| 0000 | 144 | Allocated to current language |
| 0070 | 32 | Guaranteed unused with BASIC |
| 0090 | 16 | Econet workspace |
| 00A0 | 8 | Allocated to current NMI owner |
| 00A8 | 8 | OS command workspace |
| 00B0 | 16 | File system scratch space |
| 00C0 | 16 | File system private space |
| 00D0 | 1 | VDU status
| Bit 0 |
VDU 2 enabled |
| Bit 1 |
Scroll disabled |
| Bit 2 |
Paged scroll selected |
| Bit 3 |
Soft scrolling |
| Bit 4 |
unused |
| Bit 5 |
VDU 5 enabled |
| Bit 6 |
Set when edit/text cursors are separated |
| Bit 7 |
Set if VDU driver disabled |
|
| 00D1 | 1 | Byte mask for current graphics point |
| 00D2 | 2 | Text colour to be ORed & EORed into memory respectively |
| 00D4 | 2 | Graphics colour to be ORed & EORed into memory respectively |
| 00D6 | 2 | Address of top line of current graphics character cell |
| 00D8 | 1 | Caps-lock/shift-lock
| 16 |
Shift lock |
| 32 |
Caps lock |
| 48 |
No locks |
|
| 00DA | 6 | Temp workspace |
| 00E0 | 2 | Pointer to row multiplication table, high byte first |
| 00E2 | 1 | Cassette filing system status
| Bit 0 |
Input file open |
| Bit 1 |
Output file open |
| Bit 2 |
Unused |
| Bit 3 |
Set if currently *CAT |
| Bit 4 |
Unused |
| Bit 5 |
Unused |
| Bit 6 |
Set if at end of file |
| Bit 7 |
Set if end of file warning issued |
|
| 00E3 | 1 | Cassette filing system options *OPT |
| 00E4 | 3 | General OS workspace |
| 00E7 | 1 | Auto repeat countdown timer |
| 00E8 | 2 | Pointer to input buffer used by OSWORD 0x01 |
| 00EA | 1 | RS423 timeout counter
| <0 |
RS423 system holds 6850 but has not yet timed out |
| =0 |
RS423 system holds 6850 but has timed out |
| =1 |
Cassette filing system using 6850 |
|
| 00EB | 1 | Cassette critical flag |
| 00EC | 1 | Internal key no of most recently pressed key |
| 00ED | 1 | Internal key no of first key pressed of those still pressed |
| 00EE | 1 | Internal key number of character to be ignored when scanning keyboard
| Note |
0xEE is also RAM copy of 1MHz bus register |
|
| 00EF | 1 | Accumulator value for most recent OSBYTE/OSWORD |
| 00F0 | 1 | X register for most recent OSBYTE/OSWORD |
| 00F1 | 1 | Y register value for most recent OSBYTE/OSWORD |
| 00F2 | 2 | text pointer for processing OS commands/filenames |
| 00F4 | 1 | RAM copy of currently selected Paged ROM |
| 00F5 | 1 | Current logical speech PHROM or ROM filing system ROM number |
| 00F6 | 2 | Address pointer into paged ROM or speech PHROM |
| 00F8 | 2 | Unused |
| 00FA | 2 | General OS workspace |
| 00FC | 1 | Accumulator saved in IRQ routine |
| 00FD | 2 | Pointer to error message |
| 00FF | 1 | Escape status
| Bit 7 |
set if ESCAPE pressed |
|