15-01-88/BUF\INF

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15-01-88/BUF\INF

This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.

Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.

Tape/disk:	Home » CEEFAX disks » telesoftware4.adl
Filename:	15-01-88/BUF\INF
Read OK:	✔
File size:	2CD6 bytes
Load address:	0000
Exec address:	0000

Duplicates

There is 1 duplicate copy of this file in the archive:

CEEFAX disks » telesoftware2.adl » BUF\INF
CEEFAX disks » telesoftware4.adl » 15-01-88/BUF\INF

File contents

                         I/O Printer Buffer  M.J.Rawlings - PAGE : 1






                          I/O PRINTER BUFFER

          Printer  buffers  can be set up anywhere in memory, sideways
ram being the favourite location,  and  there  are  numerous  versions
available.  But if you have no sideways ram or you have already filled
up your sideways ram with utilities you may be wondering how  you  can
set up a printer buffer. This program is the answer, it can be used to
put  a printer buffer anywhere in the I/O memory (the main memory area
for those unfortunates without second processors), it can be as  large
or as small as space allows.

          The  program  as  broadcast is the version I use, it gives a
22.75K buffer and is suitable for a system with second  processor  and
running  a  program  that  uses  mode  7  only, but this can easily be
altered to be compatible with any BBC or  ELECTRON  or  MASTER/COMPACT
setup with or without a second/co processor. Even the smallest printer
buffer  can  make  a  big  difference  to  the waiting time before the
computer is back under your control, although a 2K buffer  (about  one
page  of  loosely spaced text) is probably the minimum practical size.
The code to do all this is 249  bytes  long  and  will  fit  into  any
available page of memory.

                          USING THE PROGRAM

          On  running  the  program the code is automatically saved to
disk or cassette with the correct I/O relocation address regardless of
the addresses chosen. Once the code has been saved the printer  buffer
can be set up simply by pressing <BREAK> then typing:-

                          *PRNTBUF  <RETURN>

          This loads and executes the code to alter the buffer vectors
but  does  not  turn  on  the new printer buffer, any operating system
calls to the buffer vectors are redirected via the new  code  back  to
the old vectors. Two new osbyte calls are then used to turn the buffer
on  or off, *FX128,128 sets up the buffer start addresses and turns on
the printer buffer flag, and *FX128,129 is used to revert to the BBC's
original buffer.





















                         I/O Printer Buffer  M.J.Rawlings - PAGE : 2





          All the usual *FX commands are enabled with the  new  buffer
as well as the ADVAL facility:-
          
          *FX15            Flush all buffers.
          *FX21,3          Flush printer buffer only.
          Osbyte &80 (128) Read ADC channel/get buffer status.
          *FX128,128       Turn on new printer buffer.
          *FX128,129       Turn off new printer buffer.
          *FX138,3,<char>  Insert character into printer buffer.
          Osbyte &91 (145) Remove character from buffer.
          Osbyte &98 (152) Examine buffer status.
          *FX153,3,<char>  Insert character into printer buffer.
          ADVAL(-4)        Returns number of free spaces in printer
                           buffer.
          ESCAPE           Pressing ESCAPE will flush all buffers.
          
Note  that *FX128,128 can also be used to flush the new printer buffer
when in use. Do not try to reset the  printer  buffer  with  a  second
*PRNTBUF  command  as  this  will incorrectly set the vectors and will
cause the computer  to  hang  up.  Pressing  break  will  restore  the
original default vectors.

                          LOCATING THE CODE

          The following addresses are suitable for storing the machine
code, simply change the Code Address (P%).

&900 to &9FF Not for cassette users.
             Not for speech system users.
             Not if sound envelopes 5-16 are in use.
             Not if RS423 port is in use.

&A00 TO &AFF Not for cassette users.
             Not if RS423 port is in use.

&B00 TO &BFF Not if function keys are in use.

&C00 TO &CFF Not if characters 224-255 are redefined.

          Alternatively  the  code  can  be located in the main memory
area before or after the space allocated to the buffer, though a below
PAGE address is safer.

          The program uses 7 bytes of zero page workspace from &78  to
&7E, if this clashes with other utilities or your own program then any
zero page space from &70 to &9F can be used, Econet users should avoid
&90 to &9F and second processor users should avoid &70 to &77.

                     LOCATING THE PRINTER BUFFER

          The  start  and end addresses must be whole page values i.e.
&7800 not &78CD, this is because only the most significant byte of the
address is used to test for the end of the buffer and  to  wrap  round
the read and write addresses back to the start.






