I should have done a bit more digging. NEC makes two masked roms. And probably more likely that they used one of their own chips since they did the design tweaks on the 8201 to make the 8300. uPD23C1000 uPD23C1010
I'm not sure that helps someone who doesn't have an original system rom for their 8300 but It's something to look at. The pinouts for the two NEC roms are different. A15 VCC A12 A14 A7 A13 A6 A8 A5 A9 A4 A11 A3 A16 A2 A10 A1 OE A0 D7 D0 D6 D1 D5 D2 D4 GND D3 -----Original Message----- From: M100 [mailto:[email protected]] On Behalf Of Kurt McCullum Sent: Friday, February 17, 2017 6:53 PM To: 'Model 100 Discussion' <[email protected]> Subject: Re: [M100] Parts for an NEC PC-8300 The only masked ROM I have found that is 128k and 28pins is: (1M) 128k x 8 mask rom (TC531000) A15 1 +-v-+ 28 Vdd A12 2 | | 27 A14 A7 3 | | 26 A13 A6 4 | | 25 A8 A5 5 | | 24 A9 A4 6 | | 23 A11 A3 7 | | 22 A16 A2 8 | | 21 A10 A1 9 | | 20 CE/ A0 10 | | 19 D7 D0 11 | | 18 D6 D1 12 | | 17 D5 D2 13 | | 16 D4 GND 14 +---+ 15 D3 Keep in mind this is a total guess based on very little information. Kurt -----Original Message----- From: M100 [mailto:[email protected]] On Behalf Of Stephen Adolph Sent: Friday, February 17, 2017 5:27 PM To: Model 100 Discussion <[email protected]> Subject: Re: [M100] Parts for an NEC PC-8300 VT simulates it with 4 rom banks. so, .. it must be 128kB. I just have no idea what the pin assignment on a 28 pin socket could be. Steve
