8 Nov
2005
8 Nov
'05
4:41 a.m.
Hi Jos,
I fully agree with you. Building your own CPU is really an exciting project.
I took me more then 3 months to debug my 110 TTL CPU with
256 words of micro code of 48 bits.
See: http://www.anysystems.nl/hjs22.html for some pictures and the
reference card.
I build this CPU & IO unit in 1976. A liitle bit younger then the
Elektor machine :-). Do you still have the Elektor machine ?
Regards Henk Stegeman.
Netherlands
What surprises me about the home-built computers from scratch is the
lack
of imagination when it comes to architecture. Most are basically
one-address-cum-accumulator designs. It would seem that larger
register
files are much easier to build nowadays and would open up the door to
some
2 and 3-address designs.
The reason is the effort it takes......
Ask anybody who actually made a CPU ( I myself did a 12 bit
TTL based, single address single accumulator machine).
The real effort is actually building and debugging the unit.
There is only so much time you have....
I've always thought that 24 bits is a nice word size for a small
computer.
Much too big to actually build in TTL.
In 1974 Elektor magazine started a series of DIY articles that described
an extensible ( 12 bit or 16 bit width ) three address, clockless
computer.
TTL based, with a shiftregister based memory. (6 or 8 512x2
shiftregisters .)
An expensive extra wasa 2102 based RAM.
The machine did hardware multiply and divide +
Instructions were build into the address map .i,e, address XX is the
adder, adress yy is a shift and so on..
The start of this series actually predates the Mark8 computer !
Jos Dreesen
8 Nov
8 Nov
7:36 p.m.
Stegeman, Henk HJ SITI-ITIBHW5 wrote:
The reason is the effort it takes......
Ask anybody who actually made a CPU ( I myself did a 12 bit
TTL based, single address single accumulator machine).
The real effort is actually building and debugging the unit.
There is only so much time you have....
Well everybody likes 12 bits...
http://www.cray-cyber.org/hardware/Hardware.php
Forget TTL, go tubes!
I've always thought that 24 bits is a nice
word size for a small
computer.
Much too big to actually build in TTL.
8:41 p.m.
On 11/8/2005 at 5:36 PM woodelf wrote:
Well everybody likes 12 bits...
http://www.cray-cyber.org/hardware/Hardware.php
Forget TTL, go tubes!
Wow, now that's ambitious!
Makes me wonder, though. Around the time the transistor was in its
ascendancy, the vacuum-tube business came up with a couple of innovations.
One was the nuvistor--an almost transistor-sized tube; and the other was a
low-voltage tube used in automobile receivers that were specified for 12.6
volts on the plate (e.g. 12AE7 dual triode). These would be coupled with a
solid-state driver and power amplifier for a auto radio with no vibrator
supply.
The first would seem to make the scale of a digital computer more
attractive; the second would seem to substantially reduce the power
requirements. To anyone's knowledge were either of these two components
ever used in digital applications?
Cheers,
Chuck
11:35 p.m.
The first would seem to make the scale of a digital
computer more
attractive; the second would seem to substantially reduce the power
requirements. To anyone's knowledge were either of these two components
ever used in digital applications?
The answer is "no".
As far as I know, no Nuvistors were computer rated. This is not a surprise
for a couble of reasons. One, Nuvistors intended to be incredibly high
quality amplifiers for things like test equipment and receiver front ends
- basically with all of the parameters that a tube doing digital work need
not be. Two, Nuvistors really did not gain too much in the space saving
category over the computer rated submini dual triodes in use at the time.
These latter tubes were well proven, and more reliable than Nuvistors (the
culprits being the sockets).
Running tubes at low plate voltages was not really an innovation -
engineers had always done this, and many normal tubes will actually work
at a quarter rated plate voltage or less. Purpose built low voltage tubes
never took off too well - ther really is not a huge advantage in the power
department, as the big share of the power bill was always the filament.
William Donzelli
aw288 at osfn.org
9 Nov
9 Nov
12:13 a.m.
On 11/8/2005 at 11:35 PM William Donzelli wrote:
Running tubes at low plate voltages was not really an
innovation -
engineers had always done this, and many normal tubes will actually work
at a quarter rated plate voltage or less.
