RomWBW/Source/Doc/ROM_Applications.md

$define{doc_title}{ROM Applications}$
$define{doc_author}{Phillip Summers}$
$define{doc_authmail}{}$
$include{"Common.h"}$

# Summary

RomWBW includes a small selection of built in utilities and
programming languages.

`\clearpage`{=latex}

# ROMWBW Monitor

The Monitor program is a low level utility that can be used 
for testing and programming. It allows programs to be entered,
memory to be examined, and input/output devices to be read or
written to.

It's key advantage is that is available at boot up. 

Its key disadvantages are that code cannot be entered in assembly 
language and there is no ability to save to memory devices.

The available memory area for programming is `0200-EDFFh`.
The following areas are reserved:

Memory Area | Function
------------|-----------------------------------
`0000-00FFh`| Jump and restart (RST) vectors
`0100-01FFh`| HBIOS configuration block
`EE00-FDFFh`| MONITOR
`FE00-FFFFh`| HBIOS proxy

Commands can be entered at the command prompt `>` 
Automatic case conversion takes place on command entry and all 
arguments are expected to be in hex format.

The current memory bank in low memory is displayed before the prompt i.e.:

`8E>`

The Monitor allows access to all memory locations but ROM and
Flash memory cannot be written to. Memory outside the normal
address range can be accessed using the B command. The first
256 bytes `0000-01FF` is critical for the HBIOS operation.
Changing banks may make this information inaccessible.

Refer to the RomWBW Architecture manual for details memory banking.

A quick guide to using the Monitor program follows:

## ? - Displays a summary of available commands.

```
Monitor Commands (all values in hex):
B                    - Boot system
D xxxx [yyyy]        - Dump memory from xxxx to yyyy
F xxxx yyyy zz       - Fill memory from xxxx to yyyy with zz
H                    - Halt system
I xxxx               - Input from port xxxx
K                    - Keyboard echo
L                    - Load Intel hex data
M xxxx yyyy zzzz     - Move memory block xxxx-yyyy to zzzz
O xxxx yy            - Output value yy to port xxxx
P xxxx               - Program RAM at address xxxx
R xxxx [[yy] [zzzz]] - Run code at address xxxx
                       Pass yy and zzzz to register A and BC
T xxxx	             - X-modem transfer to memory location xxxx
S xx                 - Set bank to xx
X                    - Exit monitor
```

## Cold Boot

B - Performs a cold boot of the ROMWBW system. A complete
re-initialization of the system is performed and the system
returns to the Boot Loader prompt.

## Dump Memory

D xxxx [yyyy] - Dump memory from hex location xxxx to yyyy
on the screen as lines of 16 hexadecimal bytes with their
ASCII equivalents (if within a set range, else a '.' is
printed). If the end address is omitted then 256 bytes is
displayed. 

A good tool to see where code is located, check
for version id, obtain details for chip configurations and
execution paths.

Examples: `D 100 1FF`

```
0100: 10 0B 01 5A 33 45 4E 56 01 00 00 2A 06 00 F9 11  ...Z3ENV...*..ù.
0110: DE 38 37 ED 52 4D 44 0B 6B 62 13 36 00 ED B0 21  Þ87íRMD.kb.6.í°!
0120: 7D 32 E5 21 80 00 4E 23 06 00 09 36 00 21 81 00  }2å!..N#...6.!..
0130: E5 CD 6C 1F C1 C1 E5 2A C9 8C E5 CD 45 05 E5 CD  åÍl.ÁÁå*É.åÍE.åÍ
0140: 59 1F C3 00 00 C3 AE 01 C3 51 04 C3 4C 02 C3 57  Y.Ã..î.ÃQ.ÃL.ÃW
0150: 02 C3 64 02 C3 75 02 C3 88 02 C3 B2 03 C3 0D 04  .Ãd.Ãu.Ã..ò.Ã..
0160: C3 19 04 C3 22 04 C3 2A 04 C3 35 04 C3 40 04 C3  Ã..Ã".Ã*.Ã5.Ã@.Ã
0170: 48 04 C3 50 04 C3 50 04 C3 50 04 C3 8F 02 C3 93  H.ÃP.ÃP.ÃP.Ã..Ã.
0180: 02 C3 94 02 C3 95 02 C3 85 04 C3 C7 04 C3 D1 01  .Ã..Ã..Ã..ÃÇ.ÃÑ.
0190: C3 48 02 C3 E7 04 C3 56 03 C3 D0 01 C3 D0 01 C3  ÃH.Ãç.ÃV.ÃÐ.ÃÐ.Ã
01A0: D0 01 C3 D0 01 C3 D0 01 C3 D0 01 01 02 01 CD 6B  Ð.ÃÐ.ÃÐ.ÃÐ....Ík
01B0: 04 54 68 69 73 20 66 75 6E 63 74 69 6F 6E 20 6E  .This function n
01C0: 6F 74 20 73 75 70 70 6F 72 74 65 64 2E 0D 0A 00  ot supported....
01D0: C9 3E FF 32 3C 00 3A 5D 00 FE 20 28 14 D6 30 32  É>ÿ2<.:].þ (.Ö02
01E0: AB 01 32 AD 01 3A 5E 00 FE 20 28 05 D6 30 32 AC  «.2­.:^.þ (.Ö02¬
01F0: 01 C5 01 F0 F8 CF E5 26 00 0E 0A CD 39 02 7D 3C  .Å.ðøÏå&...Í9.}<
```

