All ZXVGS functions are called by RST #08 with number of function placed in following byte (hook code) and the program is continued from address next to hook code.
RST #08 DEFB funcion
On the next tables, in the columns titled input are registers that contain arguments of the function. In the columns titled output are registers in which the function returns its values - other ones are not changed. AF is ignored on input and returned F is not defined. In some situations a function can set bit 7 in R register what means one or more frame INT is missed.
|errors||#00||BASIC interpreter errors|
|errors, I1||#10||BASIC interpreter errors||Interface 1 hook codes|
|I1||#20||Interface 1 hook codes|
|I1, DISCiPLE||#30||I1 h.c.||DISCiPLE command codes|
|DISCiPLE||#40||DISCiPLE command codes|
|internal||#70||used internally by RSXes||#7F|
|screen output||#90||scrreen support - not used yet||#9F|
|disks||#C0||current path||directories||disk informations||file managing|
|files||#D0||direct file access|
|data||#E0||handling files with headers||images||savegames||raw data||fileselectors|
Code #7F is reserved for internal system code. It is used to call the ZXROM from inside of the system.
Note. Calls of #80..#83 functions can be interrupted by user. To prevent from quiting program without saving user work, use function #A3 (will be available in next releases).
It is possible to use 4 independent joysticks. Usually first two are used. The meaning of bits 0..4 is compatibile with value readed from Kempston port (#1F, b0=right, b1=left, b2=down, b3=up, b4=fire). Bit 5 is second fire (usually not used). Bits 6 and 7 are common to all joysticks means two more buttons. Bit 6 (HALT) should cause pause in game (when set) or activate options. Bit 7 (EXIT) should stop the game or go to main menu.
|#80||J0||read joysick 0||none||A=state|
|#81||J1||read joysick 1|
|#82||J2||read joysick 2|
|#83||J3||read joysick 3|
You can use external mouse (serviced outside main program), also one that generates interrups. Calculating absolute coordinates, painting of pointer and events detection belong to your program duties. To use mouse in any program follow these points.
NOP NOP NOP JP ownintThe "ownint" is address of standard frame interrupt service. If you don't need own frame interrupt service, you can place
EI: RETIinstead of this jump.
NOPs. Also will change interrupt table if neccesary.
For old programs it is adviced to place
XOR A:RET at the
beginning of the buffer to avoid program crash while call before mouse
The coordinates will be changed at given addresses. They are 8 bit values, you can only read them and compare to former value to determine changes. To check buttons just call the beginning of the buffer. It will return button status in A, preserving other registers (b0=LMB, b7=RMB; set means pressed).
Please note that some kinds of mouse (RS232, AMX) can generate own
interrupts that aren't useful for the program. All the non-frame interrupts
are "eaten" (return address is
POPed). And if return
address points to byte after
HALT opcode, it will be
decremented to continue
HALT til frame interrupt.
Mouse can be deactivated by giving 0 as buffer address (in HL). Values returned in this case are useful for RSXes - they can uninstall driver used by main program, install own driver to operate an requester, then uninstall own driver and install back the driver of main program.
|ask about mouse||HL=???||A=result|
|#85||MSEGET||get status - only for internal use (driver)||none||A=keys|
Function #87 switches the CPU into high speed mode. The extra speed isn't defined - just the program works faster.
Function #88 switches the CPU back to 3.5MHz.
|#87||FAST||(Scorpion) - switches Z80 clock up||none||A=result|
|#88||SLOW||(Scorpion) - switches Z80 clock to 3.5MHz|
Extended keyboard should be used to enter text in some programs. Allows use of some additional keys (emulators, SAM Coupé, ZX128 keypad).
Will be used in BASIC if patches or INT traps are available.
Call of function #8F??? should be placed in IM 2 service, at least after pushing AF. Or with disabled interrupts should be called about 50 times per second.
Do not use!!! This isn't finished!!!
|#8C?||KBDGET||get char from buffer||()(A)|
|#8D?||KBDTST||read char from buffer and leave it||()(A)|
Functions #90..#9F are designed to generate menu, move mouse pointer and display texts in 42, 51 or 64 colums. Also on additional screen modes.