I had a few of those submini dual triodes, wire leads and all.
I seem to remember a code practice oscillator built around a 6SL7 with
nothing but a 6.3vac filament transformer for power (out of an old ARRL
handbook, maybe?). It put out enough to be heard in headphones.
Cheers,
Chuck
12:30 a.m.
Chuck Guzis wrote:
On 11/8/2005 at 11:35 PM William Donzelli wrote:
The 6418 tube runs 1.25 volts @ 10 ma. You can't beat that for low
power. :)
In some ways today is good time to play with tubes ... you can get
them cheap
compared to the past era's.
Running tubes at low plate voltages was not really
an innovation -
engineers had always done this, and many normal tubes will actually work
at a quarter rated plate voltage or less.
I had a few of those submini dual triodes, wire leads and all.
10 Nov
10 Nov
2:37 p.m.
From: "William Donzelli" <aw288 at osfn.org>
Running tubes at low plate voltages was not really an
innovation -
engineers had always done this, and many normal tubes will actually work
at a quarter rated plate voltage or less. Purpose built low voltage tubes
never took off too well - ther really is not a huge advantage in the power
department, as the big share of the power bill was always the filament.
I have a couple of valve (tube) radio circuits with an HT (B+) voltage of
only 3V. Mullard made a range of valves designed for 12V anode, and 12V
heater use (intended for car radios in the late50s - they were used as the
RF and IF stages, driving a Germanium power transistor (usually OC16) as the
AF ouput.
Jim.
9 Nov
9 Nov
12:35 a.m.
On 11/8/05, Chuck Guzis <cclist at sydex.com> wrote:
On 11/8/2005 at 5:36 PM woodelf wrote:
It is funny that I am a tube fan too.
The 12.6 volt tubes won't save you any power; On the contrary, they
sucks much more power than normal tubes. Because they need a lot of
current to heat the cathode to emit more electrons; and they have a
positive first grill to 'pull' electrons out from cathode.
Nuvistors are not good to use for homebrew computers either, because
they are expensive. Months ago I saw a board with 10+ nuvistors. I
didn't buy it ($9.99) because I was not small-tube fan. I checked the
second hand price at that time and it was significantly higher than
those sub $1 tubes.
vax, 9000
Well everybody likes 12 bits...
http://www.cray-cyber.org/hardware/Hardware.php
Forget TTL, go tubes!
Wow, now that's ambitious!
Makes me wonder, though. Around the time the transistor was in its
ascendancy, the vacuum-tube business came up with a couple of innovations.
One was the nuvistor--an almost transistor-sized tube; and the other was a
low-voltage tube used in automobile receivers that were specified for 12.6
volts on the plate (e.g. 12AE7 dual triode). These would be coupled with a
solid-state driver and power amplifier for a auto radio with no vibrator
supply.
The first would seem to make the scale of a digital computer more
attractive; the second would seem to substantially reduce the power
requirements. To anyone's knowledge were either of these two components
ever used in digital applications? 
9:58 a.m.
>>>> "Chuck" == Chuck Guzis
<cclist at sydex.com> writes:
Chuck> ... the other was a low-voltage tube
Chuck> used in automobile receivers that were specified for 12.6
Chuck> volts on the plate (e.g. 12AE7 dual triode). These would be
Chuck> coupled with a solid-state driver and power amplifier for a
Chuck> auto radio with no vibrator supply.
Chuck> ... the second would seem to substantially reduce
Chuck> the power requirements. To anyone's knowledge were either of
Chuck> these two components ever used in digital applications?
I doubt it for the 12 volt tube case. For car radios they make sense,
for the reasons you gave. (I built a radio for our camper using
those, as a boy scout project. Tubes for the RF/IF stages, a very
early (1971 or so) op amp as AF preamp, and totem pole transistor AF
final amp.)
But I don't think the electrical parameters were all that good, given
the unusually low anode voltage. And I don't see any reason for the
power consumption to be less. Lower voltage, sure, but the current
may go up in proportion. And the filaments were still the usual,
which accounts for a fair chunk of the power.
paul
3:19 a.m.
woodelf wrote:
Stegeman, Henk HJ SITI-ITIBHW5 wrote:
They can't calculate the difference between 926kB and 926MB though -
look at those filesizes! Either they've got that wrong or NTL have
given me one hell of an upgrade overnight.
