I put some useful subprograms of the monitor here. These subprograms can be used by the assembler command CALL followed by the entry point address.

The contents of the registers shown by "Protected registers" in the following descriptions will remain unchanged by the associated subprogram, while the contents of registers not shown must be saved first if necessary by the use of the assembler command PUSH reg prior to the call of the subprogram and must be restored by the assembler command POP reg when the subprogram terminates.

Entrypoint	$0000
Function	start monitor
Symbolic name	MONIT
Protected registers	none
Description
This is the entry point to the monitor program after resetting the MZ-700 or after switching the power on. Invoking this subroutine will take the same effect like pressing the RESET key: the MZ-700 restarts. Note, the workarea will be cleared and some other functions are performed too. To this see the monitor's source code ( 50KB ). This entry of the monitor program may be used by a CALL instruction but no control will be given back to the caller. There will be no difference between using a CALL instruction or a JP instruction in your program to go to this entry. An example using this entry follows. To modify something in the monitor's code the ROM is to copy to the RAM and then the monitor program is to restart: B000 210000 LD HL,$0000 ;copy from ROM $0000 B003 110012 LD DE,$1200 ;to RAM $1200 B006 010008 LD BC,$0800 ;in the length of $0800 B009 EDB0 LDIR ;do the copy now B00B D3E0 OUT ($E0),A ;bank switch ROM to RAM B00D 210012 LD HL,$1200 ;and copy from RAM $1200 B010 110000 LD DE,$0000 ;to RAM $0000 B013 010008 LD BC,$0800 ;in the length of $0800 B016 EDB0 LDIR ;do copy B018 C30000 JP $0000 ;go to monitor (reset) First the monitor's ROM is to copy into any RAM location. I have chosen the RAM area from $1200 to $19FF. Use another location if needed. The move will be done by the instructions at locations $B000, $B003, $B006, and $B009. When the copy is completed the ROM area must be switched to the RAM area ( done by the instruction at location $B00B ). The contents of the ROM previous copied to the RAM up from location $1200 can be removed now to its executable location up from $0000 but in the RAM ( $B00D, $B010, $B013, and $B016 ). Then the monitor in the RAM will be executed by the instruction at location $B018. The monitor exists now in the RAM, executes in the RAM, and can be modified for own purposes by the command M. This area can be saved every time if needed by the monitor's command L. Follow the previous links for a detailed description of the commands M or L.

Entrypoint	$0003
Function	get line
Symbolic name	GETL
Protected registers	all
Description
This subroutine waits for a keyboard input string up to max. 80 characters in length. The characters typed in will be stored starting up from the memory location specified by the register DE. The register DE must point to an input area of 80 bytes in length and must be established before calling this subroutine. The execution of this routine stops by pressing CR or by pressing SHIFT and BREAK coincidentally. If the CR key is used the string entered will be suffixed by $0D. If no string was entered but the CR key, then the key code of CR ( $0D ) only is placed in the input area addressed by DE. If SHIFT andBREAK were pressed coincidentally then the input area contains the break key code $1B followed by the CR key code $0D, so any program can take effect to this condition. Because all registers are protected / saved by this subroutine no information about the length of the character string that was entered is available on return from this subroutine. If the caller of this subroutine needs the length of the input string all characters must be counted until the key code $0D in the input area will be found. This is done by the following example. Example: B000 1100C5 LD DE,$C500 ;at $C500 is my input area 80 bytes ;in length B003 CD0300 NON: CALL $0003 ;execute monitor's GETL subroutine B006 1A LD A,(DE) ;get 1st character of string if any B007 FE1B CP $1B ;check for break key code B008 CAxxxx JP Z,BREAK ;if break go to the BREAK routine B00B FE0D CP $0D ;check if none input B00D CAxxxx JP Z,NONE ;I don't allow no input, again user B010 0600 LD B,$00 ;init counter of string length B012 FE0D CNT: CP $0D ;end of string? B014 2805 JR Z,STRE ;yes, go to process string. ;B contains length of the string B016 04 INC B ;counter + 1 B017 13 INC DE ;address to next character B018 1A LD A,(DE) ;get it B019 18F7 JR CNT ;check next character B01B STRE: ;at this point I can process the string Subroutine BREAK not shown.

Entrypoint	$0006
Function	2 new lines
Symbolic name	LETNL
Protected registers	all except AF
Description
This subroutine sets the cursor to the first column of the line after the next line ( spaces 1 line ). Example: B000 CD0600 CALL $0006 ;new line B003 C3AD00 JP $00AD ;goback to monitor No more instructions were needed.

Entrypoint	$0009
Function	new line
Symbolic name	NL
Protected registers	all except AF
Description
This subroutine sets the cursor to the first column of the next line. Example: B000 CD0900 CALL $0009 ;new line B003 C3AD00 JP $00AD ;goback to monitor No more instructions were needed.

Entrypoint	$000C
Function	print space
Symbolic name	PRNTS
Protected registers	all except AF
Description
This subroutine prints a space character at the current cursor position. Example: B000 CD0C00 CALL $000C ;print single space character B003 C3AD00 JP $00AD ;goback to monitor No more instructions were needed.

