I picked up a Z-120 from a local recycler here in Northern VA but it has a broken CRT (literally- the neck is broken; CRT ruined). It occurs to me that the Z100 might be a good candidate for replacing the CRT with an LCD. I know Norberto messed with this a bit on the H19 (without satisfactory results as I recall) but my thinking is that the Z100 might be more straightforward?
My idea is to pull the CGA signal off the video board (DB9 connector in back) and use a CGA converter like the GBS-8200 on mikesarcade.com. Does anyone on this list have thoughts on this pro or con? How easy might it be to find an LCD that would fit in the Z100 12” opening? It would be pretty cool to have a “color” Z100 all-in-one configuration! Is the connector on the back of the Z100 a fairly “standard” CGA connection?
Tx.
It's been almost forty years, but my recollection is that many of the video parameters may easily be reprogrammed in the CRTC. Things such as front/back porch, dot clock frequency, etc., are all programmed in the boot ROM. Look in the listing(s).
Don't know which operating system you intend to use, and I can't remember if MS-DOS reprograms things or not. Have no clue about CP/M, having known Barry, it probably reprograms everything, and I am given to understand that it doesn't use the (patented) magic hardware to increase character mode performance either.
It would also probably be pretty easy to change the fonts, etc., if a different character size worked better for your monitor, although I remember things to be 640 wide: 8x?. Height would be easy to change. I seem to remember using an NEC Multi-Sync with my Z100, which worked quite well. Don't remember using CGA signal though. We did higher resolution than CGA. I thought we did at least EGA, if not full VGA resolution. My memory is a bit fuzzy as to the specifics though.
We used NEC monitors in Zenith cases when initially showing the Z100. Zenith's first color monitor that we used for development was more TV than monitor. It was huge and wasn't in a cabinet. It sat in a lab on a wooden cart. I was always a bit concerned about electrocuting myself. It cackled quite a bit as I remember.
Mark's first implementation of Babu's first video design was a wire-wrap board, with at the wire wrap at least an inch thick on the back of the card. My recollection is that it worked first time--or close to it--which was good, as fixing a nest of wires that deep would have been a real job. Mark was pretty good, and Babu's initial design was a good starting point. We played with it quite a bit to add hardware so that we could optimize software performance of graphics and character display.
Although the Z100 proceeded VGA, the I remember VGA graphics to be architecturally very similar to what we did in the Z100--much closer than CGA.
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Yes it was the one with the blown CRT. They said that “it worked” … well maybe that was before someone broke the tube neck! Anyway they slowly lowered the price and once it got dirt cheap I decided to spring for it. This place is a local electronics recycler (Manassas, VA) that seems to get a lot of gov’t surplus equipment. This system apparently was used by the Air Force. I also picked up a terminal that was formerly NASA equipment.
The Z120 was filthy on the outside but is cleaning up nicely (household cleaners and a lot of elbow grease!). From the outside it looked like absolute junk but it’s actually turning out to be a pretty clean system (well except for the blown CRT!) Pics at:
https://photos.app.goo.gl/T9G4cWrUA8hYh2QE6
This morning I powered on the motherboard (with external monitor attached) and it came up fine! Passes the ROM-based keyboard and memory tests. Next to try the floppy controller -I’ll have to dig around for my copy of the Z100 test disk – it has some pretty comprehensive tests on it.
This machine also has a 256k RAM card and a hard disk/controller combo! I’m curious to see if the hard drive still works and (maybe even) boots!?
Thanks for the advice on the GBS-8200. If this system boots and looks promising I may steal the CRT from my other one (H120 that I built as a kit) just to continue making progress.
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Thanks Gregg! I agree there’s a ton of configurability in the hardware.
My reference to “CGA” was in response to this old posting from Barry Watzman on comp.os.cpm:
“disconnect the entire internal monitor, do this by disconnecting it's
power cable going to the deflection board on the left side of the
computer. The socket for an external CGA monitor (a DB-9 socket) is
already present and connected, you don't need to do anything. If you
want a composite TV signal, you will have to make up a cable (you may
even have to add a part or two and/or change some jumpers on the video
board). The Z-100 manuals, with schematics, are available online for
free downloading from several sites, with Howard Harte's site probably
being the best (I think it's www.s100-manuals.com or something close to
that) [I know, because I scanned and submitted them].
Barry Watzman
Former Product Line Director and architect of the Z-100”
To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/1536721155.81942864%40apps.rackspace.com.
The Military, Heathcare, and CNC Manufacturing industries still have CRT-based systems.
Thomas Electronics (Clyde, New York) supplies these industry segments with replacement CRTs.
They have a Chicago area facility, not far where original Zenith CRTs were mfg. (and 4 miles west of me).
https://www.thomaselectronics.com/manufacturers/#about_thomas
Thomas Electrinics
Addison, Illinois
330 S. LaLonde Ave.
Addison, IL 60101
P: 315-923-2051
F: 315-923-4401
BUT they have now migrated to LCD replacements.
http://www.omnivisionusa.com/index.html
Omni Vision Inc.
504 Congress Circle North. Unit B.
Roselle, IL 60172. USA.
PHONE: 1.630.893.1720
FAX:1.630.893.9991
Email: in...@omnivisionusa.com
The Z100 did higher resolution than CGA. My recollection is that CGA is essentially a composite specification, i.e. low resolution. I may remember wrong.
You must take some of Barry's comments with a grain of salt. (May he Rest In Peace.) He was not the architect of all (?or even most?) that was in the Z100. He wanted the 8085. He might have contributed the bank switching. Other than that, I would argue that Babu was really the architect of the Z100. Many of us contributed to Babu's design. Barry was definitely not the architect of the video subsystem. I worked with Babu and Mark as we figured it out.