## Fill Memory

F xxxx yyyy zz - Fill memory from hex xxxx to yyyy with
a single value of zz over the full range. The Dump command
can be used to confirm that the fill completed as expected. A
good way to zero out memory areas before writing machine data
for debug purposes.

## Halt System

H - Halt system. A Z80 HALT instruction is executed. The
system remains in the halt state until the system is
physically rebooted. Interrupts will not restart the
system. On systems that support a HALT status LED, the
LED will be illuminated.

## Input from port

I xxxx - Input data from port xxxx and display to the screen.
This command is used to read values from hardware I/O ports
and display the contents in hexadecimal. 

## Keyboard Echo

K - Echo any key-presses from the terminal. Press 'ESC' key
to quit. This facility provides that any key stroke sent to
the computer will be echoed back to the terminal. File down
loads will be echoed as well while this facility is ‘on’.

## Load Hex format file into memory

L - Load a Intel Hex format file via the terminal program.
The load address is defined in the hex file of the
assembled code.

The terminal emulator program should be configured to
give a delay at the end of each line to allow the monitor
enough time to parse the line and move the data to memory.

Keep in mind that this will be a transient unless the
system support battery backed memory. Saving to memory drive 
is not supported.

## Move memory

M xxxx yyyy zzzz - Move hex memory block xxxx to yyyy to
memory starting at hex location zzzz. Care should be taken
to insure that there is enough memory at the destination so
that code does not get over-written or memory wrapped around.

## Output to port

O xxxx yy - Output data byte xx to port xxxx. This command is
used to send hexadecimal values to hardware I/O ports to
verify their operation and is the companion to the I operation.
Use clip leaded LEDs to confirm the data written.

## Program memory location

P xxxx - Program memory location xxxx. This routine will
allow you to program a hexadecimal value 'into memory starting
at location xxxx. Press 'Enter' on a blank line to
return to the Monitor prompt.

The limitation around programming memory is that it must be 
entered in hexadecimal. An alternative is to use the L command
to load a program that has been assembled to a hex file on the
remote computer.

An excellent online resource for looking up opcodes for entry
can be found here: [https://clrhome.org/table](https://clrhome.org/table)

## Run program

R xxxx [[yy] [zzzz]] - Run program at location xxxx. If optional
arguments yy and zzzz are entered they are loaded into the
A and BC register respectively. The return address of the
Monitor is saved on the stack so the program can return
to the monitor. On return to the monitor, the contents of
the A, HL, DE and BC registers are displayed.

## Set bank

S xx - Change the bank in memory to xx. Memory addresses
0000-7FFF (i.e. bottom 32k) are affected. Because the
interrupt vectors are stored in the bottom page of this
range, this function is disable when interrupt mode 1 is
being used (IM1). Interrupt mode 2 is not affected as the
associated jump vectors are stored in high memory. 

Changing the bank also impacts the restart vectors (RST),
so executing code that call the HBIOS using the RST 08
assembly code will not work.

The monitor stack resides in high memory and is not affected
but any code that changes the stack to low memory will be
affected.