Entrypoint	$000F
Function	print TAB
Symbolic name	PRNTT
Protected registers	all except AF
Description
This subroutine sets the cursor to the next tabulator position depending on the current cursor position. Tabulator positions are the columns 1, 11, 21, and 31. For example, if the current cursor position is 25 then the cursor will be set to column 31. The next output of a print command starts printing at column 31. Example: B000 CD0F00 CALL $000F ;set cursor to next tab position B003 C3AD00 JP $00AD ;goback to monitor No more instructions were needed.

Entrypoint	$0012
Function	print character
Symbolic name	PRNT
Protected registers	all except AF
Description
This subroutine displays at the current cursor position the ASCII character stored in the accumulator register A . The conversion from ASCII code to the display code will be done internally. Additional all cursor control characters will take effect to its associated function. Example: B000 3E16 LD A,$16 ;force clear screen B002 CD1200 CALL $0012 ;print clear screen B005 3E43 LD A,$43 ;load character "B" B007 CD1200 CALL $0012 ;print character B00A C3AD00 JP $00AD ;goback to monitor First the screen will be cleared by the instruction sequence from $B000 to $B002, then the letter "B" will be printed by $B005 and $B007.

Entrypoint	$0015
Function	print message
Symbolic name	MSG
Protected registers	all
Description
This subroutine displays a character string at the current cursor location. The string is contained in a memory area and the start of this area must be pointed to by the register DE . The end of the character string must be indicated by the carriage return control character $0D, but no carriage return will take effect on the screen. Any other cursor control characters $11 - $16 contained in the character string will take effect like pressing its associated key function ( e.g. cursor control keys or clear screen key ). A new line function cannot be invoked by this subroutine. If a new line function is needed the message must be split into two print messages and the new line control function must be invoked between the print functions of the two messages. Example: B000 1100AF LD DE,$AF00 ;pointer to string 1 B003 CD1500 CALL $0015 ;print string 1 B006 CD0900 CALL $0009 ;new line B009 1107AF LD DA,$AF07 ;pointer to string 2 B00C CD1500 CALL $0015 ;print string 2 B00F C3AD00 JP $00AD ;goback to monitor   AF00 16 46 49 52 53 54 0D 53 .FIRST.S AF08 45 43 4F 4E 44 0D xx xx ECOND... The register DE points to an ASCII string to be printed from the memory. The register DE will be established by the instruction at $B000 and the print function will be done by the CALL at location $B003. First, the screen will be cleared by printing the control character $16 contained in the first position of the string. Next, the string "FIRST" at location $AF01 will be printed at the top of the screen. The CR control character at location $AF06 indicates the end of this string and will not be printed but the print function of this string will be terminated by this. A new line will be printed by the CALL at location $B006. The string "SECOND" is addressed by the instruction at $B009 and printed out at this new line by the CALL at location $B00C. The print function ends by the CR at location $AF0D.

Entrypoint	$0018
Function	print message
Symbolic name	MSGX
Protected registers	all
Description
This subroutine displays a character string at the current cursor location. The string is contained in a memory area and the start of this area must be pointed to by the register DE . The end of the character string must be indicated by the carriage return control character $0D, but no carriage return will take effect on the screen. Any other cursor control characters $11 - $16 contained in the character string will be printed as a character ( e.g. cursor down = $11 is displayed as ), no other control character function is performed. Example: B000 1100AF LD DE,$AF00 ;pointer to string B003 CD1800 CALL $0018 ;print string B006 C3AD00 JP $00AD ;goback to monitor   AF00 16 44 45 46 47 48 0D xx .DEFGH.. The register DE points to an ASCII string to be printed from the memory. First, the character $16 will be printed as and no other control key function will be performed. Next, the string "DEFGH" at location $AF01 will be printed at the current cursor position.

Entrypoint	$001B
Function	get key
Symbolic name	GETKY
Protected registers	all except AF
Description
This subroutine scans the keyboard but it doesn't wait for any key input. If no key was active the accumulator register A contains $00 on return to the caller, otherwise the accumulator register A contains the ASCII code of the associated key. The code of an active key neither will be displayed on screen nor any control function ( e.g. clear screen ) will be performed. The control keys return the following codes in the accumulator register A ( additional display code is shown for further information ): Key(s) Contents of the accumulator register A Display code cursor down $11 $C1 cursor up $12 $C2 cursor right $13 $C3 cursor left $14 $C4 home $15 $C5 clear $16 $C6 DEL $60 $C7 INST $61 $C8 ALPHA $62 $C9 GRAPH $63 $CA SHIFT+BREAK $64 $CB CR $66 $CD Example: B000 CD1B00 CALL $001B ;get key B003 C4C303 CALL NZ,$03C3 ;display key code if register A not $00 ;2 digits hexadecimal notation B006 C300B0 JP $B000 ;loop until hard reset The keyboard will be scanned by CALL $001B. The contents of register A will be displayed at the current cursor position and will be shown in a 2-digits hexadecimal notation by a conditional CALL NZ,$03C3. The condition 'no key pressed' is suppressed by this call. That means $00 will not be displayed. Note, this routine loops until the reset key is activated.

