8 Jun
2001
8 Jun
'01
7:45 a.m.
Hi all...
I've been trying to get some action from this IMSAI for awhile now. Main
problem is I don't know what is on the EPROMs on the EconoROM board. It
looks like banks A & B, OR banks C & D, can be enabled together starting at
address 0000h. There are 6 2708's in A0 through B1, and 8 2708's in C0
through C3.
I've been looking for an EPROM burner that can read/write 2708's with no
luck so far. We have TWO machines at work, and neither will do it. Anyone
know of a burner that WILL?
I manually read the first 256 bytes of the first chip, and disassembled it,
also manually - I'm looking for a good disassembler program too! I've got
one called DASM V1.2 by John Wilson, but have been having some trouble with
it.
If you've got a few minutes, have a look at what I've included below - the
first 128 bytes of code. Let me know if any of it looks familiar. (Or if I
messed up the job!) The comments are for my own benefit - I'm pretty rusty
with assembler.
Addr. Hex Value Mnemonic Comments
0000 AF XRA A ;Exclusive Or A with A (clears A)
0001 C3 3B 00 JMP 003B ;Jump to 003Bh
0008 C3 EE EF JMP FFEE ;Jump to FFEEh
0010 C3 F1 FF JMP FFF1 ;Jump to FFF1h
0018 C3 F4 FF JMP FFF4 ;Jump to FFF4h
0020 C3 F7 FF JMP FFF7 ;Jump to FFF7h
0028 C3 FA FF JMP FFFA ;Jump to FFFAh
0030 C3 FD FF JMP FFFD ;Jump to FFFDh
0038 C3 D3 09 JMP 09D3 ;Jump to 09D3h
003B D3 F0 OUT F0 ;Send contents of A register to port F0h
003D C3 11 D2 JMP D211 ;Jump to D211h
0040 3B DCX SP ;Decrement stack pointer
0041 00 NOP ;Do nothing
0042 C3 5C 00 JMP 005C ;Jump to 005Ch
0045 21 00 F0 LXI H,00 F0 ;Load register pair H & L with F000h
0048 0E 4E MVI C,4E ;Move 4E to register C
004A AF XRA A ;Clear register A
004B 77 MOV M,A ;Move register A to loc'n given in H & L
004C 23 INX H ;Increment H & L registers
004D 0D DCR D ;Decrement register C
004E C2 4B 00 JNZ 004B ;Jump on no zero to address 004Bh
0051 06 18 MVI B,18 ;Move 18h into register B
0053 21 2A F1 LXI H,F12A ;Load H & L registers with F12Ah
0056 77 MOV M,A ;Move register A to loc'n given in H & L
0057 23 INX H ;Increment H & L registers
0058 05 DCR B ;Decrement register B
0059 C2 53 00 JNZ 0053 ;Jump on no zero to address 0053h
005C 31 9E F0 LXI SP,F09E ;Load stack pointer with F09Eh
005F CD 42 01 CALL 0142 ;Transfer program control to addr 0142h
0062 06 2A MVI B,2A ;Move 2Ah into register B
0064 CD 51 01 CALL 0151 ;Transfer program control to addr 0151h
0067 CD 7A 00 CALL 007A :Transfer program control to addr 007Ah
006A 23 INX H ;Increment H & L registers
006B 7E MOV A,M ;Move value from loc'n in H & L to reg A
006C FE 3A CPI 3A ;Compare A with 3Ah (A - 3Ah)
006E DA 7A 05 JC 057A ;Jump on carry to 057Ah
0071 CD DE 01 CALL 01DE ;Transfer program control to addr 01DEh
0074 CD 94 01 CALL 0194 ;Transfer program control to addr 0194h
0077 C3 5C 00 JMP 005C ;Jump to address 005Ch
007A 21 BC F0 LXI H,F0BC ;Load H & L registers with F0BCh
007D 22 50 F0 SHLD F050 ;Store H & L registers at F050h
Joel A. Weder
jweder(a)telusplanet.net
403-556-4020
8 Jun
8 Jun
10:04 a.m.
On Fri, 8 Jun 2001 10:45:45 -0600, Joel Weder wrote:
#Hi all...
#
#I've been trying to get some action from this IMSAI for awhile now.
Main
#problem is I don't know what is on the EPROMs on the EconoROM board.
It
#looks like banks A & B, OR banks C & D, can be enabled together
starting at
#address 0000h. There are 6 2708's in A0 through B1, and 8 2708's in C0
#through C3.
#
#I've been looking for an EPROM burner that can read/write 2708's with
no
#luck so far. We have TWO machines at work, and neither will do it.
Anyone
#know of a burner that WILL?
Yes. The Data I/O 29B with Unipak 2B will. I just burned one a couple
of weeks ago.
As I learned from Pete Turnbull, the reason almost no modern burner can
handle a 2708 is that it is a 3-rail chip, requiring, among other
things, +12V. Beginning with most 2716s, eproms only used +5V.
But, I have the machine, it works, and I would be happy to do it for
you, if you supply the chips and code.
Louis
9:16 p.m.
Joel Weder wrote:
Hi all...
I've been trying to get some action from this IMSAI for awhile now. Main
problem is I don't know what is on the EPROMs on the EconoROM board. It
looks like banks A & B, OR banks C & D, can be enabled together starting at
address 0000h. There are 6 2708's in A0 through B1, and 8 2708's in C0
through C3.
I've been looking for an EPROM burner that can read/write 2708's with no
luck so far. We have TWO machines at work, and neither will do it. Anyone
know of a burner that WILL?
Yep, I can read 'em.
10:50 p.m.
