MCODE - IS THIS FOR YOU
                             Part 2

References:

A.   DATAFILE V6N6 and V6N4.
B.   DATAFILE V5N4.
C.   HP-41 MCODE for Beginners - Ken Emery.

INTRODUCTION

1.   My apologies for the late arrival of the second part of this series.  Due 
to the length of this series there will be a third part to complete the
original target functions and I may produce more.

2.   Mark Powell has given me permission to absorb some of his routines into my 
code.  The routines are well described at reference A.

DISCUSSION

3.   I left you with a command jump table which summarised the relationship of
the functions.  Please ammend your table as follows:

     a.   CLBUFF is now DELBUF

     b.   SF7 should have the address F0B7 next to it.

4.   The functions that will be covered are:

     a.   DELBUF

     b.   STOBUFF

     c.   STOKEYS

DELBUF

5.   Reference A descibes the code.

STOBUFF

6.   The essence of this routine is covered by 5 procedures:

     a.   Is there a working Data file - exit if no.

     b.   How much space available from the pointer to the end of the file.

     c.   Locate the buffer - exit if non-existent.  Calculate the number of
     registers in the buffer.

     d.   Will it fit - exit if no.

     e.   Store the registers in the Data file.

STOKEYS

7.   As for STOBUFF with the following difference:

     c.   Locate key assignments - exit if non-existent.  Calculate the number
     of assignment registers.

PASSING OF VARIABLES BETWEEN ROUTINES

8.   M and N are used to hold important information:

     a.   M = 44 01 ss sx xx xn nn
     See reference B but this time nnn= number of Data file registers.

     b.   N = HH NN .. .. .. .a aa
     HH= buffer header, NN = number of buffer/key assignment registers, 
     aaa = address of buffer header or 0C0 for key assignments.

LISTING

9.   The remarks should help understand the functions - remember the ZENROM
does not dis-assemble co-located quad Xeq and Gto's correctly-I have crossed
out the appropriate text.

DELBUF

10.  Place buffer ID in X execute DELBUF.

STOBUFF/STOKEYS

11.  Set data pointer to place in the file where you wish to store.  For a
buffer place the ID in X and execute STOBUFF, for key assignments just execute
STOKEYS.   The pointer will be updated to point at the register beyond the block
taken for these 2 functions.  Error messages are:

     a.   NO WORK FILE - a Data File has not been declared.

     b.   NO ROOM - insufficient space between the pointer and the end of the
     file.

     c.   NONEXISTENT - no buffer or key assignments.

FAT TABLE

12.  Update the table as follows:

     a.   F001 007
          F008 000
          F009 0AB
          F00A 000
          F00B 0B6
          F00C 001
          F00D 0F2
          F00E 002
          F00F 0A3

     b.   F10B 369
          F10C 03C
          F10D 2E9


13. Part 3 will contain RCLBUFF and RCLKEYS.   Please forward a disc for the RSU
image or ZENROM's user register format.  Send a SAE for a reply to any queries
and finally has any one found any bugs?

John Bruce
164N