Entrypoint	$001E
Function	check control keys BRK / SHIFT / CTRL
Symbolic name	BRKEY
Protected registers	all except AF
Description
This subroutine tests if a control key or a combination of the SHIFT key and the BREAK key is pressed coincidentally but it doesn't wait for any key input. If one or more of the control keys were used the zero flag is set ( Z = 1 ), otherwise it is reset ( Z = 0 ). The following table will help to determine which key(s) is / are pressed: Key(s) Contents of the accumulator register A Carry flag ? Zero flag ? no key $7F no no BREAK $3F no no SHIFT $40 yes no CTRL $20 yes no SHIFT+BRK $00 no yes Example: This example determines which control key was used and invokes the associated routine. B000 CD1E00 CALL $001E ;check break B003 CAxxxx JP Z,BRK ;break condition ; ;SHIFT and BREAK used B006 DA00B1 JP C,OTHER ;SHIFT or BREAK key used B009 FE3F CP $3F ;BREAK key pressed? B00B CAxxxx JP Z,BRK ;yes, break condition 2 allowed B00E ; at this point no control key was pressed B00E ; normal processing follows here.   ; identify which key used, SHIFT or BREAK B100 FE20 OTHER: CP $20 ;CTRL key? B102 CAxxxx JP Z,CTRL ;yes, do CTRL procedure B105 C3xxxx JP SHIFT ;no, do SHIFT procedure Executing the subroutine $001E by a CALL $001E sets the zero flag, the carry flag, and the accumulator register as necessary. The zero flag is set only by pressing the SHIFT and BREAK keys, so this condition is noticed by the command JP Z,BRK. The carry flag is set by pressing the CTRL key or the SHIFT key, further checks to determine which key was used follow by the routine named OTHER. To this, the routine named OTHER is invoked by a single command JP C,OTHER. At least 2 conditions remain: using the BREAK key alone or using no control key. CP $3F checks if the BREAK key was used alone and the following command JP Z,BRK will be executed if this condition is true. The routines BRK, CTRL, and SHIFT are not shown, any coding may follow.

Entrypoint	$0021
Function	write header info
Symbolic name	WRINF
Protected registers	all except AF
Description
This subroutine writes the tape header on tape. The tape header is located at $10F0. All information needed must be written to the tape header prior to the execution of this subroutine. For further information see the structure of the tape header. The user will be prompted to press the RECORD.PLAY button at the data recorder to start the tape if not already done. Then the message "Writing filename" will be shown on the screen. The carry flag is set on return to the caller if the break condition did occur during the execution of this subroutine ( SHIFT+BRK keys pressed ). Please take a note of the description of the tape data processing too. Example: B000 CD2100 CALL $0021 ;write tape header B003 DAxxxx JP C,BREAK ;break condition occurred during write   10F0 01 20 51 44 52 4F 4D 0D . QDROM. 10F8 20 20 20 20 20 20 20 20 1100 20 20 00 08 00 E8 AD 00 ....ü. 1108 00 00 00 00 00 00 00 00 ........ 1110 00 00 00 00 00 00 00 00 ........ 1118 00 00 00 00 00 00 00 00 ........ 1120 00 00 00 00 00 00 00 00 ........ 1128 00 00 00 00 00 00 00 00 ........ 1130 05 01 00 12 43 64 00 00 ....C... 1138 00 00 FF 00 00 06 00 00 ........ 1140 00 06 01 00 05 00 00 EA ........ 1148 10 00 00 00 00 00 00 00 ........ 1150 00 00 00 00 00 00 00 00 ........ 1158 00 00 00 00 00 00 00 00 ........ 1160 00 00 00 00 00 00 00 00 ........ 1168 00 00 00 00 00 00 00 00 ........ The complete information must be stored into the tape header before invoking the routine by CALL $0021. You'll find the information needed to construct the tape header here. To write the data of a file to tape see the next subroutine $0024.

Entrypoint	$0024
Function	write data
Symbolic name	WRDAT
Protected registers	all except AF
Description
This subroutine stores the data to be saved on the tape. The carry flag is set on return to the caller if the break condition did occur while executing this subroutine. Please take a note of the description of the tape data processing too. Example: B000 CD2100 CALL $0021 ;write tape header B003 DAxxxx JP C,BREAK ;break condition occurred during write B006 CD2400 CALL $0024 ;write file data to tape B009 DAxxxx JP C,BREAK ;break condition occurred during write B00C C3AD00 JP $00AD ;goback to monitor Note, the tape header must be written to tape before writing a file by CALL $0024. To this, see the subroutine $0021.

Entrypoint	$0027
Function	read header info
Symbolic name	RDINF
Protected registers	all except AF
Description
This subroutine reads the next tape header found on tape and copies it to the memory beginning at $10F0. Click on the following link for further details about the structure of the tape header. The user will be prompted to press the PLAY button at the data recorder to start the tape if necessary. The following conditions can occur on the return to the caller: Contents of the accumulator register A Contents of the carry flag Meaning $00 0 normal end of process $01 1 read error on tape occurred $02 1 break condition Please take a note of the description of the tape data processing too. Example: B000 CD2700 CALL $0027 ;read tape header B003 B7 OR A ;set flags B004 CAxxxx JP Z,OK ;header read without any problem B007 3D DEC A ;A = A - 1 B008 CAxxxx JP Z,RDERROR ;A = 1 means error during read B00B C3xxxx JP BREAK ;break condition occurred during read Read the tape header prior to the data to get the information needed about the file ( e.g. length of the file, target location in the storage ).