It's probably not a bad idea to modify the EPROM board to accept the
single-supply (Intel-style) 2716, or even 2732. It's not difficult, and, once
that's done, you simply read the 2708's and transfer their content into
2716's
or 2732's. You can hack the voltage regulator circuit such that the two
additional regulators become pass transistors for the +5, which is the only
supply the I2716's and I2732's need.
Almost every programmer you encounter can handle these later, single supply
EPROMs.
Dick
----- Original Message -----
From: "Bob Shannon" <bshannon(a)tiac.net>
To: <classiccmp(a)classiccmp.org>
Sent: Saturday, June 09, 2001 12:16 AM
Subject: Re: IMSAI EPROMS
Joel Weder wrote:
Hi all...
I've been trying to get some action from this IMSAI for awhile now. Main
problem is I don't know what is on the EPROMs on the EconoROM board. It
looks like banks A & B, OR banks C & D, can be enabled together starting at
address 0000h. There are 6 2708's in A0 through B1, and 8 2708's in C0
through C3.
I've been looking for an EPROM burner that can read/write 2708's with no
luck so far. We have TWO machines at work, and neither will do it. Anyone
know of a burner that WILL?
Yep, I can read 'em.
9 Jun
9 Jun
11:52 a.m.
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1:05 p.m.
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3:34 p.m.
New subject: EPROM replacement and other helpful hints, was Re: IMSAI EPROMS
On Sat, 9 Jun 2001 23:05:59 +0100 (BST), Tony Duell wrote:
#>
#> Tony Duell wrote:
#> >
#> > 2764s are available everywhere and are cheap. And _every_ modern
#> > programmer can handle them (I've seen a few programmers that can
#> > handle nothing smaller than the 2764).
#>
#> Heh heh. Don't we all collect classic programmers as well?
#
#Well, _I_ certainly do, but then I'm not the person who can't program
#2708s :-). I think at least one my programmers can manage those, and
#maybe even the 2704 (512*8, otherwise similar to the 2708).
#
#However, even though I can program them, blank 2708s are getting hard
to
#find over here, so it's nice to have a way to use easy-to-get cheap
parts.
#
#-tony
Tony's suggestion that older eproms can be replaced by a 2764 on a
daughterboard is certainly helpful information, like many of Tony's
suggestions.
While I am sure the circuit is "trivial", some of us are electronics
novices, and no circuit is trivial. If I might suggest, it would be
extremely helpful if Tony's hints, and those of others, could be posted
to a web site in the form of schematics or diagrams. For those of us
who are electronically impaired, that would be a tremendous asset.
Thanks,
Louis
10 Jun
10 Jun
8:45 a.m.
New subject: EPROM replacement and other helpful hints, was Re: IMSAI EPROMS
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10:32 a.m.
New subject: EPROM replacement and other helpful hints, was Re: IMSAI EPROMS
top 3 address lines (A10--A12). Assuming you burn the
code into the
lowest 1K locations of the EPROM ,then simply connect those 'extra'
address lines to ground. That will mean only the bottom 1K of the EPROM
is ever accessed which is what you want.
I would be tempted to use a dip switch, then you could dump a bunch of code
and bank switch it.
10:45 a.m.
New subject: EPROM replacement and other helpful hints, was Re: IMSAI
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11:26 a.m.
New subject: IRC
There's been a discussion of labour/management relations on Rovernet, and
this has led to the Industrial Recovery Corporation.
Does anyone know if the IRC meddled with the British computer industry,
as they did with the motor industry?
11:35 a.m.
New subject: EPROM replacement and other helpful hints, was Re: IMSAI
My own approach would probably be different, i.e. I'd attempt to use the board
itself, but minimize the amount of hardware required to make it work. If the
board was intended to be used as an 8K board, I'd have to decide whether to make
it into a 64K board or to leave it as an 8K board, but since, in the original
poster's case, it was an 8K (?) board with 1K devices he couldn't conveniently
program, I'd say he'll be happy with an 8K board when he's done.
My own preference would be for using a single site and putting either an 8K
EPROM or BBRAM (with a physical switch on the nWrite line) in that site and
being done with it. Once you have the board, the BBRAM is the way to go, since
you don't really need a programmer.
BTW, 2716-compatible BBRAMs are quite common, though the 2716's are less so.
Dick
----- Original Message -----
From: "Tony Duell" <ard(a)p850ug1.demon.co.uk>
To: <classiccmp(a)classiccmp.org>
Sent: Sunday, June 10, 2001 1:45 PM
Subject: Re: EPROM replacement and other helpful hints, was Re: IMSAI
Sure, I was trying to keep it simple for the non-electronics-experts here.
If you're going to us a DIP switch, then the best way to do it is to wire
one section of the DIP swtich between an 'extra' address line and ground.
Connect a 10k resistor (or thereabouts, this is not critical) between the
'extra' address line and +5V. You will need a DIP switch with at least 3
on/off (form A, SPST) sections (get a 4 section one and ignore the last
switch) and 3 10k resistors.
Then you have have 8 1K blocks of code in the 2764, and select them using
the DIP switch. It means you can have 8 attempts at writing the code
before you have to erase the EPROM.
But if you're just trying to replace a 2708, and you have the code and
you know it works, you don't need to bother with this. Stick the code in
the first 1024 locations of the 2764 and tie A10, A11 and A12 to ground.
-tony
top 3 address lines (A10--A12). Assuming you burn
the code into the
lowest 1K locations of the EPROM ,then simply connect those 'extra'
address lines to ground. That will mean only the bottom 1K of the EPROM
is ever accessed which is what you want.
I would be tempted to use a dip switch, then you could dump a bunch of code
and bank switch it. 
12:38 p.m.
New subject: sync on green to horizontal and vertical wiring seperator.
Hi!
