Hacking the S-100 Bus

	Pegasus II Repair Like many machines of the era, the Pegasus II is a turnkey S-100 system that runs CP/M. This one came with a pile of diskettes and documentation, but some weird problems.
	Repairing an Unexpanded Altair 8800 This rev 0 Altair 8800 is the first I've worked on that was completely unexpanded! Only two S-100 card sockets were installed, and the system came with its original 8080 CPU board and 1K static RAM board.
	IMSAI SIO2 Modifications for MITS Disk System Compatibility The IMSAI SIO2 conflicts with MITS' disk controller when both are at default addressing. It's possible to change the address on the SIO2, but this breaks compatibility with IMSAI software. Turns out it's not difficult to modify the SIO2 to make it compatible, with little to no reduction in functionality.
	S-100 Computer Products 32K Static RAM Fixing up a S-100 Computer Products 32K Static RAM board. This board uses 2114 type 1K x 4 SRAMs and after repair was running very hot. 5V supply was modified, and addressing was changed to system-specific needs.
	Quick and Timely SBC 2/4 Repair and Modifications When a request from a fellow vintage computer hacker came through for a Z80 based S-100 system capable of running banked CP/M Plus, I chose a Quick and Timely SBC 2/4 as the CPU board, as I had two on hand. In repairing it, I came up with a convenient way to add extended memory management.
	North Star Horizon Restoration This North Star Horizon arrived with a larger lot of equipment. It had clearly been a mouse house at some point in its life, but the bulk of the mouse mess had been removed, hiding the full extent of the damage. Repair involved replacing many sockets and even some S-100 slots.
	IMSAI SIO-2 Compatibility with the Processor Tech 3P+S The Processor Technology 3P+S is an early S-100 universal I/O board, providing both parallel and serial I/O. It is a versatile board, allowing the builder to select from many onboard options via jumpers. As shipped, it can be configured to be compatible with many other manufacturers' serial interfaces; however, making it compatible with the IMSAI SIO-2 requires some modification.
	Repairing The TDL SMB The SMB (System Monitor Board) is one of Technical Design Labs' best known products. I received two of these boards almost completely stripped of parts, and worked through them to get them back to operational condition. Along the way, upgrades, fixes, and reproduction of original parts were done which will hopefully help other hobbyists get their SMB boards operational.
	Reproducing the Solid Sate Music IO-2 The Solid State Music IO-2 is one of my favorite S-100 boards due to its versatility and flexibility. It is usually the board I grab when I want to quickly interface something to the S-100 bus. Vintage IO-2 boards are difficult to find and usually require rework to remove the previous owner's projects, so I decided to reproduce the IO-2 and make the boards available to others.
	TEI MCS-CPU 8080 CPU Board I picked up a TEI MCS-CPU 8080 board at the Vintage Computer Festival East XI. The board came with no documentation, and no documentation was available online. It mostly worked, but had a few functions that weren't behaving correctly.
	Ferroelectric RAM Part 1 Prototyping This board has taken so long to get together, my sample ICs are from before Cypress bought Ramtron! Ferroelectric RAM is basically core on silicon, using tiny magnetic domains deposited on silicon -- it's even destructive read. I've used it in several projects, and have been working on interfacing it to the S-100 bus.
	IBM FSU RAM Board for the S-100 Bus Wait...an IBM made S-100 RAM card, using IBM FSU static RAM modules?! Apparently, yes. Here's a look at the card and the story about why this even exists.
	Cromemco 4FDC Floppy Controller This one goes back to my first bit of S-100 hacking -- getting a Cromemco 4FDC up and running. Five years later, my 4FDC finally formats a floppy! Here we will discuss some of the tips, tricks, resources and myths about the lowly 4FDC.
	Pragmatic Designs DBM-1 EPROM Simulator I picked this board up from a popular online auction site with no documentation or cables. It's an EPROM simulator -- it can replace two 1K EPROMs or a single 2K EPROM with RAM for rapid development without the need to program/erase EPROMs. A handy board, but no one has information on it!
	Power On Jump Board for the S-100 Bus One of my S-100 systems uses a CPU board that doesn't have a power-on jump function. The ROM board doesn't have it either. It's a turnkey system with no front panel, so I had to come up with a way to get the CPU to jump into the ROM board's address space without starting the ROMs at 0x0000.
	A 1702A ROM and 2101 RAM Board Using the IO-2 Building up a Solid State Music IO-2 board as a 1702A PROM reader and 2101 static RAM board using period components. Useful for reading 1702As and testing 2101 SRAMs for use in other projects.
	The Dajen SCI -- A System Central Interface for the S-100 Bus The Dajen SCI is a relatively unknown S-100 board with a ton of highly useful features! Documentation and information on repairing, using and modifying the SCI.
	A Debug Board for the S-100 Bus Details on my S-100 debug board. This board is the result of much testing (and fixing) with my original debug board, which was far less thought out. An essential device for low-level debugging without a front panel, especially if you've got a CPU card that may or may not be working!