Thanks for digging that out Steve. I'll double check it later tonight. I've only played with Bank2 replacing the main ROM one time. I guess it's useful for developing a replacement system ROM but other than that I don't know what one would do with that feature.
Kurt On Mon, Jun 24, 2019, at 2:45 PM, Stephen Adolph wrote: > U11 pin 10 and pin 15. I think bank 2 occurs when > Pin 15 is 0 and pin 10 is one. > > U53 pin 10 should indicate when bank 2 ram is in use as an upper ram block. > > Bank 2 ram can replace the Roms also in the lower 32k. > > > On Monday, June 24, 2019, Kurt McCullum <[email protected]> wrote: >> __ >> Thanks Steve. I pulled out the tech manual and it does seem like that is the >> right pin. I've got a unit split open so I'll check later tonight to see if >> it's pulsing as Brian suggested. Could be the case. From the diagram, I was >> hoping it would be 5v when selected and 0v when grounded. >> >> Kurt >> >> On Mon, Jun 24, 2019, at 12:51 PM, Stephen Adolph wrote: >>> I'll take another look tonight.. >>> >>> On Mon, Jun 24, 2019 at 11:36 AM Kurt McCullum <[email protected]> wrote: >>>> __ >>>> Initial inspection of pin 8 on u38 gives me 5.5v when bank 2 is selected >>>> and 3.5v when bank 1 is selected. Strange results but I'll keep digging. >>>> >>>> Kurt >>>> >>>> On Sun, Jun 23, 2019, at 7:35 PM, Kurt McCullum wrote: >>>>> Thanks Steve. I'll track that down and see if I can make it work. I >>>>> appreciate the information! >>>>> >>>>> >>>>> Kurt >>>>> >>>>> On Sun, Jun 23, 2019, at 7:33 PM, Stephen Adolph wrote: >>>>>> Ah I misunderstood! sorry Kurt. >>>>>> Looks to me (page 102 of 136 in the 8201 service manual), without >>>>>> investing a ton of time on it, that U53 is the register that tracks the >>>>>> bank settings, and U38 pin 8 appears to have the signal BANK#2. >>>>>> >>>>>> Steve >>>>>> >>>>>> On Sun, Jun 23, 2019 at 10:23 PM Kurt McCullum <[email protected]> >>>>>> wrote: >>>>>>> __ >>>>>>> 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 >>>>>>> >>>>> >>>> >>