This is getting frustrating.
This is fairly on topic because I run older Macs (1987 to 1991, and
many nubus video cards) that does not have native separate syncs by
design. I'm using a very dim Mac high resolution monitor. If
adjusted brighter, it will lose sharpness. It's already adjusted
perfectly and this doesn't helped. That's bad tube, caps that I can
check with my ESR are replaced already.
This is killing my eyes staring at that dim monitor bought about this
thinking to solve that problem because finding decent monitors with
sync on green and composite features that does have good tube is
getting harder to find. I do have a semi-working Nec 3D but tube is
real small! And at other extreme, I have 20" Nec monitor but I'm not
gonna drag that thing here. HUGE and power hungry.
Except I have this dead 17" with all this features is IDEK Liyama
waiting for schematic but that will be long awhile till I have money.
The important details I need is fusiable resistors, they blew and
cooked off the numbers completely.
But I might have one or two monitors I might able to extract certain
IC to split the sync out to drive a peecee monitors which are in
plenty around here.
Otherwise if there a way to build that thing from scratch is nice.
Cheers,
Wizard
10:49 p.m.
New subject: sync on green to horizontal and vertical wiring seperator.
On 10 Jun, jpero(a)sympatico.ca wrote:
But I might have one or two monitors I might able to
extract certain
IC to split the sync out to drive a peecee monitors which are in
plenty around here.
Otherwise if there a way to build that thing from scratch is nice.
You can use a
LM1881 to separate syncs from the green signal. Have a
look at the natsemi web site:
http://www.national.com/search/search.cgi/main?keywords=lm1881&GO.x=8&a…
At the other side: Most modern PeeCee monitors can do sync on green.
But have a look into the manual bevore you by...
--
tsch??,
Jochen
Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/
11:44 p.m.
New subject: sync on green to horizontal and vertical wiring seperator.
This is getting frustrating.
This is fairly on topic because I run older Macs (1987 to 1991, and
many nubus video cards) that does not have native separate syncs by
I finally in just the last 6 months or so have bought a couple real Griffin
Technology mac video adapters, and it is just so sweet to be able to plug a
monitor in and have it work right off. The only other adapter I have that
comes close is some old Belkin with a dial, but it isn't 100% all the time
and so far the Griffin is.
11 Jun
11 Jun
6:37 a.m.
New subject: PDP 8/e Help - File Transfer
Hi, all,
I have a PDP-8E system with 24K (2x8K core, 8K DRAM), RK8E with two RK05's,
RX01 8" floppy drive system, and a paper tape reader/punch (the reader
needs work). I'm running OS/8 V3D.
It was working perfectly for the longest time, then, very suddenly when
accessing either RK05 drive, I get errors that are kind of strage.
I don't get I/O errors, but errors appear to be corruption of data, e.g.,
a stuck bit or the like. Doing a DIR on a drive gives an invalid directory
error rather than an I/O error. So, whatever is happening, the data seems
to be coming off the drive OK (no CRC errors or other drive errors), but in
the process of getting dumped into memory, it gets messed up.
The machine boots up just fine off RX01 and runs beautifully, and completely
reliably. Based on this, it appears that the problem is likely in the
RK8E controller.
On the RK05's, I've got KERMIT and ENCODE/DECODE, which made it easy to
get programs off of a PC onto the 8/e. However, since I can't talk to the
RK05's, I don't have access to these anymore. I don't have copies of these
programs available on floppy.
I need to somehow get the MAINDEC RK8E diagnostic loaded onto the machine
to try to see what is going on with the disk controller.
I need a simple way to transfer the binary image of the paper-tape
version of the diagnostic from a DOS PC to the 8/e, without having
to toggle in a big program.
Any ideas?
Thanks,
Rick Bensene
The Old Calculator Web Museum
http://www.geocities.com/oldcalculators
7:34 a.m.
New subject: PDP 8/e Help - File Transfer
See: http://highgate.comm.sfu.ca/pdp8/
The Software section contains wehat you need. The dump and restore utilities
contain programs for downloading files from PC to PDP 8/E, and you can
also use the send.c and rim.c programs if you want.
-Lawrence LeMay
[ Charset ISO-8859-1 unsupported, converting... ]
Hi, all,
I have a PDP-8E system with 24K (2x8K core, 8K DRAM), RK8E with two RK05's,
RX01 8" floppy drive system, and a paper tape reader/punch (the reader
needs work). I'm running OS/8 V3D.
It was working perfectly for the longest time, then, very suddenly when
accessing either RK05 drive, I get errors that are kind of strage.
I don't get I/O errors, but errors appear to be corruption of data, e.g.,
a stuck bit or the like. Doing a DIR on a drive gives an invalid directory
error rather than an I/O error. So, whatever is happening, the data seems
to be coming off the drive OK (no CRC errors or other drive errors), but in
the process of getting dumped into memory, it gets messed up.
The machine boots up just fine off RX01 and runs beautifully, and completely
reliably. Based on this, it appears that the problem is likely in the
RK8E controller.
On the RK05's, I've got KERMIT and ENCODE/DECODE, which made it easy to
get programs off of a PC onto the 8/e. However, since I can't talk to the
RK05's, I don't have access to these anymore. I don't have copies of these
programs available on floppy.
I need to somehow get the MAINDEC RK8E diagnostic loaded onto the machine
to try to see what is going on with the disk controller.
I need a simple way to transfer the binary image of the paper-tape
version of the diagnostic from a DOS PC to the 8/e, without having
to toggle in a big program.
Any ideas?
Thanks,
Rick Bensene
The Old Calculator Web Museum
http://www.geocities.com/oldcalculators
12:20 a.m.
New subject: sync on green to horizontal and vertical wiring seperator.
