[Coco] Considering new HD6309E based board

iggybeans at comcast.net iggybeans at comcast.net
Sun Oct 6 14:36:38 EDT 2013


After playing around with an 130XE equipped with Boisy's Liber809 board, I've decided I want something faster. 
I've ordered eleven each of the following. 

Hitachi HD6309E processors. 
WDC 65C22 versatile interface adapters. 
16550 UARTS. 
Yamaha V9958 VDPs . 

I'm still trying to decide on the static ram for the processor and video . 
And I can't make up my mind as to whether to use a Yamaha YM2149F sound chip or something a little more modern ( very slightly more modern like a YM2612 or a YMF262 - there is virtually no price difference in these and the last probably is probably the best option). 

Also there are a lot of 74LS chips needed that I haven't sourced yet. 

The initial work is being protyped on ISA breadboards installed in an Amiga 2000 (purely for convenience, I'm not following ISA signal convention, its just nice to have a ready form and a power supply). 

The prototype will only have 64K of RAM, but my goal is to modify that to at least 512K . 

I just don't feel like addressing a memory management scheme yet. 

MC68B29 chips are still available, but I've never really cared for that design (I've had one on hand since before the Coco3 was introduced, Motorola sent me XC samples when I worked at Delmar Co.). 

I've also looked at the 68B44 DMA controller, but I think faster solutions could be designed with more modern components (the transfer rate nly the 68B44 is surprisingly low). 

So, basically, we're looking at something like an MSX2 system, but with a 6309 processor. 

I'm keeping a couple for mods (like swapping in a V9990 VDP) , but I'd like to give one to Boisy and will offer any additional units to anybody interested. 

Keep in mind, these will have almost no Color Computer compatibility. 

I just wanted something with a higher clock speed (between 3.58 and 4MHz) a more colorful display, and better sound (and Boisy's project has me fixated on sprites and video display processor that actually has an instruction set - the GIME is a bit primitive). 

I was going to keep quiet about this until I was a little further along, but after ordering several hundred dollars worth of parts, I 'm just a little psyched. 

Besides, I could use some outside input. 

I can readily change the breadboards, but once I get to a circuit board design (I have the software for that) then the design will be static (except for any corrections I'll need to make - I've had to cut traces and add wires to devices in the past, I'm not expecting to have it perfect on the first batch). 

I also wanted everyone's input on several other ideas I'll mention as this progresses. 

But the first ideas is this, how about more than one 63C09E (two, four, who knows)? 

So, sorry for the long winded message. 

Now, your inputs? 

Jim 







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