External memory connector?

A project log for nedoPC-85

Started in 2004 as a simple breadboard-friendly computer on Intel 8085 microprocessor...

shaosSHAOS 04/01/2018 at 01:344 Comments

As you can see I plan to have 8K of external memory (like a cartridge or something) in the address range 0x6000...0x7FFF, so question is - what should it be physically? Connector must have 2 power signals (+5V and GND), 13 address signals (to cover 8K address range), 8 data signals and also 3 control signals: /CS, /RD, /WR, so total is 26. 

Should it be 1 row of pins? 2 rows of pins? Male? Female? D-SUB connector? Edge connector? Or may be something else? Please share you thoughts in comments below! Thank you ;)


Yann Guidon / YGDES wrote 04/01/2018 at 02:46 point

Definitely the dual-row at the bottom, it's much more practical.

DBxx won't cut it (you'll also have to adapt between imperial and metric spacings) and card edge connectors are a PITA...

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SHAOS wrote 04/01/2018 at 03:04 point

Yea, I think about this similarly, but there is a problem it's 40 pins (the only one that could be currently found for less than $1) - so it will have some spare pins for future ;)

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Yann Guidon / YGDES wrote 04/01/2018 at 04:25 point

Yeah that's a prob.... oh wait...

Anyway there is a standard width with 34 pins, which is a compromise (I have "some", gotten from eBay brokers). But 2×20 is great because 1) more grounds/powers and 2) use old PATA cables and connectors 3) also used by the latest Raspberry Pis

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SHAOS wrote 04/01/2018 at 05:15 point

I hate Pis :)

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