### Bank codes and descriptions

TYPE | DESCRIPTION        |BANK| DETAILS
-----|--------------------|----|---------------------
RAM  | COMMON BANK        | 9F | 1024K RAM SYSTEM
RAM  | USER BANK          | 9E | 1024K RAM SYSTEM
RAM  | BIOS BANK          | 9D | 1024K RAM SYSTEM
RAM  | AUX BANK           | 9C | 1024K RAM SYSTEM
RAM  | OS BUFFERS END     | 9B | 1024K RAM SYSTEM
RAM  | OS BUFFERS START   | 98 | 1024K RAM SYSTEM
RAM  | RAM DRIVE END	  | 97 | 1024K RAM SYSTEM
RAM  | COMMON BANK        | 8F | 512K RAM SYSTEM
RAM  | USER BANK          | 8E | 512K RAM SYSTEM
RAM  | BIOS BANK          | 8D | 512K RAM SYSTEM
RAM  | AUX BANK           | 8C | 512K RAM SYSTEM
RAM  | OS BUFFERS         | 8B | 512K RAM SYSTEM
RAM  | OS BUFFERS         | 8A | 512K RAM SYSTEM
RAM  | OS BUFFERS         | 89 | 512K RAM SYSTEM
RAM  | OS BUFFERS         | 88 | 512K RAM SYSTEM
RAM  | RAM DRIVE END	  | 87 | 512K RAM SYSTEM
RAM  | RAM DRIVE START    | 80 |
ROM  | BOOT BANK          | 00 | COLD START & HBIOS
ROM  | LOADER & IMAGES    | 01 | MONITOR, FORTH
ROM  | ROM IMAGES CONTD.  | 02 | BASIC, ETC
ROM  | FAT FILESYSTEM     | 03 | UNA ONLY, ELSE UNUSED
ROM  | ROM DRIVE START    | 04 |
ROM  | ROM DRIVE END      | 0F | 512K ROM SYSTEM
ROM  | ROM DRIVE END      | 1F | 1024K ROM SYSTEM

## X-modem transfer

T xxxx - Receive an X-modem file transfer and load it into
memory starting at location xxxx. 

128 byte blocks and checksum mode is the only supported 
protocol.

If the monitor is assembled with the DSKY functionality,
this feature will be exclude due to space limitions.


## NOTES:

The RTC utility on the CP/M ROM disk provides facilities
to manipulate the Real Time Clock non-volatile Memory. 
Use the C or Z option from the Boot Loader to load CP/M 
and then run RTC to see the options list.

# FORTH

CamelForth is the version of Forth included as part of the boot
ROM in ROMWBW. It has been converted from the Z80 CP/M version
published here [www.camelforth.com/page.php?5](www.camelforth.com/page.php?5). The author is Brad
Rodriguez who is a prolific Forth enthusiast, whose work can be
found here: [www.bradrodriguez/papers/index.html](www.bradrodriguez/papers/index.html)

For those are who are not familiar with Forth, I recommend the
wikipedia article [en.wikipedia.org/wiki/Forth_(programming_language](en.wikipedia.org/wiki/Forth_(programming_language))
and the Forth Interest Group website [www.forth.org](www.forth.org)

## Important things to know

Forth is case sensitive.

To exit back to the boot loader type ***bye***

To get a list of available words type ***WORDS***

To reset Forth to its initial state type ***COLD***

Most of the code you find on the internet will not run unless modified or additional Forth
words are added to the dictionary.

This implementation does not support loading or saving of programs. All programs
need to be typed in. Additionally, screen editing and code blocks are not supported.

## Structure of Forth source files

File          | Description
--------------|-----------------------------
camel80.azm   | Code Primitives
 camel80d.azm | CPU Dependencies
 camel80h.azm | High Level words
 camel80r.azm | ROMWBW additions
glosshi.txt   | Glossary of high level words
glosslo.txt   | Glossary of low level words
glossr.txt    | Glossary of ROMWBW additions

## ROMWBW Additions

Extensions and changes to this implementation compared to the original distribution are:

The source code has been converted from Z80mr assembler to Hector Peraza's zsm.

An additional file camel80r.azm has been added for including additional words to 
the dictionary at build time. However, as currently configured there is very little space
allocated for addition words. Exceeding the allocated ROM space will generate an error
message when building.

James Bowman's double precision words have been added from his RC2014 version:
[https://github.com/jamesbowman/camelforth-z80](https://github.com/jamesbowman/camelforth-z80)

Word    | Syntax                     | Description
--------|----------------------------|---------------------------------
D+	| d1 d2 -- d1+d2             | Add double numbers
2>R	| d --                       | 2 to R
2R>	| d --                       | fetch 2 from R
M*/	| d1 n2 u3 --  d=(d1*n2)/u3  | double precision mult. div
SVC	| hl de bc n -- hl de bc af  | Execute a ROMWBW function
P!	| n p --                     | Write a byte to a I/O port
P@      | p -- n                     | Read a byte from and I/O port

# BASIC

For those who are not familiar with BASIC, it stands for Beginners All purpose Symbolic
Instruction Code. 

