View Full Version : Help with XOR 64K-DQ Dynamic Memory Card Configuration

May 6th, 2017, 02:30 PM
Help with XOR 64K-DQ card configuration.

Is there anyone who is using an XOR 64K-DQ dynamic memory card.
I need some help in getting mine configured so that it will work.
When I first got the board several years ago, I tested the regulators,
replaced the tantalums and then tested all of the chips on board,
including the memory chips which I tested on another board. I then
tried to follow the instructions to get the board configured in Mode II
which is the extended address mode (Mode I is a port address mode).
My intention was to configure it as the 0-64K block of memory.
The notes on each configuration are confusing. Both versions say
jumper T-S should be removed but the schematic looks like it needs
to be installed in extended address mode.

I know that there is a better chance of getting a memory board to work
with a processor from the same manufacturer. So, I recently acquired
a Delta Products DP-CPU. Both companies have the same address so I
hoped there was just a name change. I hoped I could get the XOR memory
to work with this processor. The CPU works with several static and
dynamic memory cards but I still can't get the 64K-DQ to work.

Here is my configuration:

Jumper T-S installed

Jumper E4-E5 installed

Bank select switch - all on.

SW1 - all on - the setting for 0-64K

SW2 - all off - since this is for Mode I port 40 board select.

There are several other trace jumpers that have not been touched.

I would appreciate any help anyone could offer.

Thanks in advance,


May 6th, 2017, 03:50 PM

I began some analysis but I have no idea about XOR/ Delta

I do recall having the docs on my website here


So anyway you maybe you can explain where the 2KB ROM is addressed on machine startup and how the CPU goes to the start of the ROM and at that point where is the RAM addressed?

For example on Cromemco Systems the way it works is the monitor ROM is at C000, the system starts with typically the lower 32KB of RAM enabled, jumps to the ROM. The ROM is read and executed and stuff is stored in that low RAM, then later the ROM is disabled and the upper 32 KB RAM enabled. I thinks what I recall (!) for the Z80 and non 68000 systems.

So how conceptually do you see it working for your XOR/Delta?


May 6th, 2017, 08:39 PM
The monitor is located at address F800 on the processor which does a Power-on-jump to that address. The monitor then makes use of whatever size ram that is available starting at address zero. As I said originally, the processor functions successfully with several different static ram cards, 8k, 16k, and 32k. It also works with an Ithaca 64k dynamic ram card configured for 48k.
My problem is that I fail to understand the confusing instructions in configuring the XOR 64K-DQ card. My hope is that there is someone who is using this card and can help me configure mine.