The 40 pin socket is for connecting to a Disk Video Interface, usually just referred to as a DVI.
http://tandy.wiki/Disk/Video_Interface The other one is for Option ROMs that contain additional software. There is a modern product call a REX that lets you load multiple different option ROM images and swap between them. http://bitchin100.com/wiki/index.php?title=REX > On 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> > <x-msg://2/#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2><ROM Ports.jpg>