Function #9F prints character on standard screeen using 64 columns mode. Put row in D, column in E, and the character in C. B should be 0 for future compatibility (will select character set for characters 128..255).
They are not available in present ZXVGS release!
|#9E?||CHOICE||ask user what to do||HL=^title|
|#9F||CHOUT||print character in 64 columns mode||D=row|
Functions #A2 and #A3 are to control hardware dependent functions. They should not be used in applications (including reading the release number), except config dedicated ones. In D is number of function being configured or #A2 for release number reading. Function #A2 returns current setting in E while the release number in AE. Function #A3 changes setting and returns effective setting (old one when no change were made, new one when change is accepted). Both function return A=0 when getting or setting configuration passed correctly (except for release number reading).
|changes||value in D||value in E||means|
|5||SAM Coupé arrows and <CNTRL>|
|6||SAM Coupé function keys|
|8||TC2068 left (AY #F5, #F6)|
|9||TC2068 right (AY #F5, #F6)|
|Mouse hardware type.|
The change fails if mouse
driver is in active mode.
|5||AY mouse (from Ukraine)|
|8||M$ Mouse in YAMOD.8250/0|
|9||M$ Mouse in YAMOD.8250/1|
|10||M$ Mouse in YAMOD.8250/2|
|11||M$ Mouse in YAMOD.8250/3|
|Release number.||#A2||AE - four BCD digits (read only)|
|Sound info binary mask.||#A4||binary mask||set bit means "off"|
|Printer output type.||#F7||not defined yet|
|#A2||GETCFG||get current setting of some functions||D=function||A=error|
|get ZXVGS release number||D=#A2||AE=release|
|#A3||SETCFG||change parametes of some functions||D=function|
Function #A4 provides information about available sound interfaces. Bit 0 coresponds with beeper in port #FE, bit 1 - BEEPER procedure in ZXROM. Reseted bit means don't generate sound this way (the user don't want to hear such effect). Set bit 2 means the AY-3-8910/2 in ports #BFFD i #FFFD (also #BEFD and #FEFD for some wrong written players) is opened, set bit 3 - the SAA 1099 (SAM Coupé) in ports #00FF i #01FF is opened. When bit of these two isn't set, you mustn't use these ports! It can crash the computer!
When this function is called without prior call of #A5 function (after #AF), it allocates all possible sound devices (near back compatibility, will be removed).
Function #A5 can be used to allocate and deallocate sound device. The device number is provided in D and some parameters in E. (Asterisk "*" means the device has fixed port addresses.) They are:
|register D||device||register E|
|#01*||AY-3-891X (ZX128)||channels (like register 7)|
|#02*||AY-3-8912 (TC2068)||channels (like register 7)|
|#03*||both above (1 & 2)||channels (like register 7)|
|#04*||SAA1099 (SAM)||channels (like register 14 & 15; b6,b7 select)|
|#08||8255 D/A (MB-02)||channels b0..b3|
|#A5||OPENSOUND||allocate sound device||D=device|
Function #A6 retuns ULA type in D, current screen mode in E and current frame length in BC.
Function #A7 opens video mode. When the frame length is not important, set BC=#0000 and D=#FF. When BC>#0000 or D is different from #FF, ZXVGS will try to change ULA properties (what is possible on emulators and dedicated hardware). Value in D has higher priority than BC (however this is another way to swith the ZS Scorpion into fast mode).
Functions #E8, #E9, #F3 use the screenmode value to load, save or print the screen.
