29/03/2024

System ROM V2.05 Beta 40 is now available on the website - see here:

68030 SBC/ROMS/System ROMS

ACRTC-2 Board support added and more commands (ACRTC specific) added to Enhanced BASIC - see release notes for more information.

Again as this is a beta release (work in progress) it is worth remembering that the BASIC keywords and required parameters may change multiple times before System ROM V2.05 is finalised.

27/03/2024

The new ACRTC-2 Board PCB's arrived from China. Two PCB's have so far been assembled and tested. Both boards are now performing as expected however it is necessary to add a small capacitor to the rear of this board to correct a signal timing issue - the RAMDAC clock signal arrives too early which results in some missing pixels and a small amount of display jitter. This will be fixed on the next PCB revision but for now this simple post production modification must be applied.

Full details of the modification have now been added to the website along with an updated BOM. The previously posted BOM was incomplete i.e. some IC sockets were not listed.

19/03/2024

Design and prototyping of the new ACRTC-2 Board is now complete and so the time has come to share some details - see here:

ACRTC-2

PCB's are on order and final testing still needs to be done once the boards are received but hopefully no changes to the PCB design will be required.

01/01/2024

For all ACRTC enabled systems - a heavily modified version of Tiny BASIC (Tiny BASIC for ACRTC) has been uploaded to the website.

Install it permanently as a CP/M-68K transient program or alternatively just download it to RAM and run it using the LO and GO commands built into the System Monitor.

ACRTC programming made easy - see here:

ACRTC/Software

29/12/2023

Currently working on a second generation ACRTC Board that supports colour.

System ROM V2.05 Beta 6 is now available on the website - see here:

68030 SBC/ROMS/System ROMS

New experimental commands (mostly ACRTC specific) added to Enhanced BASIC - see release notes for more information.

As this is a beta release (work in progress) it is worth remembering that the BASIC keywords and required parameters may change multiple times before System ROM V2.05 is finalised.

21/12/2023

Transferring files from a Windows PC to a Mega-680x0 Computer System running CP/M-68K is now effortless thanks to a great piece of software called C-Kermit. C-Kermit is a powerful Terminal Emulator with a built in Kermit Server. Full setup instructions have been added to the website - see here:

Software/C-Kermit

For CP/M-68K users this is a must have.

05/11/2023

System ROM V2.04 is now available on the website - see here:

68030 SBC/ROMS/System ROMS

04/11/2023

Documented another new board revision - the IDE-2 Board. Information on this board has now been pushed to the website.

29/10/2023

Documented another new board revision - the 68230-2 Board. Information on this board has now been pushed to the website.

23/10/2023

The new 68030 SBC-2 is up and running! - the PCB's arrived from China and a fully populated board has been working flawlessly for a couple of weeks now.

Finally documented a couple of new board revisions too - a 68000 CPU-2.1 Board and a Memory-3.1 Board. Information on both of these boards has now been pushed to the website.

18/09/2023

Been quietly working on a new 68030 SBC since the last blog post and now a major milestone has been reached it is time to share some details - see here:

68030 SBC-2

PCB's are on order and testing will begin once the boards are received.

26/04/2023

System ROM V2.04 Beta 26L is now available on the website - see here:

68030 SBC/ROMS/System ROMS

When used with a Mega-68000 Computer System this release will now identify when a 68010 processor has been substituted for a 68000 and display which of the two processors is in use on the boot screen.

If a 68230 Board or 68230-2 Board is present - timer interrupts are enabled, checked, and if all is well reported as [ Running  ] on the boot screen. If the interrupts are not running the system will now wait indefinitely displaying 'Timer Interrupts ...... [ Starting ]' on the boot screen.

Changed is the default configuration of the 68230 ports - ports A and B are now configured as input ports at start-up - in hindsight it may have been better to have one input port and one output port so this configuration may only be temporary (still deliberating) - for now though, they are both input ports.

This System ROM release also includes an updated CP/M-68K BIOS - this new BIOS (V1.2) fixes a recently discovered issue with the CP/M-68K DDT utility.

20/04/2023

The Mega-Micro's Discord Server is now live. Anyone who owns, wants to own, or has a keen interest in 680x0 processor-based systems is more than welcome to join but please be kind and respectful at all times.