Gordon.
The reason is the effort it takes......
Ask anybody who actually made a CPU ( I myself did a 12 bit
TTL based, single address single accumulator machine).
The real effort is actually building and debugging the unit.
There is only so much time you have....
Well everybody likes 12 bits...
http://www.cray-cyber.org/hardware/Hardware.php Forget TTL, go tubes! I've always thought that 24 bits is a nice
word size for a small
computer.
Much too big to actually build in TTL.
3:32 a.m.
woodelf wrote:
Stegeman, Henk HJ SITI-ITIBHW5 wrote:
Which is what I don't understand from my experiences with my own CPU
long ago. 16 bit would be okay and maybe even more bits, but I decided
against classical 4, 8 or 12 bits those days, although these sizes were
quite popular then for "real" CPUs. The point is that I didn't want to
have sophisticated instruction decoding logic, this disallowed multiple
word instructions. I knew about microprogramming, of course, but this
were out of reach because of lacking facilities to burn PROMs (I was a
pupil then).
For memory addresses and immediate operands, this meant a single
instruction should hold enough address or data bits. With 12 bits you
are restricted to too few possible instructions or too few address bits
(4 bit instruction or 8 bit address/immediate data was not enough for my
ambitious plans. 16 bit were suitable even if it required two "load
immediate" instructions (for the low and the high byte). However the
first architecture had 16 bit instructions but an 8 bit data path only
(except the separate 12 bit address increment/index logic).
Holger
The reason is the effort it takes......
Ask anybody who actually made a CPU ( I myself did a 12 bit
TTL based, single address single accumulator machine).
The real effort is actually building and debugging the unit.
There is only so much time you have....
Well everybody likes 12 bits... I've always thought that 24 bits is a nice
word size for a small
computer.
Much too big to actually build in TTL.
11:42 a.m.
Holger Veit wrote:
woodelf wrote:
Well everybody likes 12 bits...
Which is what I don't understand from my experiences with my own CPU
long ago. 16 bit would be okay and maybe even more bits, but I decided
against classical 4, 8 or 12 bits those days, although these sizes
were quite popular then for "real" CPUs. The point is that I didn't
want to have sophisticated instruction decoding logic, this disallowed
multiple word instructions. I knew about microprogramming, of course,
but this were out of reach because of lacking facilities to burn PROMs
(I was a pupil then).
I thought that is why they went to 16 or 18 bits word length for the
small machines..
For memory addresses and immediate operands, this
meant a single
instruction should hold enough address or data bits. With 12 bits you
are restricted to too few possible instructions or too few address
bits (4 bit instruction or 8 bit address/immediate data was not enough
for my ambitious plans. 16 bit were suitable even if it required two
"load immediate" instructions (for the low and the high byte). However
the first architecture had 16 bit instructions but an 8 bit data path
only (except the separate 12 bit address increment/index logic).
The current 18 bit computer I a building using CPLD's has a 128 cell
CPLD for the 9 bit slices and
a 128 cell CPLD for the CONTROL unit. The biggest pain is byte swapping
for character data,
another 84 pin CPLD for memory. The 5 th CPLD is a glue chip with the
IDE Interface , 8 bit I/O
buss for the 6821's and 6850's and a 128 x 18 bootstrap rom. I
suspect if the design was done
in TTL the control section would be 1/3 with the other 2/3's data path
for about 300 SSI chips.
Holger
The fun part of this design is I am doing the cpu structure as
monolithc cpu in a 48 pin
package and the memory bus swap buffer as a undefined 48 pin package.
This design
is about just after the z80 or 6809 came out but before the 16 bit cpu's
with large memory
addressing. The next version could be real TTL with a MMU and dynamic
memory.
( 64k and 256k chips -- no 16k chips from the 70's era )
11 Nov
11 Nov
6:29 p.m.
Stegeman, Henk HJ SITI-ITIBHW5 wrote:
Hi Jos,
I fully agree with you. Building your own CPU is really an exciting project.