BC - frame length between interrupts in Z80 tacts, measured in IM2, both code and IM 2 table are in fast RAM (not slowed by ULA). To get number of tacts per frame, multiply the BC value by 18 and add 66 (ZX48) or 60 (ZX128) tacts. (However for the Sam Coupé BC must be multiplied by 20, not 18.) Please note that while both ZX48 and TC2048 have the same frame length, the starts of screen drawig are in different tacts.
|timing in BC||computer name||graphics|
|England||#00||3879||Sinclair ZX Spectrum (+)||ULA 6C001E-7|
|#01||3936||Sinclair ZX+ 128||AMSTRAD 40056|
|#02||3936||Amstrad ZX +2||ULA 7K010E5|
|#03||3936||Amstrad ZX +2A/+2B/+3||GATE ARRAY 40077|
|#0C||5987||MGT SAM Coupé||ASIC|
|#20||3257||Timex Sinclair 2068||TS 2068 - 60Hz|
|#21||3879||Timex Computer 2068||TS 2068 - 50Hz, grey|
|#22||3879||Timex Computer 2048||TS 2068 - 50Hz, black|
|Poland||#80||(unknown)||ELWRO 800 Junior||?|
LINT interface generates interrupt before line set in port #F9 is displayed. Interrupts can be recognized by reading port #F9. Presence should be checked with function #A???. (At this moment only SAM Coupé contains this feature.)
|base modes||switched modes|
|value in register E||description||value in register E||description|
|#00||standard screen at #4000||#08||standard screens at #4000 and #C000|
|#01||standard screen at #6000||#09||standard screens at #4000 and #6000|
|#02||high colour screen at #4000||#0A||high colour screens at #4000 and #C000|
|#03||hires screen at #4000||#0B||hires screens at #4000 and #C000|
|#04||standard screen at #C000||#0C||four standard screens at #4000, #6000, #C000 and #E000|
|#05||standard screen at #E000||#0D||standard screens at #C000 and #E000|
|#06||high colour screen at #C000||#0E||high colour screen at #4000 and #C000 - 1:3|
|#07||hires screen at #C000||#0F||hires screen at #4000 and #C000 - 1:2|
For HL>#4000 at HL is placed relocateable code to select one of base screen mode. In this case L contains length of the code and H - number of tacts it needs. For calls with H=0 the mode is selected directly.
|#A7||OPENVIDEO||sets screen mode||BC=frame|
Function #AC is used to load RSX into system memory without activation. In case of no error (A=0), the handle for selected RSX is returned in D.
Function #AD? calls internal functions of present RSX.
Function #AE is dedicated to control all loaded RSXes. For E=0 places at HL name of file that cause to load the program or error when the program was run directly, not by its file. BC should contain buffer size, at least #0080.
Function #AF loads RSX specified by extension of file name and then this RSX loads required file. E.g. for file "GAME.Z80" the RSX is loaded from file "ZX:Z80.RZX". This doesn't happen for extensions "V00" (ZXVGS native program) and "RZX" (loads RSX directly, not "RZX.RZX").
Function #AF loads:
|#AD?||RSXCTRL||call RSX function||D=handle|
|#AE||RSXINFO||info about RSX||E=what|
|#AF||RSXLOAD||load file with RSX||DE=^filename||A=error|
With these functions you can manage up to 4MB RAM. (What gives totally 4128kB in 16kB mode or 8208kB in 32kB mode.)
There is 16kB of RAM switched in section D (#C000..#FFFF). It is possible to use virtual banks, which contents will be software moved. Banks #00..#07 are privileged and can be switched faster, with separate functions #B0..#B7 without arguments.
The bank must be opened before any operation on it. If while opening there's no enough memory (RAM for non-virtual bank or external one for virtual) fatal error is generated. Check free space before! Opened bank is filled with zeros. None of functions check PC, SP nor I contents, so using them in wrong context will cause system crash.
If because of hardware reasons it isn't possible to switch section D, only virtual banks are allowed (long time switching). If because of hardware reasons only both C and D sections can be switched together at a time (32kB, #8000..#FFFF) then switching of section D can be simulated with or without rewriting section C. In this case it isn't possible to open bank that is switched fast and don't modifies C section. Section C is copied while opening.
There are three types of banks:
Functions #B0..#B7 select one of ptivileged bank. Function #B8 selects any bank - its number is provided in E register.
