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Błąd uniemożliwiający wykorzystanie NMI
Jednym z błędów (chyba najpoważniejszym) w ROM ZX Spectrum jest błędna zawartość komórki o adresie 112 (70h). Oryginalnie jest tam 225 (E1h) zamiast 233 (E9h), czyli zamiast rozkazu JP (HL) znajduje się POP HL, co umiemożliwia prawidłowe wykonanie przerwania niemaskowalnego.
Spis procedur w ROM
Procedury w ROM ZX Spectrum zajmują 14kB, są napisane kodzie maszynowym i umieszczone w 16kB kości ROM. Poniżej znajduje się ich spis (po angielsku) wraz z adresami (hex):
Procedury restartów i tablice
Address Routine ------- ------- 0000 Start 0008 Error restart 0010 Print a character 0018 Collect a character 0020 Collect next character 0028 Calculator restart 0030 Create free locations in work space 0038 Maskable interrupt routine 0053 Error-2 routine 0066 Non-maskable interrupt routine 0074 CD_ADD + 1 subroutine 007D Skip over 0095 Token tables 0205 Key tablesProcedury obsługi klawiatury
Address Routine ------- ------- 028E Keyboard scanning 02BF Scan keyboard and decode value 0310 Repeat key routine 031E Test key value 0333 Keyboard decodingProcedury obsługi głośniczka
Address Routine ------- ------- 03B5 Routine to control loudspeaker 03F8 Handle BEEP command 046E Semi-tone tableProcedury obsługi magnetofonu
Address Routine ------- ------- 04C2 Save header and program/data bytes 053F Reset border and check BREAK key for LOAD and SAVE 0556 Load header and block of information 05E3 Check signal being loaded 0605 Entry point for tape commands 07CB Handle VERIFY control 0802 Load a data block 0808 Handle LOAD control 08B6 Handle MERGE control 0970 Handle SAVE control 09A1 Canned cassette messagesProcedury obsługi ekranu i drukarki
Address Routine ------- ------- 09F4 General PRINT routine 0A11 Control character table 0A23 Cursor left routine 0A3D Cursor right routine 0A4F Perform carriage return 0A5F Print comma 0A69 Print question mark 0A6D Control characters with operands 0AD9 Print character(s) 0ADC Store line, column, and pixel address 0B03 Fetch position parameters 0B24 Print any character 0B7F Print all characters 0BDB Set attribute 0C0A Message printing 0C3B Handle recursive printing 0C41 Table search 0C55 Test for scroll 0CF8 `scroll?' message 0D4D Temporary colour items 0D6B Handle CLS command 0DAF Clearing whole display area 0DD9 Set line and column numbers 0DFE Handle scrolling 0E44 Clear bottom lines of display 0E88 Attribute handling 0E9B Handle display with line number 0EAC Handle COPY command 0ECD Pass printer buffer to printer 0EF4 Copy line routine 0F2C Editor routine for BASIC and INPUT 0F81 Add code to current line 0FA0 Editing keys table 0FA9 Handle EDIT key 0FF3 Cursor down editing 1007 Cursor left editing 100C Cursor right editing 1015 DELETE editing 101E Ignore next 2 codes from key-input routine 1024 Enter editing 1031 Move cursor when editing 1059 Cursor up editing 1076 Use of symbol and graphics codes 107F Editor error routine 1097 Clear work space 10A8 Handle keyboard input 111D Lower screen copying 1190 Point to first and last locations of work space 11A7 Remove floating point from line numberProcedury wykonawcze
Address Routine ------- ------- 11B7 Handle NEW command 11CB Main entry (initialization) 11DA Check RAMTOP 12A2 Main execution loop 1319 Canned report messages 155D Handle addition of BASIC line 15AF Initial channel information 15C6 Initial stream data 15D4 Control for input subroutine 15E6 Make HL point to input address 15EF Main printing 1601 Open channel 1615 Set channel flags 162D Channel code look-up table 1634 Channel K flag 1642 Channel S flag 164D Channel P flag 1652 Just one space required? 1655 Otherwise, make room 1664 Hold pointers for making room 168F Collect line number 169E Handle reserve room 16B0 Clear various editing areas 16D4 Reclaim edit-line 16DB Look through tables 16E5 Handle CLOSE# command 1716 CLOSE stream look-up table 171E Stream data 1736 Handle OPEN# command 177A OPEN stream look-up table 1793 Handle CAT, ERASE, FORMAT, MOVE commands 1795 Handle LIST, LLIST commands 1795 Perform AUTO-LIST 17F5 Handle LLIST 17F9 Handle LIST 1855 Print a whole BASIC line 18B6 Check for a number marker 18C1 Print a flashing character 18E1 Print the cursor 190F Get line number of next line 1925 Printing characters in a BASIC line 196E Get starting address of line, or line after 1980 Compare line numbers 1988 Find each statement 19B8 Get next one 19DD Difference routine 19E5 Handle reclaiming space 19FB Read line number of line in editing area 1A1B Report and line number printingInterpreter BASIC-a
