>is adjusted to give an output pulse width on pin#1 of the 74LS121
> of 5.5 ls." I assume "ls" is an oddball abbreviation for microsecond?
The l comes from the misinterpretation of the 'micro' symbol, a long
tailed u. Anyhow 5.5us is correct and going from the resistor values
and T=CR for the 74121 gives a value of 275pF. 270pF will do but with
the range of adjustment in the circuit anything from 100pF to 500pF
should work.
Lee.
.
Send instant messages to your online friends http://uk.messenger.yahoo.com
> I was feeling nostalgic recently and would like to figure out some
> way of recreating my introduction to computing in 7th grade (an
> ASR-33 with acoustic coupler, timeshared to a PDP-8 at the nearest
> university 60 mi. away, running Edusystem 50). The good old
> days... when a large hard drive was 256Kw and functional programs
> could be run in 8K of core!
SAME here...except the PDP was in the building, and we were running full TSS/8 [1972]
> I have a TTY basket case which is "very restorable" :) but don't
> have the time or space to keep a real PDP-8 up and running. Is
> there a decent program I can run on a PC? Or should I invest in an
> SBC6120? A front panel with blinkenlights would be neat but not
> essential to the TTY "experience".
>
I have an SBC6120 and a PDP-8 up an running. If you cant get (or in your case dont have room) I strongly recommend theSBC6120 over an emulator.
Even though I have both, A lot of the "switch banging" I do on the SBC....hey if a paddle breaks, they are easier to repair!
I was feeling nostalgic recently and would like to figure out some way of recreating my introduction to computing in 7th grade (an ASR-33 with acoustic coupler, timeshared to a PDP-8 at the nearest university 60 mi. away, running Edusystem 50). The good old days... when a large hard drive was 256Kw and functional programs could be run in 8K of core!
I have a TTY basket case which is "very restorable" :) but don't have the time or space to keep a real PDP-8 up and running. Is there a decent program I can run on a PC? Or should I invest in an SBC6120? A front panel with blinkenlights would be neat but not essential to the TTY "experience".
thanks
Charles
I have noticed a few recent posts about older TI systems including a
question about locating a trainer/dev (?) system described a '76 byte
magazine. This got me thinking about a TI chassis I have been unable to
locate documentation. Can anyone help shed some light on the following. .?
The closest thing I could find on the Internet was (an earlier model's
users guide), but nothing about the card chassis that holds it.
http://computer-refuge.org/bitsavers/ti/tm990-100/TM990-100M_usersGuide.pdf
The card chassis:
Within a Steel 4-slot Texas Instruments card chassis the size of a shoe box
are four Texas Instruments cards manufactured in the US. These cards
resemble a regular s-100 card but the 100 contacts are off center, to the
left when viewing the component side with the 100 pin side down. Printed
on the chassis is Assy No. is 0994676-0001 and Diag No. 0394677. I do not
have a power supply, but I assume you'd attach to terminals on the back of
the chassis somehow (?).
Inside are 4 cards.
Two cards are similar are RAM/EPROM cards with 32K in each (8 x 4 rows I
assume = 32K ?). The RAM is a mix of TMS 4045-30NL, TMS 4045-30, and TMS
4014NL. There are no Eproms installed, but there are two rows of empty
slots on the card. Each card has 8 dip switches.
The third card is labeled TM990/101 M. This appears to be a
processor/modem/term card with a TMS 9900JL EP7840 ceramic/gold processor,
and a TMS 9901NL chip, etc. The card has two 25 pin female connectors
apparently for serial i/o.
The fourth card is labeled "universal prototype board TM990/512". This card
may be newer than the rest and has an Intel P8253 chip (date = '80). There
is extensive wiring on the back of the card, it could be for a disk drive,
I don't know. The card has 2 40 pin flat connectors.
I am hoping someone can point me in the direction for a TM990/101 M Users
Guide or documentation about the chassis and/or individual components. I
can post pictures by request.
-Bill
Just futzing around with this Manta board (SCSI floppy controller).
The docs I have say that pin 2 of the floppy connector is normally an
input to the controller from the drive, but that some drives expect pin
2 to be an output to the drive from the controller (e.g. for changing
rotation speed on a drive capable of 300 and 360rpm)
That sounds wrong to me; surely most drives either don't use pin 2 for
anything, or they expect it to be an output from the controller (to cope
with things like speed changes)
What drives use it as a signal driven by the drive, and what for?
I'm tempted to ignore the docs I have and configure it as an output from
the controller - I'd just rather not blow up a drive or controller
board :-)
cheers
Jules
Any one with experience on doing electrical troubleshooting on (Maxtor) ATA
Drives, please drop me a note off-list. I just had a PS failure and it
"took-out" a drive with some fairly critical data. I believe the board
(rather than the platter itself) took the bullet, and I want to explore
options before sending the drive out for $6K+ in repair costs.
