Readme.txt for Contralto v1.2: 1. Introduction and Overview ============================ ContrAlto aspires to be a faithful emulation of the Xerox Alto II series of pioneering graphical workstations developed at Xerox PARC in 1973. This document covers installation and use on Windows platforms. See readme-mono.txt for instructions for Unix and OS X platforms. 1.1 What's Emulated ------------------- ContrAlto currently emulates the following Alto hardware: - Alto I and Alto II XM CPU - Microcode RAM (in 1K RAM, 1K RAM/2K ROM, or 3K RAM configurations) - 256KW of main memory (in 64KW banks) - Two Diablo Model 31 or 44 drives - Ethernet (encapsulated in either UDP datagrams or raw Ethernet frames on the host machine) - Standard Keyboard/Mouse/Video - Audio DAC (used with the Smalltalk Music System) 1.2 What's Not -------------- At this time, ContrAlto does not support more exotic hardware such as Trident disks, printers or audio using the utility port, the Orbit printer interface, or the keyset input device. 2.0 Requirements ================ ContrAlto will run on any Windows PC running Windows Vista or later, with version 4.5.3 or later of the .NET Framework installed. .NET should be present by default on Windows Vista and later; if it is not installed on your computer it can be obtained at https://www.microsoft.com/net. As ContrAlto is a .NET application it will also run under Mono (http://www.mono-project.com/) on Unix and OS X -- please see the readme-mono.txt file for details on using ContrAlto on these platforms as there are some differences. A three-button mouse is essential for using most Alto software. On most mice, the mousewheel can be clicked to provide the third (middle) button. Laptops with trackpads may have configuration options to simulate three buttons but will likely be clumsy to use. 3.0 Getting Started =================== Installation of ContrAlto is simple: Double-click the installer file, named "ContraltoSetup.msi" and follow the on-screen instructions. The installer will install all of the necessary files and create two icons on your Start menu, one for ContrAlto itself, and one for its documentation (the file you're reading now!) 3.1 Starting the Alto ===================== To launch ContrAlto, simply click on the shortcut created by the installer on your Start Menu (or Start Screen, depending on your Windows version.) Two windows will appear: a console window for diagnostic output and the main display window, labeled "ContrAlto." This latter window is where you will interact with your virtual Alto. On a real Alto, the system is booted by loading a 14" disk pack into the front of a Diablo 31 drive, waiting for it to spin up for 20 seconds and then pressing the "Reset" button on the back of the keyboard. Booting an emulated Alto under ContrAlto is slightly less time-consuming. To load a disk pack into the virtual Diablo drive, click on the "System" menu and go to "Drive 0 -> Load...". You will be presented with a file dialog allowing selection of the disk image (effectively a "virtual disk pack") to be loaded. Disk images are not included with ContrAlto but may be found in various places on the Internet -- see Section 3.1.3 for details. Once the pack has been loaded, you can start the Alto by clicking on the "System->Start" menu (or hitting Ctrl+Alt+S). The display will turn white and after 5-10 seconds a mouse cursor will appear, followed shortly by the banner of the Xerox Alto Executive. Congratulations, your Alto is now running! Click on the display window to start interacting with it using the keyboard and mouse (and if you need your mouse back for other things, press either "Alt" key on your keyboard.) See Section 3.1 for details on using ContrAlto. 3.1 Using the Alto ================== 3.1.1 Mouse ----------- ContrAlto uses your computer's mouse to simulate the one the Alto uses. In order to accurately simulate the mouse, ContrAlto must "capture" the real mouse, which effectively makes your system's mouse exclusive to the ContrAlto window. (If you've ever used virtualization software like VMWare, VirtualBox, Virtual PC, or Parallels, you may be familiar with this behavior.) Clicking on the ContrAlto display window will cause ContrAlto to capture the mouse. Once the mouse has been captured, any mouse movements will be reflected by the Alto's mouse cursor. While ContrAlto has control of the mouse, you will not be able to use the mouse for other programs running on your PC. To release ContrAlto's control, press either "Alt" key on your keyboard. Mouse movements will return to normal, and you will not be able to control the Alto's mouse until you click on the ContrAlto display window again. The Alto mouse is a three-button mouse. Alto mouse buttons are mapped as you would expect. If you have a real three-button mouse then this is completely straightforward. If you have a two button mouse with a "mousewheel" then a mousewheel click maps to a click of the Alto's middle mouse button. If you have a trackpad or other pointing device, using the middle mouse button may be more complicated. See what configuration options your operating system and/or drivers provide you for mapping mouse buttons. 