here initially ;overwritten by second screen CMPSCR:equ #4000 ;compressed piccy's address BUFFER:equ #8000 ;disc buffer SCST:equ #8000 ;address of screen store RAMBAS:equ #c0 ;bank no for unswapped ram RAMTIT:equ #c4 ;bank no for stored title screen RAMFIS:equ #c5 ;bank no for stored fishes RAMTNK:equ #c6 ;bank no for stored tank org MASK2B+FISHSZ NOFISH:defb 3 ;number of fishes to choose from ;poke whatever value you like in here ent $ ld hl,0 add hl,sp ;hl=stack base ld (STACK),hl ;store away restrt:call init1 ;load background,etc call init2 ;select fishes etc again:call right ;main loop call left jr again STACK:defw 0 ;stack base START:defb 0 ;starts at zero, set to one once ;we've loaded everything - restart without reloading right:;move fish right ld a,(MOVEX) ld b,a right1:push bc call esc ;test for esc key ld de,MASK1 ld ix,FISH1 call loadfi res 7,h ;now points at lower screen ld de,MASK2 ld ix,FISH2 call loadfi inc iy inc hl set 7,h ;and now higher screen pop bc djnz right1 ret left:;move fish left ld a,(MOVEX) ld b,a left1:push bc call esc ;test for esc key ld de,MASK1B ld ix,FISH1B call loadfi res 7,h ;now points at lower screen ld de,MASK2B ld ix,FISH2B call loadfi set 7,h ;and now higher screen dec iy dec hl pop bc djnz left1 ret esc:;tests whether esc key is pressed ld a,(RAM) ;unless we are expanded ignore & ret cp 1 ret nz ld a,66 ;esc = key 66 push hl ;save hl call #bb1e ;km test key pop hl ret z ;esc not pressed -return ld a,#c0 ;reset screen to high location call #bc08 ;scr set base ld hl,(STACK) ;load saved stack base ld sp,hl ;reset stack jp restrt loadfi:;moves fish to screen ;hl must contain screen address of top left point ;iy must contain corresponding address of stored background ;de must contain address of mask to use ;ix must address fish to use ;fish is ORed onto the AND of the mask and the stored ;background, then result sent to screen ;this preserves the background inside the fish window push hl ;save screen addresses push iy ld a,(YSIZE) ld b,a ;b=lines to shift next3:push bc ;store line count ld a,(XSIZE) ld b,a ;no of bytes to shift push iy ;save background address push hl ;save screen address next4:ld a,(de) ;next mask and (iy) ;add to background or (ix) ;add fish ld (hl),a ;result to screen inc hl inc de inc ix inc iy djnz next4 ;next byte pop hl ;start of line again ld bc,#0800 add hl,bc ;start of next line? bit 6,h ;gets reset on overflowing screen jr nz,no3 ld bc,#c050 ;adjust for next screen block add hl,bc no3:pop iy ;start of background line ld bc,#0050 add iy,bc ;start of next line pop bc ;line count djnz next3 call #bd19 ;wait frame flyback ld a,h ;half of screen address call #bc08 ;switch screens pop iy;get back screen addresses pop hl ret ;**************************** init1: ;loads title screen, loads fishes ld a,(START) ;are we restarting? cp 0 jr nz,rest1 ;if yes jump ;test whether expanded machine or not ld hl,#4000 ;switchable ram address ld (hl),1 ;if we get a 1 back=ram there ld bc,#7f00+RAMFIS out (c),c ;switch banks (possibly) ld (hl),0 ;if we get a 0 back=ram not there ld bc,#7f00+RAMBAS out (c),c ;switch back ld a,(hl) ld (RAM),a ;store the answer ld a,0 ;new screen mode call #bc0e ;set mode call zerink ;set inks to 0 ld hl,TITLE ;title screen call readsc ;read screen into #c000 call setink ;set inks ld a,(RAM) ;test for expanded memory cp 1 jr nz,noram1 ;no ram ld c,RAMTIT ;bank no call hi2low ;save screen in banked ram noram1:ld a,5 ;ink 5=bright yellow call #bbde ;gra set ink