01/04/2023

System ROM V2.04 Beta 23L is now available on the website - see here:

68030 SBC/ROMS/System ROMS

This release brings a number of improvements but the big one is that CP/M-68K now runs on systems with only 2MB RAM thus we no longer need surface mount components - the 68030 SBC can be populated with standard DIP RAM chips and still run CP/M-68K.

The IDE Board - If you wish to use the IDE Board with a Mega 68030 SBC it is highly recommended that you use an IDE DOM (Disk-On-Module) instead of a Compact Flash Card - testing is still ongoing with this board but numerous DOM's have been in use here for a good while now and all have been 100% reliable.

Added to the website are some simple programs written in 'C' which better demonstrate the drawing speed of the Advanced CRT Controller on the ACRTC Board - see here:

ACRTC/Software/C

Together with the source files are step by step instruction on how to generate the .68K executables under CP/M-68K on any Mega-680x0 Computer System using the 'C' Compiler and Linker included in the CP/M-68K distribution.

12/02/2023

The new 68230 Board PCB's arrived from China. One of the PCB's has now been assembled and tested.  No issues were found and the board performed as expected.

29/01/2023

The 68230 Board PCB design is complete and an image of the PCB layout has been added to the website. PCB's are on order and testing will begin once the boards are received. The board schematic on the website has been updated - minor changes were made to simplify trace routing. The BOM and jumper information for the board has also been added to the website.

12/01/2023

An update on the IDE Board - work on this board has been suspended for now. A HUGE amount of time has been spent tweeking the design and testing this board with both the Mega-68000 Computer System and the 68030 SBC. You can find the IDE Board + CF Adapter test results for the Mega-68000 Computer System on the website - you will see it works well (but not perfectly) across a wide range of system clock frequencies with a number of different CF Cards. When testing with the 68030 SBC however it became clear that this design was not going to make the grade - test results were inconsistent and different IDE Boards would return different results. This wont be a quick fix and so rather than spend MORE time on this we need to move on and return to this problem later.

So, what's cooking now? - well the design of a 68230 Board for the Mega-68000 Computer System is almost complete. Prototype hardware and software is now operational. Hope to start on the PCB layout for this board shortly, but so you can see what this board will do, the board description and schematic has already been added to the website - see here:

68230

09/11/2022

The Archimedes Spiral program that produces the well-known 'hat' image has been modified to work with the ACRTC Board and added to the website - see here:

ACRTC/Software/Basic

30/10/2022

Added to the website a program which demonstrates some of the standard drawing capabilities of the Advanced CRT Controller on the ACRTC Board - see here:

ACRTC/Software/Basic

12/10/2022

The IDE Board has now been tested with the Mega-68000 Computer System. The board functions with CP/M-68K and so on to testing of the IDE Board with the Mega-68030 Computer System (68030 SBC).

20/08/2022

The IDE Board PCB design is complete and an image of the PCB layout has been added to the website. PCB's are on order and testing will begin once the boards are received.

07/08/2022

The firmware for the ACRTC Board was missing from the website - this has now been added.

06/08/2022

The latest IDE Board schematic, BOM, and firmware has been added to the website. Compact Flash diagnostics software has been added too.

20/07/2022

System ROM V2.04 Beta 8L is now available on the website - see here:

68030 SBC/ROMS/System ROMS

There were problems using the following Compact Flash Cards:

This update fixes the above and guarantees CP/M-68K will work with a wider range of CF Cards.

13/05/2022

System ROM V2.04 Beta 3L is now available on the website. This version of System ROM is currently being used to test the IDE Board - see here:

68030 SBC/ROMS/System ROMS

The IDE Board / Compact Flash Interface and System ROM V2.04 Beta 3L is designed for use with the 68030 SBC but it can also be used with the Mega-68000 Computer System.

10/05/2022

The IDE Board / Compact Flash Interface for the 68030 SBC is now useable under CP/M-68K.

07/05/2022

Started work this week on the design of an IDE Board / Compact Flash Interface for the 68030 SBC. A prototype board and some software to read a single sector of data (512 bytes) from a 128MB CF Card is now operational - early days but not a bad start.

19/04/2022

Finally released System ROM V2.03 - it is now on the website. This is the first fully functional and hopefully bug free version of System ROM for the 68030 SBC - see here:

68030 SBC/ROMS/System ROMS

System ROM V2.03 can also be used with the Mega-68000 Computer System.