3.1.2 Keyboard -------------- ContrAlto emulates the 61-key Alto II keyboard. The vast majority of keys (the alphanumerics and punctuation) work as you would expect them to, but the Alto has a few special keys, which are described below: Alto Key PC Key -------- ---------- LF Down Arrow BS Backspace Blank-Top F1 Blank-Middle F2 Blank-Bottom F3 <- (arrow) Left Arrow DEL Del LOCK F4 3.1.3 Disk Packs ---------------- A real Alto uses large 14" disk packs for disk storage, each containing approximately 2.5 megabytes (for Diablo 31) or 5 megabytes (for Diablo 44) of data. ContrAlto uses files, referred to as "disk images" or just "images" that contain a bit-for-bit copy of these original packs. These are a lot easier to use with a modern PC. Disk images can be loaded and unloaded via the "System->Drive 0" and System->Drive 1" menus. A file dialog will be presented showing possible disk images in the current directory. If you modify the contents of a loaded disk (for example creating new files or deleting existing ones) the changes will be written back out to the disk image when a new image is loaded or when ContrAlto exits. For this reason it may be a good idea to make backups of packs from time to time (just like on the real machine.) ContrAlto does not come with any disk images, however an assortment of Alto programs can be found on Bitsavers.org, at http://www.bitsavers.org/bits/Xerox/Alto/disk_images/. Images include: AllGames.dsk - A collection of games and toys for the Alto Bcpl.dsk - A set of BCPL development tools Diags.dsk - Diagnostic tools NonProg.dsk - The "Non-Programmer's Disk," containing Bravo Xmsmall.dsk - Smalltalk-76 3.1.4 Startup, Reset and Shutdown --------------------------------- The system can be started at any time by using the "System->Start" menu, though in general having a pack image loaded first is a good idea. Similarly, the "Start->Reset" menu will reset the Alto. You can shut down the Alto by closing the ContrAlto window; this will commit disk changes made to the currently loaded disks back to the disk image files. However, you will want to be sure the software running on the Alto is ready to be shutdown first, or else you may lose work or corrupt your disk. 3.2 Additional Reading Materials ---------------------------------- The Bitsavers Alto archive at http://http://bitsavers.org/pdf/xerox/alto is an excellent repository of original Alto documentation, here are a few documents to get you started: - The "Alto User's Handbook" is indispensable and contains an overview of the Alto Executive (the OS "shell"), Bravo (great-granddaddy of Microsoft Word) and other utilities. http://bitsavers.org/pdf/xerox/alto/Alto_Users_Handbook_Sep79.pdf - "Alto Subsystems" documents many of the common Alto programs and tools ("subsystems" in Alto parlance) in detail. http://bitsavers.org/pdf/xerox/alto/AltoSubsystems_Oct79.pdf - "Alto Operating System Reference Manual" is useful if you are going to do any programming for the Alto. http://bitsavers.org/pdf/xerox/alto/AltoSWRef.part1.pdf http://bitsavers.org/pdf/xerox/alto/AltoSWRef.part2.pdf - "BCPL Reference Manual" is definitely required if you are going to do any programming on the Alto (in BCPL, anyway...) http://bitsavers.org/pdf/xerox/alto/bcpl/AltoBCPLdoc.pdf - "Bravo Course Outline" is a tutorial that will show you how to use the Bravo editor. http://bitsavers.org/pdf/xerox/alto/BravoCourse.pdf - The "Alto Hardware Manual" is fun to read through if you're planning on writing an Alto emulator of your own. If you're into that sort of thing. http://bitsavers.org/pdf/xerox/alto/AltoHWRef.part1.pdf http://bitsavers.org/pdf/xerox/alto/AltoHWRef.part2.pdf - "A Field Guide to Alto-Land" is a casual perspective on Alto use (and the culture that grew around it) at Xerox PARC. http://xeroxalto.computerhistory.org/_cd8_/altodocs/.fieldguide.press!2.pdf 4.0 Configuration ================= ContrAlto provides a number of configuration options via the "System->System Configuration..." menu. Selecting this menu item will invoke a small configuration dialog with three tabs, which are described in the following sections. 4.1 CPU ------- This tab allows selection of the CPU configuration. Normally, this setting should not need to be changed from the default (Alto II, 2K Control ROM, 1K Control RAM). If you need to run software that demands a specific configuration (which is very rarely the case) then change the configuration here. The system will need to be reset for the change to take effect. 