How does the pc engine turn off the cart port(what pin carries )

[bigsanta]

Just in response to an answer i got regarding an  IC region mod question.

How is the cart port turned off and what pin carries this enable/disable signal ?

[NFG]

Pin 24 is /CE and pin 26 is /OE.

By applying Vcc (TTL high) to either pin the chip will go into hi-Z (floating) mode.

Mostly.  I think Street Fighter uses /CE for an extra address line (but my memory's fuzzy on this point).

[bigsanta]

Ok.The reason being for the question is, i have the required MC14551B  Ics for the region mod and it's all finished and complete. Using a ne555 bistable which uses a spst  momentary button to switch regions and two LEds to show when the region is switched (ON = US) ,though i might add another 555  (controlled by the first 555's output )which operates in a monostable mode ,so when the region is switched ,the monostable operates the LED for 5 seconds ,then goes off,instead of just having the LED on all the time ,as it's a bit distracting when it's on permanently .

Right, back to the point.As you say, about either pin being applied a high Vcc to send it to a HI impedance state,well i have some SN74LS257BNes http://octopart.com/sn74ls257bn-texas+instruments-40689 TRI state ICs ,and if it's G (control pin) is taken High ,then the 74ls output will be z(hi impedance).Knowing this ,can i simply connected the stated pin (pc engine) to the 74ls's control pin and get another working version of the region mod with these 74ls ?

I've got plenty of space inside of my pc engine ,as i've moddified the original ribbon cable,(removed and replaced it )so space is not a problem now when having this many added ICs inside.Also i have some connectors which fit perfectly inside the expantion connector ,so no need to cut down anything to fit it.Now i plan on making the original HU card pcb HOT swappable as i have all the parts needed and doing something with the expantion port now i have these perfect fit connectors