The Memotech MTX Series
Memotech Compact Flash System - Version 2
CFX - II Firmware
The CFX-II ROM provides versions of both the MTX SDX BASIC ROM
and a CP/M ROM based on the original Memotech CP/M ROM with 80
Column Card support.
The video display from the SDX BASIC ROM is generated by the
MTX VDP, with output through the MTX TV and Video connectors.
The video display from the CP/M ROM is generated by the
Parallax Propeller on the CFX-II
board, with output through the VGA connector on the
CFX-II PCB. Bill has documented Version 2 of his
Parallax Propeller firmware
in this file.
MTX SDX BASIC ROM
The Memotech SDX BASIC ROM added disk functions to MTX BASIC
through USER commands, such as
USER LOAD, USER SAVE,
etc. These commands loaded and saved files in Memotech's
.BAS format. Andy describes the structure of
files on the
in the MEMU
section of his
The same page also describes the structure of
files, Memotech supplied some games in this format for systems
with the SDX ROM. They were executed by the USER RUN
command from BASIC.
These days, the majority of Memotech software is available in
files, described by Andy as "disk files containing the same
bytes, in the same order, as would be found on an MTX cassette
tape." These files are used by most emulators, including
hardware enhancements such as
REMEMOrizer but were not supported by the original SDX.
Given the prevalence of .mtx files in the Memotech software
library, Martin has added a USER MTX
command to the SDX ROM in CFX to support loading of
.mtx files from SDX BASIC.
CFX Version 1 used a copy of Andy's SCPM ROM
that was written to enable CP/M to run on a Memotech computer without the need for an 80-Column card, the
MTX VDP was used to generate a low quality 56 column text mode.
Andy also patched NewWord to run in this 56 column mode. The
SCPM ROM was eventually used in
Memotech's Video Wall product.
CFX-II includes an emulation
of the Memotech 80 column card and generates full colour 80
Column output to a VGA monitor. MTX BASIC and games output is
still through the original Memotech video output port.
As with CFX Version 1, CFX-II
CP/M mode does has a significant speed advantage over SDX mode in certain
cases. Due to the way that the CFX "disk" code works, program
loading from SDX BASIC takes considerably longer than loading a
comparable program from CP/M, for example, TURBO.RUN
takes 4.6 seconds to load in CFX SDX mode, while
TURBO.COM is near instantaneous from CFX CP/M
CFX ROM Selection
Since CFX can co-exist with MAGROM and also
has two different ROM images available, there has to be a
mechanism for selecting the appropriate ROM to call when the
MTX is powered on or reset. The MTX OS ROM checks for the presence
of option ROMs in sequence, e.g., ROM 4, ROM 5, ROM 7, the
CFX CP/M ROM is implemented as ROM 4.
|After power on or reset, the MTX will boot from
the CFX ROM, display the CFX splash screen and check
for the presence of a "disk" (CF Card) in the card
If a card can be read, the other boot
time options are displayed for information and the
user prompted to "Press <RET> to enter SDX BASIC".
|If the "drive" cannot be read within the
configured time-out period (currently ~15 seconds),
a warning message is displayed and the remainder of
the splash screen is displayed.
<RET> key will enter SDX BASIC,
albeit that there will be no "disk" available unless
the CF card hardware is present and a card is
|Selecting "I" from the
boot screen brings up a helpful crib sheet showing
the additional commands available from SDX BASIC.
Pressing <RET> continues to SDX BASIC
|The boot time options are :-
combination (Reset + < key >)
||CFX - SDX CP/M
||MTX - no CFX or MAGROM support
||CFX Boot ROM - displays Splash screen
enters CFX - SDX BASIC ]
||[ < I >
Displays SDX USER crib sheet ]
|As a result of the ROM processing
order noted earlier, there are a couple of
incidental effects that can be used when hitting <RET>
to exit the boot screen :-
|<space> + <RET>
+ <alpha key>
||boots MAGROM and loads the game found in the
slot matching the key pressed, e.g., "0" would load
|Output from the emulated 80
column board displayed on a VGA monitor.
The Propeller starts up in a colour
mode, compatible with the MTX 80 column card using colour
output, but can be switched to two alternative modes :
Compatible with the MTX 80 column
card using monochrome output, or
An enhanced colour mode,
providing the full capabilities of the Propeller card
character sequences (escape codes) are used to
switch between modes:
||MTX 80 Column Card Colour
||MTX 80 Column Card
Monochrome compatible mode
Bill has fully documented the features of his Propeller
Log - Hardware
First production board, committed to
1 Andy Key's Memotech Hardware page
2 Que Publishing, Upgrading and
Repairing PCs, 21st Edition, ISBN-13: 978-0-7897-5000-6.
Sample Chapter : The ATA/IDE Interface