Digital Equipment PDP-12 User manual

DEC-12-YU2A-D
March, 1970
Copyright~l970 by Digital Equipment Corporation
Specifications contained in this manual are for
general information only. Actual specifications
are subject to change without notice. The draw-
ings, specifications, and descriptions herein are
the property of Digital Equipment Corporation and
shall not be reproduced or copied or used in whole
or in part as the basis for the manufacture or
sale of items without written permission.
The following are registered trademarks of Digital
Equipment Corporation, Maynard, Massachusetts
DEC
PDP
FLIP CHIP FOCAI,
DIGITAL
COMPUTER LAB
The equipment described herein is covered by patents
and patents pending.

1.0 INTRODUCTION
The PATCH program will modify any location in any TBLK on
tape unit 1. I
function is to a method for
making small patches to LINCtape binaries. For example, PATCH
can be used to modify load and go arguments in a LAP6-DIAL
1
header TBLK. Because PATCH converses with the user
via r}ANDA, undcrs of QANDA conventions is necessary
before us
PATC!l. Refer to DEC-12-FISA-D for that information.
2. 0 HARDWARE
The minimum conf is a PDP-12B.
3.0 CORE USAGE
PATCH
fi),2, and 3 of segment 2 and MBLK 4 of seg-
ment 3. The s
address is 4020.
4.0
HOCEDUEE
PATCH is loaded the command
+LO PA'I'CH, UNIT )
The tape to be modified must be on transport unit l; it can
be on unit 1 either before or after PATCH. PATCH
is a load and go program.
1
LAP6-DIAL is hereafter referred to as DIAL.
1

5.0 SENSE SWITCH OPTIONS
Raising Sense Switch J causes PATCH to return to DIAL.
Therefore, MAKE SURE SENSE SWITCH J IS DOWN BEFORE LOADING PATCH.
6.0 QANDA DIALOGUE
PATCH will query the user by presenting him with 4 sue-
cessive scope messages. All input is from the Teletype
1
and
output is to both the scope and the Teletype. Pressing LINE
FEED
causes the program to advance to the next message in se-
quence. There is no option to repeat the displayed messages.
All input must be octal and must be three or four digits,
as appropriate. Leading zeros, if any, are required. RUBOUT
will delete the previous characters typed, one at a time.
6.1 MESSAGE 1
When PATCH is started, it displays the following message:
TBLK
At this point the user types in the number of the tape
block to be modified.
1
Teletype is the registered trademark of the Teletype Cor-
poration.
2

When the LINE FEED key is pressed, PATCH will read in the re-
quested TBLK.
played.
If the input is not octal, the message is redis-
6.2
2
The next message is
LOC
Now the user must type in a value between 000 and 377
to specify which word within the TBLK is to be modified. If
the value is not between 0-377, the message will be redisplayed.
Location 000 is defined as the first word in the TBLK; location
377 is defined as the last word in the TBLK. When the LINE
FEED
key is pressed, PATCH retrieves the contents of the
requested location and displays them in the next message.
If non-octal characters are typed, "LOC" is redisplayed.
6.3 MES 3
OLD VAL xlx2x3x4
NEW VAL
is the current contents of the requested loca-
tion. The user may now type in the change. If, upon examina-
tion, no change is to be made, retype the old value as the new
3

value input, followed by LINE FEED. When LINE FEED is pressed,
NEW VAL will replace OLD VAL in core. If an error was made in
TBLK, simply type LINE FEED or some non-octal characters follow-
ed by LINE FEED. The first display (TBLK _) will reappear.
(Note that any previous changes made in core up to this point
will not be written onto the tape.)
6.4 MESSAGE 4
DO
1 WRITE
2
MORE CHANGES
If the user types LINE FEED or any key other than 1 followed
by LINE FEED, PATCH returns to message 2 to accept more changes
within the same TBLK. If option 1 is requested, all the changes
up to that point are written out on the requested TBLK and PATCH
goes back to message 1. The program can be aborted at any point
and reinitialized by stopping and restarting at 4020. A return
to DIAL can be effected while any display is active simply by
raising Sense Switch ~.
4