1. Software PDR Overview

1.1 Introduction

This is the third in a series of reviews planned for DEIMOS:
1. November 1994:	Instrument PDR
2. November 1995:	Mechanical/Electrical/Optical CDR
3. March 1996:		Software PDR
4. April 1996:		Mechanical/Optical Structure Review	
5. mid-1996:		CCD Detectors/Controllers Review
6. late-1996:		Flexure Compensation & TV Guider Review
7. late-1996:		Software CDR
While the November 1994 review contained a brief section on software, the two reviews held to date have focused primarily on optical/mechanical design and fabrication issues. The primary purpose of this review is to verify that the overall software functional requirements for DEIMOS are understood and that a preliminary design exists which meets those requirements. Other items to be evaluated by this review include:
  1. Suitability of inherited designs and software
  2. Standards
  3. Support hardware and software requirements and plans
  4. Preliminary operations planning
  5. Major concerns, open items, and proposed resolutions
  6. Schedule and budget
Several parts of the DEIMOS instrument are not yet sufficiently well-defined for detailed discussion here, and (as indicated) will be the subject of separate reviews to be held later this year. Accordingly, portions of the preliminary software design for the CCD control system are being deferred to review number 5, and the software requirements and design for the flexure compensation system are being entirely deferred to review number 6. However, the software functional requirements and preliminary design of many of the major subsystems are reasonably complete, and the decision to hold this PDR now represents a practical compromise between overall completeness and the need to move forward with those subsystems which are ready to proceed to detailed design.

This review is intended to be as thorough a discussion of the topics presented here as is possible before we start expending significant labor on detailed design, evaluation of software and hardware tools, and extensive testing of prototypes. Advice from the review committee (and other reviewers) will be used as much as possible in the selection and evaluation of tools and in the detailed design effort. The detailed design for those subsystems discussed today will be reviewed at the software CDR (review 7) to be held late this year, along with the designs for those subsystems whose preliminary software reviews have been deferred to reviews 5 and 6.

Major purchases of computing hardware and software tools and major expenditure of labor for software implementation will begin in early 1997, following the software CDR. In establishing priorities for completion of the various major components of the DEIMOS software, we have identified the following six target dates:

A. Spring 1997:	Test readout of partial CCD mosaic

B. Summer 1997: Start of instrument integration in Lick Labs

C. Spring 1998: Begin DEIMOS commissioning at Keck

D. Summer 1998: Begin DEIMOS science observations at Keck

E. Summer 1999: Observing + 1 year:
	        complete first round software upgrades

F. Summer 2000: Observing + 2 years: 
		complete final upgrades; release public data
In establishing these dates, we make explicit our intention that the DEIMOS software development effort will not cease with delivery of the instrument to Hawaii in early 1998. Rather, it will continue for up to two more years, ramping down to final completion in mid-2000. Our software schedule and budget (presented in Chapter 12) reflects this plan. In describing the various software components reviewed here, we have attempted to identify which portions are needed at each of the target dates.

DEIMOS is planned as a dual-beam instrument, but due to current funding limitations only one beam will be built for first light. When additional funding becomes available, the second beam will be built here and installed in Hawaii. Since both beams are nearly identical, construction of the second beam primarily involves duplication of the hardware and software developed for the first beam. Those features of the control software which are either unique to the second beam, or involve interactions between the two beams, will be included in our initial one-beam detailed software design effort, but their implementation will probably be deferred until the funding for the second beam is secured. If such funding is secured in time, implementation of the software for the second beam would be included in the first round of DEIMOS software upgrades planned for Summer 1999.

The remainder of this chapter describes our primary assumptions and our software design philosophy, and identifies the major challenges to be tackled. The remaining chapters are organized as follows: