When converting games across, you must be aware of differences between the counters / flags in differing machines.

I'll update this list as I have time and more manuals to compare / test.

Flag 0 = Dark / Light. Spectrum and CPC versions: 0 = light, any other value is dark.

Flag 0 = Light / Dark. BBC version: 255 = Light, any other value is dark.


Flag 1 = Object counter. This is the same for all versions. The value contained is the total number of objects the player is carrying


Flag 2 = Spectrum and CPC versions: This is decreased (if greater than zero) every time a location is described / redescribed.

Flag 2 = BBC Version. This contains the current room number.


Flag 3 = Spectrum and CPC versions: This is decreased (if greater than zero) every time a location is described / redescribed but only if it is dark, ie flag 0

Flag 3 = BBC Version. Standard single byte flag for user purposes.


Flag 4 = Spectrum and CPC versions: This is decreased (if greater than zero) every time a location is described / redescribed and object 0 is not present. Object zero is a special object regarded as being a source of light, ie a torch.

Flag 4 = BBC Version. Standard single byte flag for user purposes.


Flags 5 to 8 = Spectrum and CPC versions: If they are greater than zero they are decreased with each turn. This is usually useful for timed operations, ie running out of air or a countdown.

Flags 5 to 8 = BBC Version. Standard single byte flags for user purposes.


Flag 9 = Spectrum and CPC versions. If above zero, this is decreased each turn when it is dark, ie flag 0

Flag 9 = BBC Version. Standard single byte flag for user purposes.


Flag 10 = Spectrum and CPC versions. If above zero, this is decreased each turn when it is dark, ie flag 0 and object 0 is not present. Object zero is a special object regarded as being a source of light, ie a torch.

Flag 10 = BBC Version. Standard single byte flag for user purposes.


Flags 11 to 29 = Standard single byte flags for user purposes.


Flag 30 = Spectrum and CPC Versions. Holds the "score" if used.

Flag 30 = BBC Version. Standard single byte flag for user purposes.


Flag 31 and 32. Spectrum and CPC Versions. Holds the turns counter. 31 is the LSB and 32 is the MSB

Flag 31 and 32. BBC Version. Standard single byte flags for user purposes.


Flags 33 to 46. Spectrum and CPC Versions. These do not exist.

Flags 33 to 46. BBC Version. Standard single byte flags for user purposes.


Flags 47 to 63. Spectrum and CPC Versions. These do not exist.

Flags 47 to 63. BBC Version. Double byte flags. The status / event commands ADD / PLUS / MINUS / SUB etc act as 16 bit calucations, they act on the chosen flag and the next higher one as well.


I'll update this with more detail / other versions as I find out more. Currently although the Spectrum / CPC versions offer some more built in functionality, they do lack a good range of free for any purpose flags compared to the BBC Version.