A new document containing basic information on VT100/ANSI ESC Sequences has been added to the website.

09/04/2022

The 68030 SBC Jumpers section of the website has been updated, details on JB1 and JB2 have been added.

System ROM V2.02 (as a single BIN file) has been added to the website for those with a device programmer with direct support for the STM M27C322 EPROM - see here:

Software/CP/M-68K/Mega-68000

Note: this is the version for use with the 68681 Board.

24/02/2022

The 68030 SBC section of the website has been updated. It now contains details of a hardware mod. which fixes an intermittent start-up issue and a beta version of System ROM V2.03 which incorporates a patch for the 68030 processor. Jumper descriptions and default settings for the 68030 SBC are also there.

06/10/2021

Step by step instructions have now been added to the website on how to use the GNU Compiler Collection to assemble (translate) simple programs written in 68K Assembly Language to executable programs that can be downloaded to a Mega-68000 Computer System and run from RAM - see here:

Software/GCC

The Linux Quick Tips page on the website has been further updated - basic information on Linux Script Files added, i.e. what they are, how to create them, and how to run them.

04/10/2021

Instructions covering the installation of the popular Linux based GNU Compiler Collection have now been added to the website - see here:

Software/GCC

The Linux Quick Tips page on the website has also been updated.

27/09/2021

Step by step instructions have now been added to the website on how to setup a Windows 10 PC to run Linux command line tools and programs - see here:

Software/WSL & Linux

Additional instructions will be added in due course covering the installation and configuration of the popular Linux based GNU Compiler Collection. The GNU Compiler Collection has an Assembler AND C Compiler that can generate code for our 680x0 devices.

03/09/2021

After months of effort it is finally here - a NEW Single Board Computer (SBC) based on the 68030 processor. The board has been tested at 25MHz without problems running Tutor, ehBasic, and CP/M-68K OS. Further information on the 68030 SBC can now be found on the website.

Added 68030 SBC board schematic and BOM to the website.

09/05/2021

Website update - added some basic information on the Altera MAX 7000S series of CPLD's and the freely available Quartus II Software needed to design with and program these devices. The information can be found in the Software section of the website.

26/03/2021

Just a quick update on the new 68000 CPU-2 Board. PCBWay in China manufactured the PCB's and delivered them in under a week. A fully assembled board has been operating 100% reliably in a reference Mega-68000 Computer System here for a good while now - long enough to conclude that this new board using the PLCC 68K CPU does deliver at the very least 'equivalent functionality' to that of the previous 68000 CPU Board designed around the DIP-64 68K CPU. Some of the extra functionality this second generation board promises still needs further testing (specifically the interrupt logic) but the on-board NMI button works as expected which is encouraging and the new Bus Error hardware works too.

10/03/2021

There is a new Dual 6850-2 Board in the making. PCB design is complete and an image of the PCB layout has been added to the website. PCB's are on order and testing will begin once the boards are received. The board schematic and BOM have also been added to the website.

08/03/2021

The new Memory-3 Board has now been populated and stress tested almost daily for nearly a month now with 8MB RAM (4x CY62167ELL) and 4MB ROM (27C322). No issues have been found to date and the board continues to perform as expected.

The 68000 CPU Board is a basic (no frills) design and while it works perfectly it lacks features. A new 68000 CPU-2 Board will be available shortly which will enhance the Mega-68000 Computer System further. PCB design is complete and an image of the PCB layout has been added to the website. PCB's are on order and testing will begin once the boards are received. The board schematic and BOM have also been added to the website.

09/02/2021

The new Memory-3 Board PCB's arrived from China. One of the PCB's has now been assembled and tested with 2MB RAM (4x AS6C4008) and 4MB ROM (27C322). No issues were found and the board performed as expected.

02/02/2021

Rolled out some long overdue website updates today, nothing very exciting just some small cosmetic changes. Pondering now over what hardware to develop next for the Mega-68000 Computer System.

01/02/2021

The new 68681 Board PCB's arrived from China. One of the PCB's has now been assembled and tested.  No issues were found and the board performed as expected.

A new ROM/RAM board PCB design is complete (Memory-3) details and an image of the PCB layout have been added to the website. PCB's are on order and testing will begin once the boards are received. The board schematic and BOM have also been added to the website.