4.2 Ethernet ------------ The Ethernet tab provides configuration options for ContrAlto's host Ethernet encapsulation. ContrAlto can encapsulate the Alto's 3mbit ("experimental") Ethernet packets in either UDP datagrams or raw Ethernet packets on a network interface on the "host" computer (the computer running ContrAlto). Raw packet encapsulation requires WinPCAP and the Microsoft Visual C++ 2010 redistributable to be installed; these can be acquired from: http://www.winpcap.org/ and http://www.microsoft.com/en-us/download/details.aspx?id=5555 ContrAlto uses binaries from the Pcap.NET project to expose WinPCAP functionality to the emulator: https://github.com/PcapDotNet/Pcap.Net Pcap.NET is released under the BSD license. 4.2.1 Host Address ------------------ The Alto's network address can be specified via the "Alto Address" box at the top of the tab. This is an octal value between 1 and 376. (The addresses 0 and 377 are reserved for broadcast and Breath Of Life packets, respectively.) The default address is "42" and need only be changed if you will be communicating with other Alto hosts on the network. Duplicate network addresses will cause odd problems in communication, so make sure all hosts have unique addresses! 4.2.2 UDP Encapsulation ----------------------- UDP Encapsulation is selected via the "UDP" radio button. This causes Alto Ethernet packets to be encapsulated in broadcast UDP datagrams. These broadcasts are sent to the IPV4 network associated with the network adapter selected in the "Host Interface" network list box. 4.2.3 Raw Ethernet Encapsulation -------------------------------- Raw Ethernet Encapsulation is selected via the "Raw Ethernet" radio button. This causes Alto Ethernet packets to be encapsulated in ethernet packets on the selected network interface. 4.3 Display ----------- The Display tab provides options governing the way ContrAlto displays the simulated Alto display. The "Throttle Framerate" checkbox will force ContrAlto to run at an even 60 fields/second (matching the speed of the original Alto). Use this if things are running too fast (for example, games that require reflexes.) Uncheck this if you want things to run as fast as possible (for example, compiling code or running Smalltalk.) The "Interlaced Display" checkbox attempts to simulate the Alto's original interlaced display. Depending on your monitor and the speed of your computer this may or may not work well. 4.4 DAC ------- The DAC tab provides options controlling the Audio DAC used by the Smalltalk Music System. The "Enable Audio DAC" does what you'd expect -- it enables or disables audio output (and audio capture). If this option is enabled, the "DAC Options" fields become available. "Enable DAC output capture" enables the capture of audio generated by the DAC to be captured to one or more WAV files in the directory specified by the "Output capture path" box. This box specifies a directory, not a file -- when the Alto starts generating audio a new WAV file will be created in this directory. If the Alto is restarted or if ContrAlto exits, this file will be closed. WAV files created by ContrAlto are 16-bit, mono at 13Khz. 4.5 Alternate ("keyboard") Boots -------------------------------- The Alto allowed the specification of alternate boot addresses by holding down a set of keys on the keyboard while hitting the "reset" switch on the back of the keyboard. Since this would be difficult to pull off by hand on the emulator due to the UI involved, ContrAlto provides a configuration dialog to select the alternate address to boot. When the "Start with Alternate Boot" menu is chosen, the system will be started (or restarted) with these keys held down on your behalf. The "Alternate Boot Options" dialog is invoked by the "System->Alternate Boot Options" menu and provides configuration for alternate boots. The boot type (disk or ethernet) can be selected via the "Alternate Boot Type" radio buttons. Ethernet booting will only work if another host on the network is providing boot services. The "Disk Boot Address" text box accepts a 16-bit octal value (from 0 to 177777) specifying the address to be booted. The "Ethernet Boot File" option provides a list box containing a number of standard boot files, or a 16-bit octal value (from 0 to 177777) can be manually supplied. 5.0 Debugger ============ ContrAlto contains a fairly capable debugger window that can be invoked via the "System->Show Debugger" menu (or Ctrl+Alt+D) at any time. When the debugger is invoked, it takes over control of the system from the main display window. The system can be micro-stepped or single-stepped and breakpoints can be set on microcode addresses or Nova instruction addresses. Usage of the debugger is mostly straightforward but it is intended for "expert" users only and still has many rough edges. 