A 6809 Single Board Computer

A place to discuss everything Dragon related that doesn't fall into the other categories.
noggin32
Posts: 7
Joined: Thu Dec 14, 2017 8:36 pm

Re: A 6809 Single Board Computer

Post by noggin32 » Fri Jan 24, 2020 8:06 pm

Remember I had to make my own from resistors :D
Not an expert but I think the 'dot' is pin 1.

Did you really buy 100? I only bought 30!

jmdlcar
Posts: 21
Joined: Tue Nov 12, 2019 8:08 pm

Re: A 6809 Single Board Computer

Post by jmdlcar » Fri Jan 24, 2020 8:29 pm

It was buy 100 or 200 I do have a lot but if someone might need some I could sell them.

jmdlcar
Posts: 21
Joined: Tue Nov 12, 2019 8:08 pm

Re: A 6809 Single Board Computer

Post by jmdlcar » Tue Feb 04, 2020 7:14 pm

I want to try or want to use rom cartridges threw the expansion header but there is no CART/. I like to know how to add it? Anyone have any idea?

Here is the schematic.
Image

sorchard
Posts: 419
Joined: Sat Jun 07, 2014 9:43 pm
Location: Norwich UK

Re: A 6809 Single Board Computer

Post by sorchard » Wed Feb 05, 2020 2:04 pm

A bit of extra decoding is required to put a cartridge ROM into the unused part of the memory map at 8000-9fff

The easiest way I can see is by feeding E, RW, A15, A14 & A13 into an LS138 decoder to generate the OE signal for the ROM. You can even get a couple of bonus signals that are active during writes to 8000 and c000 if you wanted for example to add a couple of registers for general outputs.

e.g.

Code: Select all

LS138 inputs:
pin 1 (A)     R/W
pin 2 (B)     A14
pin 3 (C)     A15
pin 4 (nG2A)  0V
pin 5 (nG2B)  A13
pin 6 (G1)    E

LS138 outputs (active low):
pin 11 (Y4)  Write 8000-9fff
pin 10 (Y5)  Read 8000-9fff (8K Cartridge ROM OE)
pin 9  (Y6)  Write c000-dfff
Stew

jmdlcar
Posts: 21
Joined: Tue Nov 12, 2019 8:08 pm

Re: A 6809 Single Board Computer

Post by jmdlcar » Wed Feb 05, 2020 9:14 pm

I'm not not sure if I understand. I know the input pin 1 (A) R/W, pin 2 (B) A14, pin 3 (C) A15, pin 4 (nG2A) 0V, pin 5 (nG2B) A13 and pin 6 (G1) E but the output I don't understand what do they hook up to?

UPDATE:

I want to play dungeons of daggorath threw the expansion header but there is no CART/.

sorchard
Posts: 419
Joined: Sat Jun 07, 2014 9:43 pm
Location: Norwich UK

Re: A 6809 Single Board Computer

Post by sorchard » Thu Feb 06, 2020 9:42 am

Y5 is the output you want to use as the missing /CART. This would go to the output enable and/or chip select of the external ROM. The other LS138 outputs are not necessary, but possibly useful for other projects.

Regarding playing Dungeons of Daggorath, if you're talking about the original game on cart, then it sounds like there may be a fair amount of work ahead of you, to modify the source code to work with the address map and I/O of the SBC, plus rework the graphics to a terminal-friendly format. It would be pretty cool if you did though!
Stew

jmdlcar
Posts: 21
Joined: Tue Nov 12, 2019 8:08 pm

Re: A 6809 Single Board Computer

Post by jmdlcar » Thu Feb 06, 2020 1:15 pm

I think I understand now. I will need to add 74LS138 to the circuit to get /CART and then add Y5 to expansion header.

sorchard Thank you very much.

jmdlcar
Posts: 21
Joined: Tue Nov 12, 2019 8:08 pm

Re: A 6809 Single Board Computer

Post by jmdlcar » Fri Feb 07, 2020 3:53 am

I receive a e-Mail today and JLCPCB is shipping my PCB Board I order shipper is DHL so maybe next week.

jmdlcar
Posts: 21
Joined: Tue Nov 12, 2019 8:08 pm

Re: A 6809 Single Board Computer

Post by jmdlcar » Tue Feb 18, 2020 7:25 am

@ noggin32 or anyone,

What program do I need to view it on a Laptop threw the RS232 USB?

noggin32
Posts: 7
Joined: Thu Dec 14, 2017 8:36 pm

Re: A 6809 Single Board Computer

Post by noggin32 » Sun Feb 23, 2020 6:36 pm

You can use any Terminal software. I used Putty. Old versions of Windows had HyperTerm built in.
Baud=115200

It's a little unreliable as there is no handshaking. Fine for typing but if you paste a basic program it will have errors.

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