23 Apr
2019
23 Apr
'19
6:35 p.m.
When I saw this thread I thought 'Oh, I have a 925!' Which was working last time
(years ago.)
But wouldn't you know. When I checked, it's a Televideo 924. Off by one.
But perhaps the character ROM content is the same?
Anyway I will see if it still works, and secure all the ROM images. Today.
I have the user manuals, but does anyone have schematics for the 925 & 924?
Guy
At 09:38 AM 23/04/2019 -0700, you wrote:
On Tue, Apr 23, 2019 at 8:25 AM Patrick Finnegan
<pat at vax11.net> wrote:
On Tue, Apr 23, 2019 at 11:02 AM Jon Elson via
cctalk <
cctalk at classiccmp.org> wrote:
The thought had crossed my mind, but only as a last resort. I'm not
entirely sure what the internal fault is, but the end result is two rows of
every character have all bits stuck "on." I've verified that the ROM
addressing is correct and that there's nothing on the output side causing
this behavior. Patrick, thanks very much for offering to read the ROM!
- Josh
Is the ROM totally bad, or just losing a few bits
here and
there? If the latter, you could probably read it out, figure
out how the rows, columns and characters are mapped, and fix it.
Considering that 925s are really common, and a replacement EPROM should be
easy to source and program, this sounds like an overly difficult approach
that will yield something different than what he wants.
Pat
23 Apr
23 Apr
7:34 p.m.
On 4/23/19 3:35 PM, Guy Dunphy via cctalk wrote:
When I saw this thread I thought 'Oh, I have a
925!' Which was working last time (years ago.)
But wouldn't you know. When I checked, it's a Televideo 924. Off by one.
But perhaps the character ROM content is the same?
Anyway I will see if it still works, and secure all the ROM images. Today.
I have the user manuals, but does anyone have schematics for the 925 & 924?
I have maint manuals for the 925.
Some photos of the boards and dumps of the keyboard firmware and controller
would be nice to add to bitsavers, since I've not come across one.
24 Apr
24 Apr
8:39 a.m.
At 04:34 PM 23/04/2019 -0700, you wrote:
On 4/23/19 3:35 PM, Guy Dunphy via cctalk wrote:
[my Televideo 924]
I have maint manuals for the 925.
Some photos of the boards and dumps of the keyboard firmware and controller
would be nice to add to bitsavers, since I've not come across one.
See pics and ROM images at http://everist.org/pics/televideo_924/
I haven't dumped the chargen chip yet, because I don't know what it is, and
suspect it's more complex than just a ROM.
24 pin character gen ROM/? at U10 is marked:
VTi (logo)
350 RN 118
2333-5006
8000142
(c)TELEVIDEO 1983
KOREA-AE
See http://everist.org/pics/televideo_924/20190424_3338_chargen.jpg
The keyboard controller is an 8049. Firmware not readable.
Guy
8:48 a.m.
On April 24, 2019 at 7:39 AM Guy Dunphy via cctalk
<cctalk at classiccmp.org> wrote:
I haven't dumped the chargen chip yet, because I
don't know what it is, and suspect it's more complex than just a ROM.
24 pin character gen ROM/? at U10 is marked:
VTi (logo)
350 RN 118
2333-5006
8000142
(c)TELEVIDEO 1983
KOREA-AE
Guy
Likely an MOS Tech 2333 ROM chip.
http://www.bitsavers.org/components/mosTechnology/_dataBooks/1982_MOS_Techn…
See page 2-145
Will
"A designer knows he has achieved perfection not when there is nothing left to add,
but when there is nothing left to take away." --? Antoine de Saint-Exupery
"The names of global variables should start with? ? // "? --?https://isocpp.org
8:08 p.m.
Thanks, I'll check that.
At 07:48 AM 24/04/2019 -0500, wrcooke at wrcooke.net wrote:
On April 24, 2019 at 7:39 AM Guy Dunphy via
cctalk <cctalk at classiccmp.org> wrote:
I haven't dumped the chargen chip yet,
because I don't know what it is, and suspect it's more complex than just a ROM.
24 pin character gen ROM/? at U10 is marked:
VTi (logo)
350 RN 118
2333-5006
8000142
(c)TELEVIDEO 1983
KOREA-AE
Guy
Likely an MOS Tech 2333 ROM chip.
http://www.bitsavers.org/components/mosTechnology/_dataBooks/1982_MOS_Techn…
See page 2-145
Will
7:55 p.m.
At 08:14 AM 24/04/2019 -0700, you wrote:
On 4/24/19 5:39 AM, Guy Dunphy wrote:
I did try reading it as an 8749. By 'not readable' I meant it read as all FF.
Using a Topmax device programmer; a fairly good brand.
Interestingly when I selected Intel 8749 it actually hung on reading. Repeatably. Never
seen that happen before.
Selecting NEC 8749, it read, but got all FFs.
Considering there's something odd going on, I was quite relieved to verify the chip
still works afterwards.
I hadn't gone as far as getting out the databooks and checking whether 8049 should be
readable.
I thought they are, but the absense of '8049' type in the chip programmer seemed
to suggest otherwise. Unless they
were 'induced' to leave it out to hinder copying?
Shall look into it further.
Guy
The keyboard controller is an 8049. Firmware not
readable.
8049s aren't protected. they are 2k versions of the 8048
and can be read as 8749s 
8:46 p.m.
On 04/24/2019 07:55 PM, Guy Dunphy via cctalk wrote:
At 08:14 AM 24/04/2019 -0700, you wrote:
The 8049 is readable just like the 8048 save for 2k device.? I worked
for NEC back then and had access to intel parts too.
