Altair 32 Front Panel Hardware

Coming Soon! Altair 32 Front Panel Front Replica Hardware Contact Rich for more information!

Introduction

The front panel hardware is a life-sized replica of the original Altair 8800 operators front panel. It measures 19" long, 6.25" high and 1.25" deep. The panel connects to the host computer over a Universal Serial Bus connection and all power for the panel is drawn from the USB host controller in the host PC.

The front panel "stack" consists of three parts:

Dress Panel

The top portion of the front panel assembly is called the "dress panel." The dress panel is 2mm gray aluminum stock engraved with the labels and lines. The original front panel from MITS was a screen printed aluminum sheet of about the same depth. The panel is machined with holes to match the switches and T1-3/4 LEDs. The "MITS" logo strip at the bottom was an adhesive backed, screen printed metal strip. On the Altair32, this strip is an adhesive vinyl strip.

The dress panel is not attached to the rest of the panel stack. Rather, it floats above the stack supported by standoffs. This eliminates the need to put screw holes in the dress panel but also necessitates that the panel stack be "framed" in something to keep it together. In the original Altair, the front panel was supported by a metal frame in the front and a metal plate in the back.

Carrier Panel

The carrier panel is a piece of 2mm natural aluminum stock with cutouts for several jacks and connectors from the Front Panel PCB. The carrier panel is the same size as the dress panel and when assembled into the stack, makes a complete, modular unit.

Front Panel PCB

This is the important part of the stack. The PCB is a double-sided PCB that contains a mix of SMD and through-hole components. The design offers a lot of flexibility in that not only does it contain the main microcontroller (a USB-capable 8051 derivative) and the LED driver, but it optionally supports a USB 2.0 host controller and a Zilog ZDI interface, enabling it to be used to drive and program an eZ80 microcontroller. The board includes three power options (USB, external adapter, ATX PC power) and two RS-232 compatible 3-wire serial ports. The serial ports can be accessed through the Altair32 Emulator, providing two real RS-232 ports to the emulator.

Circuit Description

The front panel is based on two VLSI integrated circuits, an RS-232 level shifter, several passives, SPDT toggle switches and LEDs. The panel is controlled by a Silicon Laboratories C8051F340 8051-based microcontroller which contains three significant built-in peripherals: a USB 2.0 controller, two RS-232 serial ports and an SPI port, in addition to RAM, flash EPROM and 32 additional bits of digital I/O. The 8051 microcontroller manages the host-panel interface as well as the communications with the integrated circuit responsible for the user interface (the LEDs and switches are controlled and monitored by an integrated circuit produced by Maxim specifically for this purpose). The front panel also contains two RS-232-compatible 3-wire serial ports which are operated under the control of the emulator. This provides two dedicated serial ports only accessible by the emulator -- perfect for connecting a serial paper tape reader to the emulator.

Software

The hardware of course is only part of the story. A special DLL (dynamic link library) is is required for Windows in order to make the front panel accessible by the Altair32 Emulator. This DLL is responsible for managing device initialization and removal and provides a protocol that the Altair32 Emulator  uses to communicate with the front panel itself. Upon initialization, the Altair32 registers various callback routines which are called upon the occurrence of various front panel events. The speed with which the front panel switches are scanned is fast enough that the response time to the operation of a switch is nearly instantaneous.

Pricing & Availability

The good news is that the design for the final front panel has been completed and is ready to go. The bad news is that most of the design files were lost in a hard drive crash in 2010 and I don't really know when me and my partner in this project will be able to perform the re-design. Therefore the front panel is not available.

Having said that, please feel free to drop me a note if you're interested and I'll keep your email address on file so I can contact those who may be interested in obtaining one someday.

Thanks for you patience and understanding.

 

Picture of the Altair 32 Panel