                         I/O Printer Buffer  M.J.Rawlings - PAGE : 3






          The  end  address depends purely on the graphics mode in use
and should be at least one page (&100) below the graphics area. If the
code is assembled above the buffer area then P% should be the same  as
the  end  address and at least 2 pages (&200) below the graphics area,
(the program as printed stores the code in this fashion). This  is  to
allow room for the basic stack (basic's temporary storage space).

          Example end addresses:-
          
          Mode0,1,2   &2F00 (&2E00 if code is above buffer)
          Mode3       &3F00 (&3E00 if code is above buffer)
          Mode4,5     &5700 (&5600 if code is above buffer)
          Mode6       &5F00 (&5E00 if code is above buffer)
          Mode7       &7B00 (&7A00 if code is above buffer)
          
          Without  a second processor the start address depends on how
much memory is being used by  your  program.  Variables  used  by  the
program  are  stored  on  the heap (from LOMEM upwards) and the lowest
available address above the  heap  can  be  found  after  running  the
program, by typing:-

          PRINT~!2 AND&FFFF

          To  be  on  the save side set HIMEM and the start address to
the next whole page+1 above this value, this avoids the possibility of
program variables corrupting the buffer. If HIMEM is set in  this  way
then  the  end address can be one page higher than the examples above.
This technique also prevents *COPY, *BACKUP and *COMPACT commands from
corrupting the contents of the  buffer  or  the  code  itself.  Second
processor  users  should, if possible, store the code below page as it
is not possible to reset HIMEM in the I/O processor  from  the  second
processor.  If  the  code does become corrupted then the computer will
hang up as the buffer vectors are constantly in use under the  control
of operating system generated interrupts.

          With a second processor and disk drives connected the lowest
default  start  address  is &1F00 (as printed), this can be lowered to
&1900 after a *FX20 command to implode the  character  definitions.  A
maximum  printer  buffer  size  of 26k is attainable by lowering OSHWM
(operating system high water mark) to &1300 with a  *FX180,19  command
but  this  allows  you  to open only one disk file at a time. Cassette
users should set the start address to &1400 (25.75k buffer)  with  the
character  definitions  exploded or &E00 (27.25k buffer) with imploded
character  definitions.  Naturally  these  address  will  have  to  be
increased  by  one  page  if  you  wish  to locate the code before the
buffer.













                          I/O Printer Buffer  M.J.Rawlings - PAGE : 4





                            ERROR HANDLING

          It is common  practice  to  use  the  BBC's  error  handling
facilites  to return control to a main menu simply by pressing escape,
unfortunately pressing escape will  also  flush  all  buffers  thereby
stopping  printer  output. Two extra bytes of code can be added to the
program to prevent this:-

          320 PLP
          330 RTS

          This alteration also stops *FX15 and *FX21,3  from  flushing
the  printer  buffer  but  does  not affect the normal action of these
commands or ESCAPE on all the other buffers. The printer  buffer  can,
however, still be flushed using *FX128,128.

                        MACHINE CODE ROUTINES

          
          set        Move insert vector from &22A,B to insert1
                     Move remove vector from &22C,D to remove1
                     Move count/purge vector from &22E,F to count1
                     Store insert2 address at &22A,B
                     Store remove2 address at &22C,D
                     Store count2 address at &22E,F
          
          ins2       New insert routine
          
          old1       Divert to original insert routine
          
          rem2       New remove routine
          
          old2       Divert to original remove routine
          
          cnt2       New count/purge routine
          
          flsh       Resets read and write addresses to start
                     sets flag to empty
          
          old3       Divert to old count/purge routine
          
          S          Subroutine to update read and write addresses


















                          I/O Printer Buffer  M.J.Rawlings - PAGE : 5





                              VARIABLES

          
          ins1       Relocated address for old insert vector
          
          rem1       Relocated address for old remove vector
          
          cnt1       Relocated address for old count/purge vector
          
          ins        Address of next free space for insertion
          
          rem        Address of next character to be removed
          
          ext        No of characters still remaining in buffer
          
          f          Indicates state of buffer
                         0 = buffer not in use
                         1 = buffer in use
                         2 = buffer empty
                         3 = buffer full
          
          start      Start address of buffer
          
          end        End address of buffer
          
          init       Address of data for initialising buffer
          
          osc        Address of string used for OSCLI call
          
          sve        Address of string for relocation address
          

                       CUSTOMISING THE PROGRAM

          The  parts of the program that can be customised are clearly
marked with REM statements. The  program  contains  its  own  detailed
tests  which  use  the  buffer in order to test it and will report any
errors found. These tests may overwrite the  program  so  remember  to
save  it  first. Also make sure that your printer is turned off before
running the program. In fact in order  to  avoid  the  possibility  of
saving  a  corrupted  version  of  the  program it is designed to self
destruct after the code has been saved! If  all  is  well  you  should
see:-


               SAVE PRNTBUF 7A00 7AF9 FFFF7A00 FFFF7A00
               
               
               
               Bad program
               >
               
               







                         I/O Printer Buffer  M.J.Rawlings - PAGE : 6





          The  final  test  is, of course, to use the buffer on a long
print run, preferably longer than the buffer size, to confirm  correct
buffer "wrap around".

