perm filename VARIAN.PUB[TH,ROB] blob sn#494258
filedate 1980-01-17 generic text, type C, neo UTF8
COMMENT ⊗ VALID 00002 PAGES
C REC PAGE DESCRIPTION
C00002 00002 .IODEVICE( VRN,350,|Varian Plotter and Interface|)
.IODEVICE( VRN,350,|Varian Plotter and Interface|)
The Varian Statos model 4224 plotter makes plots on 22" wide paper, using
coated paper and an electrostatic process. This plotter features very
good linearity (especially across the paper), and a very wide plotting
bed. The Varian's primary drawback is that it requires coated paper.
Coated paper doesn't feel as wonderful as plain paper, is expensive (by
XGP standards), suffers occasionaly from poor contrast, and is not as
universally suitable as plain (XGP) paper. It has a resolution of 200
pixels per inch, with a 21.12 inch wide plotting bed, giving an effective
width of 4224 pixels. The paper comes on 500 foot rolls, so there is
little restriction on the length of a plot.
The primary function of the interface is to take a 36 bit word from the
host processor (currently a KA-10), unpack it, and to send it to the
Varian as four nine-bit bytes.
18:29 777700 unused
30 000040 VTEST Test (described below)
31 000020 unused
32 000010 VPIENB Interrupt enable
33:35 000007 VPIMSK PI channel assignment
18:19 600000 unused
20 100000 VSDONE Video scan complete
21 040000 VNOTOK The Varian is not ready for some reason or other
22 020000 VBFBSY The line buffer is busy
23 010000 VPCBSY Paper controller is busy
24 004000 VBTFRM Bottom of form (unused)
25 002000 unused
26 001000 VRDRDY Read ready
27 000400 VOFFLN Not on-line (i.e., off-line)
28 000200 VSUPLO Supplies low
29 000100 VVDBSY Video busy
30 000040 unused
31 000020 VDATRQ Data request (cleared by any DATAO)
32 000010 VPIENB The Varian in interrupting
33:35 000007 VPIMSK PI channel assignment
The interface takes a 36-bit DATAO word, and sends it to the Varian as four
Each byte is either 'printing data' (400 bit off) or 'command data' (400 bit on).
Here are the commands that the Varian understands:
500 VCMCGS ;Character generator select ("default on reset")
560 VCMMUX ;Select character generator in MUX mode
740 VCMRAS ;Raster write select
644 VCMRAA ;Autostep raster write select (comes on automatically???)
445 VCMCLA ;Autostep mode reset (undoes VCMRAA)
443 VCMLF ;Line sync/step (print buffer and advance paper)
663 ;VCMFF ;Form feed ("no-op on 22 inch wide paper")
400 VCMNOP ;No-op for clearing VDATRQ and for padding DATAO words.
464 VCMSTP ;Step (print buffer and advance paper)
665 ;VCMSLW ;Slew (advance paper 8.5" to bring last line printed into view)
For diagnostic purposes, this instruction reads in the current contents of the
data buffer. If the plotter is running, the data in the buffer will be constantly
changing as the data is shipped out to the plotter, in which case this instruction
doesn't make much sense.
The interface has an internal shift register which it uses to unpack
36-bit words into four 9-bit bytes. Setting the TEST bit in the CONO word
makes the interface go through the internal gyrations of shifting the data
over nine bits, just as it would if it were sending data to the Varian.
If you suspect someting is wrong with the data path of the interface, you
can test it by doing:
DATAO VRN,[some data]
DATAI VRN,[some cell]
The data you find in [some cell] should be the data you had in [some data],
but shifted over nine bits.
The Varian interface lives in the P2 TTL-IOBus Extension, built on two of the
ubiquitous DEC W943 wire wrap modules.
CONNECTION TYPE LOCATION DESCRIPTION
THINGS THAT CAN GO WRONG:
(Aside from running out of paper, toner, or concentrate)
Sometimes the paper skews to one side, gets wrinkled, or has dropouts
in printing. This is probably due to uneven pinch roller pressure.
Remove the front door, and look for two little holes, about 3/4" diameter,
on the left and right hand edges of the face. Inside are phillips head
screws that control the pinch roller pressure.
Assuming that the paper is skewing to the left, tighten the screw on the
left side about a turn. (Yes, tighten the right hand screw if the paper
skews to the right.) Open the platen and straighten out the paper by
pulling out a foot or so. Close the platen. Then try running some paper
for several feet while watching for evidence of further skewing. Repeat
these steps until the paper runs straight. You may have to loosen the
screws at some point, rather than tighten them.
Often, a new roll of paper will hit the top of the case, causing it
to bind and slip. No cure is known except to waste some paper by
loosening the platen and pulling the paper out by hand.
Varian "Service and Maintenance Manual for Statos 41/42 Series Printer/Plotters."