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 On Fri, Feb 17, 2017 at 8:20 PM, Stephen Adolph <[email protected]> wrote: > ROM0 is 28 pins. I went downstairs to open it up again and count... > can't be 27c1001. that's 32 pins as you say Mike. > > so, still a mystery. > > I thought maybe it could just be a 64k ROM - that clearly can fit in a > 28pin socket. > > Steve > > > On Fri, Feb 17, 2017 at 8:13 PM, Stephen Adolph <[email protected]> wrote: >> oh that's very interesting. ok. I wonder what the pin assignment is. >> >> what does the 8300 need 96k of rom for 8300 mode for, vs only 32k rom for >> 8201? >> >> a schematic would be golden. All I can say is there is no other ROM >> on the board. >> >> Steve >> >> On Fri, Feb 17, 2017 at 6:51 PM, Kurt McCullum <[email protected]> wrote: >>> I don't have an 8300 here but web8201.net has some detailed technical docs. >>> Here is a page describing the PROM as 128k >>> >>> http://web8201.net/NEC8201emulation.asp >>> >>> Kurt >>> >>> -----Original Message----- >>> From: M100 [mailto:[email protected]] On Behalf Of Stephen >>> Adolph >>> Sent: Friday, February 17, 2017 2:53 PM >>> To: Model 100 Discussion <[email protected]> >>> Subject: Re: [M100] Parts for an NEC PC-8300 >>> >>> from my perspective- >>> >>> * there is a single socket ROM0 for the main ROM >>> * ROM1 is for option roms. >>> * there is no other ROM in the unit. >>> * it is a 32pin socket, and so it must be no larger than a 64kB rom. >>> Not likely to be 32kB. >>> * i'd bet that OUT163,2 sets A15 on the socket. >>> * no idea what the pinout is but it could be deduced quickly. I think since >>> the PC8201 uses normal pinouts, so too does the 8300. >>> >>> So my bet would be a 27C512 would do it. It is possible however that it >>> is still just a 32kB rom. Perhaps OUT163,2 sets a signal on the PIO or >>> otherwise that the processor can check, to decide what mode it should be in. >>> >>> Steve >>> >>> >>> >>> On Fri, Feb 17, 2017 at 4:19 PM, Frederick Whitaker <[email protected]> >>> wrote: >>>> Mike >>>> >>>> There are places for two ROMS. In the regular PC-8300 there is only >>>> one ROM used for Basic. >>>> 83100 - 438 >>>> N83A Basic >>>> 1986 >>>> Microsoft >>>> 8649 - Z69 >>>> >>>> In the other unit, which no longer has it's regular ROM, there are two ROMs >>>> D276256D-20 >>>> D276256G-25 >>>> >>>> I hope this helps. On the PC-8300 there is a wide access on the back >>>> with three screws. Only two ROM sockets are visible and usable without >>>> dismantling the case. >>>> >>>> I hope this helps. >>>> >>>> Fred Whitaker >>>> >>>> >>>> On 2/17/2017 2:15 PM, Mike Stein wrote: >>>>> >>>>> Looks like it's up to you, Fred: >>>>> >>>>> Can you open up the 8300 and tell us exactly how many and what kind >>>>> of ROMs or EPROMs are in there, i.e. any labels and/or part numbers? >>>>> >>>>> Since at least one is custom firmware it's probably in an EPROM (as >>>>> opposed to a ROM) and will probably have a standard number like 27C512. >>>>> >>>>> From what I've read it looks like there should be three 28-pin >>>>> sockets with a 27C512 in two of them and the third one empty or with >>>>> an Option ROM in it. >>>>> >>>>> Let me know what you find. >>>>> >>>>> m >>>>> >>>>> ----- Original Message ----- >>>>> From: "Fred Whitaker" <[email protected]> >>>>> To: "Model 100 Discussion" <[email protected]> >>>>> Sent: Sunday, February 12, 2017 3:32 PM >>>>> Subject: Re: [M100] Parts for an NEC PC-8300 >>>>> >>>>> >>>>>> Mike >>>>>> >>>>>> I don't have an image. I don't know if the ROM you are referring to >>>>>> will do the job. The 8300 ROM is bigger than the 8201, but I believe >>>>>> it uses the same chip as the 8201. >>>>>> >>>>>> I was under the impression that someone had uploaded a copy of the >>>>>> 8300 ROM contents, but I don't remember where or when. >>>>>> >>>>>> I could send you one of my ROMs, from another machine, but I don't >>>>>> know if that would help. >>>>>> >>>>>> Fred Whitaker >>>>>> >>>>>> On 2/11/2017 7:48 PM, Mike Stein wrote: >>>>>>> >>>>>>> Hi Frederick, >>>>>>> >>>>>>> If you can send me or point me to an image of that ROM I can >>>>>>> probably burn an EPROM for you, assuming it's a JEDEC-standard 27xxx >>>>>>> type. >>>>>>> >>>>>>> m >>>>>>> >>>>>>> ----- Original Message ----- >>>>>>> From: "Frederick Whitaker" <[email protected]> >>>>>>> To: "Model 100 Discussion" <[email protected]> >>>>>>> Sent: Saturday, February 11, 2017 6:27 PM >>>>>>> Subject: [M100] Parts for an NEC PC-8300 >>>>>>> >>>>>>> >>>>>>>> I am interested in a replacement keyboard for my NEC PC-8300. I >>>>>>>> also need a new Main ROM, When I received this machine it had a >>>>>>>> specialized ROM in it. It will not boot. >>>>>>>> >>>>>>>> If I had those two items I could use this machine. I have asked in >>>>>>>> the past if anyone could make a main ROM for this machine but >>>>>>>> never received an answer. >>>>>>>> >>>>>>>> Fred Whitaker >>>> >>>> >>>