The place to look for the signals isn't in the monitor, but on the video
generation circuitry. If there's a horizontal and vertical sync available
anywhere in your video generation circuitry, you'll want to measure their
durations and frequencies, as well as polarity. There may not be separate sync
at all if it's generated as composite sync in some specialized IC. That's
adequate for sync-on green, but if you want to attach a PC monitor you'll have
to go to some trouble.
You can generate the negative-going sync most easily by using a negative supply.
If you use a current mirror controlled current sink that pulls the 75-ohm
resistance to ground down by half a volt or maybe 3/4 volt, and then use a
diff-amp made from a couple of transistors to switch the sync on and off, you
can get negative sync from one transistor or the other's collector. Clamp the
base of one (depending on the polarity of your sync) to gnd with a schottky with
about 0.3 volts forward voltage, and limit the current at that base with yet
another transistor also controlled by the current mirror, such that the voltage
at the base of these transistors ranges from as high as the clamp will allow, to
about the same amount below gnd, by limiting the current from the sync signal,
with a resistor, typically 1K-ohms. attach the appropriate transistor in the
diff-amp to the green video. Set the current in the transistor that sinks the
current from the diff-amp to such that the sync voltage is about half a volt
below ground. If you need more details, let me know. I normally use VERY fast
transistors in a 5-transistor array (CA3127/3227) to do all this. A CA3183
would probably also do the job, but I like the sharp edges the UHF array
produces.
Dick
----- Original Message -----
From: <jpero(a)sympatico.ca>
To: <classiccmp(a)classiccmp.org>
Sent: Sunday, June 10, 2001 3:38 PM
Subject: sync on green to horizontal and vertical wiring seperator.
Hi!
This is getting frustrating.
This is fairly on topic because I run older Macs (1987 to 1991, and
many nubus video cards) that does not have native separate syncs by
design. I'm using a very dim Mac high resolution monitor. If
adjusted brighter, it will lose sharpness. It's already adjusted
perfectly and this doesn't helped. That's bad tube, caps that I can
check with my ESR are replaced already.
This is killing my eyes staring at that dim monitor bought about this
thinking to solve that problem because finding decent monitors with
sync on green and composite features that does have good tube is
getting harder to find. I do have a semi-working Nec 3D but tube is
real small! And at other extreme, I have 20" Nec monitor but I'm not
gonna drag that thing here. HUGE and power hungry.
Except I have this dead 17" with all this features is IDEK Liyama
waiting for schematic but that will be long awhile till I have money.
The important details I need is fusiable resistors, they blew and
cooked off the numbers completely.
But I might have one or two monitors I might able to extract certain
IC to split the sync out to drive a peecee monitors which are in
plenty around here.
Otherwise if there a way to build that thing from scratch is nice.
Cheers,
Wizard
8:27 a.m.
New subject: sync on green to horizontal and vertical wiring seperator.
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9:03 a.m.
New subject: sync on green to horizontal and vertical wiring seperator.
From: ard(a)p850ug1.demon.co.uk (Tony Duell)
Subject: Re: sync on green to horizontal and vertical wiring seperator.
To: classiccmp(a)classiccmp.org
Date: Mon, 11 Jun 2001 18:27:07 +0100 (BST)
Reply-to: classiccmp(a)classiccmp.org
Before you give up, 2 checks..
1) Is the EHT voltage correct _and stable when you increase the
brightness_. You didn't mention the picture also got larger as the
brightness was turned up (a common symptom of EHT problems), but it's
still worth checking.
No expanding when I change brightness, very stable. But items would
grow colorful trails to the right if I broost too much gain or screen
on each gun, it has set of 2 pots for each R, G, B guns. But this is
not the problem apprently.
2) Try boosting the heater a bit. If there's a
resistor in series with
the CRT heater, reduce it or short it out. If the heater supply comes
from its own regulator, try tweaking it up a bit. If you can do neither
of those, disconnect the existing heater supply and try running the
heater from 3 (or so) turns of wire wound round the flyback core. Every
6.3V CRT heater I've tried will stand 8V at least. This may not help, but
it might get you a couple more months out of an old CRT
I'll try that. I already have traced the wiring for that heater, it
leads directly from fly to the heater. I think there is a disc cap
and a resistor. Have to open it up and look again. It's very
service-friendly monitor, RF shield snaps off to expose the CRT
board, main board swings out on pair of plastic hinges. Well built
monitor, heavily shielded. Only difference on this monitor both
screen and focus is on seperate circuit board not on fly itself.
Doesn't the heater demands lot of current flow?
Doesn't this monitor can be affected by too low voltages for B+
power?
But I might have one or two monitors I might able
to extract certain
IC to split the sync out to drive a peecee monitors which are in
plenty around here.
Otherwise if there a way to build that thing from scratch is nice.
Get the data sheet on the National Semiconductor LM1881 (or the Elantec
version that's a bit better). It's an 8 pin chip that's a video sync
separator. That should be able to pull the sync off the sync-on-green signal
(which after all is electically the same as a composite mono signal).
-tony
2:50 p.m.
New subject: sync on green to horizontal and vertical wiring seperator.
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1:43 p.m.
New subject: sync on green to horizontal and vertical wiring seperator.
From: ard(a)p850ug1.demon.co.uk (Tony Duell)
Subject: Re: sync on green to horizontal and vertical wiring seperator.
To: classiccmp(a)classiccmp.org
Date: Tue, 12 Jun 2001 00:50:03 +0100 (BST)
Reply-to: classiccmp(a)classiccmp.org
If it comes from the flyback anyway. try winding a couple more turns
round the flyback core and putting them in series with the existing
heater supply winding. One way will reduce the heater voltage (and may
even cause the screen to go blank), the other way will boost it.