          Next  week  we will be broadcasting a program that will give
the I/O printer buffer a thorough test:- a program that incorporates a
teletext page storage system capable of storing  up  to  764  teletext
pages  on one disk (depending on type of DFS and drive), together with
instant printout and editing facilities.

00000000  20 20 20 20 20 20 20 20  20 20 20 20 20 20 20 20  |                |
00000010  20 20 20 20 20 20 20 20  20 49 2f 4f 20 50 72 69  |         I/O Pri|
00000020  6e 74 65 72 20 42 75 66  66 65 72 20 20 4d 2e 4a  |nter Buffer  M.J|
00000030  2e 52 61 77 6c 69 6e 67  73 20 2d 20 50 41 47 45  |.Rawlings - PAGE|
00000040  20 3a 20 31 0d 0d 0d 0d  0d 0d 0d 20 20 20 20 20  | : 1.......     |
00000050  20 20 20 20 20 20 20 20  20 20 20 20 20 20 20 20  |                |
00000060  20 20 20 20 20 49 2f 4f  20 50 52 49 4e 54 45 52  |     I/O PRINTER|
00000070  20 42 55 46 46 45 52 0d  0d 20 20 20 20 20 20 20  | BUFFER..       |
00000080  20 20 20 50 72 69 6e 74  65 72 20 20 62 75 66 66  |   Printer  buff|
00000090  65 72 73 20 20 63 61 6e  20 62 65 20 73 65 74 20  |ers  can be set |
000000a0  75 70 20 61 6e 79 77 68  65 72 65 20 69 6e 20 6d  |up anywhere in m|
000000b0  65 6d 6f 72 79 2c 20 73  69 64 65 77 61 79 73 0d  |emory, sideways.|
000000c0  72 61 6d 20 62 65 69 6e  67 20 74 68 65 20 66 61  |ram being the fa|
000000d0  76 6f 75 72 69 74 65 20  6c 6f 63 61 74 69 6f 6e  |vourite location|
000000e0  2c 20 20 61 6e 64 20 20  74 68 65 72 65 20 20 61  |,  and  there  a|
000000f0  72 65 20 20 6e 75 6d 65  72 6f 75 73 20 20 76 65  |re  numerous  ve|
00000100  72 73 69 6f 6e 73 0d 61  76 61 69 6c 61 62 6c 65  |rsions.available|
00000110  2e 20 20 42 75 74 20 69  66 20 79 6f 75 20 68 61  |.  But if you ha|
00000120  76 65 20 6e 6f 20 73 69  64 65 77 61 79 73 20 72  |ve no sideways r|
00000130  61 6d 20 6f 72 20 79 6f  75 20 68 61 76 65 20 61  |am or you have a|
00000140  6c 72 65 61 64 79 20 66  69 6c 6c 65 64 0d 75 70  |lready filled.up|
00000150  20 79 6f 75 72 20 73 69  64 65 77 61 79 73 20 72  | your sideways r|
00000160  61 6d 20 77 69 74 68 20  75 74 69 6c 69 74 69 65  |am with utilitie|
00000170  73 20 79 6f 75 20 6d 61  79 20 62 65 20 77 6f 6e  |s you may be won|
00000180  64 65 72 69 6e 67 20 68  6f 77 20 20 79 6f 75 20  |dering how  you |
00000190  20 63 61 6e 0d 73 65 74  20 75 70 20 61 20 70 72  | can.set up a pr|
000001a0  69 6e 74 65 72 20 62 75  66 66 65 72 2e 20 54 68  |inter buffer. Th|
000001b0  69 73 20 70 72 6f 67 72  61 6d 20 69 73 20 74 68  |is program is th|
000001c0  65 20 61 6e 73 77 65 72  2c 20 69 74 20 63 61 6e  |e answer, it can|
000001d0  20 62 65 20 75 73 65 64  20 74 6f 0d 70 75 74 20  | be used to.put |
000001e0  20 61 20 70 72 69 6e 74  65 72 20 62 75 66 66 65  | a printer buffe|
000001f0  72 20 61 6e 79 77 68 65  72 65 20 69 6e 20 74 68  |r anywhere in th|
00000200  65 20 49 2f 4f 20 6d 65  6d 6f 72 79 20 28 74 68  |e I/O memory (th|
00000210  65 20 6d 61 69 6e 20 6d  65 6d 6f 72 79 20 61 72  |e main memory ar|
00000220  65 61 0d 66 6f 72 20 74  68 6f 73 65 20 75 6e 66  |ea.for those unf|
