Raspberry Pi Interface to Cosmac Elf
Intro
The Unix philosophy emphasizes building simple, short, clear, modular, and extensible code that can be easily maintained and repurposed by developers other than its creators. The Unix philosophy favors composability as opposed to monolithic design.

This is a good opportunity to merge old SBC technology (COSMAC Elf e.g. Elf Membership Card) with a new one (Raspberry Pi and GNU/Linux). If you are new to GNU/Linux get involved! I have always admired the UNIX philosophy, I hope this project achieves the UNIX goals.

elf2bin (download tool)

NAME
elf2bin - Copies the Elf (Membership Card) memory to a binary file on the Raspberry Pi.

SYNOPSIS
elf2bin [-s hexadr] [-e hexadr] [-w] [-r] [file]

DESCRIPTION
Copies the Elf memory to a binary file (or stdout) on the Raspberry Pi. The Raspberry Pi GPIO is used as interface to the Cosmac Elf SBC (e.g. Elf Membership Card parallel port). The generated data is written to the standard output stream or to a file. Caution: Overwrite file if it exists. Use > for redirecting (save the file) or | for piping to another command (e.g. hexdump). All toggle switches on the Elf Membership Card have to be on the up position except for the READ switch, the READ switch has to be on the down position.

OPTIONS
Non argument options that are duplicated on the command line are not harmful. For options that require an argument, each duplication will override the previous argument value.
-s hexadr
start address in hex (0 is default)
-e hexadr
end adress in hex (0xFFFF is default)
-w
write enable when copying is finished
-r
go to run mode when copying is finished

bin2elf (upload tool)

NAME
bin2belf - Copies the content of binary file on the Raspberry Pi to Elf (Membership Card) memory .

SYNOPSIS
bin2elf [-s hexadr] [-e hexadr] [-w] [-r] [file]

DESCRIPTION
Copies the content of binary file on the Raspberry Pi to Elf (Membership Card) memory. The Raspberry Pi GPIO is used as interface to the Cosmac Elf SBC (e.g. Elf Membership Card parallel port). Use < for redirecting or | for piping from another command. All toggle switches on the Elf Membership Card have to be on the up position except for the READ switch, the READ switch has to be on the down position.

OPTIONS
Non argument options that are duplicated on the command line are not harmful. For options that require an argument, each duplication will override the previous argument value.
-s hexadr
start address in hex (0 is default)
-e hexadr
end adress in hex (0xFFFF is default)
-w
write enable when copying is finished
-r
go to run mode when copying is finished

elf (command line tool)

NAME
elf - Controls the mode, sets data switches and gets LED data of an Elf (Membership Card).

SYNOPSIS
elf [-s hexadr] [-i] [-n] [-v] [load|run|wait|reset|read|get|put] [switch]

DESCRIPTION
Controls the mode, sets data switches and gets LED data of an Elf (Membership Card). The Raspberry Pi GPIO is used as interface to the Cosmac Elf SBC (e.g. Elf Membership Card parallel port). If a command is missing, the default command is then get. All toggle switches on the Elf Membership Card have to be on the up position except for the READ switch, the READ switch has to be on the down position.
load
sets the mode to load (WAIT and CLR active, is equivalent to switches down)
run
sets the mode to run (WAIT and CLR inactive, is equivalent to switches up)
wait
sets the WAIT to active (is equivalent to switch down), option -n inverts the WAIT to inactive (is equivalent to switch down)
reset|clear
sets the CLR to active (is equivalent to switch down), option -n inverts the CLR to inactive (is equivalent to switch down)
read
sets the WE to active (is equivalent to switch down), option -n inverts the CLR to inactive (is equivalent to switch down)
get
gets the mode and the switch data and the LED data
put switch
puts the switch data to the data switches. The data is in hex.