Entrypoint	$002A
Function	read data
Symbolic name	RDDAT
Protected registers	all except AF
Description
This subroutine reads the next data file of a tape. The file will be stored to the storage location as defined by the tape header. To this, see the structure of the tape header. The possible conditions on return to the caller are the same as previously defined at the subroutine $0027. The tape header should be read prior to the execution of this subroutine. Please take a note of the description of the tape data processing too. Example: B000 CD2A00 CALL $002A ;read file B003 B7 OR A ;set flags B004 CAxxxx JP Z,OK ;no error, no break B007 3D DEC A ;A = A - 1 B008 CAxxxx JP Z,RDERROR ;A = 1 means error during read B00B C3xxxx JP BREAK ;break condition occurred during read Read the tape header prior to the data to get the information needed about the file ( e.g. length of the file, target location in the storage ).

Entrypoint	$002D
Function	verify
Symbolic name	VERFY
Protected registers	all except AF
Description
This subroutine verifies the data stored on tape and must immediately subfollow a save process. The possible conditions on return to the caller are the same as previously defined at the subroutine $0027. Please take a note of the description of the tape data processing too. Example: B000 CD2D00 CALL $002D ;read file B003 B7 OR A ;set flags B004 CAxxxx JP Z,OK ;no error, no break B007 3D DEC A ;A = A - 1 B008 CAxxxx JP Z,RDERROR ;A = 1 means verify error B00B C3xxxx JP BREAK ;break condition occurred during read If a verify error occurs the file must be resaved.

Entrypoint	$0030
Function	play melody
Symbolic name	MELDY
Protected registers	all except AF
Description
This subroutine plays a melody defined by a character string pointed to by DE. The character string must be defined like the definitions of the BASIC command MUSIC and must be terminated by $0D or $C8. On return to the caller the carry flag is set to 0 normally. If the execution of the melody subroutine is terminated by BREAK then the carry flag is set at return to caller. See the subroutine $0041 to play the melody by a specified tempo. Valid notes are C, D, E, F, G, A, B, and additional a preceding # to play a seminote is valid, for example, #C, #D, #F, #G, and #A. Code R to rest between notes. A numeric suffix from 0 to 9 is valid and specifies the time of the note / rest to be played. See the following table: Suffix value Meaning 0 1 / 32 note 1 1 / 16 note 2 Dotted 1 / 16 note 3 1 / 8 note 4 Dotted 1 / 8 note 5 1 / 4 note 6 Dotted 1 / 4 note 7 1 / 2 note 8 Dotted 1 / 2 note 9 Whole note A preceding - or + specifies the octave. Code - for the lower octave and + for the upper octave. Nothing specified plays the normal / middle octave. $CF specifies the lower octave too. $D7 specifies the upper octave too. The volume can be controlled only by the volume control ( potentiometer ) at the reverse side of the MZ-700. Try this example: B000 1150B0 LD DE,$B050 ;address to string to be played B003 CD3000 CALL $0030 ;execute music play B006 C3AD00 JP $00AD ;return to monitor and set the area starting from $B050 to the following values by the "M"-command: B050 2B 41 33 2B 23 46 31 2B +A3+#F1+ B058 41 2B 42 33 41 2B 44 2B A+B3A+D+ B060 23 46 31 41 2B 44 33 41 #F1A+D3A B068 2B 44 2B 23 46 31 41 2B +D+#F1A+ B070 44 33 2B 23 46 31 41 2B D3+#F1A+ B078 44 2B 45 2B 23 46 2B 47 D+E+#F+G B080 2B 41 33 52 0D +A3R. Now execute the jump command JB000 and Beethoven's sonata D major ( opus 25 ) should be played, sure, not at all :-) The tempo can be set by $0041. Please refer to the description of the 8253 too ( how to play a melody ).

Entrypoint	$0033
Function	set time
Symbolic name	TIMST
Protected registers	all except AF
Description
This subroutine sets and starts the internal clock. On entrance the register DE must contain the time in seconds. The maximum value accepted is $A8C0 or 43,200 seconds ( 12 hours ). To indicate AM or PM set the accumulator register to a value shown by the following table: Contents of the accumulator register A Meaning $00 AM $01 PM Please take a note of the description of the internal clock too. Example: To set the time to 05:32:12 PM you have to compute this time in seconds. First set the accumulator to the PM value of $01. Compute the hours: 5 x 60 minutes x 60 seconds result into 18,000 seconds. Now you have to compute the minutes. There are 32 minutes x 60 seconds per minute result into 1,920 seconds. Add the remaining 12 seconds and the other two values: 18,000 + 1,920 +12 = 19,932 seconds. At last compute this decimal value into a hex value ( $4DDC ) and load DE with this value: B000 3E01 LD A,$01 ;PM value to the accu B002 11DC4D LD DE,$4DDC ;time value to DE (05:32:12) B005 CD3300 CALL $0033 ;invoke time set subroutine B008 C3AD00 JP $00AD ;goback to monitor The clock is set now and works. If you have to convert other values use my calculator written in Java ( activate JavaScript and Java applets of your browser ).

Entrypoint	$0038
Function	interrupt routine
Symbolic name	none
Protected registers	all
Description
This subroutine invokes the interrupt routine as pointed to by the location $1038. During the startup of the monitor this storage location was initiated with $C38D03. The translated mnemonic to this is: JMP $038D. The subroutine starting at $038D toggles the AM / PM value for the internal clock and reinitiates the clock to 12:00h. The toggled AM / PM-value is located at $119B. Changing the address of the jump command at location $1038 enables you to write your own interrupt routine located anywhere in the memory. Set the timer to any value needed. For example, you can write a program that will take effect to any self programmed function key F1 - F10. To this, the timer must be set to an acceptable value. This means, if you store a low value into the timer the function key will be processed quick but then there may be a high rate of interrupts and by this your system processing time slows down. If the rate of interrupts is reduced by a higher timer value then it may be the time a function key will be noticed is too slow. Tuning must be done to get an acceptable timer value between system processing time and the time when a function key stroke will be noticed. May be some time critical subroutines ( e.g. write / read tape and so on ) may not function correct. Please take a note of the description of the time interrupt too.

