Hi everyone,
I'm on the lookout currently for a 32K memory cart for a TI99 PEB, as well as extended basic.
I'm also interested in any ACT Sirius hardware anyone has currently hanging around.
Many thanks for any help.
Stu
I've been asked if I can find any information on the following, can
anybody help?
'We acquired a number of years ago a Senosa Limited Directdata 640
Transmission Processor with Digico Teletype from a local company but it
came with no information. Could you please point me in the right direction
for some information about how these items work, date of production etc.'
Simon Webb
Curator, Museum of Computing
www.museum-of-computing.org.uk
Tel: 07939 582544
>From: "John Honniball" <coredump(a)gifford.co.uk>
>
>Jay West wrote:
>> Since the blank chips are nigh impossible to find anymore... is it possible
>> to use something like a PIC chip on a small DIP carrier card, that could be
>> plugged into an existing loader rom or microcode rom socket and function
>> just like the "real thing" to the system?
>
>You wouldn't use a PIC chip for something like this. A PIC would be
>used in a microcontroller-type application, where program-controlled
>behaviour is required. To replace a ROM, we could simply use another
>ROM (or PROM, EPROM, EEPROM, Flash ROM, etc.) with a pinout adaptor.
>
>People are already doing this for PROMs in mobile radios. These PROMs
>are in fact the same chips as one finds in a PDP-11 for booting (M9312)
>and for storing the 8008 firmware in an 11/34 console card. The
>PROMs in question are 82S131, 74S571 or Am27S13 types (512x8). I have
>some blanks here to fix a console card, as it happens.
>
>Scroll down here:
>
> http://www.open.org/~blenderm/syntorx/legacy.html
>
>to the section headed "EPROM Conversion" to read about the PROM
>replacements for Syntor radios. And see this page:
>
> http://www.open.org/~blenderm/syntorx/legacyeprom.html
>
>for photos of a completed adaptor.
>
>Do you know the chip numbers and/or specs for the ROMs you wish to
>emulate?
>
>--
>John Honniball
>coredump(a)gifford.co.uk
>
Hi John
Most of the applications Jay is talking about require faster
than 100ns someplace. Most EPROMs just are not in that range.
Dwight
>Since actual error distributions on crystals are bimodal, not Gaussian, you would
>normally get just about that error.
This sounds interesting. Any ideas why?
-Charles
>From: charlesmorris(a)direcway.com
>
>>Since actual error distributions on crystals are bimodal, not Gaussian, you
would
>>normally get just about that error.
>
>This sounds interesting. Any ideas why?
>
>-Charles
>
What Why? Bimodel is quite common for tuned circuits that
are lightly loaded. Still, if one goes out on the skirts
of the curves, you'll be as close to Gaussian as you'd
ever want to be.
Dwight
I need the power supply for a V-marc 88a or the information about it so that
I can get the computer tested that I have. Also missing the plastic cover
for the printer area if anyone has an extra. Thanks in advance.
Hi Marvin
There is a front panel schematic, someplace on
the net but I don't recall where. There was
a CDROM set released that had it as well ( as I recall ).
You should also note that any card with DRAM on it
is most likely not going to work unless things are
matched with the CPU card. Most early machines did
different things for the refresh clocking. I know
that I added a kludge to my Poly88 CPU card to get
the EconoRam board to work with it, that I got from
SD Sales. Other DRAM boards have different setups.
Dwight
>From: "Marvin Johnston" <marvin(a)rain.org>
>
>
>"Dwight K. Elvey" wrote:
>
>> It sounds like the front panel isn't jamming the correct
>> instructions onto the data bus ( or something on the data
>> lines of the CPU is loading one of the data lines ).
>> The front panel works by either jamming a JMP ( 0C3h ) instruction
>> onto the CPU's bus or a NOP ( 00h ). This allows for both changing
>> address and incrementing the address. The front panel can then
>> override the read and write operations to the physical memory
>> during the increment.
>
>Since this does appear to be related to the databus and getting the
>correct information to the CPU, I'll start by checking to make sure the
>JMP and NOP instructions are getting out on the bus. What is interesting
>is that the switch settings seem to have almost no effect on anything
>until I turn them all on. But the JMP and NOP buffers could well cause
>some problems. Wish I could find my Jade Board quickly :). Right now,
>I'm using a Bob Mullens S-100 extender card with the High, Low, Pulse
>LED indicators ... may have to actually fire up the scope if I don't
>find out the problem fairly soon.
>
>> The most common problem I've seen that causes similar effects
>> is that there are several 7406 ( or similar OC buffers ) connected
>> from the front panel to the data lines of the CPU. One or more
>> of these devices has failed ( I suspect this is mostly do to
>> some overlap timing and stressing of the parts but that is
>> the way they are designed ). One other thing that I've seen
>> is that the data lines going to the CPU from the front panel
>> were wired upside down. This is that cable between the two.
>> ( soemone put the cable together backwards )
>
>This is one of the original style Altairs where the wiring between the 4
>slot motherboards and the front panel are all done with discrete wires.
>Makes me wonder if the 2 MHz clock speed is too fast :). I've checked
>out all the data and control lines from the front panel to the bus and
>everything seems to be correct. I did notice that the Phase 2 clock
>doesn't register on the Bob Mullens card, but that may be because the
>pulse length is too short for the card to read (123 w/ 10 pf cap and
>about 6.? K resistor.)
>
>Thanks!
>