Tony,
Got right direction of turns first try, Just two turns too much!
Got nice bright orange glow like electric stove coil on full without
pot sitting on it and bright raster lines! Whoa.
Will try one turn even just a pass through.
Normally about 6.3V at 1A for a colour CRT IIRC.
1 amp!? No wonder I see dust beard tracing out that heater traces.
Cheers,
Wizard
2:07 p.m.
New subject: Heater boosting update.
From:
ard(a)p850ug1.demon.co.uk (Tony Duell)
Subject: Re: sync on green to horizontal and vertical wiring seperator.
To: classiccmp(a)classiccmp.org
Date: Tue, 12 Jun 2001 00:50:03 +0100 (BST)
Reply-to: classiccmp(a)classiccmp.org
If it comes from the flyback anyway. try winding a couple more turns
round the flyback core and putting them in series with the existing
heater supply winding. One way will reduce the heater voltage (and may
even cause the screen to go blank), the other way will boost it.
Tony,
Got right direction of turns first try, Just two turns too much!
Got nice bright orange glow like electric stove coil on full without
pot sitting on it and super-bright raster lines! Whoa.
Will try one turn even just a pass through.
12 Jun
12 Jun
1:11 p.m.
New subject: Heater boosting update.
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1:06 p.m.
New subject: sync on green to horizontal and vertical wiring seperator.
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11 Jun
11 Jun
9:16 a.m.
New subject: sync on green to horizontal and vertical wiring seperator.
If you establish that the LM1881 can do this little job at the frequency at
which the monitor operates, please share details with me. I've used the LM1881
in the past, but only in connection with NTSC video.
Dick
----- Original Message -----
From: "Tony Duell" <ard(a)p850ug1.demon.co.uk>
To: <classiccmp(a)classiccmp.org>
Sent: Monday, June 11, 2001 11:27 AM
Subject: Re: sync on green to horizontal and vertical wiring seperator.
Hi!
This is getting frustrating.
This is fairly on topic because I run older Macs (1987 to 1991, and
many nubus video cards) that does not have native separate syncs by
design. I'm using a very dim Mac high resolution monitor. If
adjusted brighter, it will lose sharpness. It's already adjusted
perfectly and this doesn't helped. That's bad tube, caps that I can
check with my ESR are replaced already.
Before you give up, 2 checks..
1) Is the EHT voltage correct _and stable when you increase the
brightness_. You didn't mention the picture also got larger as the
brightness was turned up (a common symptom of EHT problems), but it's
still worth checking.
2) Try boosting the heater a bit. If there's a resistor in series with
the CRT heater, reduce it or short it out. If the heater supply comes
from its own regulator, try tweaking it up a bit. If you can do neither
of those, disconnect the existing heater supply and try running the
heater from 3 (or so) turns of wire wound round the flyback core. Every
6.3V CRT heater I've tried will stand 8V at least. This may not help, but
it might get you a couple more months out of an old CRT
But I might have one or two monitors I might able
to extract certain
IC to split the sync out to drive a peecee monitors which are in
plenty around here.
Otherwise if there a way to build that thing from scratch is nice.
Get the data sheet on the National Semiconductor LM1881 (or the Elantec
version that's a bit better). It's an 8 pin chip that's a video sync
separator. That should be able to pull the sync off the sync-on-green signal
(which after all is electically the same as a composite mono signal).
-tony
9:31 a.m.
New subject: sync on green to horizontal and vertical wiring seperator.
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10:52 a.m.
New subject: sync on green to horizontal and vertical wiring seperator.
On 11 Jun, Tony Duell wrote:
[LM1881]
And I think that at least the Eleantec version can
handle the
sync rates of (at least) VGA monitors,
From the features section of the National Semiconductor LM1881 data
sheet:
Horizontal scan rates to 150kHz
--
tsch??,
Jochen
Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/
12:06 p.m.
New subject: sync on green to horizontal and vertical wiring seperator.
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8:46 a.m.
New subject: sync on green to horizontal and vertical wiring seperator.
From: ard(a)p850ug1.demon.co.uk (Tony Duell)
Subject: Re: sync on green to horizontal and vertical wiring seperator.
To: classiccmp(a)classiccmp.org
Date: Mon, 11 Jun 2001 22:06:25 +0100 (BST)
Reply-to: classiccmp(a)classiccmp.org
On 11 Jun, Tony Duell wrote:
[LM1881]
Which would seem to be fast enough for any normal PC or Mac monitor.... And I think that at least the Eleantec version
can handle the
sync rates of (at least) VGA monitors,=20
From the features section of the National Semiconductor LM1881 data
sheet:
Horizontal scan rates to 150kHz
-tony
2:46 p.m.
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2:40 p.m.
New subject: sync on green to horizontal and vertical wiring seperator.
Hi!
My (modern) Mitsubishi Diamond Pro 21TX accepts both Sync-on-green
and separate sync. I suspect that most PC monitors with BNCs will
do the same.
Clint
On Sun, 10 Jun 2001 jpero(a)sympatico.ca wrote:
Hi!
This is getting frustrating.
This is fairly on topic because I run older Macs (1987 to 1991, and
many nubus video cards) that does not have native separate syncs by
design. I'm using a very dim Mac high resolution monitor. If
adjusted brighter, it will lose sharpness. It's already adjusted
perfectly and this doesn't helped. That's bad tube, caps that I can
check with my ESR are replaced already.
This is killing my eyes staring at that dim monitor bought about this
thinking to solve that problem because finding decent monitors with
sync on green and composite features that does have good tube is
getting harder to find. I do have a semi-working Nec 3D but tube is
real small! And at other extreme, I have 20" Nec monitor but I'm not
gonna drag that thing here. HUGE and power hungry.