Entrypoint	$003B
Function	read time
Symbolic name	TIMRD
Protected registers	all except AF and DE
Description
This subroutine reads the internal clock. On exit the register DE contains the time in seconds. The maximum value returned can be $A8C0 or 43,200 seconds ( 12 hours ). The monitor subroutine indicates AM or PM by the accumulator register A and to this it contains one of the values shown by the following table: Contents of the accumulator register A Meaning $00 AM $01 PM Please take a note of the description of the internal clock too. Example: The returned value contained in the register DE must be computed from seconds into hours, minutes, and seconds. To this you can use my calculator written in Java ( activate JavaScript and Java applets of your browser ). You can download an example ( 7KB ) that displays the current time. The clock counts from 00:00:00 to 23:59:59. The ZIP-file to download contains the source code for this routine, an assembler output listing, and an executable MZF-formatted file. The source is completely documented by my comments for each instruction sequence. The clock will not be set by my program. Maybe, you'll program an input routine that prompts the user for the time to be set and that computes the time to seconds before setting the time by a CALL $0033. ;) Then combine both programs and... don't forget to post me your result ;-)

Entrypoint	$003E
Function	activate bell
Symbolic name	BELL
Protected registers	all except AF
Description
Performing this subroutine a beep tone ( upper octave note A 1 / 32 note = +A0, 880 Hz ) will come over the loudspeaker. Please take a note of the description of the sound functions too. Example: B000 CD3E00 CALL $003E ;beep B003 C3AD00 JP $00AD ;goback to monitor No more instructions were needed.

Entrypoint	$0041
Function	set tempo
Symbolic name	XTEMP
Protected registers	all except AF
Description
This subroutine sets the tempo ( speed ) to play music by the subroutine $0030. The accumulator register must be established by the appropriate value: Contents of the accumulator register A Meaning $01 slow ( Lento, Adagio ) $04 medium ( Moderato ) $07 quick ( Molto Allegro, Presto ) Please take a note of the description of the sound functions too. Example: B000 3E07 LD A,$07 ;presto B002 CD4100 CALL $0041 ;set tempo B005 1150B0 LD DE,$B050 ;address to string to be played B008 CD3000 CALL $0030 ;play melody B00B C3AD00 JP $00AD ;goback to monitor   B050 2B 41 33 2B 23 46 31 2B +A3+#F1+ B058 41 2B 42 33 41 2B 44 2B A+B3A+D+ B060 23 46 31 41 2B 44 33 41 #F1A+D3A B068 2B 44 2B 23 46 31 41 2B +D+#F1A+ B070 44 33 2B 23 46 31 41 2B D3+#F1A+ B078 44 2B 45 2B 23 46 2B 47 D+E+#F+G B080 2B 41 33 52 0D +A3R. Please take a kindly note of the description of the subroutine $0030 too.

Entrypoint	$0044
Function	start a continuous audible tone
Symbolic name	MSTA
Protected registers	BC and DE
Description
This subroutine starts a continuos tone which is audible by the loudspeaker. The frequency of the tone is computed by: f = 1108.8 kHz / nn' nn' is a 2 bytes hex value to be stored into the storage at locations $11A1 and $11A2. n is the high order byte and must be stored into location $11A2 and n' is the low order byte and must be stored into location $11A1. The value of 1108.8 kHz = 1.1088 MHz ( kilo-Hertz, kilocycles; Mega-Hertz, Mega cycles ) can vary by your MZ-700. I measured a value of 1.108372 MHz of my MZ-731 with a frequency counter. Note, your program must stop the tone by the following subroutine $0047 or by your own subroutine before your program invokes the next tone otherwise an unpredictable frequency value is invoked. Please take a note of the description of the sound functions too. Example: A continuos tone of 100 Hz is to invoke. For computations and conversions use my calculator written in Java ( activate JavaScript and Java applets of your browser ). nn' = 1108.8 kHz / f ( f = 100 Hz ) nn' = 1108.8 * 103 Hz / 100 Hz = 11,088 11.088 is to convert into hex, that is $2B50 and this value is to load into $11A1 / $11A2. B000 21502B LD HL,$2B50 ;load counter value B003 22A111 LD ($11A1),HL ;into memory B006 CD4400 CALL $0044 ;start tone of 100 Hz B009 C3AD00 JP $00AD ;goback to monitor At this point a tone of 100 Hz is audible. To stop the tone use the subroutine $0047.

Entrypoint	$0047
Function	stop audible tone
Symbolic name	MSTP
Protected registers	all except AF
Description
This subroutine stops the tone started by $0044. Please take a note of the description of the sound functions too. Example: B000 CD4700 CALL $0047 ;stop the tone B003 C3AD00 JP $00AD ;goback to monitor At this point no tone is audible.

Entrypoint	$004A
Function	start the monitor
Symbolic name	START
Protected registers	none
Description
This is the entrypoint of the monitor. Transferring control to this location takes the same effect like executing the subroutine $0000. See the description of the subroutine $0000.