Address Routine ------- ------- 1A48 Syntax tables 1B17 Main parser (BASIC interpreter) 1B28 Statement loop 1B52 Temporary pointer to entries in table 1B6F Check for syntactical spaces 1B76 Come here after interpretation 1B8A Run at a given line number 1B9E Find start address of new line 1BB2 Handle REM command 1BB3 End of line? 1BBF General line checking 1BD1 Go to next line 1BEE End of program? 1BF4 Go to next statement 1C01 Command class table 1C0D Command classes---00, 03, and 05 1C16 Jump to appropriate command 1C1F Command classes---01, 02, and 04 1C22 Variable in assignment 1C56 Fetch a value 1C79 Expect numeric/string expression 1C96 Set permanent colours (class 07) 1CBE Command class---09 1CDB Command class---0B 1CDE Fetch a number 1CEE Handle STOP command 1CF0 Handle IF command 1D03 Handle FOR command 1D86 Find DATA, DEF FN, or NEXT 1DAB Handle NEXT command 1DDA Perform NEXT loop 1DEC Handle READ command 1E27 Handle DATA command 1E39 Check statement for DATA or DEF FN 1E42 Handle RESTORE command 1E4F Handle RANDOMIZE command 1E5F Handle CONTINUE command 1E67 Handle GO TO command 1E7A Handle OUT command 1E80 Handle POKE command 1E85 Check parameters on calculator stack 1E94 Find integers 1EA1 Handle RUN command 1EAC Handle CLEAR command 1EED Handle GO SUB command 1F05 Check available memory 1F1A Free memory 1F23 Handle RETURN command 1F3A Handle PAUSE command 1F54 Check for BREAK key 1F60 Handle DEF FN command 1FC3 Returning early from subroutine 1FC9 Handle LPRINT command 1FCF Handle PRINT command 1FF5 Print carriage return 1FFC Print items 2045 End of printing 204E Print position 2070 Alter stream 2089 Handle INPUT command 21B9 Used during input 21D6 Only called for channel K 21E1 Colour item routines 226C Handle change of colour 2294 Handle BORDER command 22AA Get pixel address 22CB Get point 22DC Handle PLOT command 2307 Put two numbers in BC register 2314 Put stack in A register 2320 Handle CIRCLE command 2382 Handle DRAW command 247D Initial parameters 24B7 Line drawingAnaliza wyrażeń
Address Routine ------- ------- 24FB Scan expression 2530 Check syntax 2535 Scanning SCREEN$ 2580 Scanning ATTR 2596 Scanning function table 25AF Scanning function routines 26C9 Scanning variable routines 2734 Scanning main loop 2795 Table of operators 27B0 Table of priorities 27BD Scanning function (FN) 28AB Used with DEF FN 28B2 Used with variables and DEF FN 2951 Stack function argument 2996 Check variable table 2A52 Handle slicing of strings 2AB6 Pass five registers to calculator stack 2ACC Return result of evaluating next expression 2AEE Subroutine 2AF4 Subroutine 2AFF Handle LET command 2BF1 Get last value from calculator stack 2C02 Handle DIM command 2C88 Check whether digit or letter 2C9B Decimal floating point 2D1B Check for valid digit 2D22 and again 2D28 Convert binary to floating point for A register 2D2B Ditto for BC register 2D3B Integer to floating pointProcedury arytmetyczne
Address Routine ------- ------- 2D4F E-format to floating point 2D7F Fetch integer 2D8E Store integer 2DA2 Floating point to BC register 2DC1 Handle LOG 2DD5 Floating point to A 2DE3 Print a floating point number 2F8B Handle printing floating point 2F9B Prepare to add 2FBA Fetch two numbers 2FDD Shift floating point number right 3004 Add back any carry 300F Handle subtraction (03) 3014 Handle addition (0F) 30A9 Used in 16 bit multiplication 30C0 Prepare to multiply or divide 30CA Handle multiplication (04) 31AF Handle division (05) 3124 Integer truncation towards zero (3A) 3293 Re-stack two `small' integers 3297 Re-stack one number in full formKalkulator zmiennoprzecinkowy
Address Routine ------- ------- 32C5 Table of constants 32D7 Table of addresses 335B Called in floating point 33A1 Handle delete (02) 33A2 Single operation (3B) 33A9 Test five-spaces 33B4 Stack number 33C0 Move a floating point number (31) 33C6 Stack literals (34) 33F7 Skip constants 3406 Memory location 340F Get from memory area (E0 etc.) 341B Stack a constant (A0 etc.) 342D Store in a memory area (C0 etc.) 343C Swap first number with second number 3449 Series generator (86 etc.) 346A Absolute magnitude (2A) 346E Handle unary minus (1B) 3492 Signum (29) 34A5 Handle IN command (2C) 34AC Handle PEEK command (2B) 34B3 USR number (2D) 34BC USR string (19) 34E9 Test for zero 34F9 Greater than zero (37) 3501 Handle NOT operator (30) 3506 Less than zero (36) 350B Zero or one 351B Handle OR operator (07) 3524 Handle number AND number (08) 352D Handle string ANF number (10) 353B Perform comparison (09--0E, 11--16) 359C String concatenation (17) 35BF Check stack pointers 35C9 Handle CHR$ (2F) 35DE Handle VAL and VAL$ (1D, 18) 361F Handle STR$ (2E) 3645 Read-in (1A) 3669 Handle CODE (1C) 3674 Handle LEN (1E) 367A Decrease the counter (35) 3686 Jump (33) 368F Jump on true (00) 369B End of calculation (38) 36A0 Modulus (32) 36AF Handle INT (27) 36C4 Exponential (26) 3713 Natural logarithm (25) 3783 Reduce argument (39) 37AA Handle cosine (20) 37B5 Handle sine (1F) 37DA Handle tangent (21) 37E2 Handle arctan (24) 3833 Handle arcsin (22) 3843 Handle arccos (23) 384A Handle square root (28) 3851 Handle exponential (06)