Except I have this dead 17" with all this features is IDEK Liyama
waiting for schematic but that will be long awhile till I have money.
The important details I need is fusiable resistors, they blew and
cooked off the numbers completely.
But I might have one or two monitors I might able to extract certain
IC to split the sync out to drive a peecee monitors which are in
plenty around here.
Otherwise if there a way to build that thing from scratch is nice.
Cheers,
Wizard
4:43 p.m.
New subject: sync on green to horizontal and vertical wiring seperator.
On Mon, Jun 11, 2001 at 05:40:03PM -0600, Clint Wolff (VAX collector) wrote:
My (modern) Mitsubishi Diamond Pro 21TX accepts both Sync-on-green
and separate sync. I suspect that most PC monitors with BNCs will
do the same.
isn't that an oxymoron? PC generally don't use BNC. :)
-brian
7:30 p.m.
New subject: sync on green to horizontal and vertical wiring seperator.
My (modern)
Mitsubishi Diamond Pro 21TX accepts both Sync-on-green
and separate sync. I suspect that most PC monitors with BNCs will
do the same.
isn't that an oxymoron? PC generally don't use BNC. :)
9:29 p.m.
New subject: sync on green to horizontal and vertical wiring seperator.
On Mon, Jun 11, 2001 at 09:30:59PM -0700, Mike Ford wrote:
Its the rage again, all the really hot new monitors have BNC (as well as
normal SVGA HD15).
i've noticed in the past that the higher end monitors came with BNC and HD15,
but those would generally be classified as workstation monitors, not PC tubes.
(more because of price than anything else, not in the pricerange of your average
home buyer)
is BNC really back? on PC monitors? why? are there PC video cards with BNC?
if so, what is this world coming to? :)
-brian
12 Jun
12 Jun
10:02 a.m.
New subject: sync on green to horizontal and vertical wiring seperator.
i've noticed in the past that the higher end
monitors came with BNC and HD15,
but those would generally be classified as workstation monitors, not PC tubes.
(more because of price than anything else, not in the pricerange of your
average
home buyer)
is BNC really back? on PC monitors? why? are there PC video cards with BNC?
if so, what is this world coming to? :)
No PC cards I have seen yet have BNC, but plenty of larger monitors have
BNC and people claim at least that it makes a big improvement. The PC
monitor market is EXTREMELY competitive right now, prices dropping and
everybody scrambling to keep market share, so any feature is quickly
adopted.
Component video is also hot in home video, so people are identifying BNC
with "high end".
5:01 p.m.
New subject: sync on green to horizontal and vertical wiring seperator.
High-end monitors typically do, probably because they also
support sync-on-green, and can be used with a variety of systems.
clint
On Mon, 11 Jun 2001, Mike Ford wrote:
Its the rage again, all the really hot new monitors have BNC (as well as
normal SVGA HD15).
My (modern) Mitsubishi Diamond Pro 21TX accepts both
Sync-on-green
and separate sync. I suspect that most PC monitors with BNCs will
do the same.
isn't that an oxymoron? PC generally don't use BNC. :)
9 Jun
9 Jun
5:41 p.m.
Oddly enough, I don't believe I've ever had anything that required 2708's,
though several of my old Multibus boards use them if one wishes. 2716's and
later were obviously the part of choice. At least one of my old S-100
programmers handles 2708's, but, in spite of that, and in spite of the fact I've
held onto a supply of the things for years, I've never had to use one.
Dick
----- Original Message -----
From: "Tony Duell" <ard(a)p850ug1.demon.co.uk>
To: <classiccmp(a)classiccmp.org>
Sent: Saturday, June 09, 2001 4:05 PM
Subject: Re: IMSAI EPROMS
Tony Duell wrote:
Well, _I_ certainly do, but then I'm not the person who can't program
2708s :-). I think at least one my programmers can manage those, and
maybe even the 2704 (512*8, otherwise similar to the 2708).
However, even though I can program them, blank 2708s are getting hard to
find over here, so it's nice to have a way to use easy-to-get cheap parts.
-tony
2764s are available everywhere and are cheap. And _every_ modern
programmer can handle them (I've seen a few programmers that can
handle nothing smaller than the 2764).
Heh heh. Don't we all collect classic programmers as well? 
10 Jun
10 Jun
8:38 a.m.
New subject: Uniform (?) for Kaypro 2
Greetings,
I recall back in my FOG days that I used to go to meetings and copy
diskettes from the library with a Kaypro. I vaguely recall that the
program for doing the conversions from Osborne (and many others)
was done with a package called Uniform.
It's possible my memory is corrupt. (Or maybe just my mind! =)
At any rate, can anyone provide me a copy? It'll make it easier to
convert stuff on my Osborne diskettes to something my C128 can
read.
As always, I'm prepared to compensate for time, disk, shipping, etc.
Thanks...
Anthony Clifton
Des Moines, Iowa
8:49 a.m.
New subject: OT: looking for an adapter
I've recently developed a need for an adapter from the "ultra-high-density"
connector used as the external port on MYLEX RAID controllers to the standard
WIDE (68-conductor) or even NARROW (50-conductor) cables used for SCSI devices.
Do any of you guys know of a reasonable source of, say, USED but functional
cables of this sort? They don't come with the controller and MYLEX wants the
price of a small country for one.
thanks,
Dick
9:38 a.m.
New subject: OT: looking for an adapter
On 10 Jun 2001 11:49:43 -0600, Richard Erlacher wrote:
I've recently developed a need for an adapter from
the "ultra-high-density"
connector used as the external port on MYLEX RAID controllers to the standard
WIDE (68-conductor) or even NARROW (50-conductor) cables used for SCSI devices.