Entrypoint	$00AD
Function	warm start of the monitor
Symbolic name	ST1
Protected registers	none
Description
This is the warm start address of the monitor. If your own subroutine terminates and transfers back the control to the monitor by a assembler JP $00AD command then you should set the stack pointer to $10F0 prior to the termination of your subroutine. Example: C530 31F010 LD SP,$10F0 ;set up stack pointer C533 c3AD00 JP $00AD ;goback to monitor The stack pointer is set to the top of its stack and then the control is transferred to the warm start entry of the monitor.

Entrypoint	$018F
Function	plot character
Symbolic name	LPRNT
Protected registers	DE and HL
Description
This subroutine plots the ASCII-character contained in the accumulator register A. .Example: B000 3E41 LD A,$41 ;char "A" to accu B002 CD8F01 CALL $018F ;plot char B005 C3AD00 JP $00AD ;goback to monitor The letter "A" is loaded into the accu A and then plotted by $018F.

Entrypoint	$01A5
Function	plot character string
Symbolic name	PMSG
Protected registers	all
Description
This subroutine plots an ASCII character string which is stored in the memory. The register DE must point to the string on entry to $01A5. The character string must be terminated by $0D. Example: B000 1124C1 LD DE,$C124 ;address to char string B002 CDA501 CALL $01A5 ;plot char string B005 C3AD00 JP $00AD ;goback to monitor   C124 41 42 43 44 0D xx xx xx ABCD..... The address of the string ABCD is $C124 and loaded into DE. Then the string is plotted by $01A5.

Entrypoint	$01C7
Function	play melody
Symbolic name	?MELDY
Protected registers	all except AF
Description
This subroutine is referenced by the vector $0030. Please follow the previous link for a detailed description.

Entrypoint	$02A6
Function	DE = DE + 4
Symbolic name	.4DE
Protected registers	all except DE
Description
This subroutine increments the register DE 4 times. Example: B000 CDA602 CALL $02A6 ;adds 4 to DE No more instructions were needed. On return from $02A6 the register DE is incremented four times, that means DE = DE + 4.

Entrypoint	$02AB
Function	start the melody
Symbolic name	MLDST
Protected registers	BC and DE
Description
This subprogram is referenced by the vector MSTA at $0044. Please follow the previous link for a detailed description. Please take a note of the description of the sound functions too.

Entrypoint	$02BE
Function	stop the melody
Symbolic name	MLDSP
Protected registers	all except AF
Description
This subprogram is referenced by the vector MSTP at $0047. Please follow the previous link for a detailed description. Please take a note of the description of the sound functions too.

Entrypoint	$02C8
Function	controls tempo and time periods
Symbolic name	RYTHM
Protected registers	C ( B is used ), DE
Description
RYTHM is used to control the tempo a melody is to be played and to control the time periods for a note / rest. This routine is used by the routine MELDY / ?MLDY which plays a melody. Follow one or both of the previous links for a detailed description. Please take a note of the description of the sound functions too.

Entrypoint	$02E5
Function	set tempo
Symbolic name	?TEMP
Protected registers	all except AF
Description
?TEMP sets the tempo of a melody to be played. This subprogram is referenced by the vector $0041 and is described in detail there. Please take a note of the description of the sound functions too.

Entrypoint	$030B
Function	set time
Symbolic name	?TMST
Protected registers	all except AF
Description
?TMST sets the time. This subprogram is referenced by the vector $0033 and is described in detail there. Please take a note of the description of the internal clock too.

Entrypoint	$0352
Function	bell data
Symbolic name	?BELD
Protected registers	No machine instruction code.
Description
This is a data area used by the BELL subroutine. 0352 D7 41 30 0D xx xx xx xx .A0..... $D7 defines the upper octave for the note A ( $41 ) and the note A will be played by a rest of 0 ( $30 ). See the description of the BELL routine for more details.

Entrypoint	$0358
Function	read time
Symbolic name	?TMRD
Protected registers	all except AF, DE
Description
?TMRD reads the internal clock. This subprogram is referenced by the vector $003B and is described in detail there. Please take a note of the description of the internal clock too.

Entrypoint	$038D
Function	time interrupt routine
Symbolic name	TIMIN
Protected registers	all
Description
This subroutine invokes the interrupt routine as defined at the location $1038. See the description of $0038 for more details. Please take a note of the complete description of the time interrupt too.

Entrypoint	$03B1
Function	display space and a byte converted into 2 display characters.
Symbolic name	SPHEX
Protected registers	all except AF
Description
This subroutine prints a space at the current cursor position. Additional one byte pointed to by HL will be converted into its 2-digits hexadecimal display codes which are then displayed on the screen. This means, the upper four bits of the byte will be converted first into a display character in the range from 0 to 9 ( display code $20 - $29 ) and from A to F ( display code $01 - $06 ). The result is put into the video RAM at the current cursor location and by this it becomes visible. Next the lower four bits are converted and displayed next ( same ranges, of course ). You can use this routine to display any byte from the memory in hexadecimal notation separated by a single space character. Example: B000 2135A0 LD HL,$A035 ;points to char B003 CDB103 CALL $03B1 ;print space & char in hex B006 C3AD00 JP $00AD ;goback to monitor A035 A1 xx xx xx xx xx xx a....... First, a space will be printed at the current cursor position. Next, the byte at location $A035 will be displayed on the screen in display code notation and split into 2 display codes, i.e. "A1" is displayed. The display code is $01 $21 which is put into the character part of the video RAM at the current cursor position becomes visible as "A1" preceded by a single space.