ld hl,80 ;y-coord ld ix,PLZWT ;message call wrline ld a,(NOFISH) ld b,a ;number of fish to read ld iy,TEMPFI ;first fish goes here ld ix,TABLE ;index to where fishes are nextfi:push bc ;save count call readfi ;read in fish pop bc djnz nextfi ;do next fish ld a,(RAM) cp 1 ;if spare ram save fishes ret nz ;no ram ld a,RAMBAS ;main bank ld (FROMBK),a ld a,RAMFIS ld (TOBK),a call low2lw ;save fishes ret rest1:;restart ld c,RAMTIT ;bank no call low2hi ;reload title screen ld a,RAMFIS ld (FROMBK),a ld a,RAMBAS ld (TOBK),a call low2lw ;reload fish ret RAM:defb 0 ;64k=0 128k=1 PLZWT:defm "please wait while fish are loaded£" init2: ;select fish to use and set up tank call wrmess ;instructions to screen call select ;display and pick fishes call where ;ask where fish should go ld a,(START) cp 0 ;restarting? jr nz,rest2 ;jump if yes ld hl,TANKNM ;screen name call readsc ;load fish tank ld a,(RAM) cp 1 ;extra memory? jr nz,noram2 ;no ram ld c,RAMTNK ;bank no call hi2low ;save tank in banked ram jr noram2 ;join up with main code again rest2:ld c,RAMTNK ;bank no call low2hi ;reload tank noram2: ld c,RAMBAS ;bank no=main bank call hi2low ;duplicate tank screen ld de,0 ld hl,(SWIMY) call #bc1d ;get screen address in hl push hl call savesc ;move the bit of screen that ;we animate to store (full width) pop hl ;screen address ld iy,SCST ;background address ld a,(XSIZE) sub 80 neg ld (MOVEX),a ;movex=80-xsize ld a,1 ld (START),a ;set flag - can now restart ret TANKNM:defm 'FISHTANK.SQR' ;tank background TITLE:defm 'FISHTITL.SQR' ;title screen FISHES:defw 0 ;address of fish XSIZE:defb 0 ;size of fish, horiz, bytes YSIZE:defb 0 ;size of fish, vert, lines XSIZEP:defb 0 ;size of fish, horiz pixels XSPARE:defb 0 ;no of bits from ;window edge to byte boundary FILENG:defw 0 ;length of fish MOVEX:defb 0 ;no of bytes to move fish TABSZ:equ 8 ;bytes/item in table TABLE:defs TABSZ*15 ;array-for storing fish data ;format of array, indexed by ix, is ;(ix),(ix+1)=address of fish ;(ix+2)=xsize in bytes ;(ix+3)=ysize in lines ;(ix+4)=xsize in pixels ;(ix+5)=xspare (must be 0 or 4 for mode 0 pics) ;(ix+6,7)=length of fish bytes zerink:;sets all inks to 0 xor a ; a=0 nxtzik:ld bc,0 ;colour=0 push af call #bc32 ;set ink pop af inc a cp #10 jr nz,nxtzik ret setink:;sets inks for picture ld ix,INKS xor a ;a=0 nextik:ld b,(ix) ld c,b push af call #bc32 ;set ink a to colour b,c pop af inc ix inc a cp #10 jr nz,nextik ret INKS:defb 2,0,6,26,1,24,20,22,13,9,15,16,21,25,11,3 readsc:;reads screen into #4000 ;title of file must be addressed by hl ;decompresses screen into #c000 ld b,12 ;length of name ld de,BUFFER call #bc77 ;file open ld hl,CMPSCR ;screen address call #bc83 ;read direct call #bc7a ;close input ;screen is compressed with a self starting decompressor ;on the front. Call it jp CMPSCR readfi:;read in fish file ld (fudge1+2),ix ;array pointer fudge1:ld (0),iy ;store start address ld a,b ;file number or #40 ;turn number to letter ld (FILENO),a ;part of file name ld b,10 ;length of name ld hl,FILENM ;name location ld de,BUFFER push ix ;save array pointer call #bc77 ;file open pop ix push ix ;save it again push bc ;file length ld hl,-5 add hl,bc ;hl=file length-5 ld (ix+6),l ld (ix+7),h ;fish size stored in array call tumuch;test file size call tumany ;test total fish sizes push iy ;start address pop hl ;start address in hl call #bc83 ;read direct pop bc ;file length add iy,bc ;start of next file pop ix ;get back array pointer ld a,(iy-4) ;x-coord lower byte srl a srl