I took me more then 3 months to debug my 110 TTL CPU with
256 words of micro code of 48 bits.
I have been trying since I was about 12. Now I am a old GEEK and still
trying to save
my pennies up parts. I can never get a clean TTL design under about 300
chips for the
data path and 150 for the control unit.
See: http://www.anysystems.nl/hjs22.html for some
pictures and the
reference card.
This is a nice CPU.
>What surprises me about the home-built computers from scratch is the
>lack
>of imagination when it comes to architecture. Most are basically
>one-address-cum-accumulator designs. It would seem that larger
>register
>files are much easier to build nowadays and would open up the door to
>some
>2 and 3-address designs.
>
>
I would bit slice would be better for that route, it is lot of
instruction types
that add up with multi-address opcodes.
In 1974 Elektor magazine started a series of DIY articles that described
an extensible ( 12 bit or 16 bit width ) three address, clockless
computer.
TTL based, with a shiftregister based memory. (6 or 8 512x2
shiftregisters .)
Living in Canada I was Computer deprived .... I'll read the DIY stuff
now and maybie build it
in 20 years :)
6:51 p.m.
On 11/11/2005 at 4:29 PM woodelf wrote:
I would bit slice would be better for that route, it is
lot of
instruction types
that add up with multi-address opcodes.
I'd think that this would be quite the reverse. Aren't most RISC
architectures 3-address? Ostensibly this is because the instructions are
simpler and easier to execute in a single cycle.
Am I missing something?
Cheers,
Chuck
7:04 p.m.
Chuck Guzis wrote:
On 11/11/2005 at 4:29 PM woodelf wrote:
Yes, but this is 3 address only for the register file.
I would bit slice would be better for that route,
it is lot of
instruction types
that add up with multi-address opcodes.
I'd think that this would be quite the reverse. Aren't most RISC
architectures 3-address? Ostensibly this is because the instructions are
simpler and easier to execute in a single cycle.
Am I missing something?
Cheers,
Chuck
.
7:31 p.m.
On 11/11/2005 at 5:04 PM woodelf wrote:
Yes, but this is 3 address only for the register file.
Yes--and that's what I was referring to. Other instructions, such as jumps
and branches are pretty much the same, regardless of architecture. You
need only one instruction to enter an immediate value into a register.
Or you could map the register file to memory (like the TI 990) and not even
need that instruction.
Cheers,
Chuck
6:54 p.m.
New subject: HP 3000 boot problem
I have a boot problem with a modern HP 3000 of a friend of mine, a HP3000
937 LX
The system display the two disk connected, with address 52.0.0.0.0.0. etc
and 56.2.0.0.0.0
say that there are 8 banks of memory for 128 mb of ram ...
but don't boot and say
Failed Inizialiting INIT_STATE = 4
See the photo of console :
http://www.retrocomputing.net/parts/hp/hp3000_937lx/HP01.jpg
any idea ?
Thanks
Alberto
------------------------------------------------------
Alberto Rubinelli Mail : alberto at a2sistemi.it
A2 SISTEMI Web : www.a2sistemi.it
Via Costantino Perazzi 22 Tel 0321 640149
28100 NOVARA (NO) - ITALY Fax 0321 391769
Il mio museo di vecchi computers/My old computers museum
http://www.retrocomputing.net
ICQ : 49872318 Skype : albertorubinelli
------------------------------------------------------
12 Nov
12 Nov
12:21 a.m.
New subject: HP 3000 boot problem
You typed that erroneously. It should read:
Failed Inizialiting INIT_STATE = -4 (as per the picture of the
readout on the monitor you have in the link).
-John Boffemmyer IV
At 06:54 PM 11/11/2005, you wrote:
I have a boot problem with a modern HP 3000 of a friend
of mine, a HP3000
937 LX
The system display the two disk connected, with address 52.0.0.0.0.0. etc
and 56.2.0.0.0.0
say that there are 8 banks of memory for 128 mb of ram ...
but don't boot and say
Failed Inizialiting INIT_STATE = 4
See the photo of console :
http://www.retrocomputing.net/parts/hp/hp3000_937lx/HP01.jpg
any idea ?