Function #B9 provides informations about banks. Do not use. To get current bank number and its mode, use #BF function.
Function #BA is used to get code that switches bank. See next section for details.
Function #BB copies present section C contents to all other opened 32kB banks or is ignored in case of 16kB chunk switching.
Function #BC tries to opens bank E in mode D, returns effective mode in D. See paramers table.
Function #BD closes bank E. If E means bank actually selected, contents of D section becomes undefined (e.g. can contain ROM contents or values #FF) till selection of another bank.
Function #BE closes all banks. Contents of D section becomes undefined.
Function #BF returns in register E the number of currently selected bank, in register D its mode. In B is returned the amount of opened banks. Register A contains amount of additional banks (not including virtual):
|bit in D||input for function #BC||output of functions #BD and #BF|
|when set (1)||when reseted (0)||when set (1)|
|0||has to switch fast (not virtual)||
|1||its choice can't change #8000..#BFFF area|
|2||has to have displayable screen||screen can't be displayed from this bank||it is possible to display screen|
|3||has to correspond with ZX128 bank||not compatibile with #7FFD port||corresponds with ZX128 bank|
|4||has to allow IM 2 table without snowing||IM 2 table in this bank causes scereen snowing||IM 2 table can be placed in this bank|
|5||CPU can't be slowed by ULA||ULA slowes CPU||CPU isn't slowed by ULA|
|6||must allow 8 graphics bitplanes (???)||one bitplane available||offers 8 graphics bitplanes (???)|
|7||open also when requiments not meet||opened||not opened|
This feature allows much faster switching of banks. Follow these points.
|#B0..#B7||BNK0..BNK7||select privileged bank|
generates fatal error if bank isn't opened
|#B8||BNKE||select any bank|
generates fatal error if bank isn't opened
|#B9||BNKCTRL||bank control - do not use||DE=infonumber||A|
|#BA||BNKCODE||get switching code||E=number|
|#BB||BNKCOPY||copy C section to other banks||none||A=?|
|#BE||BNKRESET||close all banks||none||A=?|
|#C0||GETPATH||Returns current path (disk and directories). The returned path always begins with disk name (followed by ":").||DE=^buf||A=error|
|#C1||SETPATH||Changes current path.||DE=^name||A=error|
Function #C2 gets entry from directory selected by function #C3. HL points to format string (defined by function #C3 is used when either H=0 or HL points to 0 byte; internal system structure is returned when H=1), DE points to a buffer. The entry as plain ASCII (ready to display) is placed at DE. (Use HL=0 to fill the fileselector, then HL=^'%f%n' to get filename selected by user in requester.)
Function #C3 selects directory, counts entries, copies entries to the internal buffer. (The buffer must be released (DE=0) after reading directory is finished.) HL points to format string (system default one is used when either H=0 or HL points to 0 byte; internal system structure is returned when H=1). Following formatters can be used:
Other characters are copied without change. A decimal number between the "%" and letter means the fixed field size. Positive values result right justification, negative - left. Value after dot means number of characters in string to cut. Examples:
"%-16.16m %-3.3e %l" - NeOS 1.0 style (DEC)
"%-8.8m<%1.1e>%3b%13l" - TR-DOS style (start values unavailable)
"%x %-9g%-9u%8l %6d %5t %n" - U*IX style (ls -l)
"%-9.8m%-4.3e%13l%9.8d%9t" - MS-DOS 6.20 style (default)
Internal system structure consists of following fields (not fully defined):
Free disk space can be get with #C4 or #C5 functions.
