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John Craker reports :
It took about 1/2 hour of careful programming just to get the video port
to work, then you had almost no RAM left to program in ! I think it was
that machine that scared me off of programming, and led me into a life of
being in hardware. :)
Dwight Tuinstra said in alt.folklore.computers newsgroup :
It had a miniature interpreted language all written out in hex code in one
of the manuals; you had to type it in and then store it to tape
(fortunately, someone in the town had already done so, and I just borrowed
the tape). My fa vorite
program (that ran over the interpreter) was called
"Kaleidoscope"; it drew patterns much like today's screen
savers. I hacked into it for the computer store so it would pause at
random intervals to choose a random advertising display screen, then
resume. I recall hand-disassembling the interpreter code, and starting in
on the monitor, before other things in life distracted me. Learned a lot.
The manuals also had an excellent section on subroutine call-and-return
techniques as part of an overall (quite decent) manual on programmingthe
1802.
William Lindley adds:
The original ELF computer was designed with just 256 bytes of memory, so
ELF programs frequently ignored the upper 8 bits in the Program Counter
register -- which is why they had to be modified to run on the VIP.
Several companies offered "Super ELF" designs which were similar
to the VIP.
The CHIP-8 language was not built-in; it ran from RAM, and you had to type
it in from the supplied manual the first time, and then record it onto
tape as a prologue for each of your programs.
The VIPER magazine, edited in later years by Tom Swan (who later would go
on to write a series of popular books on C++), each month published
hardware and software projects.
Misc information about RCA computers
by Richard Dienstknecht:
About the video resolution, The CDP 1861 fetches eight bytes per row, so
64 is the horizontal resolution and a fixed value.
128 is the maximum vertical resolution. Since video data was passed to the
1861 with an interrupt routine this vertical resolution could be lowered
by passing the same row several times. Usually this resulted in
resolutions like 64 x 16 (popular on single board Elf computers with only
256 bytes (!) RAM since this uses only 128 bytes for video memory).
Typically 64 x 32 (256 bytes video RAM) or 64 x 64 (512 bytes video RAM)
were used.
Only 64 x 32 produces huge, but fairly square pixels. All other modes are
somewhat limited in use by the odd aspect ratios of the pixels. That and
the video memory of one whole kilobyte made the maximum resolution of 64 x
128 fairly useless. The pixels were extremely wide and flat.
The Super Elf and Elf II were improved versions of the original Elf, but
software was without or with only minor adaptations (I/O ports)
interchangable. In fact, Quest Electronics offered hardware for the Elf
II, which was made by Netronics. Compatibility ended of course when some
uncommon pieces of hardware, especially graphic cards, were added.
The Super Elf had additional status LEDs and Address displays while the
Elf II was built more for expandibility (5 bus slots for expansion cards).
Even if it's not called 'Elf', the RCA VIP also belongs into this group.
All Elf computer shared a common design, so they should be considered
different incarnations of the same computer, and not as different
machines. Optically they don't look alike at all.
Robert Donald (USA) recalls:
I purchased my system during my college days and used this system to learn about how processors, software and the supporting hardware actually work.
While I was looking for work after graduation, I designed and built a Bus Monitor board (displayed the address and data lines, against various processor states), a single step board (which provided for true debugging of machine code) and several other peripheral display and memory expansion boards.
Fabulous learning tool... much of the foundation of what I know today started with this little machine.
I still have all the hardware and often think of powering it up after all these years - but haven't as of yet!
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