ae0cad26e4
- Formerly, the floppy controller buffered an entire diskette image in memory using the unit buffer, and flushed it out on detach or shutdown. This worked well enough, but it's better to have the device use the SIMH disk sector read and write routines and behave like a true disk. - Read Only (Write Protect) logic has also been enabled in the floppy controller, allowing users to mount images that do not have write permissions. - The IF (Integrated Floppy) and ID (Integrated Disk) device names were poorly chosen. They conflict with built-in scp commands and mess up the help system. This commit changes them to IFLOPPY and IDISK, respectively. NOTE!! THIS IS A BREAKING CONFIG CHANGE!!
122 lines
3.5 KiB
Markdown
122 lines
3.5 KiB
Markdown
AT&T 3B2 Simulator
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==================
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This module contains a simulator for the AT&T 3B2 Model 400 microcomputer.
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Full documentation for the 3B2 simulator is available here:
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- https://loomcom.com/3b2/emulator.html
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Devices
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-------
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The following devices are simulated. The SIMH names for the simulated
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devices are given in parentheses:
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- 3B2 Model 400 System Board with 1MB, 2MB, or 4MB RAM (CSR, NVRAM)
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- WE32100 CPU (CPU)
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- WE32101 MMU (MMU)
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- PD8253 Interval Timer (TIMER)
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- AM9517 DMA controller (DMAC)
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- SCN2681A Integrated DUART (IU)
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- TMS2793 Integrated Floppy Controller (IFLOPPY)
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- uPD7261A Integrated MFM Fixed Disk Controller (IDISK)
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- Non-Volatile Memory (NVRAM)
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- MM58174A Time Of Day Clock (TOD)
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- CM195B 4-port Serial MUX (PORTS)
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- CM195H Cartridge Tape Controller (CTC)
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Usage
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-----
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To boot the 3B2 simulator into firmware mode, simply type:
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sim> BOOT
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You will be greeted with the message:
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FW ERROR 1-01: NVRAM SANITY FAILURE
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DEFAULT VALUES ASSUMED
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IF REPEATED, CHECK THE BATTERY
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FW ERROR 1-02: DISK SANITY FAILURE
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EXECUTION HALTED
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SYSTEM FAILURE: CONSULT YOUR SYSTEM ADMINISTRATION UTILITIES GUIDE
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NVRAM and Time of Day can be saved between boots by attaching both
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devices to files.
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sim> ATTACH NVRAM <nvram-file>
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sim> ATTACH TOD <tod-file>
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If you have no operating system installed on the hard drive, on
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subsequent boots you will instead see the message
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SELF-CHECK
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FW ERROR 1-02: DISK SANITY FAILURE
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EXECUTION HALTED
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SYSTEM FAILURE: CONSULT YOUR SYSTEM ADMINISTRATION UTILITIES GUIDE
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Once you see the `SYSTEM FAILURE` message, this is actually an
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invisible prompt. To access firmware mode, type the default 3B2
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firmware password `mcp`, then press Enter or carriage return.
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You should then be prompted with:
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Enter name of program to execute [ ]:
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Here, you may type a question mark (?) and press Enter to see a list
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of available firmware programs.
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Booting UNIX SVR3
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-----------------
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UNIX SVR3 is the only operating system available for the 3B2. To boot
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UNIX, attach the first disk image from the 3B2 "Essential Utilities"
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distribution.
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sim> ATTACH IFLOPPY <floppy-image>
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sim> BOOT
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Once you reach the `SYSTEM FAILURE` message, type `mcp` to enter
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firmware mode. When prompted for the name of a program to boot, enter
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`unix`, and confirm the boot device is `FD5` by pressing Enter or
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carriage return.
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Enter name of program to execute [ ]: unix
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Possible load devices are:
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Option Number Slot Name
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---------------------------------------
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0 0 FD5
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Enter Load Device Option Number [0 (FD5)]:
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Installing SVR3
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---------------
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To install SVR3 to the first hard disk, first, attach a new image
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to the IDISK0 device:
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sim> ATTACH IDISK0 <hd-image>
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Then, boot the file `idtools` from the "3B2 Maintenance Utilities -
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Issue 4.0" floppy diskette.
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From `idtools`, select the `formhard` option and low-level format
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integrated disk 0. Parameters for the default 72MB hard disk are:
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Drive Id: 5
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Number cylinders: 925
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Number tracks/cyl: 9
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Number sectors/track: 18
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Number bytes/sector: 512
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After low-level formatting integrated disk 0, boot the file `unix`
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from the first diskette of the 3B2 "Essential Utilities" distribution,
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and follow the prompts.
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