6809 Angel

[Editor]

Here I have made a sector dump from a USB stick attached to a ch376.

This is pretty impressive!

More recently I've been working on about 4 projects concurrently, 2 at the PCB manufacturing stage, and 1 that I'm currently PCB routing.
Unfortunately, commitments are also ramping-up for the "end of year" period, which are also competing for my time. But, hopefully I'll get some more of my projects completed, before this year is out!

Based on your posts, you've achieved a lot in recent months! Well done, and keep up the impressive work! (well, at least until end of year commitments start to take over your free time as well!).

[djrm]

My 6309 MECB Forth79 system has acquired a new home in a repurposed 19 inch eurocard rack cabinet, complete with Vero 5/24 power supply.
I'm using my backplane extension, I shall make some plates to hold the system switches and connectors and maybee a small display too. David

[djrm]

This is a simplified AIM-65 recreation using a 6522, 6520, and 6532 chips on a prototype board running modified AIM-65 software driving some original parts I'm testing. The machine code monitor is working ok, but not yet the BASIC. Patching the I/O map has been giving me problems and I think the 6532 is faulty too but its taking shape now. David

[djrm]

A brief note about the TTL to RS232 adaptor I have used to connect the MECB 6850 to my Wyse terminal. The adaptor needs a 5v DC supply, this has been obtained by feeding 5v to the otherwise unused pin 3 of the board connector J3. On my board I feed it through a small 22 ohm resistor soldered on the back of the motorola i/o card to limit the current in case of mishap.

The adaptor shown has a PCB fault on it which makes the handshake line CTS unusable, the photo shows the correction I made to the board with a small wire swapping two pins on the MAX3232. The 9 pin D plug is mates with the socket on the terminal without problem. To connect to a PC a null modem female to female with RTS/CRS and TxD/RxD swapped is needed.

Other styles of RS232 adapter exist without this fault though many do not have any handshake lines, these were quite inexpensive - I wonder why?...
hth, David

[Editor]

A brief note about the TTL to RS232 adaptor I have used to connect the MECB 6850 to my Wyse terminal. The adaptor needs a 5v DC supply, this has been obtained by feeding 5v to the otherwise unused pin 3 of the board connector J3. On my board I feed it through a small 22 ohm resistor soldered on the back of the motorola i/o card to limit the current in case of mishap.

Good idea, in terms of the needed 5V supply for the TTL to RS232 adapter.

I left the 5V off the serial connector (pin 3), as I was concerned that someone might inadvertently connect it to the (now) more commonly used USB to TTL serial adapter from their PC (which sources the 5V). The other option, for the MECB board design, would have been to add schottky diode protection, but (at the time), I instead decided the 5V connection generally wasn’t necessary.

[djrm]

Ive been spending time with the AIM-65 video cards, I have one working on an actual AIM-65 but now I have one working on a 6809 MECB computer running Assist09 for starters. Eventually the plan is to get Flex running on the MECB, this will entail getting memory management working which should be fun.

I've joined a flex user group and found a 6845 driver for flex and have modified this to work with Assist09. In the process I learnt a bit more about driving the 6845 chip. In particular I found one of the settings was not optimal in the setup for the 6502. I have a few different varieties of 6845, one, a GS6845S I couldn't get to work on the 6502 board, but it works quite well on the 6809. I must have a closer look at the bus timings on the two systems so see if I can identify the problem.

My simple PC video capture card does not work very well on the 6845 composite output, but the telly I'm using shows a nice crisp picture. I shall try and patch the display into my Forth system. One reason for getting this board is because it should be able to display a 16x64 forth screen editor.

Here is a photo of my Assist09 with disassembler output on the 6845 feeding a telly.