ROMWBW contains two versions of ROM BASIC, a full implementation and a "tiny" BASIC.

The full implementation is a version of Microsoft BASIC from the NASCOM Computer.

A comprehensive instruction manual is available in the Doc\\Contrib directory.

## ROMWBW specific features

- Sound
- Graphics
- Terminal Support

## ROMWBW unsupported features

-  Cassette loading
-  Cassette saving

# TastyBASIC

TastyBASIC offers a minimal implementation of BASIC that is only 2304 bytes in size. 
It originates from Li-Chen Wang's Palo Alto Tiny BASIC from around 1976. It's small size suited the tiny memory capacities of the time. This implementation is by Dimitri Theulings and his
original source can be found here [https://github.com/dimitrit/tastybasic](https://github.com/dimitrit/tastybasic)

## Features / Limitations

 Integer arithmetic, numbers -32767 to 32767
 Singles letter variables A-Z
 1-dimensional array support
 Strings are not supported  

## Direct Commands

- `LIST`,`RUN`, `NEW`, `CLEAR`, `BYE`

## Statements

- `LET`, `IF`, `GOTO`, `GOSUB RETURN`, `REM`, `FOR TO NEXT STEP`, `INPUT`, `PRINT`, `POKE`, `END`

## Functions

- `PEEK`, `RND`, `ABS`, `USR`, `SIZE`

## Operators

- `>=`, `#`, `>`, `=`, `<=`, `<`

- Operator precedence is supported.

Type ***BYE*** to return to the monitor.

# Play a Game

## 2048

2048 is a puzzle game that can be both mindless and challenging. It
appears deceptively simple but failure can creep up on you suddenly.

It requires an ANSI/VT-100 compatible colour terminal to play.

2048 is like a sliding puzzle game except the puzzle tiles are 
numbers instead of pictures. Instead of moving a single tile all 
tiles are moved simultaneously in the same direction. Where two 
tiles of the same number collide, they are reduced to one tile with
the combined value. After every move a new tile is added with
a starting value of 2. 

The goal is to create a tile of 2048 before all tile locations are
occupied. Reaching the highest points score, which is the sum of all
the tiles is a secondary goal. The game will automatically end when 
there are no more possible moves.

Play consists of entering a direction to move. Directions can be entered
using any of three different keyboard direction sets.

```
Direction | Keys
----------|----------
Up        | w ^E 8
Down      | s ^X 2
Left      | a ^S 4
Right     | d ^D 6
```
The puzzle board is a 4x4 grid. At start, the grid will be populated
with two 2 tiles. An example game sequence is shown below with new
tiles to the game shown in brackets.

```
Start             Move 1 - Up       Move 2 - Left     Move 3 - Left
+---+---+---+---+ +---+---+---+---+ +---+---+---+---+ +---+---+---+---+
|   |   |   |(2)| |   |   |   | 4 | | 4 |   |   |   | | 4 |   |   |   |
+---+---+---+---+ +---+---+---+---+ +---+---+---+---+ +---+---+---+---+
|   |   |   |   | |   |   |   |   | |   |   |   |(4)| | 4 |   |   |   |
+---+---+---+---+ +---+---+---+---+ +---+---+---+---+ +---+---+---+---+
|   |   |   |(2)| |   |   |   |   | |   |   |   |   | |   |   |   |   |
+---+---+---+---+ +---+---+---+---+ +---+---+---+---+ +---+---+---+---+
|   |   |   |   | |   |   |(2)|   | | 2 |   |   |   | | 2 |   |(2)|   |
+---+---+---+---+ +---+---+---+---+ +---+---+---+---+ +---+---+---+---+

Move 4 - Left     Move 5 - Up       Move 6 - Right    Move 7 - Up
+---+---+---+---+ +---+---+---+---+ +---+---+---+---+ +---+---+---+---+
| 4 |   |   |   | | 8 |   |   | 4 | |   |   | 8 | 4 | |   |   | 8 | 8 |
+---+---+---+---+ +---+---+---+---+ +---+---+---+---+ +---+---+---+---+
| 4 |   |   |(4)| | 4 |   |   |   | |   |   |   | 4 | |   |   |   | 2 |
+---+---+---+---+ +---+---+---+---+ +---+---+---+---+ +---+---+---+---+
|   |   |   |   | |   |   |   |   | |   |   |   |   | |   |   |   |   |
+---+---+---+---+ +---+---+---+---+ +---+---+---+---+ +---+---+---+---+
| 4 |   |   |   | |(2)|   |   |   | |(2)|   |   | 2 | |(2)|   |   |   |
+---+---+---+---+ +---+---+---+---+ +---+---+---+---+ +---+---+---+---+
```
This is how I lost this game:
```
+---+---+---+---+
| 4 | 2 | 16| 4 |
+---+---+---+---+
| 32| 64| 8 | 2 |
+---+---+---+---+
| 4 | 8 |128| 32|
+---+---+---+---+
|(2)| 16| 8 | 4 |
+---+---+---+---+
```
Press Q at any time to bring up the option to Quit or Restart the game.

