Programming Interface To Csdp - RCA COSMAC Operator's Manual

PROGRAMMING INTERFACE TO CSDP
Machine language coding. even of a trivial program. should
convince the novice programmer that. to do any serious pro-
gramming. one should take advantage of the set of software
support aids which are available. Veterans in the program-
ming community are already aware of the fundamental necessity
for assembly and simulation facilities. Such OSMAC support
services are available via timesharing using a system of
RCA-developed programs known collectively as CSDP (COSMAC
SOFTWARE DEVELOPMENT PACKAGE). The user manual for this set
of programs is the COSMAC SOFTWARE MANUAL. To do any non-
trivial programming. it is essentIal that the reader be
familiar with the facilities provided by CSDP. We proceed
here. then. assuming the reader already has a reasonably
detailed knowledge of the CSDP assembler and simulator system.
As discussed in the COSMAC Software Manual, much of program
development via CSDP is accomplished without the need for
direct Microkit involvement. Typically. a source file is
constructed, assembled, edited (if the assembler objects to
the source code), reassembled ••••• etc. The simulator is
then used to run the program. during which time program bugs
are isolated and removed via further editing and reassembly
of the source file. Eventually. the object code is ready
for loading and running in the real hardware (the Microkit)
for further testing. It is this part of the process that we
are concerned with here.
We have already discussed the use of the '!M' UT2 feature
to load the Microkit RAM from the keyboard or from paper
tape. One ultimate purpose of the CSDP system is to generate
an object code file. compatible with the required !M format.
and (on command) to transmit this file over the telephone
link to the Microkit system. Clearly. it is possible for
the user to punch this file onto a paper tape and subsequently
load the Microkit using this medium. We are concerned here,
however, with the automatic mechanism by which the !M-compat-
ible object file, coming over the telephone line. is loaded
into the Microkit RAM directly.
We must distinguish between three different data communication
paths: First, there is the I/O typewriter - Micro~lt path,
already discussed. Second, there is the
1/0
typewriter -
Time Sharing System link (via an appropriate modem). which
is implied in the use of CSDP for assembly and simulation.
And third. there is the Time Sharing System - Microkit link
(again via a modem). which is essential to the autmoatic.
direct-load process.
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