My recollection is that the Z100 did have a composite video option, but you are better off interfacing to the non-composite video, it should be higher resolution. I am pretty sure that the NEC Multi-Sync, which I still have, was used with my Z100.
-----Original Message-----
From: "G. Beat" <gregor...@gmail.com>
Sent: Wednesday, September 12, 2018 10:56am
To: "SEBHC" <se...@googlegroups.com>
Subject: [sebhc] LCD replacement (Z100)
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Barry also wanted the S-100 bus.
-----Original Message-----
From: in...@esx.com
Sent: Wednesday, September 12, 2018 11:37am
To: se...@googlegroups.com
Subject: RE: [sebhc] LCD replacement (Z100)
I’ve gotten everything cleaned up on the Z120 I got from the recycle center. This morning I installed the 256K RAM card and it passes the built-in-ROM memory tests. Tonight I reconnected the hard drive and 5.25” floppy. From the boot ROM I can attempt to boot from either device and the activity lights come on. The hard drive sounds good but fails to boot, however this drive would certainly have been wiped at some point as this was an Air Force computer so perhaps it just needs to be initialized. I’ll look around for test disks and may even try to PREP/PART the hard drive. Still no CRT of course – I’m using an external monitor for now…
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Well the drive isn’t bootable but it seems responsive. I’m working on recreating a copy of the Winchester utilities disk so I can experiment to see if it’s still alive.
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For anyone interested I’ve finished my cleanup & initial restore of the Z120 I got from the recycle center. Pictures on my google photos album:
https://photos.app.goo.gl/T9G4cWrUA8hYh2QE6
(I’ve also included the shots from the original eBay posting so you can see where I started). These machines clean up nice! For now I just have black cardboard in for the CRT but you can envision how an LCD would look if/when I find a solution that works (and that I can afford!).
It passes most tests with flying colors! (there does appear to be a bad video RAM chip but I haven’t seen any problems with the display). The system has a minimal VRAM configuration so can only do monochrome at the moment.
Next step is to find or recreate the Winchester utilities disk so I can see if the hard drive is any good. Herb Johnson is helping with that…
Many of the CNC shops for automotive industry manufacturers ....
use the original monitor chassis / frame for their LCD retrofits.
https://youtu.be/wPTg-SpA12M
Repair Zone
Bill Hamilton, tech
615 Andre St
Bay City, MI 48706
Phone: 989-922-0043
Email: sup...@repairzone.com
Owned and Operated By York Repair, Inc.
If you could send me a floppy disk that would be great! I can get the IMD on line but don’t currently have a way to run ImageDsk to write out to a disk… can you contact me off line to follow up?
Where did you locate an ST-225? They seem to be available from a number of sources as “refurbished” – wonder what that really means? Surely not truly remanufactured…
If I can get the hard drive to function I’ll steal some hardware from the H120 I built years ago to get a fully functioning system… then I can follow in your footsteps (and perhaps help!)
Thanks.
From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Darrell Pelan
Sent: Wednesday, September 19, 2018 3:16 PM
To: SEBHC <se...@googlegroups.com>
Subject: Re: [sebhc] Re: LCD replacement (Z100)
Hi Glenn,
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Another update on my Z100 restoration. With Help from Darrell Pelan and Herb Johnson I was able to get the Winchester utilities and the version of the Z100 diagnostics that has the Winchester diag program on it. With that (and a few re-reads of the manuals plus some trial and error) I was able to get this Z-120 to PREP, PART and FORMAT the disk. I now have a bootable system! To try things out I loaded a version of CP/M-85:
https://photos.app.goo.gl/H6WC8tTUf7Hj4uME8
https://photos.app.goo.gl/5URJJU5gPazFFgVf8
I realize one has to worry about these old hard drives and how long they’ll last. This one seems pretty strong. I wonder if re-running “PREP” somehow rejuvenates the drive a bit?? it certainly identifies questionable/problematic sectors and locks them out (for fun I will take a look at the Bad Sectors table and see how many are locked out…)
Anyway, now I can figure out how I want to configure the system. I will probably steal components from other Z100s that I have to get the best overall setup.
Overall pictures of before, during and after are in my google photos album:
https://photos.app.goo.gl/T9G4cWrUA8hYh2QE6
Thanks to all but especially Darrell and Herb!
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Darrell: I’ve got the full set of CP/M-86 doc’s including the Winchester supplement information. In storage unit but I’m going by there later.. I’ll grab that.
From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Darrell Pelan
Sent: Monday, October 01, 2018 3:05 PM
To: se...@googlegroups.com
Subject: Re: [sebhc] Re: LCD replacement (Z100)
Hi Lee,
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BOOT217.CMD is actually a system image; it is not a program that can be executed from the command line.
CP/M-86 uses a command “LDCOPY” to copy the OS between disks (including from floppy to hard drive). Fortunately, it has help built in so LDCOPY ? should give you what you need.
I was able to create a bootable CP/M-86 partition by:
Creating a partition (using PART) called CPM86, then from CP/M-86 command prompt:
ASSIGN C:=CPM86
FORMAT … C:
LDCOPY … Source:A:BOOT217.CMD
PIP C:=A:*.*[RV]
Then to boot from Z100 ROM:
B <f3>:CPM86
From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Darrell Pelan
Sent: Monday, October 01, 2018 3:05 PM
To: se...@googlegroups.com
Subject: Re: [sebhc] Re: LCD replacement (Z100)
Hi Lee,
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