HC11 Transistor Architecture

You want to build an HC11 using resistor-transistor logic?

I suppose it's possible -- you could build one from relays if you had enough of them, but why on earth would one attempt such a thing?

I believe Vijay is referring to Register Transfer Level representation of the HC11. It's essentially a programmatic method of simulation.

-- Noel Henson

Ah. I thought it must be something other than resistor-transistor logic, but all Google came up with was the German TV netowrk. I probably should have thrown in a few more keywords.

Is RTL synthesizable, or is it just for simulation?

RTL isn't a specific language, it's a level of abstraction. I'm not sure of a formal definition, but in general it involves defining registers and the data paths and conbinatorial logic that links them.

RTL code would most commonly be written in Verilog or VHDL, though other suitable languages exist. Normally an RTL design should be sythesizable; the non-synthesizable constructs in the HDLs generally aren't appropriate for an RTL design. An obvious example would be a VHDL statement such as "wait 5 ns"; such a statement isn't consistent with RTL.

Eric

Thanks. Got it. I thought it was a specific language, but couldn't find anything concrete about it.

Grant:

Only the old duffers in the group would remember RTL. (I be one). Fairchild was the supplier I remember best. The venerable 723/923 flip flop and the 900 buffers. The packages were great little blobs of epoxy similar to the transistors of the day. We, of course, felt empowered by such technology.

Blakely

Grant Edwards wrote:

I must admit that I never actually used RTL (but it was still covered briefly when I was in school). One of the first places I worked still had a few drawers of RTL parts for maintenance purposes.

My first IC's - MC 700 series, NOR logic with severely limited fan-in and fan-out. Year 1968 or 1969.

Wasn't Fairchild the only supplier?

They were also great little hand warmers on cold days.

It beat discrete components!

No, there were many suppliers. Motorola and TI also made RTL. I think Signetics did as well, but I'm not 100% certain.

Motorola may have been the vendor to most recently discontinue RTL; some of the RTL parts were still available from them in the late 1980s.

Eric

Look for the "Cycle-by-Cycle Bus Activity" description in the programmers reference or datasheet. Digging on the bookshelf, the old (1985) Programmer's Manual MC68HC11PM/AD gives a lot more information on what happens on a cycle by cycle basis than the later Reference Manual (which puts this on the page for each instruction instead of a seperate section).

Getting a more detailed block diagram (than shows up in the later 68HC11 documents) of the CPU section out of a 6800 or 6801 may add some insight.

Mark Zenier snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)