00000230  6f 72 74 75 6e 61 74 65  73 20 77 69 74 68 6f 75  |ortunates withou|
00000240  74 20 73 65 63 6f 6e 64  20 70 72 6f 63 65 73 73  |t second process|
00000250  6f 72 73 29 2c 20 69 74  20 63 61 6e 20 62 65 20  |ors), it can be |
00000260  61 73 20 20 6c 61 72 67  65 0d 6f 72 20 61 73 20  |as  large.or as |
00000270  73 6d 61 6c 6c 20 61 73  20 73 70 61 63 65 20 61  |small as space a|
00000280  6c 6c 6f 77 73 2e 0d 0d  20 20 20 20 20 20 20 20  |llows...        |
00000290  20 20 54 68 65 20 20 70  72 6f 67 72 61 6d 20 20  |  The  program  |
000002a0  61 73 20 20 62 72 6f 61  64 63 61 73 74 20 69 73  |as  broadcast is|
000002b0  20 74 68 65 20 76 65 72  73 69 6f 6e 20 49 20 75  | the version I u|
000002c0  73 65 2c 20 69 74 20 67  69 76 65 73 20 61 0d 32  |se, it gives a.2|
000002d0  32 2e 37 35 4b 20 62 75  66 66 65 72 20 61 6e 64  |2.75K buffer and|
000002e0  20 69 73 20 73 75 69 74  61 62 6c 65 20 66 6f 72  | is suitable for|
000002f0  20 61 20 73 79 73 74 65  6d 20 77 69 74 68 20 73  | a system with s|
00000300  65 63 6f 6e 64 20 20 70  72 6f 63 65 73 73 6f 72  |econd  processor|
00000310  20 20 61 6e 64 0d 72 75  6e 6e 69 6e 67 20 20 61  |  and.running  a|
00000320  20 20 70 72 6f 67 72 61  6d 20 20 74 68 61 74 20  |  program  that |
00000330  20 75 73 65 73 20 20 6d  6f 64 65 20 20 37 20 20  | uses  mode  7  |
00000340  6f 6e 6c 79 2c 20 62 75  74 20 74 68 69 73 20 63  |only, but this c|
00000350  61 6e 20 65 61 73 69 6c  79 20 62 65 0d 61 6c 74  |an easily be.alt|
00000360  65 72 65 64 20 74 6f 20  62 65 20 63 6f 6d 70 61  |ered to be compa|
00000370  74 69 62 6c 65 20 77 69  74 68 20 61 6e 79 20 42  |tible with any B|
00000380  42 43 20 6f 72 20 20 45  4c 45 43 54 52 4f 4e 20  |BC or  ELECTRON |
00000390  20 6f 72 20 20 4d 41 53  54 45 52 2f 43 4f 4d 50  | or  MASTER/COMP|
000003a0  41 43 54 0d 73 65 74 75  70 20 77 69 74 68 20 6f  |ACT.setup with o|
000003b0  72 20 77 69 74 68 6f 75  74 20 61 20 73 65 63 6f  |r without a seco|
000003c0  6e 64 2f 63 6f 20 70 72  6f 63 65 73 73 6f 72 2e  |nd/co processor.|
000003d0  20 45 76 65 6e 20 74 68  65 20 73 6d 61 6c 6c 65  | Even the smalle|
000003e0  73 74 20 70 72 69 6e 74  65 72 0d 62 75 66 66 65  |st printer.buffe|
000003f0  72 20 20 63 61 6e 20 20  6d 61 6b 65 20 20 61 20  |r  can  make  a |
00000400  20 62 69 67 20 20 64 69  66 66 65 72 65 6e 63 65  | big  difference|
00000410  20 20 74 6f 20 20 74 68  65 20 77 61 69 74 69 6e  |  to  the waitin|
00000420  67 20 74 69 6d 65 20 62  65 66 6f 72 65 20 74 68  |g time before th|
00000430  65 0d 63 6f 6d 70 75 74  65 72 20 69 73 20 62 61  |e.computer is ba|
00000440  63 6b 20 75 6e 64 65 72  20 79 6f 75 72 20 63 6f  |ck under your co|
00000450  6e 74 72 6f 6c 2c 20 61  6c 74 68 6f 75 67 68 20  |ntrol, although |
00000460  61 20 32 4b 20 62 75 66  66 65 72 20 20 28 61 62  |a 2K buffer  (ab|
00000470  6f 75 74 20 20 6f 6e 65  0d 70 61 67 65 20 20 6f  |out  one.page  o|
00000480  66 20 20 6c 6f 6f 73 65  6c 79 20 73 70 61 63 65  |f  loosely space|
00000490  64 20 74 65 78 74 29 20  69 73 20 70 72 6f 62 61  |d text) is proba|
