ACU March 1985 - Type-ins

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Cover Image

Boolean operations demonstration

RUN"BOOLEAN"

Electric Eddy

RUN"EDDY"

Electric Fencing

RUN"FENCING"

Flashman

RUN"FLASHMAN"

Jeremy Vine's music routine

RUN"MUSIC"

Machine code fill routine and demonstration

RUN"MCFILL"

Manipulating the Amstrad CPC464 Screen Display

SCREEN1.ASM, SCREEN2.ASM, SCREEN3.ASM, SCREEN4.ASM, SCREEN5.ASM contain the Z80 assembler code for the "Manipulating the Amstrad CPC464 Screen Display" article.
See Amstrad Computer User, March 1985, page 103 for more details.

Number Sort routine

RUN"SORT"

Prime Numbers (1)

RUN"PASCAL3"

Prime Numbers (2)

RUN"PASCAL4"

Screen Dump (DMP1)

DMPDMP1.ASM contains the Z80 assembler code for the "Events & Screen Dumps" article.
DMPLIST2.BAS and DMPLIST4.BAS contain the related BASIC code.
See Amstrad Computer User, March 1985, page 90 for more details.

Screen Dump (Epson)

DMPEPSON.ASM contains the Z80 assembler code for the "Events & Screen Dumps" article.
DMPLIST2.BAS and DMPLIST4.BAS contain the related BASIC code.
See Amstrad Computer User, March 1985, page 90 for more details.

Sum Numbers

RUN"PASCAL5"

Trench

RUN"TRENCH"

Unerase

The Z80 assembler code for David Link's Unerase program.
See Amstrad Computer User, March 1985, page 40 for more details.

						; Unerase a file in CP/M - 04/11/84
						; Copyright David Link 1984

						; A program to unerase a file that has been accidentally
						; erased. Should be used immediately after erasing the
						; file since if user later, some blocks may have been re-used.

						; Format is - UNERA filename

DEFCB		EQU	&5C

fnamelen	EQU	8
extlen		EQU	3
extent		EQU	12
dirlen		EQU	32

						; CP/M BDOS call numbers

OPEN		EQU	15
CLOSE		EQU	16
SEARCH		EQU	17
SRCH_AGAIN	EQU	18
MAKE		EQU	22
SETDMA		EQU	26

						; Default workspace for file reads

tbuff		EQU	128

						; Macro to call CP/M setting DE and C

DOS		MAC
		LD	DE,=0
		LD	C,=1
		CALL	Dos
		ENDM

						; Macro to call CP/M setting C.

SDOS		MAC
		LD	C,=0
		CALL	Dos
		ENDM

						; COM files begin at &100

		ORG	&100

		LD	SP,(6)			; set stack to top of TPA
		DOS	DEFCB,SEARCH		; Does file exist?
		INC	A
		JP	NZ,0			; File exists, return to CCP
		LD	HL,FCBSPACE		; Initialise pointer to current FCB
		LD	(FCBPTR),HL
		DOS	tbuff,SETDMA		; set disc I/O to tbuff
		DOS	DUMFCB,SEARCH		; and search for the first entry in directory

More_Search	INC	A
		JR	Z,End_of_Directory	; No more entries

						; Compare found filename with the required filename

Continue	DEC	A			; adjust because we INCed it
		ADD	A,A			; multiply by dirlen to get postion
		ADD	A,A			; of entry in catalogue
		ADD	A,A
		ADD	A,A
		ADD	A,A
		LD	D,0
		LD	E,A
		LD	HL,tbuff		; point to found file
		ADD	HL,DE

Again		PUSH	HL			; and compare it with required filename
		INC	HL
		LD	B,fnamelen+extlen	; both name and type (8, name : 3, type)
		LD 	DE,DEFCB+1		; filename starts at FCB + 1

Match		LD	A,(DE)
		LD	C,(HL)
		RES	7,C			; some CP/Ms set bits on filename
		CP	C			; so make sure top bit is reset for comparison
		INC	HL
		INC	DE
		JR	NZ,NoMatch		; not this one
		DJNZ	Match			; good so far... keep going

						; Match found

		POP	HL			; filename match, but...
		PUSH	HL
		LD	A,(HL)			; ... is it erased?
		CP	&E5			; e% in first byte of directory = erased
		JR	NZ,NoMatch		; not erased... so search some more
		LD	(HL),0			; it was erased, so unerase it
		LD	DE,(FCBPTR)		; and store the FCB information in
		LD 	BC,dirlen		; our temporary table
		LDIR
		LD	(FCBPTR),DE		; updating our table pointer afterwards

						; Search for another entry

NoMatch		POP	HL
		DOS	DUMFCB,SRCH_AGAIN	; search for next entry in directory
		JR	More_Search

						; we have now exhausted the directory search and built
						; up our table of directory entries for the required file

End_of_Dir	LD	DE,FCBSPACE		; start processing table of matched
						; directory entries
MAIN_LOOP	LD	HL,(FCBPTR)		; have we reached end of table?
		OR	A
		SBC	HL,DE
		JP	Z,0			; finished, so return
		PUSH	DE			; save table pointer
		LD	HL,extent		; address extent byte
		ADD	HL,DE
		LD	A,(HL)			; make an extent of new,
		LD	(DEFCB+extent),a	; unerased file...
		DOS	DEFCB,MAKE
		POP	DE			; recover pointer to FCB...
		SDOS	CLOSE			; and close it
		LD	HL,dirlen
		ADD	HL,DE			; have we reached end of table?
		EX	DE,HL
		JR	MAIN_LOOP

Dos		PUSH	HL
		PUSH	DE
		PUSH	BC
		CALL	5
		POP	BC
		POP	DE
		POP	HL
		RET

FCBPTR		DEFS	2

DUMFCB		DEFM	"????????????"
		DEFW	0,0
		DEFS	16
		DEFW	0,0

FCBSPACE	EQU	$