Jon,

CBLOCK is an assembler directive that defines named constants. In your snippet,
CBLOCK is used to assign RAM locations to variable names. ENDC is used to mark t
he
end of the definitions. There is information about CBLOCK in the MPASM.HLP file.
Microchip has not indexed their help files very well, so use the 'find' tab in t
he
'search' dialog to locate help for a particular subject.

In your example, the constant CHANNELA is assigned the value of 12, CHANNELB is
assigned the value of 13, etc. It is not necessary to add ':1' to each of the
constant names as shown in your example. The assembler automatically increments
by
1 when assigning values in a CBLOCK section.

Use the ':<increment>' to override auto-increment. For example -

CBLOCK 0x10       ; define some RAM locations
    TEMP1         ;  0x10
    TEMPWORD:0    ;  0x11
    TEMPWORDH     ;  0x11 (TEMPWORD = TEMPWORDL)
    TEMPWORDL     ;  0x12
    TEMPBUFF:4    ;  0x13 (reserves 4 RAM locations)
    TEMP2         ;  0x17
ENDC

Hope this helps. I am glad you asked the question - I didn't know about the
':<increment>' option until I looked at MPASM.HLP this morning. Thanks!

Dave

PHXSYS wrote:

> Here is a code snip. I have limited programming experience and don't know what
> the "CHANNELA:1..." means. Does the :1 have something to do with pages? I have
> never used this before. I have not used and ENDC command either? Can someone
> provide a simple explanation?
>
> Thanks
>
> Jon
>
> CBLOCK  12      ; Start of user registers
>      ; initially selected dummy channel
>         CHANNELA:1      ; contents of Channel A, 0..255
>         CHANNELB:1
>         CHANNELC:1
>         CHANNELD:1
>         CHANNELE:1
>         CHANNELF:1
>         CHANNELG:1
>         CHANNELH:1
>
>         SSHIFT  :1      ; serial receiver shift register
>         STIME   :1      ; serial bit timer
>         SCOUNT  :1      ; serial bit counter
>         SSTATE  :1      ; serial receive state
>         SINDEX  :1      ; which channel is addressed by serial port (0..7)
>         SDATA   :1      ; accumulate decimal digits
>         INDEX   :1      ; function dispatch index
>         DELAY   :1      ; delay being generated
>         PULSE   :1      ; width of pulse to be generated
>         SERVOLN :1      ; Servo line to be activated
>         PHASE   :1      ; PWM phase
>         GUARDTMR:1      ; signal loss guard timer
>         FLAGS   :1      ; Program flags
>
>         ENDC
>         PAGE