OPTIONS
Non argument options that are duplicated on the command line are not harmful. For options that require an argument, each duplication will override the previous argument value.
-s hexadr
start address in hex (0 is default). Pre increment to the start address before the data is read and written.
-i
post increment. The IN is set active for > 100 us after the data is read and written
-n
not, invert the command. No effect for load, run, get, and put.
-v
verbose, output looks like "LED:01 Q:1 Rx:1 IN:0 WAIT:1 CLR:1 READ:0 SWITCH:0c"

How to get and build the RaspiElf tools

Get the source from the GIT repository (if you have not installed GIT yet, then install it with sudo apt-get install git), type only the bold text after the $ sign:

pi@cosmac:~/elf $ git clone https://github.com/spyren/RaspiElf
Cloning into 'RaspiElf'...
remote: Counting objects: 68, done.
remote: Compressing objects: 100% (37/37), done.
remote: Total 68 (delta 32), reused 62 (delta 29), pack-reused 0
Unpacking objects: 100% (68/68), done.
Checking connectivity... done.
pi@cosmac:~/elf $

Build (compile) from the sources:

pi@cosmac:~/elf $ cd RaspiElf
pi@cosmac:~/elf/RaspiElf $ cd tools/
pi@cosmac:~/elf/RaspiElf/tools $ make
cc -g -c elf2bin.c
cc -g -c raspi_gpio.c
cc -g -o elf2bin -lwiringPi elf2bin.o raspi_gpio.o
cc -g -c bin2elf.c
cc -g -o bin2elf -lwiringPi bin2elf.o raspi_gpio.o
cc -g -c elf.c
cc -g -o elf -lwiringPi elf.o raspi_gpio.o
pi@cosmac:~/elf/RaspiElf/tools $ 

Install the binaries into /usr/local/bin

pi@cosmac:~/elf/RaspiElf/tools $ sudo make install
install -m 557 elf2bin bin2elf elf /usr/local/bin

Sample session

Type only the bold text after the $ sign.

Initialise the Elf memory with 00H (32 Kib):

pi@cosmac:~/elf/RaspiElf/chase $ bin2elf -e 7fff </dev/zero
0x8000 bytes written

Upload and run the chase lighting program (details see ChaseLighting):

pi@cosmac:~/elf/RaspiElf/chase $ bin2elf -w -r chase.bin
0x002d bytes written

Stop the program an go into the load state:

pi@cosmac:~/elf/RaspiElf/chase $ elf load
01 1 0 0 1 1 0 0c

Hexdump the Elf memory until address 0x3f (hexdump is standard UNIX tool and is included in Raspbian and other GNU/Linux'):

pi@cosmac:~/elf/RaspiElf/chase $ elf2bin -e 3f | hexdump -C
0x0040 bytes read
00000000  c0 00 03 e3 90 b3 f8 30  a3 f8 01 53 64 6c 23 fa  |.......0...Sdl#.|
00000010  fe 3a 1a f0 f6 c7 f8 80  30 1f f0 fe c7 f8 01 53  |.:......0......S|
00000020  f8 14 b2 22 92 3a 23 c5  7a 38 7b 30 0c 00 00 00  |...".:#.z8{0....|
00000030  04 ff 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000040

Get the mode and the data (LEDs and swiches)

pi@cosmac:~/elf/RaspiElf/chase $ elf
02 1 1 0 1 1 1 ff
pi@cosmac:~/elf/RaspiElf/chase $ elf -v 
LED:01 Q:1 Rx:1 IN:0 WAIT:1 CLR:1 READ:0 SWITCH:0c

Write enable (not READ)

pi@cosmac:~/elf/RaspiElf/chase $ elf -n read
02 1 1 0 1 1 0 ff

Run mode (starts the chase lighting again)

pi@cosmac:~/elf/RaspiElf/chase $ elf run

Put 0000'0000B to the switches (chase LEDs from right to left)

pi@cosmac:~/elf/RaspiElf/chase $ elf put 0
40 1 1 0 0 0 0 00

Put 1000'0000B to the switches (chase LEDs from left to right)

pi@cosmac:~/elf/RaspiElf/chase $ elf put 80
10 1 1 0 0 0 0 80

Get the mode and data while the program is running (LEDs and Q are changing)

pi@cosmac:~/elf/RaspiElf/chase $ elf -v
LED:40 Q:1 Rx:1 IN:0 WAIT:0 CLR:0 READ:0 SWITCH:80
pi@cosmac:~/elf/RaspiElf/chase $ elf -v
LED:02 Q:0 Rx:1 IN:0 WAIT:0 CLR:0 READ:0 SWITCH:80

