(r19) McForth < Cosmac

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<cite>
Computers are machines just like the marionette. They must be told exactly what to do, in specific language. And so we need a language which possesses two seemingly opposite traits:
On the one hand, it must be precise in its meaning to the computer, conveying all the information that the computer needs to know to perform the operation. On the other hand, it must be simple and easy-to-use by the programmer.
</cite>

From chapter "Introduction for Beginners", Leo Brodie, Starting FORTH
https://www.forth.com/starting-forth/

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---+ Rc/Forth and IDIOT Monitor for RaspiElf (Membership Card)

Mark Abene made FORTH work on the Membership Card.

   $ forth.hex: Modified version of Mike Riley's Rc/Forth, ROM version. Changed to work with my modified version of IDIOT. Loads in at 0500h. You can get it from the [[https://groups.yahoo.com/neo/groups/cosmacelf/files/Mark%20Abene/forth.hex][COSMAC ELF yahoo group]].
   $ idiot_new.hex: New version of IDIOT with SCRT routines, along with TYPE, MSG, READ, and INPUT routines for basic console I/O. Loads in at 0000h. You can get it from the [[https://groups.yahoo.com/neo/groups/cosmacelf/files/Mark%20Abene/idiot_new.hex][COSMAC ELF yahoo group]]. For details see http://www.retrotechnology.com/memship/mship_idiot.html

Concatenated this two files as mc-forth.hex and convert it to a binary file:
<pre>
pi@cosmac:~/elf/forth $ <b>cat idiot_new_qhi.hex forth.hex > mc-forth.hex</b>
pi@cosmac:~/elf/forth $ <b>hex2bin mc-forth.hex</b> 
hex2bin v2.5, Copyright (C) 2017 Jacques Pelletier & contributors

Allocate_Memory_and_Rewind:
Lowest address:   00000000
Highest address:  00001633
Starting address: 00000000
Max Length:       5684

Binary file start = 00000000
Records start     = 00000000
Highest address   = 00001633
Pad Byte          = FF
pi@cosmac:~/elf/forth $ <b>ls -l</b>
insgesamt 40
-rw-r--r-- 1 pi pi 12132 Jan 13 12:36 forth.hex
-rw-r--r-- 1 pi pi  2890 Jan 13 12:36 idiot_new.hex
-rw-r--r-- 1 pi pi  5684 Jan 13 12:41 mc-forth.bin
-rw-r--r-- 1 pi pi 15022 Jan 13 12:36 mc-forth.hex
</pre>

Now upload and start Rc/Forth (mc-forth.bin):
<pre>
pi@cosmac:~/elf/forth $ <b>bin2elf -w -r mc-forth.bin</b>
0x1634 bytes written
</pre>
clear high (8th) bit of input characters
<pre>
pi@cosmac:~/elf/forth $ <b>stty -F /dev/ttyS0 istrip</b>
</pre>
and start the terminal emulator (console):
<pre>
pi@cosmac:~/elf/forth $ <b>microcom -s 600</b>
connected to /dev/ttyS0
Escape character: Ctrl-\
Type the escape character followed by c to get to the menu or q to quit
<b><i>[CR]</i></b>
IDIOT/4
*<b>$P500</b>
Rc/Forth 0.1
(c) copyright 2006 by Michael H. Riley
ok <b>15 5 + .</b>
20 ok <b>BYE</b>

IDIOT/4
*
</pre>
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---+ Rc/Forth and Chuck's Super Monitor for RaspiElf (Membership Card)

Mark Abene made Rc/Forth also work with Chuck's Super Monitor. I prefer this monitor because of its ability to communicate with 9600 baud.

   $ mcsmp_rcforth.hex: Mike Riley's Rc/Forth, modified to work with Chuck Yakym's MCSMP20 firmware.  You can get it from the [[https://groups.yahoo.com/neo/groups/cosmacelf/files/Mark%20Abene/mcsmp_rcforth.hex][COSMAC ELF yahoo group]].
   $ !MCSMP20B.bin: Chuck's Super monitor. Loads in at 0000h. You can get it from the [[http://www.sunrise-ev.com/MembershipCard/MCSMP20B.bin][Lee A. Hart's website The COSMAC ELF Membership Card ]]. 