a rrc (iy-3) ;x-coord higher byte rrc (iy-3) ;divide by 4 add a,(iy-3) ;add on and then.. ld (ix+4),a ;x-size divided by 4 dec a srl a inc a ld (ix+2),a ;x-size / 8 rounded up call tuwide ;test width of window ld a,(iy-2) ld (ix+3),a ;y-size=no of lines call tuhigh ;test height of window ld a,(iy-5) ld (ix+5),a ;xspare bits stored ld bc,-5 ;take red tape of end of file add iy,bc ;by adjusting pointer to next file call adjust ;tinker with fish pic ld bc,TABSZ add ix,bc ;increment pointer tmerr:push ix ;save array pointer call #bc7a ;close file pop ix ;array pointer ret FILENM:defm 'FISH-' FILENO:defb 0 defm '.WIN£' tumuch:;test if fish is too big ;and give error message if necessary. size is in bc ld hl,FISHSZ ;max size of a fish xor a ;resets carry sbc hl,bc ;neg if fish>max ret p ;ok - return pop hl ;discard return address pop hl ;discard saved data word ;array pointer is still on stack call cltext ;clear text window ld hl,60 ;give error message ld ix,FILENM call wrline ld ix,ERR1 call wrline ld ix,CONT call wrline call #bb18 ;wait for key pop ix ;get back array pointer jp tmerr ;close file etc ERR1:defm "is too large - max " ;note that we allow 200 bytes expansion of file for ;adding 2bytes down the side of window defb FISHSZ-200/1000?10+"0" defb FISHSZ-200/100?10+"0" defb FISHSZ-200/10?10+"0" defb FISHSZ-200/1?10+"0" defm " bytes allowed£" CONT:defm "hit any key to continue£" tumany:;test whether fish will cause ;total size of all fishes to exceed space available ;size is always #4000 - size of a ram bank push iy ;start address pop hl ;now in hl add hl,bc ;add to size ld bc,TEMPFI+#4000 ;end of fish space xor a ;reset carry sbc hl,bc ret m ;result should be negative pop hl ;discard return address pop hl ;discard saved data word ;array pointer is still on stack call cltext ;clear text window ld hl,80 ;give error message ld ix,FILENM call wrline ld ix,ERR4 call wrline call wrline ld ix,CONT call wrline call #bb18 ;wait for key pop ix ;get back array pointer jp tmerr ;close file etc ERR4:defm "is too large - total size£" ERR5:defm "of all fish must be < 16kbytes£" tuwide:;test width of window and ;give error if too much. width in a cp MAXXSZ ;max width ret m ;ok call cltext ;clear message window push ix ;save array pointer ld hl,60 ld ix,FILENM call wrline ld ix,ERR3 call wrline ld ix,CONT call wrline call #bb18 ;wait for key pop ix ;get back array pointer ld (fudge5+2),ix ;array pointer fudge5:ld iy,(0) ;reset start address pop hl ;discard return address jp tmerr ;go close file etc ERR3:defm "is too wide - max " defb MAXXSZ/10?10+"0" defb MAXXSZ/1?10+"0" defm " bytes allowed£" tuhigh:;test height of window and ;give error if too much. height in a cp MAXYSZ ;max height ret m ;ok push ix ;save array pointer call cltext ;clear message window ld hl,60 ld ix,FILENM call wrline ld ix,ERR2 call wrline ld ix,CONT call wrline call #bb18 ;wait for key pop ix ;get back array pointer ld (fudge6+2),ix ;array pointer fudge6:ld iy,(0) ;reset start address pop hl ;discard return address jp tmerr ;go close file etc ret ERR2:defm "is too high - max " defb MAXYSZ/10?10+"0" defb MAXYSZ/1?10+"0" defm " lines allowed£" wrmess:;write instructions to screen call cltext ;clear window for messages ld a,2 ;ink 2=bright red call #bbde ;gra set pen ld hl,80 ;y-coord ld ix,INST1 ;message call wrline call wrline call wrline ret INST1:defm "pick a fish, any fish!