000004a0  62 6c 79 20 74 68 65 20  6d 69 6e 69 6d 75 6d 20  |bly the minimum |
000004b0  70 72 61 63 74 69 63 61  6c 20 73 69 7a 65 2e 0d  |practical size..|
000004c0  54 68 65 20 63 6f 64 65  20 74 6f 20 64 6f 20 61  |The code to do a|
000004d0  6c 6c 20 74 68 69 73 20  69 73 20 32 34 39 20 20  |ll this is 249  |
000004e0  62 79 74 65 73 20 20 6c  6f 6e 67 20 20 61 6e 64  |bytes  long  and|
000004f0  20 20 77 69 6c 6c 20 20  66 69 74 20 20 69 6e 74  |  will  fit  int|
00000500  6f 20 20 61 6e 79 0d 61  76 61 69 6c 61 62 6c 65  |o  any.available|
00000510  20 70 61 67 65 20 6f 66  20 6d 65 6d 6f 72 79 2e  | page of memory.|
00000520  0d 0d 20 20 20 20 20 20  20 20 20 20 20 20 20 20  |..              |
00000530  20 20 20 20 20 20 20 20  20 20 20 20 55 53 49 4e  |            USIN|
00000540  47 20 54 48 45 20 50 52  4f 47 52 41 4d 0d 0d 20  |G THE PROGRAM.. |
00000550  20 20 20 20 20 20 20 20  20 4f 6e 20 20 72 75 6e  |         On  run|
00000560  6e 69 6e 67 20 20 74 68  65 20 20 70 72 6f 67 72  |ning  the  progr|
00000570  61 6d 20 74 68 65 20 63  6f 64 65 20 69 73 20 61  |am the code is a|
00000580  75 74 6f 6d 61 74 69 63  61 6c 6c 79 20 73 61 76  |utomatically sav|
00000590  65 64 20 74 6f 0d 64 69  73 6b 20 6f 72 20 63 61  |ed to.disk or ca|
000005a0  73 73 65 74 74 65 20 77  69 74 68 20 74 68 65 20  |ssette with the |
000005b0  63 6f 72 72 65 63 74 20  49 2f 4f 20 72 65 6c 6f  |correct I/O relo|
000005c0  63 61 74 69 6f 6e 20 61  64 64 72 65 73 73 20 72  |cation address r|
000005d0  65 67 61 72 64 6c 65 73  73 20 6f 66 0d 74 68 65  |egardless of.the|
000005e0  20 61 64 64 72 65 73 73  65 73 20 63 68 6f 73 65  | addresses chose|
000005f0  6e 2e 20 4f 6e 63 65 20  74 68 65 20 63 6f 64 65  |n. Once the code|
00000600  20 68 61 73 20 62 65 65  6e 20 73 61 76 65 64 20  | has been saved |
00000610  74 68 65 20 70 72 69 6e  74 65 72 20 20 62 75 66  |the printer  buf|
00000620  66 65 72 0d 63 61 6e 20  62 65 20 73 65 74 20 75  |fer.can be set u|
00000630  70 20 73 69 6d 70 6c 79  20 62 79 20 70 72 65 73  |p simply by pres|
00000640  73 69 6e 67 20 3c 42 52  45 41 4b 3e 20 74 68 65  |sing <BREAK> the|
00000650  6e 20 74 79 70 69 6e 67  3a 2d 0d 0d 20 20 20 20  |n typing:-..    |
00000660  20 20 20 20 20 20 20 20  20 20 20 20 20 20 20 20  |                |
00000670  20 20 20 20 20 20 2a 50  52 4e 54 42 55 46 20 20  |      *PRNTBUF  |
00000680  3c 52 45 54 55 52 4e 3e  0d 0d 20 20 20 20 20 20  |<RETURN>..      |
00000690  20 20 20 20 54 68 69 73  20 6c 6f 61 64 73 20 61  |    This loads a|
000006a0  6e 64 20 65 78 65 63 75  74 65 73 20 74 68 65 20  |nd executes the |
000006b0  63 6f 64 65 20 74 6f 20  61 6c 74 65 72 20 74 68  |code to alter th|
000006c0  65 20 62 75 66 66 65 72  20 76 65 63 74 6f 72 73  |e buffer vectors|
000006d0  0d 62 75 74 20 20 64 6f  65 73 20 20 6e 6f 74 20  |.but  does  not |
000006e0  20 74 75 72 6e 20 20 6f  6e 20 20 74 68 65 20 6e  | turn  on  the n|
000006f0  65 77 20 70 72 69 6e 74  65 72 20 62 75 66 66 65  |ew printer buffe|
