What are you looking at? > For the OPTION rom: In M100 and T102, pin 23 is NC. In T200, pin 23 is connected to ALE
On the schematics pins 23 of the option ROM sockets of both the M100 and the T102 are labelled ALE (and in fact are connected to ALE), as is pin 23 of the 'old' M100 main ROM. Since they're all intended for the same type of chip why would they not all be connected the same way? > Pin 27 of the optrom socket is labelled /CE while pin 27 of the main rom is > labelled /CS, Pin 27 is labelled /CS on both the main and option ROM sockets, and is the only pin that is not connected in parallel to both sockets. As you say, a modern replacement (which normally only has one chip select/enable) can probably ignore pin 23. The lower address lines are already latched, so the purpose of the ALE connection isn't obvious; perhaps the original ROMs had some critical timing requirement that needed ALE even though the addresses were already latched. Maybe Steve has an idea? ----- Original Message ----- From: Brian White To: [email protected] Sent: Friday, June 29, 2018 2:18 AM Subject: Re: [M100] nn - getting back involved. Also to add to the confusion (are /CE and /CS synonymous? Are they maybe even tied together in the original main rom package or on the M100 motherboard?) Pin 27 of the optrom socket is labelled /CE while pin 27 of the main rom is labelled /CS, and it's not obvious that it's just a synonym for /CE, because there is another pin actually labelled /CE on the same socket, and, the two sockets are documented in the same manual, so it's not just a difference of convention between one author and another. The same authors labelled pin 27 two different ways in the two different sockets in the same documet. It could still just be a meaningless cosmetic blemish and the pins all mean the same thing, it's not an automatic assumption just from these docs. It needs to be determined. On Fri, Jun 29, 2018 at 2:02 AM Brian White <[email protected]> wrote: Mayyyyybe none that matters, but, I have these notes about the option rom socket: https://drive.google.com/open?id=1ktI-KbRSu9drAOxGeEwzE2eil3YPtd_a6uABg_X1maA And Bitchin100 has this about the main rom: http://bitchin100.com/wiki/index.php?title=Model_100_ROM And the only potential discrepency is pin 23. For the MAIN rom: In the early M100s, it's labelled /CE, but that is confusing because there is already a /CS on pin 27, and I thought they were just different possible names for the same thing. But sure enough it's written that way in the manual too: http://ftp.whtech.com/club100/doc/m100ServiceManual.pdf#page=125 For the OPTION rom: In M100 and T102, pin 23 is NC. In T200, pin 23 is connected to ALE, but you can ignore it if you're making a rom adapter and leave that pin disconnected in the adapter. If you were making an adapter, or simply writing a cheat sheet document for mapping the pins, that was supposed to work in both the main and option rom locations, I'm not sure if there is any single mapping that is ok in all cases (all models option rom sockets and old M100 main rom socket), even though in most cases it *looks* like you just ignore it and leave it unconnected when you're talking about putting a new part into the old socket. -- bkw On Thu, Jun 28, 2018 at 3:11 PM Mike Stein <[email protected]> wrote: ----- Original Message ----- From: Brian White To: [email protected] Sent: Wednesday, June 27, 2018 2:59 PM Subject: Re: [M100] nn - getting back involved. ... > Also, the rearranged pinout for Model 100 main rom is different from the rearranged pinout for the option rom! ... Interesting; what is different? m -- bkw -- bkw
