The IMSAI Series Two I/O board utilizes an SMC Super-I/O chip to provide two serial ports, a parallel port, keyboard and mouse ports, as well as floppy disk support.  External logic is used to support two independent IDE channels, and adapts the standard IDE interface to the 8-bit IEEE-696 bus.  The full text of the IEEE-696 specification can be downloaded here.  

Super-IO Board:  [Now Shipping!]

Documentation, software, and design files for the Super-I/O Controller are located here.  You can also order a Super-I/O controller from this page, or try one out via the Internet.

The Super I/O Controller is a single-board solution to your S-100 peripheral woes.  This board allows modern peripherals to be used with your vintage S-100 system. 

I designed the architecture for the Super-I/O controller, created the schematics, and did the board layout.  95% of the Super-I/O controller was routed manually to allow this design to fit on a double-sided PC board.  

IMSAI Series Two Quick Links

• Pre-order an IMSAI Series Two Limited Edition now.
• Visit the Official IMSAI Series Two website. 
• IMSAI Series Two FAQ.
• IMSAI Series Two Production Status.
• You can also join the IMSAI User's Group mailing list hosted by Yahoo.

You can download the latest Architecture Specification for the IMSAI Series Two (Revision 0.42, dated December 21, 2002. 

Table of Contents: 

1.	Introduction				5
1.1.	What you need to complete the system:	6
2.	Hardware Specification			7
2.1.	Chassis					7
2.2.	Power Supply				9
2.3.	Power Supply Booster			12
2.4.	EXP-9/AT Backplane (Motherboard)	13
2.5.	MPU-C Processor Board			20
2.5.1.	Zilog Z8S180 Microprocessor		21
2.5.2.	Memory Subsystem			23
2.5.3.	I/O Subsystem				26
2.5.4.	MPU-C IEEE-696 Bus Intf/Localbus Bridge	27
2.5.5.	Hardware Interrupts			28
2.5.6.	Direct Memory Access			31
2.5.7.	MPU-C SLAVE Mode			31
2.5.8.	MPU-C Connector Pinouts			31
2.6.	CPA Programmer's Front Panel		33
2.7.	IMSAI Super-I/O Board			34
2.7.1.	IEEE-696 Slave Bridge Registers		35
2.7.2.	Super-I/O Controller Connector Pinouts	37
3.	References				42

The MPU-C processor board utilizes the Zilog Z8S180 microprocessor and provides a complete system on an IEEE-696 compatible S-100 board.  The MPU-C consists of the following on-board subsystems:

·        Microprocessor – Zilog Z8S180 CPU

·        Memory Subsystem (SRAM, FLASH, EPROM)

·        I/O Subsystem

·        IEEE-696 and to Z8S180 Localbus Bridge

·        Priority Interrupt Controller Subsystem

·        Temporary Master Access (TMA) Subsystem

·        Voltage Regulator Subsystem

·        In-Circuit-Programming interface for programmable logic components.

Harte Technologies is responsible for all phases of the development of the MPU-C processor board.  

IMSAI EXP-9/AT Backplane:

The IMSAI Series Two utilizes the IMSAI EXP-9/AT backplane designed with active termination and interleaved ground planes between lines, thus allowing S-100 boards to operate at 10 MHz. or higher.  The IMSAI Series Two comes with a nine-slot active termination S-100 backplane standard (first slot reserved for the front panel.) A 20-slot EXP-20/AT backplane is optional.  Please note that using the 20-slot backplane precludes mounting an ATX motherboard inside the enclosure.

The backplane is constructed of a sturdy 0.093” thick FR-4 laminate printed-circuit board and utilizes press-fit S-100 connectors.  Power is supplied to the backplane via seven ¼” spade terminals.  The backplane includes a header for connecting an external system reset switch if desired.  Two test points are provided toward the front of the backplane to aid in measuring and adjusting the termination voltage.

The EXP-9/AT backplane was jointly designed by Tom Fischer and I, and I did the layout for this board.  The prototype boards (constructed of 0.063 FR-4 laminate without silk screen or solder mask) are a perfect mechanical fit for the chassis, and are fully functional.  The artwork for the production boards has changed slightly to include additional test points, a RESET# connector, and power indicator LEDs for the +8, +16, and -16V supplies.  

Software:

The IMSAI Series Two uses the IMSAI S2 Monitor, which is a direct descendent of the original IMSAI MPU-B 2K monitor.  This is the defalt bootstrap for the Series Two.  The source code for this monitor was obtained from original source listings, and I modified it in a few hours to work with the IMSAI Series Two system.  More work is needed to provide monitor support for some of the more advanced features of the Series Two, such as the FLASH memory programming, the IDE controller, modern floppy disk formats.

The IMSAI Series Two is designed to support various 8-bit operating systems including: Digital Research CP/M 2.2 and CP/M 3.0 (CP/M-PLUS) and ZSDOS.

Check out the original IMSAI 8080 on my Computer History Page