00000700  72 2c 20 61 6e 79 20 6f  70 65 72 61 74 69 6e 67  |r, any operating|
00000710  20 73 79 73 74 65 6d 0d  63 61 6c 6c 73 20 74 6f  | system.calls to|
00000720  20 74 68 65 20 62 75 66  66 65 72 20 76 65 63 74  | the buffer vect|
00000730  6f 72 73 20 61 72 65 20  72 65 64 69 72 65 63 74  |ors are redirect|
00000740  65 64 20 76 69 61 20 74  68 65 20 6e 65 77 20 20  |ed via the new  |
00000750  63 6f 64 65 20 20 62 61  63 6b 20 20 74 6f 0d 74  |code  back  to.t|
00000760  68 65 20 6f 6c 64 20 76  65 63 74 6f 72 73 2e 20  |he old vectors. |
00000770  54 77 6f 20 6e 65 77 20  6f 73 62 79 74 65 20 63  |Two new osbyte c|
00000780  61 6c 6c 73 20 61 72 65  20 74 68 65 6e 20 75 73  |alls are then us|
00000790  65 64 20 74 6f 20 74 75  72 6e 20 74 68 65 20 62  |ed to turn the b|
000007a0  75 66 66 65 72 0d 6f 6e  20 20 6f 72 20 6f 66 66  |uffer.on  or off|
000007b0  2c 20 2a 46 58 31 32 38  2c 31 32 38 20 73 65 74  |, *FX128,128 set|
000007c0  73 20 75 70 20 74 68 65  20 62 75 66 66 65 72 20  |s up the buffer |
000007d0  73 74 61 72 74 20 61 64  64 72 65 73 73 65 73 20  |start addresses |
000007e0  61 6e 64 20 74 75 72 6e  73 20 6f 6e 0d 74 68 65  |and turns on.the|
000007f0  20 70 72 69 6e 74 65 72  20 62 75 66 66 65 72 20  | printer buffer |
00000800  66 6c 61 67 2c 20 61 6e  64 20 2a 46 58 31 32 38  |flag, and *FX128|
00000810  2c 31 32 39 20 69 73 20  75 73 65 64 20 74 6f 20  |,129 is used to |
00000820  72 65 76 65 72 74 20 74  6f 20 74 68 65 20 42 42  |revert to the BB|
00000830  43 27 73 0d 6f 72 69 67  69 6e 61 6c 20 62 75 66  |C's.original buf|
00000840  66 65 72 2e 0d 0d 0d 0d  0d 0d 0d 0d 0d 0d 0d 0d  |fer.............|
00000850  0d 0d 0d 0d 0d 0d 0d 0d  0d 0d 20 20 20 20 20 20  |..........      |
00000860  20 20 20 20 20 20 20 20  20 20 20 20 20 20 20 20  |                |
00000870  20 20 20 49 2f 4f 20 50  72 69 6e 74 65 72 20 42  |   I/O Printer B|
00000880  75 66 66 65 72 20 20 4d  2e 4a 2e 52 61 77 6c 69  |uffer  M.J.Rawli|
00000890  6e 67 73 20 2d 20 50 41  47 45 20 3a 20 32 0d 0d  |ngs - PAGE : 2..|
000008a0  0d 0d 0d 0d 20 20 20 20  20 20 20 20 20 20 41 6c  |....          Al|
000008b0  6c 20 74 68 65 20 75 73  75 61 6c 20 2a 46 58 20  |l the usual *FX |
000008c0  63 6f 6d 6d 61 6e 64 73  20 61 72 65 20 65 6e 61  |commands are ena|
000008d0  62 6c 65 64 20 77 69 74  68 20 74 68 65 20 20 6e  |bled with the  n|
000008e0  65 77 20 20 62 75 66 66  65 72 0d 61 73 20 77 65  |ew  buffer.as we|
000008f0  6c 6c 20 61 73 20 74 68  65 20 41 44 56 41 4c 20  |ll as the ADVAL |
00000900  66 61 63 69 6c 69 74 79  3a 2d 0d 20 20 20 20 20  |facility:-.     |
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00000920  2a 46 58 31 35 20 20 20  20 20 20 20 20 20 20 20  |*FX15           |
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000027b0  54 68 65 20 20 70 61 72  74 73 20 6f 66 20 74 68  |The  parts of th|
000027c0  65 20 70 72 6f 67 72 61  6d 20 74 68 61 74 20 63  |e program that c|
000027d0  61 6e 20 62 65 20 63 75  73 74 6f 6d 69 73 65 64  |an be customised|
000027e0  20 61 72 65 20 63 6c 65  61 72 6c 79 0d 6d 61 72  | are clearly.mar|