19/01/2021

68681 Board PCB design is complete and an image of the PCB layout has been added to the website. PCB's are on order and testing will begin once the boards are received. The board schematic and BOM have also been added to the website.

02/01/2021

System ROM V2.02 is now available on the website. Support for the ACRTC Board has been added. System ROM V2.02 now automatically discovers and initialises the ACRTC Board at system start-up. If no board is present the system boots as before.

31/12/2020

Step by step instructions have now been added to the website on how to assemble (translate) simple programs written in 68K Assembly Language to executable programs that run on the CP/M-68K OS - see here:

Quick Tips/CP/M-68K

The section Basic CP/M-68K Commands has also been extended to cover renaming files and copying files.

27/12/2020

System ROM V2.01 is now available on the website. Support for the XR68C681 DUART on the Prototype 68681 Board has been added.

17/12/2020

System ROM V2.0 is now available on the website. Support for the Prototype 68681 Board has been added. In this release all code sections (Monitor, Basic, and CP/M-68K) use common I/O routines.

13/12/2020

The Quick Tips section of the website has been updated. Instructions on saving memory to an S-Record file and loading memory from an S-Record file with TUTOR have been added.

12/11/2020

Making progress now with the Prototype 68681 Board. Channel A transmitter and receiver working at 38400 Baud and hardware handshaking also working.

The ACRTC diagnostics software has been updated. The new software release is acrtc_diagnostics_v1.12 and it can be downloaded from the website here:

ACRTC/Testing

This version initialises the ACRTC and displays the test pattern at run time.

Testing now complete on the new hardware handshaking feature built into System ROM V1.0 and the results are in ....

You can now write/edit BASIC programs on the PC using your favourite PC text editor and RELIABLY download and run them by sending the program text to a Console Window displaying a BASIC Ready prompt. No more lost characters, no more syntax errors - it just works.

You MUST hook-up the hardware handshaking (flow control) signal on the Dual 6850 Board and you MUST also enable flow control in the Terminal Emulation software on the PC - this will prevent the PC sending data when the CON ACIA is busy.

Tests were conducted using Tera Term for Windows V4.105 with the following settings applied: 38400 Baud, RTS/CTS flow control, and NO end of line or inter-character delays.

21/10/2020

More documents and datasheets added to the website. Currently working on a 68030 CPU Protoboard. It is designed to test some recently acquired MC68030RC33C and MC68030RC50C parts, however later it may be used to develop a working 68030 CPU Board for the Mega-68000 Computer System.

10/10/2020

Step by step instructions have now been added to the website on how to compile (translate) simple programs written in BASIC or C to executable programs that run on the CP/M-68K OS - see here:

Quick Tips/CP/M-68K

08/10/2020

CP/M-68K and Linux pages added to the Quick Tips section of the website. Linux wont be coming to the Mega-68000 Computer System anytime soon, however a Linux software development environment opens up some interesting possibilities so watch this space.

03/10/2020

The design and test of a new 2M x 8 RAM Adapter is now complete. Four of these adapters can replace the four AS6C4008 RAM chips on a Memory-2 Board increasing its RAM capacity by a factor of four.

New firmware is also available for the Memory-2 Board that unlocks the additional RAM as well as the additional ROM provided by the 27C322 ROM Adapter.

A single Memory-2 Board can now be configured with 8MB RAM + 4MB ROM which is more than enough even for a Mega-68000 Computer System running the CP/M-68K Operating System.

10/09/2020

Been working hard on this one for a good while now, but it's finally here and is a major step forward - you can now selectively run CP/M-68K on the Mega-68000 Computer System. Typing OS at the command prompt now launches CP/M-68K. Further information can be found on the website here:

Software/CP/M-68K/Mega-68000

04/09/2020

Finished testing a new 27C322 (2M x 16) ROM Adapter. The ROM Adapter plugs into the 27C4096 ROM socket on a Memory-2 Board increasing its ROM capacity to 4MB. This ROM Adapter will be required for all future software updates.

15/07/2020

Added a small but hopefully useful feature to the software that runs the Mega-68000 Computer System - I/O compatibility with Sim68K to assist with program development/debugging.