David
"Some days you have all the (bad) luck"
I visted one of my "sources" today and he had a surprise for me, a
Tektronix 4025 terminal!* I brought it home but haven't had time to try it
out yet. I googles but didn't find much about it. Can anyone tell me more
about this thing?
* Also three more Intel 86/330 computers, two Intel 80/20 computers and
a big pile of manuals :-)
Joe
Hello,
I have been searching the web for the past week, looking
for an online copy of the bits for a version (any version)
of the TI 990 "DX-10" operating system.
Anyone know where I might be able to find them?
I'm aware of MESS (mess.org), which has a 990 simulator.
It looks like a significant piece of work, but they only
create (software-based) hardware emulators. Without the
bits to a version of DX-10, running a virtual 990 is not
quite the experience I had hoped for ....
I'm also aware of http://www.cozx.com/~dpitts/ti990.html,
and I've been able to download and run TXDS. It's cool,
but again, it's not really anywhere near what it would be
like to really (ok, virtually-really :-) run DX-10 again.
They aren't at bitsavers.org either. Some great manuals
(score!) but not the software itself.
Any leads or ideas as to how I might get in touch with
these bits again would be appreciated. I'm open to the
idea of helping to finance or otherwise help in ensuring
that these bits aren't lost forever.
Best,
John Sambrook
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Ok, I finally found an 8" drive that worked. I don't think there's a
coincidence that it's half-height, and seems to have been made in the 1982
timeframe. I can't tell who the manufacturer is because I haven't
unbolted it from the chassis it's installed in to check yet.
I was able to format a disk mostly successfully (more on this in a bit)
and transfer MS-DOS 6.22 to it. It was pretty nifty booting DOS on my PC
off an 8" drive ;)
So anyway, when I was formatting the disk, it didn't seem to like the last
4-6 tracks or so. Above the clatter of the noisy fan (bad bearings) I
could hear the head recalibrating. When the format finished, it reported
107520 bytes in bad sectors. This comes out to 210 bad sectors (assuming
512 bytes per sector) which comes out to some weird number of tracks.
Aren't there supposed to be 26 sectors per track?
The main hurdle has been jumped, so I'm in good shape at this point.
Thanks for the tips, all!
--
Sellam Ismail Vintage Computer Festival
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> Jerome Fine replies:
>
> Once done, the SET command values are held in the
> DU.SYS device driver file. You do NOT need to
> do the SET commands each time. Probably not
> recommended in any case.
Ahaaa... Is that saved in DU.SYS when you issue the commands, then? Makes
sense. I'll try it when I get home.
> Assuming you are booting from an RL02, then the
> DU.SYS device driver my be LOADed for a bit faster
> response after the first usage. In addition, I
> strongly suggest you use RT11FB rather than RT11SJ
> unless the added size of the RT11FB monitor has
> a serious impact on the program which you run.
Well, the idea is to load TSX-Plus over it, which requires the SJ monitor.
> In addition, it would be helpful to know the full
> version number of the RT-11 version which you are
> using. Based on the above SET commands, it must
> be at least V05.03 or RT-11 which was released
> in 1985. There are certain features which later
> versions of RT-11 have that you may wish to be
> aware of. the RT-11 command:
> SHOW CONFIG
> will provide the information, as will the banner
> when RT-11 first boots.
On bootup, and in SHOW CONFIG, the version is given as 5.00.
> Finally, I strongly recommend against the SET
> values which have been suggested since they
> impact very negatively with regard to booting
> RT-11. You will not lose anything with a
Ok, why is that?
> different combination of SET parameters, but
> you will gain with respect to what drives
> can be booted, in particular from a cold start.
In this instance I want to boot from a "clean" install of RT-11 from DL0,
but eventually I will be booting from DU0.
> The exact nature of which disk drives are being
> used will also help. I suspect an RD53 and an
> RX50, but please confirm. Most novice RT-11
OK, this is where it gets tricky. I'm not totally sure how to identify
the ST506 drives fitted to the machine. One is a full-height 5.25" drive,
with (seemingly) about 65,000 blocks on each partition. The other is
half-height, with considerably less on each partition - one is around
40,000 blocks, one is around 16,000 blocks (if I remember correctly - I'm
not actually near the machine right now to check). The smaller drive is
made by Fujitsu, may be something like M224XAS ? The label is rather hard
to read.
The other drives are an RL02 (I have two but lack the cable that links the
two drives) and an RX02.
Gordon.
