Microcontroller

The core of the RLV12 emulator is based on a ATMega1284P microcontroller and it’s firmware. The microcontroller emulates the RLV12 functions and maps the units to either partitions or to disk images on a MBR formatted SD‑Card. The SD‑Card interface supports sizes up to 64Gbyte and disk images are standard disk images files that are stored on a FAT‑16 or FAT‑32 volume.

The firmware implements a command line interface to the user which allows to change various aspects of the emulator. The command line interface can be accessed via a serial interface and using a terminal emulation program and is set to 115'200baud, 8 bit data, no parity and one stop bit.

Startup

During startup the microcontroller initialises the emulation and checks for an SD‑Card inserted. If no SD‑Card is inserted it stops initialisation and presents a command line prompt.

In case a SD‑Card is inserted it will read the partitions. If it finds a FAT‑16 or FAT‑32 partition it will try to read an initial configuration file in the root directory and starts executing the commands in the configuration file. If there is no configuration file it will then look for any partition that has the exact size of a RL01 or RL02 volume and bind them to the individual units. If there are 4 or more partitions then the first 4 partitions will be assigned to the 4 units. Else it will assign only as many partitions to the units as there are valid partitions and the remaining units will be set offline.

During the initialisation it will show the progress and status and in case of problems display an error message.

Command Line Interface

The command line interface implements the following commands

• insert
• cd
• hello
• show
• dir
• type
• pwd
• fdisk
• attach
• detach
• help
• activate
• initialise
• logging
• number
• load
• readinit
• dump
• dmaaddress
• dmaread
• damwrite
• linked
• free
• dmatest
• bootrom
• mount

The command line interface allows editing the command line and has a one command history buffer.

insert

insert [cartridge|pack] into [volume:|drive:]

This command does nothing, it is just there to test the features of the table driven parser used by the user interface.

cd

cd does a change directory. This will set the default director for other file commands. This will act on the first FAT volume found on the SD-Card. A no volume message will be shown if there is no SD‑Card or if no FAT volume was found on the SD‑Card.

hello

hallo

This command does nothing, it is just there to test the features of the table driven parser used by teh user interface

show

show is used to show the status of various things

• logging
• units
• partitions
• version
• status
• bootrom

dir

dir lists the current directory of the FAT volume

type

type shows the content of the file on the FAT volume

pwd

pwd prints the current working directory

fdisk

fdisk shows the partitions on the SD‑Card

attach

attach

Attaches a file or partition to a unit

detach

detach

Detaches the file or partition from a unit

help

Shows the help screens

activate

Activates a previously inactive paritition. This command changes the partition type from FAT‑12 to Linux. This is useful as Windows or macOS cannot set the partition type to Linux when partitioning a SD‑Card.

initialise

Initialises a active partition, that is it writes a standard bad block information at the end of a RL01 or RL02 volume

logging

Manipulates the current logging or shows the current logging option

number

Translates a number into other base, ie. from octal, decimal, hex to octal, decimal and hex.

load

load [<address>|<filename>]

On startup the RLV12 emulator loads a default boot ROM into the local memory of the microcontroller. This boot ROM has a size of 256. words and is then visible from the PDP-11 at address 173000₍₈₎.

This image can also loaded to the normal PDP‑11 memory using the load command with an address. Using the load command with a filename will read the first 512. bytes from the file from the FAT volume and load this instead of the default boot ROM into the local memory of the microcontroller.

dump

dump -b -c -r

Dumps a block from a unit. It reads the block number of the partition or file attached to the unit starting with block number 0. It then displays the content as octal words and optionally decoded as ASCII or RADIX‑50.

dmaaddress

Sets the DMA address for later reads or writes

dmaread

Reads a word from the current DMA address

dmawrite

Writes a word to the current DMA address

linked

show a linked cluster on the mounted FAT volume

free

List the internal free dynamic memory

memtest

Tests the host memory

mount

Mounts a FAT volume on the SD‑Card

bootrom

With the bootrom command you can

• enable the boot ROM
• write enable the boot ROM
• disable the boot ROM
• set the image for the boot ROM
• show the status of the boot ROM

By default the boot ROM is enabled, you can disable the boot ROM by using the no bootrom command. You reenable the boot ROM by using the bootrom command. With show bootrom you can display the status of the boot ROM.

Per default the boot ROM is write enabled. This is usefull if you want to enter a small programm via ODT. The write enable can be set with the bootrom rw and the bootrom ro commands. With bootrom reset you reload the original bootrom and with bootrom load <file> you can load a boot ROM file from the FAT volume.

Configuration File

During startup the emulator will try to read a file RLV12.INI in the root directory of the first FAT partition. Then it will read the file line by line until it finds a line containing the keyword [RLV12]. Once it has seen this line every other line will be treated as a command line, however only a subset of commands is allowed in the configuration file

• attach
• bootrom
• logging
• load

Parameters

Parameters of the command can take the following formats

Switches

Switches are a dash followed by a single character and optionally take another parameter, e.g.

dir -a

shows the current directory including the hidden files. This can be followed by an optional directory name.

Strings

Strings are just a list of characters except the blank. If you want to include blanks in your string you need to surround the string with single or double quoats.

Units

Units is the keyword for the disk drive followed by a single digit. The drive name for RLV12 units is RL.

Partitions

Partitions are identified by the keyword partition immediately followed by a single digit