Hello Charles! Welcome to Club 100 :) You are correct about the ports under the ROM door. The 40-pin DIP is the system bus connector; it's used for direct system bus peripherals such as the Disk/Video Interface. The odd Molex socket is for Option ROM modules. BITD, you would buy software from Radio Shack and it would come on ROM modules which they would install for you at purchase time. A fair amount of third-party software was also available shortly thereafter, and came on modules that used various form-factors to be compatible with this socket.
In modern-day use, the most popular options for option ROMs is to use a REX, which is a modern flash-based multi-bank ROM that allows you to have multiple option ROM images "installed" in your machine and switch between them using a software menu. It has other cool features, too. http://bitchin100.com/wiki/index.php?title=REX REX can be purchased online from: https://www.arcadeshopper.com/wp/?page_id=11#!/REX/p/102954443/category=28313042 but it looks like he might be out of stock at the moment (basically meaning - I need to assemble some more; full disclosure: I did not design REX, I merely assemble them). While we're doing intros, have you addressed the internal memory battery, yet? If it hasn't been replaced yet, it is probably leaking and poses serious risk to your system logic board due to corrosion. -Josh On Mon, Dec 17, 2018 at 9:40 AM Charles Hudson <[email protected]> wrote: > Hello to the members of the bitchin100 mailing list. I am a newcomer to > the list and am posting here - at the suggestion of MikeS - because I am > the new owner of a Model 100. It is my first TRS and I have a lot to > learn, although the VCFED members have helped where they can. > > I have some documentation: the Radio Shack Model 100 manual and a book The > TRS-80 Model 100 Computer, by David Lein. But I have a question about the > expansion ROM port and am hoping someone can help me to understand better: > > In the expansion bay are two sockets; a 28-pin and a 40-pin. The 40-pin > is referenced on page 208 of the RS manual as "40-pin extended bus" and a > chart of the signals is given along with a pinout diagram. What is the > purpose of this bus? Was / is there any device that used it? > > Am I correct in assuming the 28-pin socket is used for the ROM Module > Cartridge referenced on page 8 of the RS manual? > > Thanks for your replies. > > -CH- > > picture attached. > > > > > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon> > Virus-free. > www.avast.com > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link> > <#m_3900484543054788430_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> >
