The Number -65536.

3. The number -65536 can fit into the 'small integer' format as 00 FF 00 00 00. It is
then the 'limiting number', the one which when twos complemented overflows (cf.
80 hex in a simple one byte or 7 bit system, i.e. -128 decimal, which when twos comple-
mented still gives 80 hex i.e. -128 decimal since the positive number 128 decimal does
not fit into the system).

4. Some awareness of this may have inspired the abortive attempt to create 00 FF 00 00
00 in 'truncate'. It is abortive since it does not even survive the INT routine of which
'truncate' is a part. It just leads to the mistake INT (-65536) equals -1.

5. But the main error is that this number has been allowed to arise from 'short addition'
of two smaller negative integers and then simply put on the stack as 00 FF 00 00 00.
The system cannot cope with this number. The solution proposed in 'addition' is to form
the full five byte floating-point form at once; i.e. test for the number first, at about
byte 3032, as follows:

3032 		PUSH 	AF 	Save the sign byte in A.
3033 		INC 	A 	Make any FF in A into 00.
3034 		OR 	E 	Test all 3 bytes now for zero.
3035 		OR 	D
3036 		JR 	NZ,3040,ADD-STORE 	Jump if not -65536.
3038 		POP 	AF 	Clear the stack.
3039 		LD 	(HL),+80 	Enter 80 hex into second byte.
303B 		DEC 	HL 	Point to the first byte.
303C 		LD 	(HL),+91 	Enter 91 hex into the first byte.
303E 		JR 	3049,ADD-RSTOR 	Jump to set the pointer and exit.
3040 	ADD-STORE 	POP 	AF 	Restore the sign byte in A.
3041 		LD 	(HL),A 	Store it on the stack.
3042 		INC 	HL 	Point to the next location.
3043 		LD 	(HL),E 	Store the low byte of the result.
3044 		INC 	HL 	Point to the next location.
3045 		LD 	(HL),D 	Store the high byte of the result.
3046 		DEC 	HL 	Move the pointer back to
3047 		DEC 	HL 	address the first byte of the
3048 		DEC 	HL 	result.
3049 	ADD-RSTOR 	POP 	DE 	Restore STKEND to DE.
304A 		RET 		Finished.

6. The above amendment (i.e. 15 extra bytes) with the ommission of bytes 3223 to
323E inclusive from 'truncate' should solve the problems. It would be nice to be able to
test this. The calls of INT-STORE should not lead to 00 FF 00 00 00 being stacked. In
'multiply' the number will lead to overflow if it occurs, since 65536 will set the carry
flag; so 'long' multiplication will be used. As noted at 30E5, the 5 bytes starting there
could probably be omitted if the above amendments were made. 'Negate' avoids stacking
00 FF 00 00 00 by treating zero separately and returning it unaltered. Truncate deals
separately with -65536, as noted above. SGN stores only 1 and -1.