£" INST2:defm "SPACE to see next fish£" INST3:defm "ENTER to select the fish you see£" wrline:;write a line of text ;using graphics system, and halfsize font ;end of line is indicated by character of £ ;ix points at string, hl holds y-coord of message push hl ;save y coord ld de,8 ;x-coord call #bbc0 ;gra move absolute nextch:ld a,(ix) ;character to print cp "£" jr z,endch ;end of string call #bbfc ;gra wr char ld a,(ix) ;same character cp "A" jp m,back ;if < capital A, backspace cp "Z"+1 jp m,noback ;if A-Z (capital) no backspace back:ld de,-16 ;x-coord ld hl,0 ;y call #bbc3 ;gra move relative noback:inc ix jr nextch endch:ld de,-20 pop hl ;get back y-coord add hl,de ;get next y coordinate inc ix ;get next character ret select:;display fishes on title screen ;and let user select one ld de,136 ;set window -left edge ld hl,503 ;right edge call #bbcf ;set win width ld de,257 ;top edge ld hl,80 ;bottom edge call #bbd2 ;set window height n13:ld ix,TABLE ;pointer to first fish n12:call disp ;display fish (ix) points at waitch:call #bb18 ;wait for a key cp " " ;if space display next fish jr nz,n11 ld bc,TABSZ add ix,bc ;point at next ld a,(ix) ;get half pointer or (ix+1) ;other half jr z,n13 ;if pointer=0,we've gone off ;the end, so go back to start, otherwise - jr n12 ;go display it n11:cp #0d ;if enter use this fish jr z,shuffl ;move this fish to start cp #8b ;other enter or return jr nz,waitch ;anything else, go again shuffl: ;fish now selected - move fish that is pointed to ;by (ix) to TEMPFI which is at start, then we can reuse ;the area that the fish were stored in to store masks etc push ix pop hl ;source of array ld de,FISHES ;destination-non array ld bc,TABSZ ldir ;move array element to start ld h,(ix+1) ld l,(ix) ;hl=start of fish ld de,TEMPFI ;destination ld bc,(FILENG) ldir ;move fish ld hl,TEMPFI ;fish address ld (FISHES),hl ;store address ld ix,FISHES ;ix points at (fish) ;add a byte of background to right side call addr ;move fish from TEMPFI where ;it was read in, to FISH1, but add a pixel of background ;to the left hand edge. This will overwrite the ;left hand pixels of the previous image as the fish moves call mover ld de,FISH1 ld hl,TEMPFI ld bc,FISHSZ ldir ;add another pix of background to left and move to FISH2 call mover ld de,FISH2 ld hl,TEMPFI ld bc,FISHSZ ldir ld hl,MASK1 ld de,FISH1 call setmsk ;create mask ld hl,MASK2 ld de,FISH2 call setmsk ld de,FISH1 ld hl,FISH1B call revfi ;mirror image fish 1 ld de,MASK1 ld hl,MASK1B call revfi ;mirror mask 1 ld de,FISH2 ld hl,FISH2B call revfi ;mirror fish 2 ld de,MASK2 ld hl,MASK2B call revfi ;mirror mask 2 ret savesc:;moves section of screen to store ;hl must contain screen address of top left point ld a,(YSIZE) ld b,a ;b=lines to shift ld de,SCST ;destination address next1:push bc ;store line count ld bc,#50 ;bc=no bytes to shift=80 push hl ;screen address ldir ;one line to store pop hl ;start of line ld bc,#0800 ;space to next line add hl,bc ;start of next line? jr nc,no1 ;yes no adjustment ld bc,#c050 ;adjust for new screen block add hl,bc no1:pop bc ;get line count djnz next1 ;do next line ret setmsk:;create mask by checking fish px by px ;any pixels =ink 0 (bright blue in our pallette) ;are changed to àf and assumed to be background ;all others are changed to 0; assumed to be fish ;hl must address mask to set, de fish to use ld bc,(FILENG) ;fish length next5:ld a,(de) ;byte of fish and #aa ;first pixel jr z,no5 ld (hl),0 ;pixel<>0 jr no6 no5:ld (hl),#aa ;mask pixel set to 15 no6:ld a,(de) ;byte of fish again and #55 ;next pixel jr nz,no7 ;if =0 then nothing to do ld