# Network Boot

# Xmodem Flash Updater

The ROMWBW Xmodem flash updater provides the capability to update ROMWBW from the boot loader using  an x-modem file transfer. It offers similar capabilities to Will Sowerbutts FLASH4 utility except that the flashing process occurs during the file transfer. 

These are the key differences between the two methods are:

Xmodem Flash Updater            | FLASH4
--------------------------------|-----------------
Available from the boot loader   | Well proven and tested
Xmodem transfer is integrated    | Wider range of supported chips and hardware
Integrated checksum utilities    | Wider range of supported platforms
Capability to copy a ROM image   | Only reprograms sectors that have changed
More convenient one step process | Ability save and verify ROM images
No intermediate storage required | Progress display while flashing
.                                | Displays chip identification information
.                                | Faster file transfer
                                 
The major disadvantages of the Updater is that it is new and relatively untested. There is the risk that a failed transfer will result in a partially flashed and unbootable ROM. There are some limitations on serial transfer speeds.
 
The updater utility was initially intended to support the Retrobrew SBC-V2-005 platform using Atmel 39SF040 flash chips but has now been extended to be more generic in operation.

Supported flash chips are 
39SF040, 29F040,  AT49F040, AT29C040, M29F040 , MX29F040,  A29010B, A29040B

The Atmel 39SF040 chip is recommended as it can erase and write 4Kb sectors. Other chips require the whole chip to be erased.

## Usage

In most cases, completing a ROM update is a simple as:

1. Booting to the boot loader prompt
2. Selecting option X - Xmodem Flash Updater
3. Selecting option U - Update
4. Initiating an X-modem transfer of your ROM image on your console device
5. Selecting option R - Reboot

If your console device is not able to transfer a ROM image i.e. your console is a VDU then you will have to use the console options to identify which character-input/output device is to be used as the serial device for transfer.

When your console is the serial device used for the transfer, no progress information is displayed as this would disrupt the x-modem file transfer. If you use an alternate character-input/output devices as the serial device for the transfer then progress information will be displayed on the console device.

Due to different platform processor speeds,  serials speeds and flow control capabilities the default console or serial device speed may need to be reduced for a successful transfer and flash to occur. The **Set Console Interface/Baud code** option at the Boot Loader can be used to change the speed if required. Additionally, the Updater has options to set to and revert from a recommended speed. 

 ## Console Options
Option ( C ) - Set Console Device

Option ( S ) - Set Serial Device

By default the updater assumes that the current console is a serial device and that the ROM file to be flashed will also be transferred across this device, so the Console and Serial device are both the same.

Either device can be can be change to another character-input/output device but the updater will always expect to receive the x-modem transfer on the **Serial Device**

The advantage of transferring on a different device to the console is that progress information can be displayed during the transfer.

Option ( > ) - Set Recommended Baud Rate

Option ( < ) - Revert to Original Baud Rate

## Programming options

Option ( U ) - Begin Update

The will begin the update process. The updater will expect to start receiving
an x-modem file on the serial device unit.

X-modem sends the file in packets of 128 bytes. The updater will cache 32
packets which is 1 flash sector and then write that sector to the
flash device.

If using separate console, bank and sector progress information will shown

```
BANK 00 s00 s01 s02 s03 s04 s05 s06 s06 s07
BANK 01 s00 s01 s02 s03 s04 s05 s06 s06 s07
BANK 02 s00 s01 s02 s03 s04 s05 s06 s06 s07 etc
```

The x-modem file transfer protocol does not provide any filename or size
information for the transfer so the updater does not perform any checks
on the file suitability.