Entrypoint	$03BA
Function	display contents of the register HL in a 4-digits hex notation.
Symbolic name	PRTHL
Protected registers	all except AF
Description
This subroutine displays the contents of HL in a 4-digit hexadecimal notation. To this the upper 4 bits of register H are converted into a displayable hexadecimal digit in the range from 0 to 9 ( display code $20 - $29 ) or A to F ( display code $01 - $06 ). It will be put into the character video RAM at the current cursor position and by this it becomes visible. Next, the lower four bits of register H will be converted and displayed by the same procedure as described. At last the contents of the register L will be displayed by the same procedure as used for the register H. On exit of this subroutine 4 characters in hexadecimal notation are displayed on the screen which represent the contents of the register HL in hexadecimal notation. The high order half of the register HL, this is the register H, is displayed first and next the register L. You can use this routine to display the contents of the register HL in hexadecimal notation. To get the contents of another register or if you want to display an address located in the memories load it into the register HL before executing this subroutine. Example: B000 2A35A0 LD HL,($A035) ;load memory contents of $A035 B003 CDB103 CALL $03BA ;print "35A1" B006 C3AD00 JP $00AD ;goback to monitor A035 A1 35 xx xx xx xx xx a!...... Two bytes from the location $A035 are split into 4 display codes The display code is $23 $25 $01 $21 which is put into the video RAM at the current cursor position and by this it becomes visible as 35A1.

Entrypoint	$03C3
Function	display contents of the accumulator register A in 2-digits hex notation..
Symbolic name	PRTHX
Protected registers	all except AF
Description
The contents of the register A will be converted into its 2-digits hexadecimal display codes which are displayed on the screen. This means, the upper four bits of register A will be converted first and the result of the conversion is a display character in the range from 0 to 9 ( display code $20 - $29 ) and from A to F ( display code $01 - $06 ) which will be displayed. Next the lower four bits are converted and displayed ( same ranges, of course ). You can use this subroutine to display the contents of the accumulator register A in hexadecimal notation. You can use this subroutine too to display the contents of any byte located in the memory if you load it into the accumulator register A prior to the execution of this subroutine. If you load another register half into the accumulator register A it will be displayed too as described above. Example: B000 7B LD A,E ;load register E into accumulator A B001 CDB103 CALL $03C3 ;print contents of accu (same as register E) B004 C3AD00 JP $00AD ;goback to monitor The contents of register E is to display in 2-digits hexadecimal notation. To this, first the contents of the register E is loaded into the accumulator register A ( $B000 ). The contents of the accumulator register A is split into 2 display codes. The display codes will be put into the character part of the video RAM at the current cursor position and by this it becomes visible ( all done by the CALL $03B1 at $B001 ).

Entrypoint	$03DA
Function	display contents of the 4 lower bits of the accumulator register A in hex notation.
Symbolic name	ASC
Protected registers	all except AF
Description
This subroutine converts the four lower bits of the accumulator register A into its associated ASCII character. The accumulator register contains this value on return to the caller. Example: B000 3E0E LD A,$0E ;load char to convert B002 CDDA03 CALL $03DA ;convert $0E to $45 B005 CD1200 CALL $0012 ;print ASCII "E" ($45) B008 C3AD00 JP $00AD ;goback to monitor The four lower bits of the accu ( 1110 of 0000 1110 ) are converted to the ASCII-character $45 by the CALL $003DA and stored back into the accu. By this the upper four bits of the accu are lost. The following CALL $0012 will print the contents of the accu as "E" at the current cursor position.

Entrypoint	$03F9
Function	puts the ASCII hex value contained in the accu into the 4 lower bits of the accumulator register.
Symbolic name	HEX
Protected registers	all except AF
Description
This subroutine converts an ASCII hexadecimal number contained in the accu A into a 4-digit binary value. The result of the conversion is stored back into the four lower bits of the accu A. The four upper bits of the accu A are set to zero. If the accu A contains a non-hex character on entry to $03F9 the carry flag is set. In this case no conversion can be done and the returned value of the accu A is invalid. Example: B000 3E45 LD A,$45 ;load char to convert B002 CDF903 CALL $03F9 ;convert $45 to $0E B005 DAxxxx JP C,NOHEX ;no hex char in accu B008 CDC303 CALL $03C3 ;print ASCII $30 $45 (ASCII 0E) B00B C3AD00 JP $00AD ;goback to monitor The ASCII-character $45 is converted into $E by the CALL $003F9 and stored back into the four lower bits of the accu A. The upper four bits of the accu are set to zero. The following CALL $03C3 will print the contents of the accu as "0E" at the current cursor position.

Entrypoint	$0410
Function	puts an 4-digits ASCII hex value into HL.
Symbolic name	HLHEX
Protected registers	BC, DE
Description
This subroutine stores 4 ASCII characters representing 4 hex digits into HL. On entry to this subroutine the register DE must point to the memory location of the 4 ASCII characters. Valid ASCII characters are 0 - 9 ( $30 - $39 ), and A - F ( $41 - $46 ), otherwise the carry flag will be set on return to the caller. Example: B000 1120B0 LD DE,$B020 ;load address of string B003 CD1004 CALL $0410 ;convert $41314539 to $A1E9 ;and store to HL B006 DAxxxx JP C,NOHEX ;invalid char found in string B009 C3AD00 JP $00AD ;goback to monitor   B020 41 31 45 39 xx xx xx xx A1E9.... The ASCII string pointed to by DE will be converted into a 4-digits hex value and this 16 bits binary value will be stored into HL. The first 2 ASCII characters are converted and stored into H, the last 2 ASCII characters are converted and stored into L.