000027f0  6b 65 64 20 77 69 74 68  20 52 45 4d 20 73 74 61  |ked with REM sta|
00002800  74 65 6d 65 6e 74 73 2e  20 54 68 65 20 20 70 72  |tements. The  pr|
00002810  6f 67 72 61 6d 20 20 63  6f 6e 74 61 69 6e 73 20  |ogram  contains |
00002820  20 69 74 73 20 20 6f 77  6e 20 20 64 65 74 61 69  | its  own  detai|
00002830  6c 65 64 0d 74 65 73 74  73 20 20 77 68 69 63 68  |led.tests  which|
00002840  20 20 75 73 65 20 20 74  68 65 20 20 62 75 66 66  |  use  the  buff|
00002850  65 72 20 69 6e 20 6f 72  64 65 72 20 74 6f 20 74  |er in order to t|
00002860  65 73 74 20 69 74 20 61  6e 64 20 77 69 6c 6c 20  |est it and will |
00002870  72 65 70 6f 72 74 20 61  6e 79 0d 65 72 72 6f 72  |report any.error|
00002880  73 20 66 6f 75 6e 64 2e  20 54 68 65 73 65 20 74  |s found. These t|
00002890  65 73 74 73 20 6d 61 79  20 6f 76 65 72 77 72 69  |ests may overwri|
000028a0  74 65 20 74 68 65 20 20  70 72 6f 67 72 61 6d 20  |te the  program |
000028b0  20 73 6f 20 20 72 65 6d  65 6d 62 65 72 20 20 74  | so  remember  t|
000028c0  6f 0d 73 61 76 65 20 20  69 74 20 20 66 69 72 73  |o.save  it  firs|
000028d0  74 2e 20 41 6c 73 6f 20  6d 61 6b 65 20 73 75 72  |t. Also make sur|
000028e0  65 20 74 68 61 74 20 79  6f 75 72 20 70 72 69 6e  |e that your prin|
000028f0  74 65 72 20 69 73 20 74  75 72 6e 65 64 20 6f 66  |ter is turned of|
00002900  66 20 62 65 66 6f 72 65  0d 72 75 6e 6e 69 6e 67  |f before.running|
00002910  20 74 68 65 20 70 72 6f  67 72 61 6d 2e 20 49 6e  | the program. In|
00002920  20 66 61 63 74 20 69 6e  20 6f 72 64 65 72 20 20  | fact in order  |
00002930  74 6f 20 20 61 76 6f 69  64 20 20 74 68 65 20 20  |to  avoid  the  |
00002940  70 6f 73 73 69 62 69 6c  69 74 79 20 20 6f 66 0d  |possibility  of.|
00002950  73 61 76 69 6e 67 20 20  61 20 20 63 6f 72 72 75  |saving  a  corru|
00002960  70 74 65 64 20 20 76 65  72 73 69 6f 6e 20 20 6f  |pted  version  o|
00002970  66 20 20 74 68 65 20 20  70 72 6f 67 72 61 6d 20  |f  the  program |
00002980  69 74 20 69 73 20 64 65  73 69 67 6e 65 64 20 74  |it is designed t|
00002990  6f 20 73 65 6c 66 0d 64  65 73 74 72 75 63 74 20  |o self.destruct |
000029a0  61 66 74 65 72 20 74 68  65 20 63 6f 64 65 20 68  |after the code h|
000029b0  61 73 20 62 65 65 6e 20  73 61 76 65 64 21 20 49  |as been saved! I|
000029c0  66 20 20 61 6c 6c 20 20  69 73 20 20 77 65 6c 6c  |f  all  is  well|
000029d0  20 20 79 6f 75 20 20 73  68 6f 75 6c 64 0d 73 65  |  you  should.se|
000029e0  65 3a 2d 0d 0d 0d 20 20  20 20 20 20 20 20 20 20  |e:-...          |
000029f0  20 20 20 20 20 53 41 56  45 20 50 52 4e 54 42 55  |     SAVE PRNTBU|
00002a00  46 20 37 41 30 30 20 37  41 46 39 20 46 46 46 46  |F 7A00 7AF9 FFFF|
00002a10  37 41 30 30 20 46 46 46  46 37 41 30 30 0d 20 20  |7A00 FFFF7A00.  |
00002a20  20 20 20 20 20 20 20 20  20 20 20 20 20 0d 20 20  |             .  |
*
00002a50  20 20 20 20 20 20 20 20  20 20 20 20 20 42 61 64  |             Bad|
00002a60  20 70 72 6f 67 72 61 6d  0d 20 20 20 20 20 20 20  | program.       |
00002a70  20 20 20 20 20 20 20 20  3e 0d 20 20 20 20 20 20  |        >.      |
