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Second PE report (section 3b)

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Second PE report (section 3b)

Facilities

Our discussion of technical issues centered around the priority A, B, and C items from the first EPE report, reproduced below. The columns in the list have the following meaning:

Serial number - a serial numbering of the items, for later reference in this report. These are numbered in priority order, not in the L-P-T-X numbering system of the earlier report.

F/I/A code - the first working group’s opinion of how important it was to provide for this item from the beginning in the system design.

F - Fundamental, much harder if not allowed for originally

I - Intermediate, somewhat harder if not allowed for

A - Add-on, difficulty does not depend significantly on pre-planning (although it may be intrinsically hard anyway)

Amount of discussion - the amount of time we spent discussing the item in the current working group.

0 - didn’t even mention it
1 - mentioned in passing
2 - significant discussion
3 - major issue

L,M,S difficulty codes - the first working group’s conclusion about how difficult it would be to implement this item in Lisp, Mesa, or Smalltalk respectively.

0 - available
1 - easy
2 - straightforward but takes time
3 - hard

Serial number
|F/I/A code
||Amount of discussion
|||L,M,S difficulty codes
||||Name of item
|||||

Priority A

(A1)F3030Object management -- garbage collection/reference counting

(A2)F3203Statically checked type system

(A3)I0000Memory management -- object/page swapping

(A4)F3302Abstraction mechanisms; explicit notion of "interface"

(A5)I3020Fast turnaround for minor program changes (<5 sec)

(A6)F3?0?Adequate runtime efficiency

(A7)F1002Large virtual address space (> 24 bits)

Priority B

(B1)F3302Encapsulation/protection mechanisms (scopes, classes, import/export rules)

(B2)F1333Well-integrated access to large, robust data bases

(B3)I3020Self-typing data (a la Lisp and Smalltalk), run-time type system

(B4)A2203Consistent compilation

(B5)I1323Version control

(B6)F2000Source-language debugger

(B7)A1121Text objects and images

(B8)I1021Uniform screen management

(B9)A3202User access to the machine’s capability for packed data (see A6)

(B10)F3111Run-time availability of all information derivable from source program (e.g. names, types, scopes)

(B11)F2222CSL control over the system’s future

Priority C

(C1)A0102Direct addressing for files (segmenting)

(C2)I0000Some support for interrupts

(C3)I3021Compiler/interpreter available with low overhead at run time

(C4)I0012Adequate reference documentation

(C5)A1222Librarian, program-oriented filing system (incl. Browser)

(C6)I3012Program-manipulable representation of programs

(C7)I1011Dynamic measurement facilities

(C8)A0222Scanned (bitmap) objects and images

(C9)A0120Press files

(C10)F0010?"Efficient" interface for experts

(C11)A0222Line objects and images

(C12)A1001Remote file storage

The two following subsections of this report cover all the topics identified as "major issues" in the above list, as appropriate for the individual language.