Path: utzoo!utgpu!attcan!uunet!cbmvax!ditto From: ditto@cbmvax.UUCP (Michael "Ford" Ditto) Newsgroups: comp.sys.tandy Subject: Re: Old peripherals (DVI) Summary: DVI contains a Z80, connects to m100 bus (8085 bus) Keywords: coco 100 102 200 disk video controller Message-ID: <4854@cbmvax.UUCP> Date: 27 Sep 88 19:20:03 GMT References: <284@pte.UUCP> Reply-To: ditto@cbmvax.UUCP (Michael "Ford" Ditto) Organization: Commodore Technology, West Chester, PA Lines: 42 In article <284@pte.UUCP> car@pte.UUCP (Chris Rende) writes: >The Disk/Video interface would (might) give my 64x16 Model I 80x25 video! It could, but it wouldn't be memory mapped like the I/III/4, and I don't think the character set would have the graphics characters (I'm not sure because mine is broken). It would be difficult to make it software- compatible (Basic would mostly work, aside from print@; anything that does direct screen I/O wouldn't work). > More than likely >this is the same type of connection use between the Model I CPU and its >Expansion Interface - i.e., a memory mapped bus of sorts. It is a 40-pin ribbon cable which connects directly to the m100 bus (i.e. it's got address lines, data bus, R/W signals, etc.). It is basically the direct 80C85 (m100's CPU) bus, which differs from the Model I's bus primarily in that it has multiplexed data/address busses. > If this is the case >then interfacing to this device might not be too bad. I was not able to get >a look at the manual for this one to see if the connector pinout spec's are >in it. The manual does have the connector pinout; so does the model 100 Technical Manual. There is also a "block diagram" which shows that the m100 cable connects to the guts of the DVI via an 8255. An 8255 is an Intel interface chip that basically has 24 bits of parallel I/O. There is no description of how this 8255 is used, however; not even whether it is controlled by the m100 bus or the internal Z80 (I would guess the former, since the latter would be real nasty). >If anyone has any insite that they can give me on either of these devices >I'd appreciate it. (What CPU is in a Model 100/102/200?) The 100 has a 80C85 running at 2.5MHz. -- -=] Ford [=- "The number of Unix installations (In Real Life: Mike Ditto) has grown to 10, with more expected." ford@kenobi.cts.com - The Unix Programmer's Manual, ...!sdcsvax!crash!elgar!ford 2nd Edition, June, 1972. ditto@cbmvax.commodore.com