VECTOR GRAPHICS 64K DRAM Card - switch settings?

From: Richard Erlacher <edick_at_idcomm.com>
Date: Thu Jun 3 20:28:47 1999

Well . . . it seems to work, now that I've fiddled with the broken jumper
wire. The wire was broken but the insulation wasn't, and it was done so
neatly, I couldn't initially believe it was a user-installed jumper wire.
Now that that's done, I can put it in the "works" box . . .

Thanks for the help.

Dick
-----Original Message-----
From: Marvin <marvin_at_rain.org>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Thursday, June 03, 1999 7:04 PM
Subject: Re: VECTOR GRAPHICS 64K DRAM Card - switch settings?




> Richard Erlacher wrote:
>
> Would anyone be able to help me with this VECTOR GRAPHICS 64K DRAM BOARD's
> switch settings? The signals seem to be OK, but no data propagates from
> the thing. I'm not anxious to count through the combinations of
> settings.

According to the schematics for the Rev-3 board, S1 is the Bank Select with
positions 0 - 7 (or probably labeled 1 - 8) corresponding to D0 - D7. D0 -
D7 go through 74175 Quad D latches and come out on the Not Q outputs. These
are then all anded together (U41 - 74ls30) to output the Bank Select signal.
Hmmm, interesting, it looks like the inputs are left floating when the
switch is open, and I have a hard time believing that with LS type
circuitry.

There is a note indicating:

Jumper Memory Enabled
1 to 3 0000h - FFFFh
5 to 3 0000h - DFFFh
4 to 3 0000h - BFFFh, E000h - FFFFh
2 to 3 0000h - BFFFh
Received on Thu Jun 03 1999 - 20:28:47 BST

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