Thanks
Alberto
------------------------------------------------------
Alberto Rubinelli Mail : alberto at a2sistemi.it
A2 SISTEMI Web : www.a2sistemi.it
Via Costantino Perazzi 22 Tel 0321 640149
28100 NOVARA (NO) - ITALY Fax 0321 391769
Il mio museo di vecchi computers/My old computers museum
http://www.retrocomputing.net
ICQ : 49872318 Skype : albertorubinelli
------------------------------------------------------
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Checked by AVG Anti-Virus.
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6:21 a.m.
New subject: HP 3000 boot problem
You typed that erroneously. It should read:
Failed Inizialiting INIT_STATE = -4 (as per the picture of the
readout on the monitor you have in the link).
you are right :)
sorry for the mistype :)
------------------------------------------------------
Alberto Rubinelli Mail : alberto at a2sistemi.it
A2 SISTEMI Web : www.a2sistemi.it
Via Costantino Perazzi 22 Tel 0321 640149
28100 NOVARA (NO) - ITALY Fax 0321 391769
Il mio museo di vecchi computers/My old computers museum
http://www.retrocomputing.net
ICQ : 49872318 Skype : albertorubinelli
------------------------------------------------------
9:50 a.m.
New subject: HP 3000 boot problem
Alberto Rubinelli - A2 Sistemi writes:
I have a boot problem with a modern HP 3000 of a
friend of mine, a HP3000
937 LX
Hello Alberto!
I have a 3000/922 at home that I've had for a while now, though I lack
MPE/iX media to get it running. I was just curious if you had copies of
MPE/iX 4.x, 5.x, 6.x, or 7.x that I could take a copy of to get my 3000
running?
Thank you,
-R
5:57 p.m.
New subject: HP 3000 boot problem
I have a 3000/922 at home that I've had for a
while now, though I lack
MPE/iX media to get it running. I was just curious if you had copies of
MPE/iX 4.x, 5.x, 6.x, or 7.x that I could take a copy of to get my 3000
running?
The HP3000 is of a friend, not mine, but I can ask him about the OS.
Allow a couple of weeks :)
Alberto.
------------------------------------------------------
Alberto Rubinelli Mail : alberto at a2sistemi.it
A2 SISTEMI Web : www.a2sistemi.it
Via Costantino Perazzi 22 Tel 0321 640149
28100 NOVARA (NO) - ITALY Fax 0321 391769
Il mio museo di vecchi computers/My old computers museum
http://www.retrocomputing.net
ICQ : 49872318 Skype : albertorubinelli
------------------------------------------------------
15 Nov
15 Nov
5:28 a.m.
New subject: HP 3000 boot problem - updates
I have a boot problem with a modern HP 3000 of a
friend of mine, a HP3000
937 LX
See the photo of console :
http://www.retrocomputing.net/parts/hp/hp3000_937lx/HP01.jpg
On the backplane board of the 3000, there is a DS1287, battery backed real
time clock. It has datecode 9125, maybe battery dead. Does anyone know if
this chip on the 3000 is used only for the clock or it store any system
parameter ?
Alberto
------------------------------------------------------
Alberto Rubinelli Mail : alberto at a2sistemi.it
A2 SISTEMI Web : www.a2sistemi.it
Via Costantino Perazzi 22 Tel 0321 640149
28100 NOVARA (NO) - ITALY Fax 0321 391769
Il mio museo di vecchi computers/My old computers museum
http://www.retrocomputing.net
ICQ : 49872318 Skype : albertorubinelli
------------------------------------------------------
6825
days inactive
6832
days old
22 comments
12 participants
participants (12)
-
alberto＠a2sistemi.it -
aw288＠osfn.org -
bfranchuk＠jetnet.ab.ca -
blairrya＠msu.edu -
cclist＠sydex.com -
gordonjcp＠gjcp.net -
henk.stegeman＠shell.com -
holger.veit＠ais.fraunhofer.de -
jim＠g1jbg.co.uk -
john_boffemmyer_iv＠boff-net.dhs.org -
pkoning＠equallogic.com -
vax9000＠gmail.com