Start BASIC3 without EPROM

There are BASIC3, Tiny BASIC, and Chuck's Super Monitor EPROM binaries on Lee Hart's The COSMAC ELF Membership Card http://www.sunrise-ev.com/membershipcard.htm website for his famous Membership Card. I have got some old 27C256 EPROMs but no programmer nor eraser.

But the MSC needs to have 64 KiB RAM, the standard 62256 RAM in the U2 socket and the CY7C199 (or IDT71256) soldered in U8.

First of all you need a serial console (terminal program) to communicate with the Elf. I prefer to use microcom (minicom or putty are good alternatives)

pi@cosmac:~/elf/basic $ sudo apt-get install microcom

The Raspberry Pi UART is used as console (default setting). Change this with raspi-config:

pi@cosmac:~/elf/basic $ sudo raspi-config
Select option 5, Interfacing options, then option P6, Serial, and select No for Would you like a login shell to be accessible over serial? and select Yes for Would you like the serial port hardware to be enabled? . Exit raspi-config. Reboot Raspi now.

Add user pi to the tty group (give user pi the right to write to /dev/ttyS0):

pi@cosmac:~/elf/basic $ sudo usermod -a -G tty pi

Get the binary from The COSMAC ELF Membership Card http://www.sunrise-ev.com/membershipcard.htm

pi@cosmac:~/elf/basic $ wget http://www.sunrise-ev.com/MembershipCard/MCSMP20J.bin
...
2017-12-26 23:08:09 (140 KB/s) - 'MCSMP20J.bin' saved [32768/32768]
pi@cosmac:~/elf/basic $ 

Upload the EPROM binary to the Membership Card at starting address 0x8000:

pi@cosmac:~/elf/basic $ bin2elf -s 8000 MCSMP20J.bin
0x8000 bytes written

Get the binary for LBR 8000 from my site:

pi@cosmac:~/elf/basic $ wget http://spyr.ch/twiki/pub/Cosmac/RaspiElf/LBR_8000.bin
...
2017-12-26 23:49:28 (102 KB/s) - 'LBR_8000.bin' saved [3/3]
pi@cosmac:~/elf/basic $ ls -l
total 36
-rw-r--r-- 1 pi pi     3 Dec 26 22:51 LBR_8000.bin
-rw-r--r-- 1 pi pi 32768 Dec 13 17:59 MCSMP20J.bin

Start from address 0x8000:

pi@cosmac:~/elf/basic $ bin2elf -w -r LBR_8000.bin
0x0003 bytes written

Start the serial console and connect to the Membership Card

pi@cosmac:~/elf/basic $ microcom -s 9600
connected to /dev/ttyS0
Escape character: Ctrl-\
Type the escape character followed by c to get to the menu or q to quit

Membership Card's Serial Monitor Program Ver. 2.0
Enter "H" for Help.
>N 


C RCA 1981
BASIC3 V1.1
C/W?
C
 READY
:PRINT "Hello Raspberry Pi"
Hello Raspberry Pi

READY
:

For other than US keyboards you can use Ctrl-4 instead of Ctrl-\.

Remote access the Elf Membership Card with a GNU/Linux PC and SSH (or a Windows PC and PUTTY):

psi@homer:~> ssh -l pi -X 192.168.1.111
pi@192.168.1.111's password: 

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
Last login: Tue Jan  2 15:53:08 2018 from homer.home
pi@cosmac:~ $ cd elf/basic/
pi@cosmac:~/elf/basic $ bin2elf -w -r LBR_8000.bin
0x0003 bytes written
pi@cosmac:~/elf/basic $ microcom -s 9600
connected to /dev/ttyS0
Escape character: Ctrl-\
Type the escape character followed by c to get to the menu or q to quit

Membership Card's Serial Monitor Program Ver. 2.0
Enter "H" for Help.
>
If your ISP supports DMZ, static IP addresses, port forwarding and dynamic DNS you have remote access to your Elf from everywhere.