a,#55 or (hl) ;next pixel set to 15 ld (hl),a no7:inc de inc hl dec bc ld a,b or c jr nz,next5 ret revfi:;L-R invert fish or mask from ;destination (hl) to source (de). All bytes are inverted ;left to right and pixels within bytes are swapped ld a,(YSIZE) ld b,a ;no of lines next11:push bc ;linecount ld a,(XSIZE) ld c,a ld b,0 dec c add hl,bc ;hl points at end of line ld b,a next12:ld a,(de) ;byte of fish and #55 ;right pixel of this byte rlca ;turn it into a left pix ld c,a ;store in c ld a,(de) and #aa ;left pixel of this byte rrca ;turn it into a right pix or c ;add 2 pix together ld (hl),a ;put to fish store dec hl inc de djnz next12 ld a,(XSIZE) ld c,a ld b,0 add hl,bc ;point at start of next line inc hl pop bc ;get line count djnz next11 ret disp:;moves fish to title screen ;(ix) points at fish call #bbdb ;clear graphics window-zaps old fish ld hl,80 ;x-coord - middle of screen ld e,(ix+2) ;no of bytes horiz ld d,0 xor a ;resets carry sbc hl,de ;hl=80-horiz push hl ;save x-coord ld hl,85 ;y-coord - middle of window ld e,(ix+3) ;no of lines srl e ;e=e/2 add hl,de ;hl=85-vert/2 pop de ;x-coord back call #bc1d ;get screen address ld d,(ix+1) ld e,(ix) ;de=fish address ld b,(ix+3) ;b=lines to shift ex de,hl ;right way round next2:push bc ;store line count ld b,0 ld c,(ix+2) ;bc=no bytes to shift push de ;screen address ldir ;one line to store pop de ;start of line ld bc,#0800 ;space to next line ex de,hl add hl,bc ;start of next line? jr nc,no2 ;yes no adjustment ld bc,#c050 ;adjust for new screen block add hl,bc no2:ex de,hl pop bc ;get line count djnz next2 ;do next line ret adjust:;adjust a window ;AAS saves windows in whole screen bytes, so the file may ;be either the size of the window, or have a spare pixel ;down left &/or right ends if window started on an odd ;pixel. objective is to get a fish window with a pixel of ;background down left side. bit 0,(ix+4) ;we test whether window ;is an even or odd number of pixels wide jr nz,adjodd bit 2,(ix+5) ;xspare pixels, either 0 or 4 jp z,adjev2 inc (ix+2) ;bump no of bytes/line ;value for file is 1 greater than value of window call blankl ;blanks out left pix call blankr ;blanks out right pix ret adjev2: call addr ;adds a byte of bground to right call mover ;move window right by a pix ret adjodd:;adjust an odd size window bit 2,(ix+5) jp z,adjod2 call blankl ;blank out left pix ret adjod2: call blankr ;blank out right pix call mover ;move right by a pix ret blankl:;turns left hand pixels of ;file to background ld b,(ix+3) ;no of lines ld h,(ix+1) ld l,(ix) ;hl points at fish ld e,(ix+2) ;no of bytes per line ld d,0 next13:ld a,(hl) ;first byte/line and #55 ;resets left pix ld (hl),a add hl,de ;hl=start of next line djnz next13 ret blankr:;turns right hand pixels of ;file to background ld b,(ix+3) ;no of lines ld h,(ix+1) ld l,(ix) ;hl points at fish ld e,(ix+2) ;no of bytes per line ld d,0 add hl,de ;start of next line dec hl ;end of first line next20:ld a,(hl) ;last byte/line and #aa ;resets right pix ld (hl),a add hl,de ;end of next line djnz next20 ret addr:;adds a byte (2 pix) onto ;right hand edge of window xor a ;a=0 ld h,(ix+7) ld l,(ix+6) ;hl=fish length ld d,(ix+1) ld e,(ix) ;de=fish address add hl,de ;hl=start of next fish dec hl ;hl=end of fish ld d,h ld e,l ;de=end of fish ld c,(ix+3) ;no of lines ld b,0 ;bc=no of lines add hl,bc ;hl=new end of fish ex de,hl ;swap push de ;save new eof for later ld b,(ix+3) ;no of lines next19:push bc ;linecount ld c,(ix+2) ;no of