Solid State Music MB-3 EPROM card question

From: Frank McConnell <fmc_at_reanimators.org>
Date: Fri Apr 19 16:00:42 2002

"Erik S. Klein" <classiccmp_at_mail.vintage-computer.com> wrote:
> code. The board has two sets of four dip switches. One is
> labeled T1 to T4 and the other A12 to A15. A jumper on the
> board that allows settings between 2k and 4k is set to 4k
> (1702s vs 1701s?)

In the absence of documentation, one trick is to examine memory
looking for plausible code for your processor. So you learn how to
use the front panel to examine memory (and maybe how to deposit too,
as that's one way to tell whether the address you're looking at might
be read-only) and maybe learn something about the processor's
instruction set too.

A12 to A15 likely set the board's base memory address at
a 4KB boundary with A15 being the most significant bit
(and A14, A13, A12 being the next three bits down). A
switch set to "on" or "closed" might be 0 or 1, so pick one
and write the bits out in A15 through A12 order. Then
invert it (1 becomes 0, 0 becomes 1) and write that group
of bits out. Now you have two ways to set the high four
address switches on the front panel, which cuts the amount
of address space you have to explore by 1/8.

A 1702 is, what, a 1Kbit device? That's 128 bytes. So start
with the low seven address switches set to 0. You can probably
assume that the ROMs are each based at a 128-byte boundary.

This leaves you five switches in the middle, so 32 steps for
each of the ways you can set the high four bits.

-Frank McConnell
Received on Fri Apr 19 2002 - 16:00:42 BST