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Hi Todd,
The IMSAI is definitely 8 bit only. You are probably right about the 8/16 bit switching. I'm not familiar with this RAM/ROM board, but you should be able to configure it for 8 bit only mode. I'm not an expert at S-100, but I think I read somewhere about the newer S-100 bus detecting an 8 or 16 bit card and then using the 8 DI and 8 DO lines to form a single 16 bit bi-directional data bus. The IMSAI FP (aka CPA) and the 8080A CPU card strictly run in 8 bit mode. I'll leave it up to someone else here in this group to instruct you on how to configure your RAM/ROM card for 8 bit only. If you do want to see my schematics for my (8 bit) RAM card, just give me your email address and we can talk. Cheers, Josh > Date: Mon, 31 Dec 2012 18:35:39 -0600 > From: litte...@mchsi.com > To: n8vem...@googlegroups.com > Subject: Re: [N8VEM-S100:1239] S-100 board reorders > > I did build that board, but could never get > it to take a deposit from the FP and from > what I remember, there was something about > 'every other' address step that was not displaying > the data from memory properly. > > It's a complex board and I think my problem is in > the 8/16 bit switching and the fact I truly don't > understand it. > > The Eprom portion works. I burned the > 'walking lights' program and it runs fine. > > I have repaired my S-100 boards and built the > SMB with success. However, I'm not an engineer. > > I'll have to put it in tomorrow to refresh > my memory. > > I was looking for a bare bones circuit just > for 64K. I have one Imsai that I'd like to > sell and it's RAM boards are flaky. > > Todd > > > > ----- Original Message ----- > From: "Tom Lafleur" <la...@lafleur.us> > To: n8vem...@googlegroups.com > Sent: Monday, December 31, 2012 6:06:00 PM GMT -06:00 Central America > Subject: Re: [N8VEM-S100:1238] S-100 board reorders > > just use the rom/ram board... cheap to build and 64k or more of fast ram > > > > > On Mon, Dec 31, 2012 at 3:39 PM, < litte...@mchsi.com > wrote: > > > I'm interested in building a simple 64K RAM board for > the same reason. I have two Imsai's, both with > multiple RAM card(s) with many memory chips. > > If someone could point me to a schematic, I'd > like to build a few. I know Don Caprio mentioned > earlier this year he had a project on the PBworks > page but I don't know where to find it. > > I'd like to look at a few designs. > > Todd > > > > ----- Original Message ----- > From: "Crusty OMO" < crus...@hotmail.com > > To: n8vem...@googlegroups.com > Sent: Sunday, December 30, 2012 9:45:54 PM GMT -06:00 Central America > Subject: RE: [N8VEM-S100:1236] S-100 board reorders > > > Hi Andrew, > > > > Cool, thanks! Just a note on what I'm using the first (buffered) prototyping board for.... > It's currently being used as a 64K RAM card in my IMSAI. This was done to establish a working system. I'll be replacing this RAM card with the old RAM cards when I test/fix them. > At that point, I'll repurpose this card to be an 8080 CPU, RAM & I/O card for another IMSAI system I'd like to resurrect. > > Cheers, > Josh > > > > > > > > > -- > ~~ _/) ~~~~ _/) ~~~~ _/) ~~~~ _/) ~~ > > Tom Lafleur > (858) 759-9692 |