Entrypoint	$041F
Function	puts an 2-digits ASCII hex value into the accu A.
Symbolic name	2HEX
Protected registers	all except AF
Description
This subroutine stores two ASCII characters representing two hex digits into the accu A. On entry to this subroutine the register DE must point to the memory location of the two ASCII characters. Valid ASCII characters are 0 - 9 ( $30 - $39 ), and A - F ( $41 - $46 ), otherwise the carry flag will be set on return to the caller. Example: B000 1120B0 LD DE,$B020 ;load address of string B003 CD1F04 CALL $041F ;convert $4131 to $A1 ;and store to accu B006 DAxxxx JP C,NOHEX ;invalid char found in string B009 C3AD00 JP $00AD ;goback to monitor   B020 41 31 xx xx xx xx xx xx A1...... The ASCII string pointed to by DE will be converted into a 2-digits hex value and this 8 bits binary value will be stored into the accu A. The first ASCII character is converted and stored into the upper 4 bits, the last ASCII character is converted and stored into the lower 4 bits.

Entrypoint	$0577
Function	activate bell.
Symbolic name	?BEL
Protected registers	all except AF
Description
A beep tone ( upper octave note A 1 / 32 note = +A0, 880 Hz ) will come over the loudspeaker performing this subroutine. This subroutine is referenced by the vector $003E. Click on the previous link for more information. Please take a note of the description of the sound functions too.

Entrypoint	$09B3
Function	waits until a key is pressed.
Symbolic name	??KEY
Protected registers	all except AF
Description
This subroutine waits until any key is pressed. On return to caller the accumulator register contains the display code of the key pressed. To see the display code for the control keys click here. Example: B000 CDB309 CALL $09B3 ;wait on key B003 CD4A09 CALL $094A ;print B006 C300B0 JP $B000 ;loop until reset CALL $09B§ waits on a key input and the next CALL to $094A will print its associated value at the current cursor position. Note, this example loops until hard reset.

Entrypoint	$0BB9
Function	ASCII code to display code conversion.
Symbolic name	?ADCN
Protected registers	all except AF
Description
This subroutine translates the MZ-700 ASCII code to the display code. Put the ASCII code into the accumulator register and call this subroutine. On return to the caller the accumulator register contains the display code, but it will not be displayed by this. Example: B000 3E45 LD A,$45 ;load ASCII "E" B002 CDB90B CALL $0BB9 ;convert to display code $05 B005 CD4A09 CALL $094A ;print B008 C3AD00 JP $00AD ;goback to monitor The ASCII character "E" will be converted into its display code $01 by the instruction sequence $B000 - B002. The next CALL $094A will display it on screen.

Entrypoint	$0BCE
Function	ASCII code to display code conversion.
Symbolic name	?DACN
Protected registers	all except AF
Description
This subroutine translates the display code to the MZ-700 ASCII code Put the display code into the accumulator register and call this subroutine. On return to the caller the accumulator register contains the ASCII code, but it will not be displayed by this. Example: B000 3E01 LD A,$01 ;load display code $01 B002 CDCE0B CALL $0BCE ;convert to ASCII code $41 B005 CD1200 CALL $0012 ;print B008 C3AD00 JP $00AD ;goback to monitor The display code $01 will be converted into its ASCII code $41 ( character "A" ) by the instruction sequence $B000 - B002. The next CALL $094A will display it on screen.

Entrypoint	$0DA6
Function	wait on VBLK
Symbolic name	?BLNK
Protected registers	all
Description
This subroutine waits on the start of a vertical blanking signal ( VBLK ). This will be when writing of a new line of the screen begins. This subroutine may be useful for programming an application using joysticks. Example: B000 CDA60D CALL $0DA6 ;wait on VBLK On return to the caller the signal VBLK is active.

Entrypoint	$0DDC
Function	screen control
Symbolic name	?DPCT
Protected registers	all
Description
Load the following value into the accumulator register prior to the call of this subroutine and the screen will be controlled by the control characters as defined in the following table: Contents of the accumulator register A Function $C0 scroll up $C1 scroll up $C2 scroll down $C3 cursor right $C4 cursor left $C5 home $C6 clear $C7 DEL $C8 INST $C9 ALPHA $CA GRAPH $CD CR Example: B000 3EC6 LD A,$C6 ;load char for clear B002 CDDC0D CALL $0DDC ;clear screen B005 C3AD00 JP $00AD ;goback to monitor The screen will be cleared while processing the control character $C6 by $0DDC.

Entrypoint	$0FB1
Function	puts address of cursor position into HL
Symbolic name	?PONT
Protected registers	BC, DE
Description
On return to the caller the register HL contains the address of the current cursor position in the character RAM starting at location $D000. You can add $800 to HL to get the current color information byte associated to this character. Example: B000 CDB10F CALL $0FB1 ;get address of cursor in char VRAM B003 ; address of cursor now available in register HL. ; you can set bit 3 of register H to point to color VRAM ; by SET 3,H and back by RES 3,H No more instructions were needed.