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Further reading ⇓

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Paper No 10: FR80 Displayer Version 3.3

R E Thomas

24 September 1975

Version 3.3 of the FR80 Displayers will shortly come into full service. The alterations that have been made to the standard displayers are as follows:

  1. £ character has been inserted as character 3748, It replaces characters 2458 and 2468.
  2. A magnetic tape error will cause the tape order and the tape status word to be printed in octal at the teletype. The latter is negative and must be complemented before the bit pattern can be deciphered.
  3. The size of the characters used in the monitor display has been changed to prevent overlap.
  4. Large characters are simulated by software using vector orders. Two-word versions of character height, character space and line space are available.

  5. The GO command may have two parameters. The second will specify the number of filemarks to be read before the program halts. CONTINUE also has two parameters.

    If both record and filemark counts are provided, the program will halt with FRAMES DONE whichever count exhausts first.

    No frame advance is caused by the filemark. Hence, multi-tape jobs can be run without extra blank frames.

  6. A data error will cause three values to be printed at the teletype:
    1. The data word itself (in octal)
    2. the current record number (in decimal), counting from the last filemark
    3. the current position within the record (in decimal).
    The current record and position will indicate the word following the one that gave rise to the error.

  7. A new order: 236N00 allows the user to change vector speeds as follows:

    N         Speed (m secs)
0           8
1           4
2           2
3           1

    This order is temporary so that the facility can be tried. It will change when the new displayer is available.

  8. A new order: 22700+N allows the user to print, in octal, the contents of some of the FR80 internal variables onto the film, starting at the current location. Leading zeros are suppressed. The values of N, together with their meanings, are given below:

    N (octal)  Variable Printed
0          Cumulative frame count
1          Cumulative picture count 
2          Tape mode (DATCOM) 
3          Vector speed
4          Colour filter number 
5          Character hits count 
6          Vector hits count
7          Point hits count
10         Record number 
11         File number
12         Current buffer pointer 
13         Data word in buffer 
14         Current buffer address 
15         Pulldown 
16         Camera number 
17         Time (first of two) 
20         Time (second of two) 
21         Depth of picture nesting 
22         Spot size 
23         Intensity 
24         Character size 
25         Character rotation 
26         Character space.
27         Line space 
30         Address indicating vector mode
31         X offset
32         Y offset 
33         IO general status
34         Magnetic tape status
35         Disc status

    This order is temporary and is intended to assist debugging only.

  9. Monitor commands (excluding the /) are printed at the teletype as they are obeyed from Load-go tapes.

  10. A set of centralised characters has been defined to assist in character plotting:

    Character code (octal)  Character
     340                  - minus 
     341                  * asterisk 
     342                  + plus 
     343                  . full stop 
     344                  O letter O 
     345                  X letter X

    The following characters are no longer available: 240,241,242,252,253,261

  11. Fiche only: Switch 8 no longer controls the resetting of any index specified in a fiche title. The index number is reset automatically.
  12. Fiche only: Monitor commands read from tape are checked to prevent buffer overflow.
  13. Colour only: The clear filter is no longer automatically inserted when frame advance is encountered.
  14. OCRB3 Fonts only: Character 1368 (circumflex) has been corrected to prevent erroneous character overwriting when III standard font is reset.
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