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9
Operating and
Programming the CDS
System Overview
The CDP18S005 COSMAC Development System
(CDSl consists of a power supply, control panel, and
a set of connectors for printed circuit boards. Many of
the 25 available positions are occupied by specific
module types. A printed circuit backplane distributes
common signal lines to all connector positions. There
are a small number of additional wire-wrapped
connections. The unassigned connectors are available
for user expansion of memory and I/O function.
Supplied modules include the CDP1802 CPU
module, an address latch and memory bank select
module, a 4-kilobyte RAM module, a ROM/RAM
module containing the Utility program, an I/O
decode module, terminal interface module, and a
control module. The position assignments of these
modules are given in Table III in the next Section. All
logic functions are implemented in CMOS operating
at
+
5 V.
The control panel provides a simple user interface.
Depressing the RESET switch initializes the system.
Depressing the RUNU switch starts the utility
program, identified as UT20. Depressing RUNP, on
the Dther hand, will start program execution from
memory location 0, the normal starting location of a
user program. A STEP/CONTINUOUS switch
allows stepping one machine cycle with each
depression of RUNU or RUNP. A 4-digit display on
the front panel shows the current address and a 2-
digit display shows the value of the data .bus or, by
switch selection, the last I/O data byte. Five ad-
ditional LED indicators monitor the State Code,
WAIT, CLEAR, and
Q
lines of the CPU while a
sixth LED indicates when the machine is running.
This RUN indicator will be ON whenever the CPU is
running and not in the IDLE mode. The LOAD
switch is used to place the CPU in the 'load mode' in
which the DMA channel can be used to load RAM.
See The User Manual for the CDPl802 COSMAC
Microprocessor,
MPM-201,
for
a
detailed
discussion of this mode. The LOAD switch is sup-
plied as a convenience for the user designing his own
system interfaces and is not used in normal CDS
operations. The supplied programs are loaded using
the Monitor program as discussed in the next section.
The CDS· is designed to work with anyone of the
following terminals:
Il
An ASR 33 Teletype' terminal (or its
electrical equivalentl which should include a
remote reader control circuit to permit the CDS
to control the paper tape reader.
2l
A TI "Silent 700" terminal"', Model 733
ASR with tape cassettes and "Remote Device
Control" option.
This terminal uses dual
program-controlled magnetic tape cartridges as
storage medium and prints at 30 characters per
seconds.
3l
Any terminal conforming to the EIA
RS232C standard interface and having a baud
rate of 110, 300, or 1200.
The CDS is designed to automatically adjust to a
variety of data terminal speeds and will accommodate
either full- or half-duplex operation.
Included with the CDS are an assembler and editor
program for software development. Loading in-
structions for these programs are given in the next
subsection. Details on operation of the Assembler and
Editor are given later in this manual. If a Floppy
Disk system is used with the CDS, refer to the Floppy
Disk Manual for operation of the Assembler, Editor,
and other programs.
, Registered Trademark, Teletype Corporation.
... Registered Trademark, Texas Instruments Corporation.
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