Chilton::ACL::SPROGS Supplement

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Early history □ Minutes of committee meetings □ Progress reports □ Other reports □ News cuttings □ In-house publications □ Committee papers □ Personal recollections □ ACL publications □ Books □ Early Atlas publications □ FR80 reports □ Atlas manuals □ ICL1906A manuals □ Other manuals

Overview □ ICL1906A reference manual □ CAMPER (Computer Aided Movie Perspectives) □ CASS (Computer-Aided Sound Synthesis) □ COCOA □ FOG manual □ FR80 user manual □ GROATS (Graphics system) □ PIGS □ PLASYD □ SMOG □ SMOG/SPROGS primer □ SOL □ SPROGS (SD4020 PDP15 Rapid Output Graphics System) □ SPROGS supplement □ TASK □ TREE-META translator writing system

Further reading □ Contents □ 1. Regions □ 2. Output □ 3. Null files □ 4. Film routines □ 5. High level routines □ 6. SPROGS macro □ 7. Miscellaneous

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⟶ ACL ⟶ Literature ⟶ ICL 1906A manuals ⟶ SPROGS supplement

⟶ ACL ⟶ Literature ⟶ ICL 1906A manuals ⟶ SPROGS supplement

ACL ACD C&A INF CCD CISD Archives

Applications Associates Literature Society Technology Software revisited

Early history □ Minutes of committee meetings □ Progress reports □ Other reports □ News cuttings □ In-house publications □ Committee papers □ Personal recollections □ ACL publications □ Books □ Early Atlas publications □ FR80 reports □ Atlas manuals □ ICL1906A manuals □ Other manuals

Overview □ ICL1906A reference manual □ CAMPER (Computer Aided Movie Perspectives) □ CASS (Computer-Aided Sound Synthesis) □ COCOA □ FOG manual □ FR80 user manual □ GROATS (Graphics system) □ PIGS □ PLASYD □ SMOG □ SMOG/SPROGS primer □ SOL □ SPROGS (SD4020 PDP15 Rapid Output Graphics System) □ SPROGS supplement □ TASK □ TREE-META translator writing system

3. NULL FILES

3.1 Reading NULL Files

Previously, NULL files (*7.6) could only be read as data using index variables (AR function). The routine:

      NULVAL(F,FN,XN,XVAL)

will set XVAL to the value of the argument of the XN-th NULL in the NULL file called F, number FN.

Hence:

      NULVAL(ANAME ('FRED'),1.0,3.0,XVAL)

will set XVAL to 6.0, taking the file defined in section 1.1.

3.2 Change to NULSET

The routine NULSET (*7.7) allows NULL files to be obeyed by giving meaning to the NULL. The argument of NULSET has been changed from a display routine name to a display routine number, as defined in (*A3).

Thus:

      NULSET(32.0)

will set NULLs to be equivalent to TOXY and:

      NULSET(33.0)

will set NULLs to be equivalent to VEC.

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