SysMem V2.0
Introduction
The arrival of the 1Mb & 2Mb Psion 3a machines meant that it was no longer so easy to determine how much system memory was free. This is because although the Psion can use up to a theoretical 1 or 2Mb of internal memory for file storage, the system memory is limited to 512Kb. The memory display on the system screen only shows the free internal RAM, and does not distinguish what is used by the system and what is used as disk storage. Thus it is possible to have say 700Kb free, and yet actually have nearly all the 512KB of system memory in use, and thus be unable to run various applications. In the worst case, some applications may partly start, crash and corrupt their data files.
SysMem
The original version of SysMem was written by JBsoft and provides a display of the used and remaining (free) system memory. It uses the macsys macro system, written by Tom Dolbilin, to provide at any time, by means of a definable hotkey set the display of the current state of affairs. Hence you can be in the Agenda, and want to start 3Fax. By checking with SysMem, it is easy to discover if there is enough free memory for this. If not and you also have the tasklist macro, it is simple to scan the started applications, and select one or more to close to free the memory you need. Using the built in display of the system via Psion-m requires many more keystrokesones and the answer is not so easy to discover.
Why version 2.0
The original code does not provide any indication of the total internal RAM used and how much, if any, of the 512K system memory has been used as disk storage. The old 256Kb & 512Kb machines share all their internal disk storage with the system memory. The bigger machines however can be used in such a way to allow the maximum use of the 512Kb system memory as memory.
To this end I rewrote SysMem to create version 2.0, which also displays the maximum available size of internal disk possible, the current space used and the current freespace available. This varies depending on the system memory used, and allows one to see just how large a file could still be stored. In addition on the 1Mb & 2Mb machines, it displays one further line if the internal disk usage is limiting the maximum size of the system memory available for use. This I term as being overdrawn, which means that the internal disk has borrowed some of the system memory. On the smaller machines, this never displays, because it is not possible to ever use any of the internal disk without impacting on the system memory available.
Installation.
To use SysMem v2.0, you need to have macsys installed and running. If you do not have this package, I would strongly suggest that you get it, as it provides some excellent features, such as simple keyboard macro recording, up to major OPL type programming macros.
The installation is very simple:
o	Copy the SYSMEM2.MCO file into your \MACRO\MCO\ directory.
o	Switch to the macsys screen.
o	Select Menu - Macro - Install or press Psion-i and install the macro SYSMEM2.
o	Select Menu - Macro - Change hotkey or press Psion-h and set a suitable hotkey.
Now whenever you need to know the system memory and/or internal disk usage, just press your selected hotkey combination, and SysMem will display the information. Then press Esc to clearthe display.
If you have the original SysMem, you can use both on different hotkeys, or you can remove the original. If you need a little extra disk space, delete the files \MACRO\MCR\SYSMEM.MCR & \MACRO\MCO\SYSMEM.MCO.
Problems.
There should be none with SysMem V2.0, but it is possible that if you are extremely short of system memory, while running macsys, that some macros may fail and/or get stuck. In this case, select the System screen and exit macsys. If you get the message "Macro is busy", you will have to kill macsys. I have need to do this a couple of times, but I run my 2Mb 3a very close to the limits.
Disclaimer.
All the usual ones. If it breaks your system, loses your data, makes your hair fall out, you are responsible. I make absolutely no warranty for this software and any other software need in order to run this code. 
Notwithstanding the above, I will do my best to answer any questions, and help solve any problems, if I feel able to do so. I also reserve the right to change, improve or withdraw this code, as I see fit.
You may provide the code to anyone freely, if you provide the original zip file containing the files SYSMEMV2.MCO, SYSMEMV2.WRD, SYSMEMV2.TXT & README.TXT.
Credits.
John Boyce of JBsoft for the original code of SysMem.
Tom Dolbilin for macsys
Psion PLC for their excellent machine.
Lord Wodehouse
Fri 14 Jun 1996
e-mail lordjohn@dial.pipex.com