68K software written in Sim68K on the PC performs basic I/O using the 68000 TRAP instruction. A task number is loaded into D0 and then a TRAP #15 instruction is executed to perform the task. Tasks 5-7 are used for keyboard input and character display output, the Mega-68000 now supports this I/O method allowing software to be written, tested, and debugged in Sim68K and then run on the Mega-68000 Computer System without change.

The new software release is tutor_v1.3.03_27c4096r.bin and it can be downloaded from the website here:

Memory-2/Tutor

01/07/2020

Information on overclocking and a recommended backplane slot configuration added to the website - see the Backplane-2 page for details.

29/06/2020

Instructions on how to generate Custom ROM's for the Memory-2 Board added to the website.

28/06/2020

The new ACRTC Board PCB's arrived from China. One of the PCB's has now been assembled and tested.

Lowering the value of the DTACK signal pull-up resistor on the 68000 CPU Board from 10K to 1K2 was necessary to fix some reliability issues when running the ACRTC Board on the newer Backplane-2. With this simple modification, processor clock speeds greater than 8 MHz are now possible.

A 68000 CPU Board fitted with a MC68HC000P16 processor clocked at 16 MHz has been operating without problems for some time now on the new 7 slot Backplane-2.

18/06/2020

ACRTC Board PCB design is complete and an image of the PCB layout has been added to the website. PCB's are on order and testing will begin once the boards are received.

23/05/2020

The new Backplane-2 PCB's arrived from China. One of the PCB's has been populated with 7x 64W A/C sockets and testing is now in progress. There are no plans to test with 96W ABC sockets until plug-in boards exist that make use of the extra bus capacity.

The ACRTC Board video output will be colour limited to a foreground colour and a background colour. The foreground colour will be white or green (set by a board jumper) and the background colour will be black. 16 colour mode will require an expansion module that will attach to the rear of the ACRTC Board. The schematic has been updated on the website and a bill of materials added. Work has started on the ACRTC Board PCB layout.

14/05/2020

The ACRTC diagnostics software has been updated. You can now modify ACRTC register values and a register read/write test has been added. The read/write test can be used to test the ACRTC's 68000 bus interface. To obtain these new features download the latest ACRTC diagnostics software - now available on the website.

03/05/2020

Documents, Datasheets, and Quick Tips pages added to the website.

01/05/2020

Been working on something a little different - a new backplane. The old backplane with only 4 slots severely limits the expansion capability of any Mega-68000 Computer System. Currently three slots are always required for a working system leaving only one slot free. Backplane-2 is a new 7 slot backplane. The schematic, PCB design, and bill of materials are all available on the website. PCB's are on order and testing will begin once the boards are received.

18/04/2020

ACRTC diagnostics software and a procedure for testing the board are now available on the website.

15/04/2020

ACRTC Protoboard hardware upgrade 2 completed. Additional DRAM added. The frame buffer now consists of four 256K x 4 DRAM chips.

14/04/2020

The frame buffer issue has now been resolved. The ACRTC Protoboard is now performing as expected in 640x480 2 Colour Single Access Mode.

08/04/2020

The latest ACRTC Protoboard schematic can now be downloaded from the website.

05/04/2020

I now have software written that can load, view, and modify ACRTC registers. I also have software that can directly exercise the frame buffer memory. A problem with the frame buffer has been identified and is currently under investigation.

31/03/2020

ACRTC Protoboard hardware upgrade completed. Added a 63487 MIVAC chip and two 256K x 4 DRAM chips to form a video frame buffer. A DE-15 monitor interface has also been added to allow the connection of a standard VGA monitor.

04/03/2020

The 63484 ACRTC Protoboard is up and running. It has no video yet, but all the ACRTC registers are readable and writeable. It took a while to figure out the ACRTC timing parameters for a 640x480 60Hz refresh VGA display, but now that's done, the ACRTC reliably outputs HSYNC and VSYNC signals when the ACRTC registers are loaded with the VGA parameters.

26/02/2020

Started work today on a new 63484 ACRTC based Graphics Board. Hoping to add a board capable of driving a standard VGA monitor to the list of boards available for the Mega-68000 Computer System. The 63484 ACRTC chip has some impressive features including hardware accelerated drawing functions.

24/02/2020

2MB RAM upgrade completed. The system now boots from a Memory-2 Board. The larger single on-board ROM contains both the TUTOR Monitor and BASIC.