00002a80  20 20 20 20 20 20 20 20  20 0d 20 20 20 20 20 20  |         .      |
00002a90  20 20 20 20 20 20 20 20  20 0d 0d 0d 0d 0d 0d 0d  |         .......|
00002aa0  0d 20 20 20 20 20 20 20  20 20 20 20 20 20 20 20  |.               |
00002ab0  20 20 20 20 20 20 20 20  20 20 49 2f 4f 20 50 72  |          I/O Pr|
00002ac0  69 6e 74 65 72 20 42 75  66 66 65 72 20 20 4d 2e  |inter Buffer  M.|
00002ad0  4a 2e 52 61 77 6c 69 6e  67 73 20 2d 20 50 41 47  |J.Rawlings - PAG|
00002ae0  45 20 3a 20 36 0d 0d 0d  0d 0d 0d 20 20 20 20 20  |E : 6......     |
00002af0  20 20 20 20 20 54 68 65  20 20 66 69 6e 61 6c 20  |     The  final |
00002b00  20 74 65 73 74 20 20 69  73 2c 20 6f 66 20 63 6f  | test  is, of co|
00002b10  75 72 73 65 2c 20 74 6f  20 75 73 65 20 74 68 65  |urse, to use the|
00002b20  20 62 75 66 66 65 72 20  6f 6e 20 61 20 6c 6f 6e  | buffer on a lon|
00002b30  67 0d 70 72 69 6e 74 20  72 75 6e 2c 20 70 72 65  |g.print run, pre|
00002b40  66 65 72 61 62 6c 79 20  6c 6f 6e 67 65 72 20 74  |ferably longer t|
00002b50  68 61 6e 20 74 68 65 20  62 75 66 66 65 72 20 73  |han the buffer s|
00002b60  69 7a 65 2c 20 74 6f 20  63 6f 6e 66 69 72 6d 20  |ize, to confirm |
00002b70  20 63 6f 72 72 65 63 74  0d 62 75 66 66 65 72 20  | correct.buffer |
00002b80  22 77 72 61 70 20 61 72  6f 75 6e 64 22 2e 0d 0d  |"wrap around"...|
00002b90  20 20 20 20 20 20 20 20  20 20 4e 65 78 74 20 20  |          Next  |
00002ba0  77 65 65 6b 20 20 77 65  20 77 69 6c 6c 20 62 65  |week  we will be|
00002bb0  20 62 72 6f 61 64 63 61  73 74 69 6e 67 20 61 20  | broadcasting a |
00002bc0  70 72 6f 67 72 61 6d 20  74 68 61 74 20 77 69 6c  |program that wil|
00002bd0  6c 20 67 69 76 65 0d 74  68 65 20 49 2f 4f 20 70  |l give.the I/O p|
00002be0  72 69 6e 74 65 72 20 62  75 66 66 65 72 20 61 20  |rinter buffer a |
00002bf0  74 68 6f 72 6f 75 67 68  20 74 65 73 74 3a 2d 20  |thorough test:- |
00002c00  61 20 70 72 6f 67 72 61  6d 20 74 68 61 74 20 69  |a program that i|
00002c10  6e 63 6f 72 70 6f 72 61  74 65 73 20 61 0d 74 65  |ncorporates a.te|
00002c20  6c 65 74 65 78 74 20 70  61 67 65 20 73 74 6f 72  |letext page stor|
00002c30  61 67 65 20 73 79 73 74  65 6d 20 63 61 70 61 62  |age system capab|
00002c40  6c 65 20 6f 66 20 73 74  6f 72 69 6e 67 20 20 75  |le of storing  u|
00002c50  70 20 20 74 6f 20 20 37  36 34 20 20 74 65 6c 65  |p  to  764  tele|
00002c60  74 65 78 74 0d 70 61 67  65 73 20 20 6f 6e 20 6f  |text.pages  on o|
00002c70  6e 65 20 64 69 73 6b 20  28 64 65 70 65 6e 64 69  |ne disk (dependi|
00002c80  6e 67 20 6f 6e 20 74 79  70 65 20 6f 66 20 44 46  |ng on type of DF|
00002c90  53 20 61 6e 64 20 64 72  69 76 65 29 2c 20 74 6f  |S and drive), to|
00002ca0  67 65 74 68 65 72 20 77  69 74 68 0d 69 6e 73 74  |gether with.inst|
00002cb0  61 6e 74 20 70 72 69 6e  74 6f 75 74 20 61 6e 64  |ant printout and|
00002cc0  20 65 64 69 74 69 6e 67  20 66 61 63 69 6c 69 74  | editing facilit|
00002cd0  69 65 73 2e 0d 0d                                 |ies...|
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