MTD 122-250 User Manual download pdf (Page 10)

This document is !licensed under a Creative Commons Attribution 3.0 License: http://creativecommons.org/licenses/by-nc-sa/3.0/

6: IMPLEMENTATION CHARACTERISTICS

The defaults for the settable options in the present implementation of ee9 are as follows:

• the default test mode is PROGRAM_MODE

• the default diagnostic mode is FAST_MODE

• the default diagnostic visibility generates all traces, the digital signature, and the histogram

• the default register checking mode is STRICT_MODE

• the default elapsed time mode is not AUTHENTIC_TIME_MODE

• the default time limit allows for effectively unlimited execution

• the default count bounds, l and h, are 0 and the time limit, respectively

• the default range bounds, a and b, are #0 and #7777, respectively

• no breakpoint, fetchpoint, storepoint, or core dump is pre-set

The following features of KDF9 remain to be implemented:

• the K5 instruction and the PHU stores

• all I/O instructions for the DR and ST device types

• the PIE, PIF, PIG, PIH, PMH, POG, and POH instructions for the FD device type

• the PMG, PMK, PML, POK, and POL instructions (for all device types other than CP, which has POK and POL)

• Time Sharing Director OUTs other than OUTs 0 through 10, and OUT 17

KDF9’s nest-depth checking caused a NOUV interrupt after the maximum or minimum depth had been transgressed.

Presently, ee9 checks for all of these violations before the offending instruction is executed. This makes little difference

in practice. KDF9 had ‘imprecise’ interrupts, which made recovery from a NOUV error impossible: Director could do no

more than terminate (or perhaps restart) the offending program. (See also the A option setting, §5.)

There is some doubt as to the semantics of the various division instructions, particularly with respect to rounding, and

their behaviour on overflow and on division by zero (other than setting the overflow bit).

All of the I/O instructions that apply to EE model 1081 magnetic tape decks (the most common kind) have been

implemented, with the important restriction that data blocks are limited to at most 512 words (4K bytes) in length. I hope

to lift this restriction in a future release.

There is considerable doubt as to the correct instruction encoding, and precise effects, of the PMG, PMH, PMK, PML,

POK, and POL orders, which are listed in the KDF9 Programming Manual but not well defined therein, nor in any other

source presently known.

It is assumed that the POF order for the TP device type has exactly the same functionality as the POE order.

It is assumed that the POC and POD orders for the Flexowriter change from writing to reading after the output of any

word that has the KDF9 paper tape code for a semicolon (34

) in its least significant six bits.

It is assumed that the fixed-head area of the FD device type is platter 0, seek area 0. Many other hypotheses have been

put into effect in the implementation of the FD device; it remains to be seen whether these are justified.

ACKNOWLEDGEMENTS

I am grateful to the group of supporters, all enthusiastic former KDF9 engineers, programmers, or satisfied users, for their

encouragement during this project; and for their superb work in recreating a software ecosystem for ee9 to run. I thank in

particular David Hawley and Brian Randell, for their crucial caches of EE documents; David Holdsworth for his

Usercode compilers and hardware insight; David Holdsworth, Brian Wichmann, Graham Toal, and Roderick McLeod for

resurrecting the Whetstone Algol system; and David Holdsworth, Mike Hore, and Bill Gallagher for compiling and

testing ee9 ports. Others, too numerous to list, know who they are: to them also, my thanks.

REFERENCES

Available at: http://www.findlayw.plus.com/KDF9

The English Electric KDF9; W. Findlay, 2011.

The Hardware of the KDF9; W. Findlay, 2010.

The Software of the KDF9; W. Findlay, (in preparation).

KDF9 Programming Manual, Publication 1002 mm (R); International Computers Ltd., 2

Edition, October 1969.

KDF9 ALGOL programming, Publication 1002 mm (R) 1000565; J.S. Green, English Electric-Leo-Marconi

Computers Ltd.

See also: http://www.findlayw.plus.com/KDF9/#Emulator which is updated periodically with ee9 news;

and the README and HOWTO files, included in the distribution of ee9.

1 2 ... 5 6 7 8 9 10 11 12 13 14 15

Comments to this Manuals

No comments

MTD 122-250 User Manual Page 10

Comments to this Manuals

Related products and manuals for Lawnmowers MTD 122-250