Note: some disks (mostly the network disks like "TCP:", "HTTP:" or "FTP:") will not show all possible subdirectories, only those that were used recently (or present in bookmarks).
|#C2||GETDIR||get dir entry||BC=number|
|#C3||SETDIR||set dir mask||HL=^format|
Functions #C4 and #C6 returns informaton of given disk/path or file. Functions #C5 and #C7 change the informaton of given disk/path or file, but only if it is possible.
|#00||free space on disk in kilobytes||HL||string ASCIIZ|
|#01||directory nesting level(1=root)||L||string ASCIIZ|
|#??||free space in allocation units||DEHL||string ASCIIZ|
|#??||free entries in directory||HL||string ASCIIZ|
|#??||allocation unit size in bytes||DEHL||string ASCIIZ|
|#??||maximal filename length||L||string ASCIIZ|
|#??||disk status||HL||string ASCIIZ|
|#??||is place for file of length DEHL||L||string ASCIIZ|
|#??||get sector size|
BC-cylinder, D-track, E-number
|#??||get allocation unit size||DEHL||string ASCIIZ|
|#??||load/save allocation unit|
BC-cylinder, D-track, E-number
BC-cylinder, D-track, E-number
|#C4||GETINFO||get parameters as numbers||DE=^name|
|#C5||SETINFO||set parameters as numbers||DE=^name|
|#C6||GETINF$||get parameters as strings||DE=^name|
|#C7||SETINF$||set parameters as strings||DE=^name|
Function #CB removes files or directory (directory must be empty).
Function #CC checks whether given file exists (error if not).
Others are still not defined.
|#C9?||FLUSH||write all buffers to disks|
|#CA?||MAKE||creates file or directory||DE=^name|
|#CB||KILL||removes file or directory (must be empty)|
|#CC||EXIST||checks whether file or directory exists|
|#CD?||ASSIGN||mounts new disk||DE=^name|
|#CE?||MOVE||moves or renames files and directories||DE=^oldname|
|#CF?||COPY||duplicate files and directories||DE=^sourcename|
These functions are for file handling. If you want to load whole file into memory or save memory part as file check #E0..#ED functions first.
Function #D0 always closes file of given handle. If 0 is given as handle, all opened files will be closed. Function #D1 opens file for input (returns error if file not exists). Function #D2 opens file for output - will delete existing file and make new with null length. Function #D3 opens file both for input and output. If file not exists, will be created with first writing.
Functions #D4..#D7 are for read and write file. Functions #D4 and #D5 send given amount of bytes (returns amount of bytes actually sent - lower value than required generates error). Function #D6 reads bytes from file to the limit or to recognize #00 or #0D values (including them). Function #D7 writes bytes till #00 value, which isn't written. Byte #00 will be written only if is first pointed byte.
Function #D8 returns present file position. Function #D9 allows move present file position of any file and returns position before operation. Shift is counted dependly on B regiser: #FF means from beginning, #00 actual position and #01 from end of file. Error value is returned when end or beginning of file are crossed. It is possible to address file of 8MB length (23 bits of address). Function #DA informs whether file is in end position. Function #DB truncates file at actual position.
Following functions are nearly direct calls of FILEDISK system structure. Its definitions can still change in future.
|#D1||OPENI||open file for input||DE=^name||A=error|
|#D2||OPENO||open file for output|
|#D3||OPENB||open file for input and output|
|#D4||READ||read from file||D=handle|
|#D5||WRITE||write to file||D=handle|
|#D6?||GETL||get line from file||D=handle|
|#D7?||PUTL||put line to file||D=handle|
|#D8||FPOS||get file position||D=handle||EHL=pos|
|#D9||SEEK||set file position||D=handle|
|#DA?||EOF||end of file info||D=handle||A=error|
|#DB?||TRUNC||truncate file at current position|
Functions #E0..#E7 are designed to handle files with headers (similar to tape files).
Before calling functions #E4..#E6 the header type must be set by one of #E0..#E3 function. This setting is valid until next call of any #E0..#E3 function. If the file exists then in specified registers will be returned values taken from header of this file. If the file not exists or required header type is collision with readed, error code is returned. This error may be ignored if write to file will be performed, but reads of that file will always resulult error.
On entry to #E3 function the buffer size can be provided in BC. Length returned in BC is limited by this size, while DE contains real size. This is to avoid the tape limitation - you cannot load from real tape some first bytes of longer file as the checksum cannot be checked. Also, BC=#1B00 and HL=#4000 will be recognized as you want to load or save the screen (however you can still load it to or save from other address).
