Intel MDS 225 (1st post)

Hi Bill, At 02:10 PM 10/13/00 -0500, you wrote: Cool! I have one of these too. Mine started out as a 225 but has been upgraded and modified. I have SOME of the docs for the system and they can only be called MASSIVE! I have seven 8 1/2 x 11" binders and each one is about 5" thick. I have several ICE units for it but I don't remember if I have the docs for them. The standard CPU in these was a 8080 or an 8085 but they could be upgraded to 8088 and I think to an 80186 or 80286. Mine has the 8088 in it. All the cards in it are a standard type card called MultiBus. All Multibus are readilty identifable because they all have two connectors on the bottom edge. One connector has 80 contacts spaced .156" on center and the other has 60 contacts spaced .100 on center. The standard card size is 12 x 6.75 inches. The operating system for these is ISIS (Intel Systtem Implementation Supervisor). This was later upgraded to ISIS-II. I think that's what I have on mine but it's been so long since I used it that I'm not sure. They also have a monitor ROM built into them. PL/M (aka PL/M-80), a Macro Assembler, BASIC-80, iCIS-Cobol and Fortran-80 were all available for them. I don't have the specs for the 225 handy but it was a 220 with one upgrade that I don't recall. I do have the 220 specs; 4 K ROM, 32K RAM expandable to 64K, Eight level maskable priority interrupts, built in interfaces for paper tape reader, PT reader/punch, printer and Universal EPROM programmer. Compaible with standard iSBC expansion modules, integral CRT with detachable full ASCII keyboard. 250K floppy drive. Standard Multibus with multi-processor and DMA capabiltiy. 2000 character upper and lower case display. OH! and a 8080A was the standard CPU. 2.6 MHz CPU clock speed. You should have an 8" floppy drive standing vertically on the right side of the CRT. The two drives in the separate box were an option. The earliest ones were mounted vertically in a narrow (relatively!) box. The later ones were mounted horizontally in a shorter but wider box. The later box is the same width as the main chassis. The orignal drives were single sided and I think single density. Mine has been upgraded to Double sided Double density. The main chassis should have a row of interrupt switchs on the front of it. There is also a similar box that does not have the interrupt switchs. That is an optional expansion chassis. I have the separate Intel EPROM burner and Intel paper tape reader with mine. The EPROM burners are common in this area but this is the first PT reader that I've seen. I also found an Intel printer that's made to go with the unit but it was incomplete so I passed it up. The best book that I've seen for getting started with these is "A Guide to Intellec MicroComputer Developement Systems" by Daniel D. McCraken. McCraken is better known for his PL/M book. Also supplied is a set of hardware that I believe is for in-circuit It's an interesting system but very antiquated! But FWIW I drug mine home about 12 years ago and it's still here. That's saying a lot considering how big it is! Joe