The updater expects the file size to be a multiple of 4 kilobytes and
will write all data received to the flash device. A system update
file (128kb .img) or complete ROM can be received and written (512kb or
1024kb .rom)

If the update fails it is recommended that you retry before rebooting or
exiting to the Boot loader as your machine may not be bootable.

Option ( D ) - Duplicate flash #1 to flash #2
 
This option will make a copy of flash #1 onto flash #2. The purpose of this is to enable
 making a backup copy of the current flash. Intended for systems using 2x512Kb Flash devices.

Option ( V ) - Toggle Write Verify

By default each flash sector will be verified after being written. Slight
performance improvements can be gained if turned off and could be used if
you are experiencing reliable transfers and flashing.

## Exit options

Option ( R ) - Reboot

Execute a cold reboot. This should be done after a successful update. If
you perform a cold reboot after a failed update then it is likely that
your system will be unusable and removing and reprogramming the flash
will be required.

Option ( Q ) - Quit to boot loader. 

The SBC Boot Loader is reloaded from ROM and
executed. After a successful update a Reboot should be performed. However,
in the case of a failed update this option could be used to attempt to
load CP/M and perform the normal x-modem / flash process to recover.

## CRC Utility options

Option ( 1 ) and ( 2 ) - Calculate and display CRC32 of 1st or 2nd 512k ROM.
Option ( 3 ) - Calculate and display CRC32 of a 1024k (2x512Kb) ROM.

Can be used to verify if a ROM image has been transferred and flashed correctly. Refer  to the Teraterm section below for details on configuring the automatic display of a files CRC after it has been transferred.

In Windows, right clicking on a file should also give you a context menu option CRC SHA which will allow you to select a CRC32 calculation to be done on the selected file.

## Teraterm macro configuration 

Macros are a useful tool for automatic common tasks. There are a number of instances where using macros to facilitate the update process could be worthwhile if you are:

* Following the ROMWBW development builds.
* Doing lots of configuration changes.
* Doing development on ROMWBW drivers

Macros can be used to automate sending ROM updates or images and for my own purposed I have set up a separate macro for transferring each of the standard build ROM, my own custom configuration ROM and update ROM.

An example macro file to send an *.upd file, using checksum mode and display the crc32 value of the transmitted file:

```
Xmodem send, checksum, display crc32
xmodemsend '\\desktop\users\phillip\documents\github\romwbw\binary\sbc_std_cust.upd' 1
crc32file crc '\\desktop\users\phillip\documents\github\romwbw\binary\sbc_std_cust.rom'
sprintf '0x%08x' crc
messagebox inputstr 'crc32'
```
## Serial speed guidelines

As identified in the introduction, there are limitations on serial speed depending on processor speed and flow control settings. Listed below are some of the results identified during testing.

Platform / Configuration       | Processor Speed | Maximum Serial Speed
-------------------------------|-----------------|---------------------
Sbc-v2  uart no flow control   | 2mhz            | 9600
sbc-v2  uart no flow control   | 4mhz            | 19200
sbc-v2  uart no flow control   | 5mhz            | 19200
sbc-v2  uart no flow control   | 8mhz            | 38400
sbc-v2  uart no flow control   | 10mhz           | 38400
sbc-v2  usb-fifo 2mhz+         |                 | n/a
sbc-mk4 asci no flow control   | 18.432mhz       | 9600
sbc-mk4 asci with flow control | 18.432mhz       | 38400

The **Set Recommend Baud Rate** option in the Updater menu follows the following guidelines.

Processor Speed | Baud Rate
----------------|----------
1Mhz            | 4800
2-3Mhz          | 9600
4-7Mhz          | 19200
8-20Mhz         | 38400

These can be customized in the updater.asm source code in the CLKTBL table  if desired.
Feedback to the ROMWBW developers on these guidelines would be appreciated.

## Notes:
All testing was done with Teraterm x-modem, Forcing checksum mode using macros was found to give  the most reliable transfer.
Partial writes can be completed with 39SF040 chips. Other chips require entire flash to be erased before before being written.
An SBC V2-005 MegaFlash or Z80 MBC required for 1mb flash support. The Updater assumes both chips are same type
Failure handling has not been tested.
Timing broadly calibrated on a Z80 SBC-v2
Unabios not supported