On Tue, 20 Jul 2004 06:43:51 -0700
"Robert Armstrong" <bob_at_jfcl.com> wrote:
> Hi Guys,
>
> I built the SBC6120 (a PDP-8/E clone based on the HD6120 chip,
> http://sbc6120.SpareTimeGizmos.com) but a bunch of the people in the
> SBC6120 group also have IM6100 chips, sometimes tubes of 'em. We've
> been having a little discussion about what to do with them on the
> SBC6120 mailing list, and when I heard about this thread I thought I'd
> open up the discussion.
>
> To start off, I can think of a couple of ways to go with the 6100:
>
> * Another machine with a real lights and switches front panel (a
> simplified SBC6120+FP6120). To save money we'd have to use cheap
> metal handle (e.g. "Altair style") toggle switches instead of paddle
> switches. There'd be no fancy silk screened faceplate like the SBC6120
> - if we had any faceplate, it'd probably be some laser printed
> graphics sandwiched between two clear sheets of plastic (again,
> "Altair style"!). You might even have to drill your own faceplate -
> STG might not offer a precut one.
>
I would 'vote' for the above. What I am looking at building is
something to toggle in machine code. I haven't bootstrapped a PDP-8
since the early 80's and the level of system I would prefer to make is a
row-of LEDs type system to run very simple code on. Maybe I should get
a real PDP-8 sometime, but it would take up a lot of space.
I have aprox. 100 6100 chips in original tubes, and have had the idea of
designing some sort of a partial 'kit' for sale. The SBC6120 is
definitely the 'practical' direction for a kit project to go in, a
row-of-LED and switch bank project would be more of a novelty
flashy-desk-toy kind of thing.
> * An Intercept Jr clone, including the octal keypad and octal
> display.
> Maybe even powered by 3 or 4 "D" cells like the original Intercept Jr.
>
>
> * A single board computer with an onboard EPROM to talk to a
> terminal
> using something like LSI-11 CODT. No lights, no switches. Basically
> a simplified (and less capable) SBC6120.
The SBC6120 fills this role admirably.
>
> All of the options would have 4K of memory and a console terminal
> interface. They'd run FOCAL-69, DECUS CHESS, or any other 4K paper
> tape software. No mass storage and no OS/8.
>
The idea of running FOCAL code has some appeal to me. I probably have a
homework assignment or two from 1979 filed away somewhere that is FOCAL
code (yes, the Intro Computer Programming Course I took in undergraduate
college in 1979 used FORTRAN and FOCAL as the target languages).
With only a 4K memory map, 'Mass storage' would amount to battery backed
up CMOS memory, sort of psuedo-core I suppose.
The 6100 processor is one of the simplest chips out there to casually
'breadboard' together into a primative computer. It has probably the
most relaxed clocking requirement of any microprocessor ever (certainly
the most relaxed of anything realistically available today). The 12 bit
data path is the most 'difficult' factor involved, since all the
garden-variety micros that common peripheral chips and memory are built
around have an 8 bit path.
Received on Tue Jul 20 2004 - 23:06:36 BST