14 Mar
2013
14 Mar
'13
5:52 p.m.
(I had the pinout)
Sure, but others might not have...
Another list member (Rob) found the ref in a 1970/1 TI book.
Apparently, it's part of a character generator series, the 4103 is
the off-the-shelf standard ASCII version in the series.
Right...
As Rob pointed out, the 9830 one must be special order to HP though,
to obtain the lazy-T cursor, unless there's some alternative tortured
As I seaid, the data sheet i have doesn't give the font pattern, so I
didn't know i the 'lazy T' was a standard cahracter or not.
way they're injecting the T into the display
scanning that I'm not
seeing.
There isn't, AFAIK.
The HP9830 display is ratehr differnet to that in the other 9800 machiens
in that it is partly hardware driven.
The CPU has a 16 bit shift regiater used for I/O (it's on the 09810-66511
PCB). When drivign the dispaly, al l16 bits are used for data, a separate
circuit genrates a strobe signal. Now, the HP9830 has a 32 character
display and the hardare dispalys 2 characters simultaneously, 16
locations apart (so 0 and 16, 1 and 17, etc). The 16 bits are used as
follows :
6 bits for the code of one of the characters (remember upper case only,
so 64 characters is enough)
6 bits for the code of the other chracter
4 bits to select where to put them (location of theleft hand character).
But the system firmware has to scan all 16 pairs of locations, otuputting
the right character codes.
There is, AFAIK, no way to dispaly anything otehr tha nthe patterns in
the chracter genrator.
One other trap fo the unwary. The display is physically a 32 chracter 5*7
dot matrix unit. That is, 160 columns by 7 rows. _Electrically_ it's
wired as 0 columns by 28 rows, this saves driver stages. Therefore
drfectinve row drivers stages will affect only part of a dot row and
defective column drivers will affect 4 colunmns on the display.
Yes, the-1-of-5 select did suggest it was an intended character
generator (although in principle it could be a straight ROM depending
upon how much ROM space one is willing to waste, although (back on
the other hand) being that wasteful would have been pushing it for
ROM sizes of the period, and the 9830 has the binary encoding right
there anyways).
At the time yo did not wast 27/32 of your ROM capactiy. You might now,m
if you had to repalce the chracter gernatore, but back then you used
verybit you had. Yo ucertianly didn't add a decoder to waste ROM space ;-)
The earlier data only indicates MOS levels (for TMS 4103 JC/NC).
Interesting. My databook cleaerly says 'fully TTL compatible' whih I take
to mean 5V levels (and not that you can drive it with open-collector 74xx
parts pulled up to 12V).
Whether the later versions could stand 12V on the inputs I don't know.
-tony