| X2 | 5B5A | 23386 | RETADDR | Return address in ROM 1 |
| X1 | 5B5C | 23388 | BANKM | Copy of last byte output to I/O port 7FFDh (32765). See Chapter 23 – The Memory. This byte must be kept up to date with the last value output to the port if interrupts are enabled |
| X1 | 5B5D | 23389 | RAMRST | RST 8 instruction. Used by ROM 1 to report old errors to ROM 3 |
| N1 | 5B5E | 23390 | RAMERR | Error number passed from ROM 1 to ROM 3. Also used by SAVE/LOAD as temporary drive store |
| 1 | 5B5F | 23391 | INKL | INK colour for LoRes |
| 1 | 5B60 | 23392 | INK2 | INK colour for Layer 2 |
| 1 | 5B61 | 23393 | ATTRULA | Attributes for standard mode |
| 1 | 5B62 | 23394 | ATTRHR | Attributes for HiRes (only paper colour in bits 5:3 is used) |
| 1 | 5B63 | 23395 | ATTRHC | Attributes for HiColour |
| 1 | 5B64 | 23396 | INKMASK | Softcopy of EnhancedULA InkMask (or 0) |
| N1 | 5B65 | 23397 | LSBANK | Temporary bank number in LOAD/SAVE and other operations |
| 1 | 5B66 | 23398 | FLAGS3 | Various flags. Bits 0, 1, 6 and 7 unlikely to be useful. Bit 2 is set when tokens are to be expanded on printing. Bit 3 is set if print output is RS232. The default (at reset) is Centronics. Bit 4 is set if a disk interface is present. Bit 5 is set if drive B: is present |
| X1 | 5B67 | 23399 | BANK678 | Copy of last byte output to I/O port 1FFDh (8189). This port is used to control the +3 extended RAM and ROM switching (bits 0..2 – if bit 0 is 0 then bit 2 controls the 'vertical' ROM switch 02 and 13), the disk motor (bit 3) and Centronics strobe (bit 4). This byte must be kept up to date with the last value output to the port if interrupts are enabled |
| X1 | 5B68 | 23400 | FLAGN | Flags for the NextZXOS system |
| 1 | 5B69 | 23401 | MAXBNK | Maximum available RAM bank |
| X2 | 5B6A | 23402 | OLDSP | Old SP (stack pointer) when TSTACK is in use |
| X2 | 5B6C | 23404 | SYNRET | Return address for ONERR |
| 5 | 5B6E | 23406 | LASTV | Last value printed by calculator |
| 1 | 5B73 | 23411 | TILEBNKL | Tiles bank for LoRes |
| 1 | 5B74 | 23412 | TILEML | Tilemap bank for LoRes |
| 1 | 5B75 | 23413 | TILEBNK2 | Tiles bank for Layer2 |
| 1 | 5B76 | 23414 | TILEM2 | Tilemap bank for Layer2 |
| X1 | 5B77 | 23415 | NXTBNK | Bank containing NXTLIN |
| X1 | 5B78 | 23416 | DATABNK | Bank containing DATADD |
| 1 | 5B79 | 23417 | LODDRV | Holds 'T' if LOAD, VERIFY, MERGE are from tape, otherwise holds 'A', 'B' or 'M' |
| 1 | 5B7A | 23418 | SAVDRV | Holds 'T' if SAVE is to tape, otherwise holds 'A', 'B' or 'M' |
| N1 | 5B7B | 23419 | L2SOFT | Softcopy of Layer 2 port |
| 2 | 5B7C | 23420 | TILEWL | Width of LoRes tilemap |
| 2 | 5B7E | 23422 | TILEW2 | Width of Layer 2 tilemap |
| 2 | 5B80 | 23424 | TILEOFFL | Offset in bank for LoRes tilemap |
| 2 | 5B82 | 23426 | TILEOFF2 | Offset in bank for Layer 2 tilemap |
| 2 | 5B84 | 23428 | COORDSX | X Coordinate of last point plotted (Layer 1/2) |
| 2 | 5B86 | 23430 | COORDSY | Y Coordinate of last point plotted (Layer 1/2) |
| 1 | 5B88 | 23432 | PAPERL | PAPER colour for LoRes mode |
| 1 | 5B89 | 23433 | PAPER2 | PAPER colour for Layer 2 mode |
| Nx | 5B8A | 23434 | TMPVARS | Base of temporary system variables (space shared with bottom of TSTACK) |