Do any of you guys know of a reasonable source of, say, USED but functional
cables of this sort? They don't come with the controller and MYLEX wants the
price of a small country for one.
What you're looking for is a VHDCI to 68-pin SCSI cable. You can do a
search
of the normal purveyors for "VHDCI" and should find what you're looking
for.
Jeff
10:01 a.m.
New subject: OT: looking for an adapter
I've recently developed a need for an adapter from
the "ultra-high-density"
connector used as the external port on MYLEX RAID controllers to the standard
WIDE (68-conductor) or even NARROW (50-conductor) cables used for SCSI devices.
Do any of you guys know of a reasonable source of, say, USED but functional
cables of this sort? They don't come with the controller and MYLEX wants the
price of a small country for one.
I've bought some from a local guy. He usually has some listed on
eBay, but you could try asking him direct. The 68-pin connector on
the other end is a right-angle connector. His email address is
denton(a)orison.dsserv.com and his name is Clay. I can't remember what
I paid for them, but it was reasonable.
If you're not in the US this probably won't help.
--
Eric Dittman
dittman(a)dittman.net
10:20 a.m.
New subject: OT: looking for an adapter
I'm amazed at the range over which the prices of these cables vary. I've found
(via google.com) 3' cables with the VHDCI connector at one end and the normal HD
68-pin at the other, for prices ranging from $178 to $35. Surely there's some
difference other than quality, though it's not obvious from the posted
information.
Dick
----- Original Message -----
From: "Eric Dittman" <dittman(a)dittman.net>
To: <classiccmp(a)classiccmp.org>
Sent: Sunday, June 10, 2001 1:01 PM
Subject: Re: OT: looking for an adapter
> I've recently developed a need for an adapter
from the "ultra-high-density"
> connector used as the external port on MYLEX RAID controllers to the
standard
> WIDE (68-conductor) or even NARROW (50-conductor)
cables used for SCSI
devices.
> Do any of you guys know of a reasonable source
of, say, USED but functional
> cables of this sort? They don't come with the controller and MYLEX wants
the
price of a
small country for one.
I've bought some from a local guy. He usually has some listed on
eBay, but you could try asking him direct. The 68-pin connector on
the other end is a right-angle connector. His email address is
denton(a)orison.dsserv.com and his name is Clay. I can't remember what
I paid for them, but it was reasonable.
If you're not in the US this probably won't help.
--
Eric Dittman
dittman(a)dittman.net
8:57 a.m.
New subject: Uniform (?) for Kaypro 2
It's possible my memory is corrupt. (Or maybe just
my mind! =)
You're correct...I've got the DOS version of Uniform running
on my IBM 5155.
At any rate, can anyone provide me a copy? It'll
make it easier to
convert stuff on my Osborne diskettes to something my C128 can
read.
I don't believe Uniform will do C128 disks as, if I remember
correctly, they used GCR for the encoding. I know it will do Osborne
and a host of other's though.
Jeff
--
Collector of Classic Microcomputers and Video Game Systems:
Home of the TRS-80 Model 2000 FAQ File
http://www.geocities.com/siliconvalley/lakes/6757
10:18 a.m.
New subject: Uniform (?) for Kaypro 2
IIRC, doesn't CP/M on the 128 read several formats of disk?? possibly
kaypro format being one (i could be mistaken)
At 01:57 PM 6/10/01 -0400, you wrote:
It's
possible my memory is corrupt. (Or maybe just my mind! =)
You're correct...I've got the DOS version of Uniform running on
my IBM 5155.
At any rate, can anyone provide me a copy?
It'll make it easier to
convert stuff on my Osborne diskettes to something my C128 can
read.
I don't believe Uniform will do C128 disks as, if I remember
correctly, they used GCR for the encoding. I know it will do Osborne and
a host of other's though.
Jeff
--
Collector of Classic Microcomputers and Video Game Systems:
Home of the TRS-80 Model 2000 FAQ File
http://www.geocities.com/siliconvalley/lakes/6757
11:45 a.m.
New subject: Uniform (?) for Kaypro 2
IIRC, doesn't CP/M on the 128 read several formats
of disk?? possibly
kaypro format being one (i could be mistaken)
It does *if* you have a 1571 disk drive. Commodore 1571 drives are dual
MFM and GCR beasts, and can read a multitude of double-density formats.
With proper programming, they can even read FAT.
Commodore CP/M 3.0 disks are natively GCR to allow them to boot from a 1541
as well. However, Commodore CP/M 3.0 is kind of pointless without a 1571 --
with it you have access to the whole CP/M software library in native formats
like Kaypro and others.
CP/M 2.2 for the 64 is GCR only and requires that dumb and flaky Z80 CPU
cartridge. Avoid. Use Commodore CP/M Plus 3.0 on the 128 and you'll love
life better. :-)
--
----------------------------- personal page: http://www.armory.com/~spectre/ --
Cameron Kaiser, Point Loma Nazarene University * ckaiser(a)stockholm.ptloma.edu
-- Funk is its own reward. -- George Clinton ----------------------------------
11:02 a.m.
New subject: Uniform (?) for Kaypro 2
Oops. Ok, what I meant was that my C128 can read Kaypro but, if memory
servers, not Osborne and other useful formats.
However, upon further consideration, maybe my best bet would be simply
to put 22disk on a pc box with a nice old disk controller and just use it to
do conversions. =)
In either case, I'm sure I'm boring the list with my mental meanderings.
;)
Anthony Clifton
Des Moines, Iowa
It's
possible my memory is corrupt. (Or maybe just my mind! =)
You're correct...I've got the DOS version of Uniform running
on my IBM 5155.
