Call for final Elf99 design input

From: Chuck McManis <cmcmanis_at_mcmanis.com>
Date: Tue Nov 24 16:16:25 1998

Is the graphics chip right out? That was the most fun part of my super-elf.
I still have the monochrome display I used with it...
--Chuck

At 02:47 PM 11/24/98 -0500, you wrote:
>
>I am cranking along with the capture of the Elf99 design (on OrCAD for DOS,
>a 10-year-old program, no less). I wanted to throw out what I have
>descided on and ask for suggestions on what is not set in stone.
>
> The Elf99 will consist of the following:
>
> o Double-sided PCB, approx 6"x8" (same as the Quest Elf design)
>
> o CDP1802 processor with discrete CMOS support logic.
>
> o Socket for 6116/62256 SRAM
>
> o EPROM enable switch.
>
> o Circuit to ghost EPROM at $0000 until first address access at $8000
>
> o Socket for 2764/27256 EPROM.
>
> o Dual TIL 311 hex latching displays accessible as output port 4
> when in run mode.
>
> o 8 toggle switches for data entry in load mode, accessible as
> input port 4 when in run mode.
>
> o Seperate LOAD and RUN switches to permit the user to set the
> computer to "reset", "wait", "load" and "run" modes.
>
> o A memory protect switch to allow reviewing the contents of
> RAM without changing it.
>
> o An "Enter" pushbutton to DMA the switch register into RAM when in
> load mode, that can be sensed on EF4 when in run mode.
>
> Options under consideration:
>
> o Sockets for two 1822/2101 256x4 SRAMs, the same style used by
> the original Elf.
>
> o A 1851 programmable input/output port -or- a pair of 4508 latches
> wired as one input and one output port (as in the COSMAC VIP)
>
> o A 1854 UART
>
> o A protoyping area of .1" spaced plated-through holes, nominally
> a few inches long by one or two inches wide.
>
> o Either a dual 4042 address latch or a single 4508 latch. One or
> the other is needed to implement more than 256 bytes of memory.
> This would be optional in a machine built with dual-256x4 SRAMs.
>
> o A pre-programmed 27256 with a "library" of simple programs
> (Accessible by enabling the ROM switch, setting the program
> number in the switch register, then setting the control switches
> to "run").
>
>Did I miss anything? Any other suggestions? I will not be including space
>for an 1861 because I have been entirely unable to locate a source.
>
>Do we still have any interested parties? I have saved the addresses of
>all who have initially expressed interest, so I only really need to know if
>these features are attracting people or putting them off.
>
>-ethan
Received on Tue Nov 24 1998 - 16:16:25 GMT