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 Post subject: TS2 SBC by Jeff Tranter.
PostPosted: Wed Aug 07, 2019 2:42 pm 

Joined: Wed Aug 07, 2019 2:04 pm
Posts: 2
Just wanted to introduce myself and describe my plans, which may or may not happen (-=

My Name is John and I've been interested in the MC68000 since I first encountered it at an electronics expo in LA when it was first announced.
My present computer at the time was an Original TRaSh-80 I got for me 14th birthday. Unfortunately, I never got a chance to use any of the 68000 based computers that came out due to bad timing and poor finances. Although I used a number of Windows-based computers in the Navy, the first Computer I was able to buy for home use was a Dual Pentium 2. But I've always wanted to get back to the 68000 family. I was especially impressed at the time that Motorola decided to drop ALL backwards compatibility in favour of a more powerful 32-bit Instruction set. Too bad IBM and Intel dominated the market with their 8-bit compatible 32 bit processors.

But getting back to my plans.
About a year ago, I discovered that Jeff Tranter had designed a 68000 based Single Board Computer based on a design from an old textbook. http://jefftranter.blogspot.com/search/label/68000

After vacillating for just over a year, I finally decided to order a circuit board and parts and build my own.
I've also looked over his KiCAD files and have started my own improvements on his design. https://github.com/jefftranter/68000/tr ... r/TS2/v2.1

He used 4 X 6264 RAM and 4 X 28C64 EEPROMs for memory. But these 8k chips are nearly pin-compatible with 32k chips.
So with very little modifications to his addressing logic, I'm pretty sure I can drop in the 32k chips instead to get 4X the memory on the same board.
I even updated his KiCAD files so I could order boards already for the increased memory layout.
His system runs TUTOR 1.3 natively, and he has also ported a few different versions of Forth and BASIC as well.
What he doesn't have is any type of expansion bus or external storage, so I don't know how something like CP/M could be added without some major re-design.

So, at the moment, I have a set of 5 original PCBs and parts arriving via slow-boat from Hong Kong.
My first step is to build an all-original board with the 8k chips and make sure everything works for me.
Next I plan to modify a spare PCB to allow the use of the 32k chips instead to make sure my modifications work the way I think they will.
I have also thought about seeing if I can make the EEPROMs and RAMs interchangeable on the board, since TUTOR and BASIC should fit in just one pair of 32k EEPROMs and that would allow more RAM on the board.

But what I'm not sure of is would this board be easily modified for running something like CP/M? I'd really like to have an Amiga-type system, but I barely know how the serial terminal works. I wouldn't know where to begin to add color graphics display capabilities.

And now this rant is about 3 times as long as I intended it.


John Gay

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