r care defined and the initial assignments are as listed bel      / 19
.[20    |use of the|"nud"|function

It is  evident  that  use  of  some  of  the foregoing value`
returning functions would fail due  to  lack  of  sufficient`
user  work  space  for  storage  prior  to evaluation. It is`
appropriate to  use  the  "nud"  null  display  function  to`
obviate  this  problem;  typical  expressions  making use of`
"nud" and some of the above functions are shown below:

%nud,xu,fm,100,200, /=  Displays from 100 to 200

%nud,xu,rcv,5,9000/=    Accepts   the   blocked   checksummed`
transmission of object code offsetting  the  load  point  by`
9000  Hex.  Assuming  that  an  8K  object code of the SAM76`
language   interpreter  intended  for  loading  at  8000  is`
received, the loading will take place at 1000 instead. While`
loading takes place progress of load  is  displayed  on  the`
user  console,  and  each  block  correctly received will be`
acknowledged to the sender; if incorrectly received  then  a`
retransmission will be requested.

  18|xu,rcv,m,0,x1,x2|  Xperimental User Receive

This valued  function  accepts data in the checksummed block`
format generated by the "xu,xmt" function. The modes are the`
same as described for the transmit function.  The  arguments`
symbolized  by  "x1" and "x2" are to force loading elsewhere`
than specified within the received block of data; "x1" is an`
offsetting value.

This function may be used to load SAM76 language object code`
distributed in the "loadit" format.

  517|xu,xmt,m,0,x1,x2|  Xperimental User X{trans}mit

This null  valued  function  is   used   to   generate   for`
transmission purposes a blocked checksummed group of records`
of the contents of memory locations between those symbolized`
in the current X base by "x1" and "x2" inclusive. The symbol`
"m"  denotes one of several modes of transmission as defined`
below:

mode 0          No local display, no error feedback
mode 1          No local display, automatic error control
mode 4          Local progress display, no error control
mode 5          Local progress display, with error control

All of the above transmissions are in the blocked checksummed`
format to be described later and are through the  "group  2"`
communications channel of the SAM76 language processor.

The argument  symbolized  by  "0" in the above expression is`
reserved for future control and selection  purposes  and  is`
undefined at this time.

Note:The format  is  that  which  is  currently  used in the`
"loadit"  software  distributed  with  the  paper  tape  and`
cassette media.

  +316|xu,wl,sym,x|               Xperimental User Write Label

This null  valued function is the reverse of the "xu,rl,sym"`
function, in that its execution will cause  the  storing  of`
the  value  symbolized  by  "x"  at  the   actual   location`
identified by the valide label symbolized by "sym".

  )15|xu,vm,x1,x2,x3,s0| Xperimental User Verify Memory

This valued  function  compares  the  contents of the memory`
between the locations symbolized in the current  X  base  by`
"x1" and "x2" inclusive with memory locations which start at`
the location symbolized by "x3". The value returned provides`
a  list  of  adresses  of the locations which are different.`
Each adress is preceded with the string symbolized by "s0".

   14|xu,tm,x1,x2|               Xperimental User Type Memory

This valued  function  contains  in  "printable"  form   the`
contents  of  the memory cells located between "x1" and "x2"`
inclusive. Non printing characters are displayed as "dots".

   13|xu,sum,x1,x2|              Xperimental User SUM

The value  of  this  function is the low order "byte" of the`
arithmetic sum of all memory  cells  between  the  locations`
symbolized in the current X base by "x1" and "x2" inclusive.`
{This  is  useful  in  verifying  portions  of  the  system;`
overlays are usually checksummed  to  zero  by  storing  the`
appropriate value in the last location of the overlay}.

  12|xu,rl,sym|         Xperimental User Read Label

This function  returns as a value the contents of the memory`
location identified by the valid label symbolized by  "sym".`
A  list of the valid labels is obtained through execution of`
the %xll, / Xamine Label List function. {Note  this  differs`
from  the  "xal,sym"  function  which  only gives the actual`
machine adress of the symbol label}.

  11|xu,mm,x1,x2,x3|    Xperimental User Move Memory

This null valued function serves to move the contents of the`
system memory between "x1" and "x2" inclusive to a  location`
whose  starting point is symbolized by "x"; all of these are`
in the current X base.

  10|xu,fm,x1,x2,s0|    Xperimental User Fetch Memory

The value  of  this  function  is the contents of the system`
memory between locations symbolized in the current X base by`
"x1" and "x2" inclusive. Each word content  is  preceded  by`
the string symbolized by "s0".

  
9|xu,dm,x1,x2,x|             Duplicate Memory

This null  valued  function  fills  memory from the location`
symbolized in the current X base by  "x1"  to  the  location`
symbolized  by  "x2" inclusive with the "byte" symbolized by`
"x". {to be used with care as for instance when  one  wishes`
to  scuttle  the  system which is about to be intruded by an`
unauthorized peeker".

  { 8Two  of  the subfunctions of "xu" were defined in Update No.`
4, namely "xu,dt,..." and "xu,ft,..."; additional  functions`
are defined below.

    7|xu,lf,s0|          Xperimental User List Functions

The value of this expression is a list of the subfunctions of`
the "xu" primitive. Each name in the list is preceded by the`
string symbolized by "s0".

    6
.[20    |the XU|family

A family  of experimental functions exist as subfunctions of`
the   "xu"  Xperimental  User  function;  a  list  of  these`
functions may be obtained by executing  &xu,lf, /= which  is`
defined as follows:

   !5This  update will discuss a number of the functions that may`
be found in SAM76 language processors  released  after  July`
1978.  These  functions  are  located  in "overlays" and are`
linked through the  POA,  POB,  POC  and  POD  locations  as`
described in previous updates.

   :4
./SAM76 Language Update No. 5 - September 1978

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