bytes ld b,a ;a=0;bc=no of bytes ld (de),a ;last byte of line is blank dec de lddr ;move a line pop bc ;get line count djnz next19 pop iy ;new eof inc iy ;iy=start of next fish inc (ix+2) ;bump no of bytes/line ld h,(ix+7) ld l,(ix+6) ;hl=filelength ld c,(ix+3) ;no of new bytes ld b,0 add hl,bc ;hl=new length ld (ix+7),h ld (ix+6),l ;store ret mover:;moves window right by one ;pixel, blanking out the vacant pix created on left ;window is left same size, so must have a spare pix ;on the right if truncation is not to occur ld b,(ix+3) ;no of lines ld h,(ix+2) ;no of bytes push ix ;save array pointer ld d,(ix+7) ld e,(ix+6) ;de=filelength ld (fudge8+2),ix fudge8:ld ix,(0) ;ix=fileaddress add ix,de ;ix=eof+1 dec ix ;ix=eof next17:push bc ;linecount ld b,h next18:ld a,(ix-1) ;prev byte of fish and #55 ;right pixel of this byte rlca ;turn it into a left pix ld d,a ;store in d ld a,(ix) ;this byte and #aa ;left pixel of this byte rrca ;turn it into a right pix or d ;add 2 pix together ld (ix),a ;put to fish store dec ix djnz next18 and #55 ;last pixel is set to 0 ld (ix+1),a ;put it to screen pop bc ;get line count djnz next17 pop ix ;retrieve array pointer ret cltext:;set and clear text window ld de,0 ;set window -left edge ld hl,639 ;right edge call #bbcf ;set win width ld de,79 ;top edge ld hl,0 ;bottom edge call #bbd2 ;set window height call #bbdb ;gra clear window ret where:;ask user where fish swims ;and then make appropriate arrangements call cltext ;clear text window ld hl,80 ;y coord ld ix,WHERE1 call wrline call wrline call wrline call wrline waitc2:call #bb18 ;wait for a key and #df ;turn lower to upper case cp "T" ;t=top jr nz,n14 ld hl,190 ;top y-value jr n16 n14:cp "M" ;m=middle jr nz,n15 ld hl,120 ;middle y jr n16 n15:cp "B" ;b=bottom jr nz,waitc2 ;anything else, go again ld a,(YSIZE) ;no of lines ld l,8 add a,l ;no of lines+8 ld l,a ld h,0 ;now in hl n16:ld (SWIMY),hl ;store away ;display message only if running on 6128 ld a,(RAM) ;test for extra ram cp 1 ret nz ;no ram call cltext ld hl,80 ld ix,ESC1 call wrline call wrline call wrline call #bb18 ;wait for key ret WHERE1:defm "where do you want the fish to swim?£" WHERE2:defm "T for top of tank£" WHERE3:defm "M for middle of tank£" WHERE4:defm "B for bottom of tank£" SWIMY:defw 0 ;store for y val fish swims at ESC1:defm "when fish is swimming, press£" ESC2:defm "ESC to restart with another fish£" ESC3:defm "press any key to start£" hi2low:;moves a screen from #c000 to #4000 ;switches banked ram first, c must have bank no ld b,#7f out (c),c ld hl,#c000 ld de,#4000 ld bc,#4000 ldir ld bc,#7fc0 ;switch back to main bank out (c),c ret low2hi:;moves a screen from #4000 to #c000 ;switches banked ram first, c must have bank no ld b,#7f out (c),c ld hl,#4000 ld de,#c000 ld bc,#4000 ldir ld bc,#7fc0 ;default bank address out (c),c ret low2lw:;moves a screen from #4000 to ;banked ram at same address via disc buffer ;bank nos must be in FROMBK and TOBK ld b,8 ;do it in 8 lots of 2k ld hl,#4000 ;start address n17:push bc ;save count push hl ;save base address of this section ld b,#7f ld a,(FROMBK) ld c,a ;bc can now switch rambanks out (c),c ld de,BUFFER ;destination address ld bc,#800 ;2k bytes ldir ld b,#7f ;switch ram banks ld a,(TOBK) ld c,a out (c),c ;switch ld hl,BUFFER ;source address pop de ;get back base address ld bc,#800 ;2k ldir ex de,hl ;next base address pop bc ;get back count djnz n17 ld bc,#7fc0 ;always switch back to main bank out (c),c ret FROMBK:defb 0 *l+ TOBK:defb 0