Atlas 1 Emulator Tutorial

Other Stuff

In this page we visit a selection of miscellanious facilities which have somehow evaded our attention thus far.

Hardware Configuration

Selecting Configure/Hardware allows you to set the machine’s core store size and drum store size in Kwords. In all three Atlas 1s the Drum Store size was 96Kwords. The core store sizes were as follows –
Manchester 16Kw
London 32Kw
Chilton 48Kw
although, of course, you are free to set your own sizes.

Visible Paging

Selecting View/Physical Pages allows you to set or unset an option to show not only the page virtual addresses in use, but also their physical location within the core store and drum store.

B-Register Display

Normally only B-registers with non-zero values are shown during execution. Selecting View/Show All B-registers allows you override this behaviour.

Engineers’ Console

Selecting View/Engineers’ Console causes a representation of part of the Engineers‘ Console to appear –

The top row shows the contents of B120 - green for 1 , red for 0.

The second row represents the console handkeys which can be read of the 1127 extracode. represents a 0, , a 1. Clicking a handkey inverts the setting.

Note that the bit numbers displayed are “engineers’ style” i.e. “big endian” the opposite to “programmers’ style”.

Pre-Supervisor Mode

Selecting Configure/Pre-Supervisor Mode allows you to set or unset an option to relax the rules about address usage.

The option was used to accomodate rediscovery of the COMPILER COMPILER which was found to have violated the rules. It is known that this work was carried out before the final Supervisor was available. Our version of the COMPILER COMPILER has been modified to work with the later version of the supervisor though the original source code has been retained as comments. It seems unlikely that this facility will be of any further use.

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