Loading and saving give error when less bytes than reqired were readed or written. Check BC in that case. Verification is equivalent to reading and acts similar to tape one - error is submitted if data varies or file is too short.
Function #E7 called before one of #E4..#E6 function alows set the shift, what gives the possibility of seqential processing of the file. It means e.g. reading succeeding parts of file to different memory banks. Error is retuned when position exceeds file length. Functions #E0..#E3 always set the shift to zero (just after header).
Calling any function of #E4..#E7 without prior call of any of #E0..#E3 causes fatal error.
The file with header can be 65535 bytes long (not including header). The rest will be truncated. The header format may vary in different filesystems. So it is not adviced to process files with header using other functions, unless they are e.g. screens or savegames.
For files with filename extension different from ".CZX", ".DZX", ".DAT", ".ROM", ".SCR" proper RSX is called. So you can e.g. load data or BASIC program from "*.Z80" file! See RSXes description for details.
|#E0||HEADER0||program file select||DE=^name|
|#E1||HEADER1||numeric array file select||DE=^name|
|#E2||HEADER2||string array file select|
|#E3||HEADER3||binary file select||DE=^name|
|#E4||LOAD||load memory from selected file||BC=len|
|#E5||SAVE||save memory to selected file||BC=len|
|#E6||VERIFY||compare memory with selected file||BC=len|
|#E7||SHIFT||change position in selected file||DE=shift||A=error|
To save or load ZX screen, functions #E8 and #E9 should be used. Operation always means 6912 bytes of memory. Separation of these functions allows graphics conversion from/to popular graphics formats. Saved screen has 256x192 pixels and 16 colours, but exceptions are possible. If contents of loaded file isn't compatibile with Spectrum limitations, the result is not defined. Error is returned if file wasn't saved or not exists or the format wasn't recognized.
In future ZXVGS releases RSX will be used to load and save images of file exentions different from ".SCR" and ".CZX". These functions can also display requester with list of available formats when no file extension is given or file not exists (loading) or the filename is empty.
Other screen modes will be also supported.
|#E8||LOADSCR||load screen from file||DE=^name|
|#E9||SAVESCR||save screen to file|
Functions #EA and #EB are designed to store and recall the state of game or configuration of utility program. Calling these funtions allows the user to select one of 10 such files. While saving user can comment the file. Files are saved with name of current program and one of "SV0".."SV9" extension (this is selected by user).
For D=0 the requester will not appear and the file with extension ".SV?" as default will be loaded or saved. In this case E contains code of character placed as 3rd one in file suffix (invalid characters are changed to "!"). This feature is to load default configuration at start of program or save configuration on exit. The comment string while saving is set to "Autosaved" (date and time can be included). This can be used together with standard calls (when the user selects an entry).
For function #EA, when HL=0, the address from header is used.
The extension "SV@" (E=#40) is reserved to store high scores
file of a game. If the file exists, ZXVGS loads "*.SV@" it just
after the "*.V00" file. Then, the file is saved when the user
calls ZXVGS menu. In new programs it should be saved with function #EB at
every highs scores table modification.
The "*.SV?" files are saved to and loaded from the "SV:" disk.
Function #EC should be used to load whole or initial part of any file to memory. Error code is returned if there were loaded less bytes than required.
Function #ED should be used to save continous area of memory to file. Error code is returned if there are saved less bytes than required (no disk space).
Always check BC in case of error.
|#EC||LOADANY||load any file||DE=^name|
|#ED||SAVEANY||save any file||A=error|
Functions #EE and #EF are designed to allow user select or enter file or directory name in easy way. It is possible to give default name and limit choice by mask. Mask can be edited by user, except "*/" what means directory selection. There is also title of operation. For result path 128 bytes of buffer must be reserved. Functions return error when fileselector was exited by <EDIT> or name is empty.
Function #EE always leaves screen (memory area #4000..#5AFF) unchanged, what in some situations manifests in limited form of selector. Function #EF always uses full-screen interface, but leaves screen in random state. Screen refresh is needed.
