ProposedChanges

User Interface

The proposal of the report was that a Digital Design Environment (DDE) should be developed. This would primarily consist of a user interface, which would be used by the designer to access all the tools. The interface would ideally be of the mouse/windows type, probably X windows; X is a widely accepted standard,and it seems likely that the designer would have access to a workstation with a bit-mapped display. The user interface provided by the DDE would have to be used to access the design tools - under no circumstances could the designer be allowed to use the tools directly. In this way, there would be a totally uniform interface to the various tools, with command line options and flags automatically taken care of.

Expand ability and Adaptability

All aspects of the DDE should be totally configurable. This would enable the designer to incorporate new tools by specifying the file formats used, the function of the tool and so Byonin.cluding a list of machines on which the tool could be run, the associated problems could be automaticallytaken care of. The structure of the menus of the user interface could also be altered according to personal taste, or to suit a particular project. Thismight include adding frequently used Unix commands to the menus, orc hanging the orders of choices, Also, the user could easily set up their favourite editor to be invoked where necessary, configure different tools to be used fodri fferentblocks, and so on.

Process Management

The design process would be closely managed by the DDE, enforcing the designer to follow the design stages in the correct order. As a design is developed, the DDE would aid the designer by automatically applying the tools where appropriate. It would also be able to collate the test results and compare them with the last results; in this way, the effects of changes in the design would be readily highlighted. The test input patterns for a block could be generated from the block’s logical description (e.g. finite state machine definition), to allow totally automatic testing.
When hurried, for example when nearing a deadline, it is all too easy to mis-type commands or forget to do certain things. With the process managementprovided by the DDE, this would not be possible.
There would also be an option to leave the DDE running through the design process unattended, if for
example, a large design was to be simulated. The running of the various tools would be done automatically, and state informationkept from stage to stage, so that followinga machine failure and reboot, the minimum of processing would have to repeated.

Design Management

The DDE would make extensive use of a revision control system (such as rcs in Unix). This would make sure that every version of every part of a design was available, along with the results of every associated simulation. The designer would have no choice but to use this, and would be forced to enter a comment for each change made. The system would also prevent unauthorised users from looking at or changing designs not created by themselves.
Hierarchical designs would be made easier by the introduction of simple descriptions outlining the relationships between different blocks in the hierarchy. Having entered these relationships, the structure of the design would be enforced. New blocks could be created easily by using a similar existing block as a basis,thereby setting up all the necessary files automatically. Shared data would ideally be held in a central with no replication, thus eliminating any problems of inconsistencies. Failing this, relationships between replicated data would be maintained, therefore allowing automatic propagation of changes through the system, and again taking the onus from the designer.

Invisibility

Finally, all the details not pertinent to the designer’s use of the system would be hidden. For example, the file format conversion required between tools would happen automatically, without the knowledge of the designer. It would be possible to introduce a common format for use with all of the tools, along with filters to be used before and after each tool to perform any required conversion. In this way, any new tool requires at most two new filters, and it can then interface with any other tool. (The EDIF language is probably most suitablefor this purpose.)
Similarly, if a certain tool runs only on certain machines, then this will be handled automatically. Even if the machine running the DDE is not able to run a certain tool, it will send the job to one which can, wait for completion and get the results, all totally invisibly to the designer.


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