cr1901 wrote:
Hello all,
I've been batting around joining for about a month, and I have a question that doesn't seem adequately answered in the forum for me to join. But that's in another thread I'll make later today.
Welcome to our 6502/65C02/65C816/??? world.
Quote:
I find the '816 an interesting chip, in design, features, and assembly language- and I like how the programmers manual is very in depth. However, it seems it's features tend to be underutilized (ABORT signal, VDA/VDP for cache)...
They appear to be underutilized, although there may be embedded applications we don't know about that do use the more arcane inputs and signals. I make use of VDA and VPA in my POC unit. ABORT is tricky—timing is exact and unforgiving. Also, ABORT doesn't actually abort instructions, it just discards the computational results. Some of the other signals, e.g., E, MX and MLB, have very limited value in the majority of applications.
Quote:
Recently, I got my amateur radio license, and have been batting around making a hardware solution for at least the digital transfer modes- a small embedded computer. I feel I could possibly put the '816 to good use in a small design for basic digital transfer modes attached to the input to an amplifier. I've done some (flawed) sketches, but so far everything I've thought of for this design is described
here.
I read your post:
Quote:
- Support cycle-steal DMA implementation using either a dedicated DMA controller or coprocessor (65C02) to maximize bus bandwidth.
Implementing 65C816-compatible DMA is something that I've chewed on ever since I got SCSI working on my POC unit—having DMA would produce a substantial performance boost. I've considered implementation by using the 65C02 as a co-processor and by making a CPLD act as a DMAC. I've abandoned the cp-processor idea, as I don't think it will produce enough of a performance gain to justify the required hardware hoop-jumping.
Although I note your aversion to using programmable logic, it really is the logical(!) path to achieving maximum performance. However, starting out using discrete logic is the best way to learn how to build a stable-running unit.
Quote:
- Use only parts which are still produced as of 2014
There is no shortage of compatible devices that are current production. The 65C816 and its support devices (65C21, 65C22, etc.) are readily available from major electronics sources. Ditto for 74-series logic, although older logic families are disappearing. I used 74AC logic in my POC unit, in PDIP.
Quote:
This forum seems pretty relaxed and accommodating to new users- and I hear you can use new younger members
.
Hey, watch it! Just because I'm old, feeble, on life support and...uh...a big, dumb dinosaur doesn't mean you young whippersnappers can just barge right on in here and take over.
Actually, I and other other members tend to be somewhat amazed about how much attention the 6502 family continues to get from new generations of computer hobbyists. So welcome and please start a topic about your ham radio project.