Subject: Bill H's pdp8 emulator OS/8 date

From: [email-masked] (Bill Haygood)
Date: 5 Jan 1994 02:12:36 GMT

With the arrival of 1994, the famous OS/8 date problem again raises its
ugly head.  I submit the following short program for use on my pdp8
emulator to set the OS/8 date high order bits for the period 1994-1999
(Jim Van Zee informs me that most OS/8 date algoritms will only work
through 1999):
-------------------------------------------------------------------------
/	SET94.PA: SET 1994 HIGH ORDER DATE BITS
/
/	Author: Bill Haygood, [email-masked]
/
	*200
/
	JMS I [7607		/ CALL SYS HANDLER
	0200			/ READ 2 PAGES
	0400			/ INTO ADDR 0400
	0			/ FROM BLOCK 0
	HLT			/ ERROR RETURN
	TAD [600		/ GET H O YEAR BITS
	DCA I [777		/ PLUG THEM INTO SYS BOOT BLOCK
	JMS I [7607		/ CALL SYS HANDLER
	4200			/ WRITE 2 PAGES
	0400			/ FROM ADDR 0400
	0			/ INTO BLOCK 0
	HLT			/ ERROR RETURN
	JMP I [7600		/ RETURN TO OS/8
/
	$
--------------------------------------------------------------------------

After the emulator comes up and OS/8 boots, type:

.COPY SET94.PA<PT:
.EX SET94

This sequence should copy the file into which you have put the above short
program and the .EX command should assemble and execute it.

--
Bill Haygood

---

From: [email-masked] (Charles Lasner)
Date: 7 Jan 1994 06:05:34 GMT

In article <[email-masked]>,
>(Jim Van Zee informs me that most OS/8 date algoritms will only work

Yes, I am working on that problem, and there are several tentative
solutions (to be discussed at another time).

However, there is no need to run the supplied (and correct!) program to set
the word, since FUTIL can do it for you:

.R FUTIL
0.377/ xxxx 0600 [hit <LF> here]
0.400/ EXIT

However, there is another problem: it is actually device-dependent as to
whether the last word of logical record 0000 actually loads into 07777,
although this is certainly correct for an RK8E (or emulator thereof).  For
versions that run on TC01/08, and various RX, it may not be true at all!

The date word format currently is good for 8 years, but many programs are
incapable of handling 2000-2001 for algorithmic purposes in input and
output routines.  Thus, we are on notice that we have at most 6 years to
fix it for 2 more years, and then no additional time to fix it at all!  I
recommend we resolve this quickly for the benefit of OS/8 V5.

cjl