If you can't read it its your programmers fault, FYI the set up is
nearly the same as 8749 but the voltage for the read
function is lower.? Here is except of page 2-19 of the intel MCS48
family manual july 78...
"The processor is placed in the READ mode by applying a high voltage
(+25V for the
8748, +12V for the 8048/8049) to the EA pin and +5V to the TO (8748
only) input pin.
RESET must be at OV when voltage is applied to EA. The address of the
location
to be read is then applied to the same lines (TTL levels) of BUS and
Port 2 which output
the address during single step (see below), The address is latched by a
"0" to "1"
transition on RESET and a high level on RESET causes the contents of the
program
memory location addressed to appear on the eight lines of BUS."
It is possible that the devices is being used with external rom/eprom
the test for that is pin7 EA, if EA is high then program access
is external.? it was very common to use any 8048/49 in place of 8035/39
in a system and often cheaper due to misprogrammed
parts that can still be used with external rom.
FYI there are no "protection bits".
Allison
On 4/24/19 5:39 AM, Guy Dunphy wrote:
I did try reading it as an 8749. By 'not
readable' I meant it read as all FF.
Using a Topmax device programmer; a fairly good brand.
Interestingly when I selected Intel 8749 it actually hung on reading. Repeatably. Never
seen that happen before.
Selecting NEC 8749, it read, but got all FFs.
Considering there's something odd going on, I was quite relieved to verify the chip
still works afterwards.
I hadn't gone as far as getting out the databooks and checking whether 8049 should be
readable.
I thought they are, but the absense of '8049' type in the chip programmer seemed
to suggest otherwise. Unless they
were 'induced' to leave it out to hinder copying?
Shall look into it further.
Guy
The keyboard controller is an 8049. Firmware not
readable.
8049s aren't protected. they are 2k versions of the 8048
and can be read as 8749s
8:51 p.m.
On 04/24/2019 08:47 PM, Al Kossow via cctalk wrote:
On 4/24/19 5:46 PM, allison via cctalk wrote:
All!? The HC were different lower power process thats all.? if it were
8051 thats different.
My samples include NMOS, NMOSII, and HCMOS.? and the NEC parts through CMOS
Allison
The 8049 is readable just like the 8048 save for
2k device.? I worked
for NEC back then and had access to intel parts too.
is that true for
"HC" parts or just NMOS?
25 Apr
25 Apr
12:02 a.m.
On Wed, Apr 24, 2019 at 8:51 PM Al Kossow via cctalk <cctalk at classiccmp.org>
wrote:
The 924 should be the same as a 955 keyboard. There seemed to be two
compatible types of the keyboard - an older thicker keyboard (shipped the
TS-803 et al, and looks like an enhanced 925/950 keyboard), and a newer
thinner profile keyboard used on later terminals.
>>> The keyboard controller is an 8049.
Firmware not readable.
It may actually be compatible with the 955 keyboard, which I was able to
read.
Key layout is the same, though the manuf is different
From what I've figured out, the 955 uses a 6-pin
connector at 9600 baud
with both Tx and Rx used, and a reset line and +12V power.
The 925/950 use
a 4-pin connector, replaces the Tx to keyboard line with a speaker
connection, drops the reset line, and runs at 1200 baud as compared to the
955 keyboard. The keyboard should be the same between the 905, 955, 970,
TS-803, and some others with the possible difference of some legends on
keycaps. The TS-802, 800A, 925, and 950 use the same keyboard +/- some
legends.
Later terminals like the 965 use a 4-pin connector with a different pinout,
and +5V supply instead of +12V, but still at 9600 baud with the same codes
as the 970/etc.
I believe that the transmitted codes are the same for all of them, but the
older 925/950 keyboard is missing some keys than the later 970/955/etc have.
The TPC-I, TPC-II, TS-1605 all use a PC/XT-like keyboard interface, but
with a +12V power supply instead of +5V. I haven't quite verified if one
can swap them with XT keyboards with an alternate power supply yet, but it
may be possible. It seems like they should be compatible since the
TS-1605/TPC-II are fairly compatible with PC/XTs.
Pat
11:55 a.m.
The 924 should be the same as a 955 keyboard.? There
seemed to be two compatible types of the keyboard - an older
thicker keyboard (shipped the TS-803 et al, and looks like an enhanced 925/950 keyboard),
and a newer thinner profile
keyboard used on later terminals.
From what I've figured out, the 955 uses a 6-pin connector at 9600 baud with both Tx
and Rx used, and a reset line and
+12V power. The 925/950 use a 4-pin connector, replaces the Tx to keyboard line with a
speaker connection, drops the
reset line, and runs at 1200 baud as compared to the 955 keyboard.? The keyboard should
be the same between the 905,
955, 970, TS-803, and some others with the possible difference of some legends on
keycaps.? The TS-802, 800A, 925, and
950 use the same keyboard?+/- some legends.?
Later terminals like the 965 use a 4-pin connector with a different pinout, and?+5V
supply instead of?+12V, but still at
9600 baud with the same codes as the 970/etc.
Alex Riedlmayer has been doing a lot of work on simulating Televideo terminals in MAME.
There should be a lot of (if cryptic) info on the logic boards and the high-level or uP
simulated
keyboards in the sources.
1948
days inactive
1950
days old
12 comments
5 participants
participants (5)
-
aek＠bitsavers.org -
allisonportable＠gmail.com -
guykd＠optusnet.com.au -
pat＠vax11.net -
wrcooke＠wrcooke.net