Create binary file and load it at 0x8000:
<pre>
pi@cosmac:~/elf/forth $ <b>hex2bin mcsmp_rcforth.hex</b>
hex2bin v2.5, Copyright (C) 2017 Jacques Pelletier & contributors

Allocate_Memory_and_Rewind:
Lowest address:   00008000
Highest address:  000091DB
Starting address: 00008000
Max Length:       4572

Binary file start = 00008000
Records start     = 00008000
Highest address   = 000091DB
Pad Byte          = FF
pi@cosmac:~/elf/forth $ <b>bin2elf -s 8000 mcsmp_rcforth.bin</b>
0x11dc bytes written
</pre>
Now upload and start the monitor, start the terminal program with 9600 baud:
<pre>
pi@cosmac:~/elf/forth $ <b>bin2elf -w -r MCSMP20B.bin</b>
0x8000 bytes written
pi@cosmac:~/elf/forth $ <b>microcom -s 9600</b>
connected to /dev/ttyS0
Escape character: Ctrl-\
Type the escape character followed by c to get to the menu or q to quit
<b><i>[CR]</i></b>
Membership Card's Serial Monitor Program Ver. 2.0B
Enter "H" for Help.
><b>R8000</b>
Currently running your program
Rc/Forth 0.1
(c) copyright 2006 by Michael H. Riley
ok 
</pre>
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---+ Night Rider in Rc/Forth
See ChaseLighting for an assembler version (much faster of course).

Here a small test program for the Rc/Forth. It's a simple night rider chase lighting, but it is using the MC LEDs (of course), the switches for setting the pace and the IN button to terminate the program.

Some interactive programming to find out how OUT is working:
<pre>
ok 1 4 OUT
ok 4 1 OUT
ok 4 2 OUT
ok : LED! 4 SWAP OUT ;
ok 4 LED!
</pre>

The rest of the program, every word can and should be tested interactively (e.g. 1 LEFT):
<pre>
: SWITCH@ 4 INP ;
: DELAY 1 SWITCH@ + 0 DO LOOP ;
: LEFT 7 0 DO 2 * DUP LED! DELAY LOOP ;
: RIGHT 7 0 DO 2 / DUP LED! DELAY LOOP ;
: NIGHTRIDER 1 DUP LED! BEGIN LEFT RIGHT EF 8 <> UNTIL DROP ;
</pre>

Push the IN button to terminate the program.
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---+ Mass storage
Forth without mass storage (blocks, screens) is a not complete. A SD-Card interface could be a reasonable solution but this is an overkill for a small Forth system. 

---++ EEPROM Serial Communication 

Serial Peripheral Interface SPI, MC is the SPI master, the host is the slave.
e.g. [[http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-8832C-SEEPROM-AT25M02-Datasheet.pdf][AT25M02]] SPI EEPROM 2Mbit (256 !KiB, $3), [[http://ww1.microchip.com/downloads/en/DeviceDoc/20005265A.pdf][25LC1024]] (128 !KiB, $2), or [[http://ww1.microchip.com/downloads/en/DeviceDoc/20005265A.pdf][25LC512]] (64 !KiB, $1.50). DIL8 Package. 64/128/256 !KiB seems very small for today's standards where storage is quantified in !GiB, but I think it's more than enough for a small Forth system. If you want more memory there is 16 !MiB serial EEPROM [[http://www.winbond.com/resource-files/w25q128jv%20spi%20revc%2011162016.pdf][W25Q128J]] from WINBOND, please note that is a 3.3 V part!
<verbatim>
CLK   MC ->- host
MOSI  MC ->- host
MISO  MC -<- host
SS    MC ->- host or other peripherals (optional)
</verbatim>

A high-to-low transition on the _CS_ pin is required to start an operation and a 
low-to-high transition is required to end an operation.