At any rate, can anyone provide me a copy?
It'll make it easier to
convert stuff on my Osborne diskettes to something my C128 can
read.
I don't believe Uniform will do C128 disks as, if I remember
correctly, they used GCR for the encoding. I know it will do Osborne
and a host of other's though.
Jeff
--
Collector of Classic Microcomputers and Video Game Systems:
Home of the TRS-80 Model 2000 FAQ File
http://www.geocities.com/siliconvalley/lakes/6757
11:28 a.m.
New subject: Uniform (?) for Kaypro 2
Oops. Ok, what I meant was that my C128 can read
Kaypro but, if memory
servers, not Osborne and other useful formats.
It's been too long since I looked at the C128's CP/M to
remember what formats it supported. I do remember that I thought
Uniform was quite nifty and flexible though.
In either case, I'm sure I'm boring the list
with my mental meanderings.
Certainly was a legitimate question for the list, plus there
are a number of people here who have been using CP/M for quite a long
time.
Jeff
--
Collector of Classic Microcomputers and Video Game Systems:
Home of the TRS-80 Model 2000 FAQ File
http://www.geocities.com/siliconvalley/lakes/6757
11:45 a.m.
New subject: Trade for CP/M 2.2 disks and manual for Heath/Zenith
I found another yummy in the closet. It's the original ring binder, in fairly
good condition (no tears or rips), containing the documentation and original
diskettes for CP/M 2.2 for Heath/Zenith computers. I'm assuming it's for
the H89. It even has the original software license agreement, some addenda
and the Heath/Zenith insert in the front cover.
And here's my wish list of some things I'd like to trade for:
- Keyboard and Mouse for Mac Plus
- AppleCat Modem
- NetBSD complete and ready to install on my MicroVax II on TK50s
(I'll provide the TK50s if necessary)
I'm not sure of the value of what I have to offer equals the value of what
I'm asking for but, if not, I'm completely open to offers. I'm also open to
trades for green paper with past executive branch electees. =)
Thanks...
Anthony Clifton
Des Moines, Iowa
1:02 p.m.
New subject: Uniform (?) for Kaypro 2
On Sun, 10 Jun 2001, Anthony Clifton - Retrocomputing.com wrote:
Oops. Ok, what I meant was that my C128 can read Kaypro but, if memory
servers, not Osborne and other useful formats.
However, upon further consideration, maybe my best bet would be simply
to put 22disk on a pc box with a nice old disk controller and just use it to
do conversions. =)
Only if your Osborne disks are SSDD or your PC FDC is capable of single
density (FM).
- don
In either case, I'm sure I'm boring the list
with my mental meanderings.
;)
Anthony Clifton
Des Moines, Iowa
It's
possible my memory is corrupt. (Or maybe just my mind! =)
You're correct...I've got the DOS version of Uniform running
on my IBM 5155.
At any rate, can anyone provide me a copy?
It'll make it easier to
convert stuff on my Osborne diskettes to something my C128 can
read.
I don't believe Uniform will do C128 disks as, if I remember
correctly, they used GCR for the encoding. I know it will do Osborne
and a host of other's though.
Jeff
--
Collector of Classic Microcomputers and Video Game Systems:
Home of the TRS-80 Model 2000 FAQ File
http://www.geocities.com/siliconvalley/lakes/6757
9 Jun
9 Jun
1:12 p.m.
Yes, that's probably better and likely to remain useable for a long time, but I
was focused on the socket size. It's pretty easy to hack the board, but
building a daughterboard is somewhat more work than hacking the PCB. If wanting
a place to put a 27C512 (also 28-pins) is a problem, a mezzanine board on the
CPU socket might work, too. Then the EPROM board can be sold on eBay to a
"collector" who won't care what it is, and will pay enough to buy a new car
...
well, maybe a new card ...
Dick
----- Original Message -----
From: "Tony Duell" <ard(a)p850ug1.demon.co.uk>
To: <classiccmp(a)classiccmp.org>
Sent: Saturday, June 09, 2001 2:52 PM
Subject: Re: IMSAI EPROMS
>
> It's probably not a bad idea to modify the EPROM board to accept the
> single-supply (Intel-style) 2716, or even 2732. It's not difficult, and,
once
What I would do is make a little daughterboard to take a 27(C)64. It's
not hard -- most of the pins are in the same place (address, data,
ground), so it's not hard to do even using stripboard. That way you keep
the EPROM board original (although I probably would replace the EPROM
sockets with turned pin types).
24 pin EPROMS, even the 2716 anmd 2732 are getting hard to find in the
UK, and are somewhat expensive. 2764s are available everywhere and are
cheap. And _every_ modern programmer can handle them (I've seen a few
programmers that can handle nothing smaller than the 2764).
It may seem a waste to replace a 1K*8 chip with an 8K*8 chip, but that's
progress,,,,
-tony
8442
days inactive
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days old
51 comments
21 participants
participants (21)
-
ard＠p850ug1.demon.co.uk -
at258＠osfn.org -
bshannon＠tiac.net -
celigne＠tinyworld.co.uk -
dittman＠dittman.net -
donm＠cts.com -
edick＠idcomm.com -
geoffr＠zipcon.net -
jhellige＠earthlink.net -
jhingber＠ix.netcom.com -
jkunz＠unixag-kl.fh-kl.de -
jpero＠sympatico.ca -
jweder＠telusplanet.com -
lemay＠cs.umn.edu -
louiss＠gate.net -
mikeford＠socal.rr.com -
rickb＠bensene.com -
spectre＠stockholm.ptloma.edu -
vaxcat＠retrocomputing.com -
vaxman＠qwest.net -
wonko＠tmok.com