Notes on VC8E Configuration:

The VC8E, and consequently the VC8E replacement card, has a number of jumpers and the like, meant to configure the board to match the display device to which it is connected.

The VC8E has ten jumpers:
W1	Device Address (VC8E only)
W2	Device Address (VC8E only)
W3	Use COLOR register bit
W4	Ignore COLOR register bit
W5	Z Axis bias, coarse
W6	Y DAC shunt (VC8E only)
W7	X DAC shunt (VC8E only)
W8	Z Axis bias, fine
W9	External X Axis shunt (VC8E only)
W10	External Y Axis shunt (VC8E only)

and two switches:
INTENS	Intensify polarity
DELAY 	Movement settling delay

First, the VC8E only stuff:
Exactly one of W1 or W2 was to be installed; W1 for device code 05, or W2 for device code 15.  The replacement card has this set permanently for 05, though it can be easily changed by reprogramming the CPLD.

W6 and W7 configure the DAC card in a VC8E to ignore the trim pot for bit 6 of X and Y co-ordinates, respectively.

W9 and W10 affect the available current at the H top edge connector, if your VC8E is being used with additional cards.  They do not affect the current available at the I/O connectors.


Next, the stuff that pertains to both:
Changing the COLOR bit in the status register triggers a delay in the manner expected by the VR14/VR20 displays (300 usec for red, 1600 usec for green). 

X and Y voltages always range between -5V and +5V.  External circuits must be used to obtain other voltages.  (Fortunately, most oscilloscopes can be adjusted so fit these voltages onto the display.)  (When designing these circuits, be aware that the outputs are connected directly to the voltage mirror, without the 47 ohm resistor present in the original VC8E.)

ERASE commands written to the status register remain active until about 1 usec after !ERASE_INTERVAL goes high, which for the VT10 should be about 450 msec.  A bug in the VT01/611 causes the device to fail to ever go ready if a second ERASE is done before the first finishes!  (This huge delay corresponds to the bright green flash generated by the scope.)

W3 and W4 handle the biasing applied to the monostable that controls the settling time after a "move" is done.  Installing W3 sets the delay to depend on COLOR, in the manner expected by the VR14/VR20 displays (5 usec for red dots, 6 usec for green).  Installing W4 sets the current to a constant value regardless of the setting of the COLOR bit, as required by the Tektronix 602/3/4 or 611/613.

The DELAY switch interacts with W3 and W4, setting the "C" half of the R/C constant used for delay.  The switch to the right uses a shorter delay (21 usec with W3, 6 usec with W4) than the switch to the left (110 usec with W3, 30 usec with W4).

W5 and W8 set up the voltage divider for the negative half of the INTENSIFY pulse, affecting the magnitude of the swing when the negative side is activated.  The positive side should be about 3-4V.  With both W5 and W8, the swing will be to about -1V, with just W5 about -2V (default), just W8 gives about -10V, and neither jumper should result in about -15V.

The INTENS switch sets the polarity of the INTENSIFY swing, so that the voltage swings either from negative to positive, or positive to negative, to perform the INTENSIFY.  (The range will be as described above.)

Capacitor C22/C63 controls the rise time of an INTENSIFY pulse.  The rise time may be at the beginning or end of the pulse, depending on it's polarity.  This is mis-wired in the first revision of the space war board, and is not effective without rework.

Applying this information to the specifications of your oscilloscope is "fun".  The VC8E is intended for a VR14, a Tektronix 602, or an RM503, but can be adapted to various devices.  The devices I intend to use are the Tektronix 464, and the DEC VT01.  (The DEC VT01 is a modified Tek 611.)

Requirements for 611/VT01:
Effective resolution: 300 x 400
Move settling time: 5 usec + 3.5 usec/cm*21cm, or 79 usec
Required Intensify length: 5 usec (to store)
Required Intensify voltage: >=+1V ON, <=0.5V OFF
Color change delay: N/A
Erase delay: 0.5 seconds

The 611, and I suspect the 613, are quite slow at movement.  Neither setting of the DELAY switch is sufficient for the worst case movement, unless W4 is installed and W3 is removed.  (In practice, the 21 usec setting will allow enough time for shorter movements, which should be the majority.)

The INTENSIFY switch should be in the positive going position, and the W5/W8 jumpering should be OK either way.

Be sure to either connect up the !ERASE_INTERVAL input, or to avoid issuing ERASE commands.  (The default should be NON_STORE mode, anyway.)

Requirements for 464:
Effective resolution: 80 x 100
Move settling time: Negligible
Required Intensify length: <1 usec
Required Intensify voltage: 5V P-P, negative is brighter
Color change delay: N/A
Erase delay: N/A (no external erase)

Since there's no ERASE input on the 464, you may just want to jumper !ERASE_INTERVAL high.

Movement should be plenty fast for the 6 usec delay setting.

The INTENSIFY switch should be in the negative going position, but the W8, not W5 jumpering should be used.