NOTE: The picture included two different system ROMs pulled from different 8300s. Included both because the numbers on the chips are slightly different, to my bewilderment. (Different releases I guess?)
On Tue, Jul 4, 2017 at 2:18 PM, Gary Weber <m100l...@gweber.org> wrote: > I'm resurrecting an old thread here. Sorry I'd missed out on the > discussion a few months back. > > Attached is an image of two NEC PC-8300 main system ROMs. Maybe the > numbers yield something useful? I can definitely confirm that the 8300 > does have four 32K images that are bank switched, and my understanding is > this: > Bank 1: Base 8300 32K image > Bank 2 & 3: Extensions to the internal applications, both TEXT & TELCOM > (w/Xmodem) enhancements. > Bank 4: An 8201A 32K image for 100% compatibility mode > > I've only ever been able to burn a 27C512 (for two 32K images) as a > replacement system ROM, using the appropriate OUT command to switch between > two images. However, I've not ever been able to reproduce the full 128K > image using any sort of chip (including a 27C1001 as others have noted). > I'm willing to bet though that a 27C1001 could be used with an adapter > board of some kind but am lost as to figure out how to go further with that > idea. > > Happy 4th of July everyone! > > Gary Weber > web8201.net > > > > > On Sun, Feb 19, 2017 at 9:20 AM, Kurt McCullum <kurt.mccul...@att.net> > wrote: > >> Steve, >> >> Keep in mind that I am guessing on the PROM based on the limited number >> of 128k 28 pin PROMs available at that time. That's a pinout for the NEC >> PROM but I don't know if that is the actual part which was used. There >> should be a number on the chip that may lead to the answer. >> >> Kurt >> >> -----Original Message----- >> From: M100 [mailto:m100-boun...@lists.bitchin100.com] On Behalf Of >> Stephen Adolph >> Sent: Sunday, February 19, 2017 5:13 AM >> To: Model 100 Discussion <m100@lists.bitchin100.com> >> Subject: Re: [M100] Parts for an NEC PC-8300 >> >> .. comparing a 27C1001 pinout to the one from Kurt, it looks like it may >> just be possible to stuff a 27C1001 and wire up only a couple of signals. >> >> >> On Sat, Feb 18, 2017 at 8:12 PM, Stephen Adolph <twospru...@gmail.com> >> wrote: >> > come to think of it, you could probably tie /CE and /OE together. >> > >> > On Sat, Feb 18, 2017 at 8:08 PM, Stephen Adolph <twospru...@gmail.com> >> wrote: >> >> I did not grasp how much information is in that 500MB tech reference >> >> doc for the 8300. Wow! >> >> >> >> probably the best documented Model T. >> >> >> >> It is clear that the ROM is 128KB, and I think it is also clear that >> >> without some custom solution, one can't make a replacement main rom >> >> for the 8300 easily. At best you might be able to program a 27C1001, >> >> and then do a custom adapter board. >> >> >> >> A normal eeprom needs both a chip select and an output enable, so >> >> some extra logic might be needed too. >> >> >
