Beginning of Architecture Construction

Here's my firs couple of hours making a simple conceptual flowchart for the architecture of the 8-Bit Portable Computer.

I don't have the protection circuitry for the 74LS612 MMU finished, so I didn't want to go into a complete electrical schematic.

The things missing in this diagram are:

Memory-mapped ROM
Memory-mapped IO

I anticipate that I may need a second 6522 ACIA in order to debug the system.

At the moment, most of the components for the computer are remaining very cheap, so I am hoping this may be able to be copied and built elsewhere.

Discussions

Blair Vidakovich wrote 04/08/2018 at 01:40

It's a famous paged memory mapper! There is loads of information about it on 6502.org

See the datasheet here: http://pdf1.alldatasheet.com/datasheet-pdf/view/116938/TI/SN74LS612.html

And here are two different web pages giving information about it:

http://www.6502.org/users/andre/icapos/mmu65.html

http://www.6502.org/users/andre/hwinfo/ls610/index.html

Are you sure? yes | no

Yann Guidon / YGDES wrote 04/08/2018 at 11:09

Thanks ! I have looked at Google and found some information.
I have never seen this chip in the wild...

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Jean Pierre Le Rouzic wrote 04/07/2018 at 21:08

It looks similar to three 74ls189 where the address buses are multiplexed onto four address bits of the CPU and the 12 data bits are used to provide the higher address bits from A12 to A23?

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Yann Guidon / YGDES wrote 04/07/2018 at 17:32

74LS612 ? Does that exist ? I have never seen that before........

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Blair Vidakovich wrote 04/07/2018 at 07:05

I think the ROM and the IO can be mapped in between the 74LS612 MMU and the RAM with some simple address logic circuitry

Are you sure? yes | no

Second Effort at Constructing Architecture

Discussions

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