Wiring

The Raspberry Pi ARM processor supply voltage is 3.3 V and the GPIOs are not 5 V tolerant. The Elf supply voltage is 5 V. This means that the GPIOs (input) has to be protected from Elf. The easiest way is to use diodes e.g. 1N4148 to protect the GPIOs from the 5 V, but the GPIOs need then pullup resistors. Thankfully the Raspi GPIOs have internal pullups and they can be controlled by software. The cathode has to be on the Elf side.

It is possible that the Elf works with 3.3 V supply voltage, but this is not within the specifications. In this case the diodes are not needed. Connect the Raspi Pin 1 to P4 Pin 3 (do NOT connect Raspi Pin 2!).

Bill of materials

Description Mouser Part#
Flat Cable 40 conductors 517-3365/40FT
D-Sub 25P male 523-L717SDBH25P
Header Connector 40 pol 571-4-215911-0
9 x 1N4148 512-1N4148

Cable

Pi Pin# Pi Function Elf Pin DSUB J2 POWER P4 Elf Function
1 3.3 V (18) (3) (VIN, +)
2 5 V (18) 3 VIN, +
3 BCM 2, SDA      
4 5 V      
5 BCM 3, SCL      
6 GND (19) 1 GND, -
7 BCM 4 1, in   IN- (EF4)
8 BCM 14, TXD (20) 4, in RXD, RX (EF3)
9 GND   6 GND, /ON
10 BCM 15, RXD (15) 5, out, Cathode TXD, TX (Q)
11 BCM 17 14, in   WAIT-
12 BCM 18 16, in   CLR-
13 BCM 27 17, in   WE-
14 GND      
15 BCM 22 2, in   IN0
16 BCM 23 3, in   IN1
17 3.3 V      
18 BCM 24 4, in   IN2
19 BCM 10, MOSI 5, in   IN3
20 GND      
21 BCM 9, MISO 6, in   IN4
22 BCM 25 7, in   IN5
23 BCM 11,SCLK 8, in   IN6
24 BCM 8, CE0 9, in   IN7
25 GND      
26 BCM 7, CE1 25, out, Cathode   O0 (*)
27 BCM 0      
28 BCM 1      
29 BCM 5 24, out, Cathode   O1 (*)
30 GND      
31 BCM 6 23, out, Cathode   O2 (*)
32 BCM 12 22, out, Cathode   O3 (*)
33 BCM 13 13, out, Cathode   O4 (*)
34 GND      
35 BCM 19 12, out, Cathode   O5 (*)
36 BCM 16 10, out, Cathode   O6 (*)
37 BCM 26 11, out, Cathode   O7 (*)
38 BCM 20      
39 GND      
40 BCM 21      

-- Peter Schmid - 2017-11-26

Comments

Topic attachments
I Attachment History Action Size Date Who Comment
Unknown file formatbin LBR_8000.bin r1 manage 0.1 K 2017-12-26 - 22:48 PeterSchmid  
PNGpng gpio-numbers-pi2.png r1 manage 53.2 K 2017-11-26 - 18:46 PeterSchmid  
JPEGjpg harness.jpg r1 manage 276.2 K 2017-12-18 - 17:46 PeterSchmid  
JPEGjpg raspi-elfmemcard-s.jpg r2 r1 manage 55.2 K 2017-12-18 - 17:49 PeterSchmid  
JPEGjpg raspi-elfmemcard.jpg r1 manage 396.7 K 2017-12-18 - 18:00 PeterSchmid  
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Topic revision: r28 - 2018-01-17 - PeterSchmid
 
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