Re: P21 Experience
On Thu, 16 Feb 1995, Dave Lowry wrote:
> Now that P21 has been out for several months, could some of the ealrly
> adopters post some of their experiences?
> Is Ting's evaluation board without SRAM useful?
I received the board well before Xmass, intending to go on a vacation and
work on a pet project. My trip was canceled due to other reasons, but
nevertheless I did put some time in trying to use the board.
It's I/O is revolving around a 20-pin jumper connector. It is relatively easy
to make the board produce a video signal. I wrapped GND and +Vcc and VidOut
to the appropriate pins, soldered an RCA video jack, connected a Radio Shack
$13 wall-plug power supply, set it on +6V and the board produced the opening
screen of OK on my TV set.
The picture was relatively stable, but there was some discernible very
low frequency modulation of the colors, travelling vertically in a
horizontal strip. Dr. Ting attributed this to the power supply picking up
variations from the AC.
The hard part, which I never came to succeding in, was connecting the inputs
to the board. Originally, it was to be driven from 7 bush-button keys. Since
I didn't have them around at home, I tried to find and buy a device, that had
them in a convinient package, but didn't succeed. I wish the board had come
with an easy connection to a standard gamepad, availbale at the video game
stores.
Then I had Jeff Fox'es eFORTH. It came on a disk, with utilities to produce a
binary image, ready to burn to EPROM. Since I have neither an EPROM, nor a
burner, I didn't get to testing it. It promisses an easier hook up, though.
It is supposed to be connected to an ASCII terminal, which is much easier to
find, but it still comes without the necessary cables and connectors.
Dr. Ting's installation comes with a disk, but in order to use it, one has to
install FPC. With a home internet account, it is at least a two-hour job to
archie and find it, ftp it, unpack it in the right directories and install
it.
I think Jeff's disk is ready to run out of the box.
> How is the video quality?
As I said, I haven't connected it to a stable power supply to check it.
> What voltage exactly does it want ti run at?
From the wall-plug Radio Shack PS it ran on 6V and 7.5V, and din't run at
4.5V. I din't connect the RESET line, though, maybe it just didn't reset
properly. Or may be the video signal didn't have the necessary magnitute -- I
didn't invetigate. I din't try it at 9V.
> Is this a great chip
> or just a curiousity?
To me it is still a curiosity with the promisse of a great chip. Since I
don't have too much time to put in right now, I would have expected something
ready to plug and play out of the box. I had to buy a power supply, solder, a
soldering iron, wire, a wrapper, some jacks, and at the end I didn't manage
to do anything with it. I don't mind hacking some hardware from time to time,
but my primary strength is software, and the board was not ready for this.
For later boards, I would recommend that they come with cables and connectors
for two or three popular setups -- a PC, a standalone keyboard, and a
gamepad/joystick. I wouldn't mind paying a few bucks extra to save days in
the process of starting to use it.
I am still committed to getting it work some day, so I'm interested in
hearing others' stories.
--
Penio Penev <Penev@venezia.Rockefeller.edu> 1-212-327-7423