5.1 The Controls ---------------- At the very bottom of the debugger window is a row of buttons. These are (from left to right): Step: Runs the Alto CPU for one clock cycle. Normally this coincides with a single microinstruction, but not always (for example, memory accesses may require multiple cycles.) The next microinstruction to be executed will be highlighted in the "Microcode Source" pane. Auto: Automatically single-steps the CPU at a relatively slow rate, while refreshing the debugger UI after every step. Not particularly useful in most circumstances (but it looks neat.) Run: Starts the CPU running normally. Execution will continue until a breakpoint is hit one of the other control buttons are pressed. Run T: Runs the CPU until the next TASK switch occurs, the next instruction executed will be the instruction after the TASK SF that caused the switch. Nova Step: Runs the CPU until the current Nova instruction is completed. This will only work properly if the standard Nova microcode is running in the Emulator task. Stop: Stops the CPU. Reset: Resets the Alto system. 5.2 Microcode Source Pane ------------------------- The pane in the upper left of the debugger window shows the microcode listings for ROM0, ROM1, and RAM0-RAM2. The listings for ROM0 and ROM1 are derived from the original source code listings. The listing for the RAM banks is automatically disassembled from the contents of control RAM (and is generally more annoying to read.) ROM0 contains the listing for the main microcode ROMs -- this 1K of ROM contains code for all of the microcode tasks (Emulator, Disk Sector, Ethernet, Memory Refresh, Display Word, Cursor, Display Horizontal, Display Vertical, Parity, and Disk Word). The source code for each task is highlighted in a different color to make task-specific code easy to differentiate. ROM1 contains the listing for the Mesa 5.0 microcode ROMs. 5.3 Memory Pane --------------- The pane near the top-middle (labeled "System Memory") shows a view into the main memory of the Alto, providing address/data and a machine-generated disassembly of Alto (Nova) instructions. 5.4 Breakpoints --------------- Breakpoints can be set on either microcode or Nova code by checking the box in the "B" column next to the instruction. Unchecking the box will remove the breakpoint. Nova code breakpoints will only work if the standard Nova microcode is running in the Emulator task. 5.5 Everything Else ------------------- The other panes in the debugger are: Tasks: Shows the current microcode task status. The "T" column indicates the task name, "S" indicates the status ("W"akeup and "R"unning), and the "uPC" column indicates the micro-PC for the corresponding task. There are 16 possible tasks, not all are used on most Altos. CPU Registers: Shows the CPU L, M and T registers as well as ALU and memory registers. General Registers: Shows the contents of the 32 R and 32 S registers (in octal). (The extra 7 sets of R and S registers on 3K CRAM machines are not yet displayed.) Reserved Memory: Shows the contents of most "well known" memory locations. See the Alto HW Reference manual (link in Sectoin 3.1.2) for what these mean. 6.0 Known Issues ================ At the moment, the following issues are known and being worked on. If you find an issue not listed here, see section 7.0 to report a new bug. - Smalltalk-80 does not run. 7.0 Reporting Bugs ================== If you believe you have found a new issue (or have a feature request) please send an e-mail to joshd@livingcomputers.org with a subject line starting with "ContrAlto Bug". When you send a report, please be as specific and detailed as possible: - What issue are you seeing? - What Alto software are you running? - What operating system are you running ContrAlto on? - What are the exact steps needed to reproduce the issue? The more detailed the bug report, the more possible it is for me to track down the cause. 8.0 Source Code =============== The complete source code is available under the GPLv3 license on GitHub at: https://github.com/livingcomputermuseum/ContrAlto Contributions are welcome! 9.0 Thanks and Acknowledgements =============================== ContrAlto would not have been possible without the amazing preservation work of the Computer History Museum. Audio output and capture on Windows is provided using the NAudio libraries, see: https://github.com/naudio/NAudio. On Unix and OS X, display and keyboard/mouse input is provided through SDL, see: https://www.libsdl.org/ and is accessed using the SDL2# wrapper, see: https://github.com/flibitijibibo/SDL2-CS. 10.0 Change History =================== V1.2 ---- - First release officially supporting Unix / OS X - Audio DAC for use with Smalltalk Music system implemented - Initial implementation of Orbit rasterization device; Dover ROS is implemented but not working properly. - Added ability to load a configuration file at startup V1.1 ---- - A few minor performance tweaks, adding to a 10-15% speed increase. - Switched back to targeting .NET 4.5.3 rather than 4.6; this works better under Mono and avoids odd issues on Windows machines running pre-4.6 frameworks. - Microcode disassembly improved slightly, annotated microcode source updated. - Nova disassembler now handles BRI, DIR, EIR, DIRS instructions rather than treating them all as TRAPs. - Fixed serious bugs in memory state machine, BravoX now runs. - Fixed minor bug in Constant ROM selection. - Raw Ethernet packets sent as broadcasts (matching IFS encapsulation behavior) V1.0 ---- Initial release.