| Dec. | Hex. | Mnemonic | System Variables: ZX BASIC |
| 16384 | 4000 | ERR-NR | The report code. Incremented before printing. |
| 16385 | 4001 | FLAGS | Bit 0: Suppression of leading space. Bit 1: Control Flag for the printer. Bit 2: Selects K or F mode; or, F or G Bit 6: FP no. or string parameters. Bit 7: Reset during syntax checking. |
| 16386 | 4002 | ERR-SP | Ptr. to the GOSUB stack. |
| 16388 | 4004 | RAMTOP | The top of available RAM, or as specified. |
| 16390 | 4006 | MODE | Holds the code for K or F |
| 16391 | 4007 | PPC | Line number of the current statement. |
| 16393 | 4009 | VERSN | Marks the start of the RAM that is saved. |
| 16394 | 400A | E-PPC | The BASIC line with the cursor |
| 16396 | 400C | D-FILE | Ptr. to Display file |
| 16398 | 400E | DF-CC | Addr. for PRINT AT position |
| 16400 | 4010 | VARS | Ptr. to variable area |
| 16402 | 4012 | DEST | Addr. of current variable in program area |
| 16404 | 4014 | E-LINE | Ptr. to workspace |
| 16406 | 4016 | CH-ADD | Ptr. for scanning a line, in program or workspace |
| 16408 | 4018 | X-PTR | Ptr. to syntax error. |
| 16410 | 401A | STKBOT | Ptr. to calculator stack bottom. |
| 16412 | 401C | STKEND | Ptr. to calculator stack end. |
| 16414 | 401E | BERG | Used for many different counting purposes |
| 16415 | 401F | MEM | Ptr. to base of table of fp. nos, either in calc. stack or variable area. |
| 16417 | 4021 | -- | Unused by ZX BASIC. Or FLAG Y for G007 |
| 16418 | 4022 | DF-SZ | Number of lines in the lower screen |
| 16419 | 4023 | S-TOP | Current line number of automatic listing |
| 16421 | 4025 | LAST-K | Last Key pressed |
| 16423 | 4027 | DEBOUNCE | The debounce status |
| 16424 | 4028 | MARGIN | Adjusts for differing TV standards |
| 16425 | 4029 | NXTLIN | Next BASIC line to be interpreted |
| 16427 | 402B | OLDPPC | Last line number, in case needed. |
| 16429 | 402D | FLAGX | Bit 0: Reset indicates an arrayed variable Bit 1: Reset indicates a given variable exists Bit 5: Set during INPUT mode Bit 7: Set when INPUT is to be numeric |
| 16430 | 402E | STRLEN | Length of a string, or a BASIC line |
| 16432 | 4030 | T-ADDR | Ptr. to 'parameter table. & distinguishes between PLOT & UNPLOT |
| 16434 | 4032 | SEED | For RANDOM function |
| 16436 | 4034 | FRAMES | Frame counter |
| 16438 | 4036 | COORDS | X & Y for PLOT |
| 16440 | 4038 | PR-CC | Print buffer counter |
| 16441 | 4039 | S-POSN | Line & Column for PRINT AT |
| 16443 | 403B | CDFLAG | Bit 6 - the true fast/slow flag Bit 7 - copy of the fast/slow flag. RESET when FAST needed |
| 16444 | 403C | PRBUFF | Printer buffer |
| 16477 | 405D | MEMBOT | room for 5 floating point numbers (meme-0 to mem- 5???) |
| 16507 | 407B | -- | unused. Or RESTART to G007 |
| 16509 | 407D | PROGRAM | The BASIC program starts here |