_Invalid Opcode_:  If an invalid opcode is received, no data will be shifted into AT25M02 and the Serial Data 
Output (SO) pin will remain in a high impedance state until the falling edge of CS is detected again. This will 
reinitialize the serial communication.

While in _Hold_ mode, the SO pin will be in a high impedance state. In addition, both the SI pin and the SCK pin 
will be ignored.

!25LCxxxx Instruction Set
| *Name*   | *Format*  | *Description*                                               |
| _READ_   | 0000 0011 | Read data from memory array beginning at selected address   |
| _WRITE_  | 0000 0010 | Write data to memory array beginning at selected address    |
| _WREN_   | 0000 0110 | Set the write enable latch (enable write operations)        |
| _WRDI_   | 0000 0100 | Reset the write enable latch (disable write operations)     |
| _RDSR_   | 0000 0101 | Read STATUS register                                        |
| _WRSR_   | 0000 0001 | Write STATUS register                                       |
| PE       | 0100 0010 | Page Erase – erase one page in memory array                 |
| SE       | 1101 1000 | Sector Erase – erase one sector in memory array             |
| CE       | 1100 0111 | Chip Erase – erase all sectors in memory array              |
| RDID     | 1010 1011 | Release from Deep power-down and read electronic signature  |
| DPD      | 1011 1001 | Deep Power-Dow                                              |

!AT25M02 Instruction Set
| *Name*   | *Format*  | *Description*                                               |
| _READ_   | 0000 0011 | Read from Memory Array                                      |
| _WRITE_  | 0000 0010 | Write to Memory Array                                       |
| _WREN_   | 0000 0110 | Set Write Enable Latch (WEL)                                |
| _WRDI_   | 0000 0100 | Reset Write Enable Latch (WEL)                              |
| _RDSR_   | 0000 0101 | Read Status Register (SR)                                   |
| _WRSR_   | 0000 0001 | Write Status Register (SR)                                  |
| LPWP     | 0000 1000 | Low Power Write Poll                                        |


---+++ Serial EEPROM Connected to Centronics Connector (Switches and LEDs)

Sharing the LED and Switch port, you loose two LEDs and one switch. Possible conflict with the bootstrap loader, if there is a read sequence (CS and read pattern 0000 0011). To prevent this, set the EEPROM into HOLD state e.g. with the <SPAN STYLE="text-decoration:overline">WAIT</SPAN> signal.

| *SPI*    | *MC (Master)*      | *25LCxxxx (Slave)*  | *Interface*                          |
| MISO     | J2.1  <SPAN STYLE="text-decoration:overline">IN</SPAN> EF4      | 2 SO                | diode e.g. 1N4148                    |
| MOSI     | J2.11 O7  LED7     | 5 SI                | direct                               |
| CLK      | J2.10 O6  LED6     | 6 SCK               | direct                               |
| CS       | J2.12 O5  LED5     | 1 <SPAN STYLE="text-decoration:overline">CS</SPAN>               | direct                               |
|          | P4.3 VDD           | 8 VCC               | +5V capacitor 100 nF to GND          |
|          | "                  | 3 <SPAN STYLE="text-decoration:overline">WP</SPAN>               | +5V                                  |
|          | J2.14 <SPAN STYLE="text-decoration:overline">WAIT</SPAN>        | 7 <SPAN STYLE="text-decoration:overline">HOLD</SPAN>             | direct                               |
|          | 21 GND             | 4 GND               | GND                                  |


%IMAGE{"%PUBURLPATH%/Cosmac/McForth/mc-eeprom-conn.png" type="thumb" caption="Schematic"}% 

Raspberry Pi can emulate SPI EEPROM. On RaspiElf the switches/LEDs are already connected to Raspi's GPIOs. No need for additional hardware. But I have to write an SPI server for the Raspberry Pi. 

