I have 3 NEC machines. 2 of them have REX units in them with the multi bank 
setup. The third unit doesn't and I wanted to simulate part of the same 
behavior without a REX unit. Thus the question about the bank 2 enable pin 
somewhere on the motherboard.

Kurt

On Sun, Jun 23, 2019, at 5:53 PM, Stephen Adolph wrote:
> why do you want 2 REX? REX supports multi-bank. You can configure option rom 
> for bank 1 and bank 2 already on one REX.
> 
> On Sun, Jun 23, 2019 at 8:11 PM Kurt McCullum <[email protected]> wrote:
>> __
>> Got a question for those who know the hardware of an NEC. I've got two REX 
>> units in my main 8201a units. That allows me to have one rom for bank 1 and 
>> another for bank 2. My third unit won't get much use so I wanted to take 
>> another route to achieve the same thing. My plan is to replace the 27C256 
>> ROM with a 27C512 with the two ROM images on it. SARDOS in the lower (Bank 
>> 1) 32k and UR-II in the higher (Bank 2) 32k. I know I can hook up pin 1, 
>> which is Address 15, to a toggle switch and it will work just fine but that 
>> requires an external switch to be added. Rather than that, I wanted to tie 
>> pin1 of the 27C512 to the Bank 2 enable pin. 
>> 
>> So the question for you hardware guys, is there an easy place on the system 
>> board to grab this signal?
>> 
>> Kurt 

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