Re: Tempest memory

Ugh... Thanks. After seeing the memory map laid out, ie
0x2000 - 0x23FF --> M3 (D0-3) and M4 (D4-7)
It make sense now.. Vram 0 M3 and M4.

So yeah now I feel silly.

Don't know why I didn't make that correlation before now. Lack of sleep I
guess.

So by doubling the ram like they do, you can now write an 8 bit word
correct?

So for example, an 8 bit word will get split between M3, and M4

I'm thinking I should have paid more attention in microprocessor class in
college some 20 years ago.

Thanks for the help.

Kevin

On Mon, Oct 10, 2011 at 12:00 AM, vectorlist-steve <
vectorlist@arcadehacking.com> wrote:

> Check out page 5 of the Tempest Drawing Package (DP-190 2nd Printing)
>
> Decoding is grouped in the Vector-Generator Address Selector box.
>
>
> VRAM
> ---------------
> 0x2000 - 0x23FF --> M3 (D0-3) and M4 (D4-7)
> 0x2400 - 0x27FF --> L3 (D0-3) and L4 (D4-7)
> 0x2800 - 0x2BFF --> K3 (D0-3) and K4 (D4-7)
> 0x2C00 - 0x2FFF --> J3 (D0-3) and J4 (D4-7)
>
> VROM
> ---------------
> 0x3000 - 0x37FF --> N/P3 (D0-7)
> 0x3800 - 0x3FFF --> R3 (D0-7)
>
>
>
>
> On 10/9/2011 9:34 PM, Kevin Moore wrote:
>
>>
>> Ok, so I don't often come across a memory problem that the tempest self
>> test doesn't point me to.
>>
>> But today my fluke is showing me a decode error at 2c00 bit 7 . Which is
>> affecting vectors in game.
>>
>> I'm trying to figure out which RAM chip is giving me problems short of
>> pulling all the chips.
>>
>> Are there any documents out the explaining how memory is allocated and
>> used on Atari boards?
>>
>> I would really like to learn how to find the correct chip or I assume
>> narrow down to two chips
>>
>> Kevin
>>
>>
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Received on Mon Oct 10 08:44:52 2011