Raspi's SPI interfaces can't be used because of conflicting port usage.
   * BCM 19 (SPI1 MISO) O5
   * BCM 20 (SPI1 MOSI) -
   * BCM 21 (SPI1 SCLK) shutdown
   * BCM 18 (SPI1 CS0)  <SPAN STYLE="text-decoration:overline">CLR</SPAN>
   * BCM 17 (SPI1 CS1)  <SPAN STYLE="text-decoration:overline">WAIT</SPAN> 

   * BCM 9  (SPI0 MISO) IN4 
   * BCM 10 (SPI0 MOSI) IN3
   * BCM 11 (SPI0 SCLK) IN6
   * BCM 8  (SPI0 CS0)  IN7
   * BCM 7  (SPI0 CS1)  O0

---++++ Read Byte

<pre>

CS0     EQU     0b1101111
CS1     EQU     0b0010000
CLK0    EQU     0b1011111
CLK1    EQU     0b0100000
DATA0   EQU     0b0111111
DATA1   EQU     0b1000000

        ; MSB first

READBYTE:
        LDI     0
        PLO     R5
        LDI     0xFF
        PHI     R6
        LDI     0xFF - 8
        PLO     R6
        SEX     R0
BITLOOP:
        OUT4,0b01000000      ; CLK for SPI 
        OUT4,0b00000000
        INC     R6
        GHI     R6           ; set CARRY
        SHRC
        GLO     R5
        B4      SETBIT       ; branch if bit set
        SHL                  ; bit not set
        BR      SAVEBIT      
SETBIT:
        SHLC
SAVEBIT:
        PLO     R5
        GLO     R6
        BNZ     BITLOOP
</pre>

about 230 cycles for one byte -> 1 ms -> 1 KiB takes about 1 s @ 1.79 MHz

---++++ Write Byte
<pre>
WRITEBYTE:
        LDI     0
        PHI     R6
        LDI     8
        PLO     R6
        SEX     R0
BITLOOP:
        GLO     R5           ; get the next bit
        SHLC                 , next bit is in the carry
        PLO     R5
        BDF     SETBIT
        OUT4,0b01000000      ; CLK for SPI with data bit cleared
        OUT4,0b00000000
        BR      NEXT
SETBIT:
        OUT4,0b11000000      ; CLK for SPI with data bit set 
        OUT4,0b10000000
NEXT:      
        DEC     R6
        GLO     R6
        BNZ     BITLOOP
</pre>

---+++ Serial EEPROM patched on MC PCB

SPI Mode 0, data is always latched in on the rising edge of SCK and always output on the falling edge of SCK. For CS one output port bis is needed e.g. O7 or N2 (INP4) to start/end operation (A high-to-low transition on the _CS_ pin is required to start an operation and a low-to-high transition is required to end an operation).

| *SPI*    | *MC (Master)*   | *25LCxxxx (Slave)*  | *Interface*                            |
| MISO     | <SPAN STYLE="text-decoration:overline">EF2</SPAN>            | 2 SO                | direct                                 |
| MOSI     | D0              | 5 SI                | direct                                 |
| CLK      | TPB & N1 (OUT2) | 6 SCK               | [[https://en.wikipedia.org/wiki/Wired_logic_connection][wired AND]]; Pullup 10 k, 2 1N4148  |
| CS       | N2              | 1 <SPAN STYLE="text-decoration:overline">CS</SPAN>               | direct                                 |
|          |                 | 8 VCC               | +5V                                    |
|          |                 | 3 <SPAN STYLE="text-decoration:overline">WP</SPAN>               | +5V                                    |
|          | J2.14 <SPAN STYLE="text-decoration:overline">WAIT</SPAN>     | 7 <SPAN STYLE="text-decoration:overline">HOLD</SPAN>             | direct                                 |
|          |                 | 4 GND               | GND                                    | 

%IMAGE{"%PUBURLPATH%/Cosmac/McForth/mc-eeprom-u1.png" type="thumb" caption="Schematic"}% 