It is adviced to use file selectors for every file with name defined by user.
When "*.SZX" or "*.SCR" is as the mask, the requester can also allow to select other graphics file format and change file extension respectively.
|#EE||FILESELL||fileselector without screen modification||DE=^default|
|#EF||FILESELH||fileselector which can modify screen|
Function #F0 returns printer control code. In E is code number, in HL addres of buffer for it. In BC is the maximal length (B is ignored - should be 0). When control codes fitted in buffer, BC (B=0) contains number of control characters and A is 0. If the buffer was too small, BC returns required space and A>0. If control code is not available, BC=0 and A>0.
Function #F1 sends required control code directly to printer. See also function #F0.
Function #F2 is equivalent to BASIC COPY.
Function #F3 prints screen (256?192) taken from given address.
Function #F4 simulates ZX Printer on normal character printer.
Function #F5 simulates ZX Printer on matrix printer, but for character printer acts like function #F4.
Function #F6 is dedicated to print texts with national characters. If there's no recoding in system is equivalent to function #F7. Values 1..5 in register D mean ISO-8859-D character set.
Function #F7 sends byte directly to printer (control sequences can be taken with #F0 function).
Functions #F0..#F6 are driven by PRINTER.RZX.
|code||meaning||default for printers|
|Helwett-Packard Laser Jet
|#00||number of wires||8||8|
|#01||before screen dump||27,65,8||?|
|#02||number of dots in mode1||224,1||?|
|#04||number of dots in mode2||192,3||?|
|#06||code for CR||13||13|
|#07||code for LF||10||10|
|#F0||GETPRINT||get printer control code||E=code|
|#F1?||SETPRINT||send printer control code||E=code||A=error|
|#F2||DUMP||print 22 lines of screen graphics||none||A=?|
|#F3?||DUMPANY||print 24 lines of screen graphics||HL=address|
|#F4||ZXPRINT||print one character like ZX Printer||E=character|
|#F5?||HLPRINT||print character defined at HL like ZX Printer||HL=^pattern|
|#F6?||DEPRINT||print character with modificator||D=modificator|
|#F7||LPRINT||direct printer output||E=character|
Functions #F8..#FB are for overlays management. Usually overlays are next levels of game. Overlay can be loaded by calling #F8 function with number of overlay. Preparation (function #F9) has only sense in server systems and allow speed up loading (e.g. with Timex FDD 3000) - isn't necessary. Loading overlays into buffer (function #FA) causes faster loading. This is ignored when there's not enough RAM for store. It should be used instead of loading overlays directly into memory banks (like games for both ZX48 and ZX128), because in the buffer overlays are in compressed form and can be also stored in RAM available under ZXROM (MB-02). Function #FB removes overlay from buffer. All functions return amount of free buffer storage in kilobytes. If there's more free space than 254kB, value 255 is returned.
|#F8||OVRLOAD||load overlay E=0 means main program||E=number||A=free|
|#F9||OVRPREPARE||load overlay into buffer only if multitasking|
|#FA||OVRSTORE||copy overlay into internal buffer|
|#FB||OVRREMOVE||remove overlay from internal buffe|
Functions #FC..#FF are for exiting from program to the system menu and quiting program.
Function #FC only calls system menu. The program is continuable. Function #FD ends the program after its finish (closes all opened files, banks, clears overlay buffer, etc.). Function #FE is similar to #FD, but displays given message before menu.
Function #FF is reserved for BASIC interpreter that executes it after last instruction. It is useless for ZXVGS programs. Usually (without RSX) word from XPTR #5C5F will be copied to CHADD #5C5D, #FF will be placed in ERRNR #5C3A and program will be continued from #0058 (error service).
|#FC||MENU||exit to menu, return with "Continue" option||none||A=???|
|#FD||QUIT||quit to menu with message "Program finished"||no return|
|#FE||FATAL||quit to menu with given message (fatal error)||DE=^text|
|#FF||OK||used by BASIC||none||jump to #0058|