---++++ Read Byte

<pre>
        ; MSB first

        LDI     0
        PLO     R5
        LDI     0xFF
        PHI     R6
        LDI     0xFF - 8
        PLO     R6
        SEX     R6
BITLOOP:
        OUT2                 ; CLK for SPI, INC Rx
        GHI     R6           ; set CARRY
        SHRC
        GLO     R5
        B2      SETBIT       ; branch if bit set
        SHR                  ; bit not set
        BR      SAVEBIT      
SETBIT:
        SHRC
SAVEBIT:
        PLO     R5
        GLO     R6
        BNZ     BITLOOP
</pre>

about 200 cycles for one byte -> 1 ms -> 1 KiB takes about 1 s


---++++ Write Byte
<pre>
WRITEBYTE:
        LDI     0
        PHI     R6
        LDI     8
        PLO     R6
        SEX     R0
BITLOOP:
        GLO     R5           ; get the next bit
        SHLC                 , next bit is in the carry
        PLO     R5
        LSNF
        OUT2,0b00000000      ; CLK for SPI with data bit cleared
        LSDF
        OUT2,0b00000001      ; CLK for SPI with data bit set 
        DEC     R6
        GLO     R6
        BNZ     BITLOOP
</pre>

---++ Kermit/ZModem
What about using KERMIT or ZMODEM protocol for the file transfer and use
the file system on the host? No need to add additional hardware (SD-card
is anyway to modern ;-) You could use an old CP/M or even a PDP11 as host. The C-Kermit Local Server mode, e.g. MC can read/write the blocks as files =block.0=, =block.2=, =block.255=.

The serial communication is really slow, not only because of the 9600 baud, but you have to wait after each character to give CDP1802 some computation time.

https://github.com/utoh/pygmy-forth/blob/master/extras/kermit/pfkerm.doc

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---+ Spare Time Gizmo’s ELF2K ROM for RaspiElf

For details see Herb Johnson's [[http://www.retrotechnology.com/memship/elf2k_mship.html][ELF 2K ROM for 1802 Membership Card]]

[[http://www.sparetimegizmos.com/Downloads/v88.hex][v88.hex]] from the [[http://www.sparetimegizmos.com/Hardware/Elf2K.htm][Spare Time Gizmos]] web site.

<pre>
pi@cosmac:~/elf/elf2k $ <b>cp v88.hex v88.hex.org</b>
pi@cosmac:~/elf/elf2k $ <b>patch v88.hex v88-mc.patch</b>
pi@cosmac:~/elf/elf2k $ <b>hex2bin v88.hex</b>
hex2bin v2.5, Copyright (C) 2017 Jacques Pelletier & contributors

Allocate_Memory_and_Rewind:
Lowest address:   00000000
Highest address:  00007FFF
Starting address: 00000000
Max Length:       32768

Binary file start = 00000000
Records start     = 00000000
Highest address   = 00007FFF
Pad Byte          = FF
pi@cosmac:~/elf/elf2k $ <b>bin2elf -s 8000 v88.bin</b> 
0x8000 bytes written
pi@cosmac:~/elf/elf2k $ <b>bin2elf -w -r LBR_8000.bin</b>
0x0003 bytes written
pi@cosmac:~/elf/elf2k $ 
</pre>
But there is "Post Code 88" -> SRAM size wrong

My MC has 64 KiB RAM and no ROM. But the RAM Size Test (part of monitor) expects ROM from 0x8000.  

Herb Johnson wrote:

<cite>
Peter, hopefully you can take it from here, find the BOOTS.ASM code at the link below, and "patch" it to accept an appropriate area for RAM. More than I can figure out today.

http://www.sparetimegizmos.com/Downloads/v88-source.zip
</cite>



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-- %USERSIG{PeterSchmid - 2019-01-13}%

---++!! Comments
Attachments
Topic attachments
I	Attachment	History	Action	Size	Date	Who
png	mc-eeprom-conn.png	r3 r2 r1	manage	20.4 K	2019-01-19 - 23:12	PeterSchmid
png	mc-eeprom-u1.png	r2 r1	manage	18.6 K	2019-01-23 - 21:26	PeterSchmid
patch	v88-mc.patch	r1	manage	1.1 K	2019-01-20 - 10:36	PeterSchmid
Topic revision: r19 - 2019-01-23 - PeterSchmid