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Insight Enterprises Z80 SBC Powerup Attempt

falter

falter

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So as I mentioned in my MC1488 post I am trying to flash up this Insight Enterprises Z80 board I got a while back. There is not a lot of info about it - the company seems to have lasted less than a year. It is basically a Big Board type deal, but it was offered fully assembled rather than as a kit as far as I can tell, and had graphics, more RAM, etc. I am doing a video as I do this, mostly for my own benefit, although it will also appear on Youtube eventually. I'm finding as my collection gets bigger the space between use of machines gets longer and longer and I often forget what I did to get something unusual like this running.

Pics of the board are here, along with dumps of the ROM.
Google only turns up a few references, mostly ads and a mention in Microconucopia.

Since there is zero documentation, my strategy is as follows:

1) Backup the EPROM
2) Trace the four pin power connector
3) Trace out the video, in hopes of finding a composite out I can tap into.
4) Hook up power and monitor and see if we get anything.
5) Figure out how to connect a parallel ascii keyboard, which the ad says this machine can handle.

I've already done 1), and 2) seems pretty straightforward. I knew where +5V was on most 74xx devices, so I used my DMM to trace that to pin 1 of the connector. Ground you can see connected to the ground pin of those chips and to the ground plane that runs around the board, so that's pin 2. I made a guess that there wouldn't be -5V on a board this late, so the other two voltages had to be +12V and -12V, since we have serial I/O. I used my DMM and confirmed VEE on that MC1488 links to pin 3, and VCC to pin 4 of the power connector. So I think I've got that solved.

For the video, I'm using my experience from fixing up my Dynalogic Hyperion, which seems to use a similar design for video. There is a CRT8002 attributes controller, and if it's like the Hyperion when it's in text mode all the text has to pass through it and out the VID pin (pin 1). So I've been tracing that out and it does seem to land over where the video componentry is.. it runs through a 7486, 7406, some resistors, etc and then takes off halfway across the board. Haven't followed it the rest of the way yet. I strongly suspect J9 is where video comes out, given its proximity to the CRT controller, static video RAM and transistor. I don't see anything about colour, so I presume it's probably like the Ferguson - it might have some ground pins, composite out, and then horizontal and vertical sync for a monochrome TTL monitor. Figuring out which is which might be tricky for me but i'm looking at other similar designs for clues.

The keyboard is the tough one. I don't think the header for it is J1, J2 or J4.. those are 34 pin and I think are for floppy. I think J10, J11, J12 and J13 are serial related. J6 or J8 is probably SASI. J7 may be the fourth floppy controller. So I'm kind of dialed in on J5. If I'm right, the trick will be figuring out where the strobe and ASCII bit pins are.

I think my odds of getting this thing to even flash up are 50/50. Comparing the ad photo to this board, I can see the ICs are not in the same positions. I'm not sure if the ad photo is of a prototype that later got changed into what I have, or the other way around. I suspect the other way around because this board has a handwritten 'IE-118' serial number and a bunch of jumper wires. If it's a prototype, it may simply not work.

Powering it up successfully may be the best outcome I can hope for. One last reference I could find to Insight Enterprises is a list of software someone posted online, referring to Insight Enterprises CP/M. If this machine powers up expecting a boot disk, I'm probably hosed. If it has a system monitor I can drop into, then at least I can explore a bit that way. I presume hooking up a floppy and trying to boot, say, a Ferguson CPM disk probably won't work.

I'm not seeing any shorts in the board for power.. but I'm wondering if I could attempt powering up with just 5V connected to start. The -12v +12v thing makes me nervous, in case I've gotten something wrong.

Anyway, wish me luck :)
 
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Tadaaaaa...

https://drive.google.com/file/d/13qffSGIGGXKv8S1DMzXXQiwvPw18u3j7/view?usp=sharing

J9 is the video header. I followed from the VID pin on the attributes controller around and around until eventually I got back there. From there I connected ground to the ground wire coming from the monitor input, and then just went pin by pin until I found a composite signal for the video pin.

I don't know how much further I can go than that.. I've no idea how to determine the pins for the keyboard output. I have a hunch as to which header they are but no idea what is bit 1, 2 3 etc.

I'm not even sure you *could* do anything even if you had the keyboard sorted out -- it may simply be waiting for a boot disk that I don't have.
 
So I was looking at other designs last night, including the Ferguson board and it looks like they often use the Z80 PIO to handle keyboard input. I note on this board there is a lone header with some nice straight traces running to a 374 latch, and this all ends up at a nearby PIO.

So I feel like if I can find power pins on this header, J5, that would be the likely location of the keyboard input. And then I would just have to figure out where strobe is. Probably the individual data pins are arranged in some kind of order, so if I can figure out first and last it should be straight forward to figure out which bit is which.

I figure to test my theory that J5 is for keyboard, I just find the strobe, and then trigger it, probably by pulling it low, and see if the cursor reacts.
 
Okay so I *think* I'm on the right track to finding the keyboard connector, although it may not work the way I think it does.

So on header J5, I can find 7 pins exactly that go into a 74LS374 d type flip flop. HP1 (Header Pin) goes to 374 pin 18, HP 2 goes to 374 pin 3, HP3 goes to 374 pin 17, HP4 goes to 374 pin 4, HP9 goes to 374 pin 14, HP10 goes to 374 pin 7, and HP11 goes to 374 pin 13, which if I understand correctly are all inputs.

I don't see anything with my logic probe at those pins, obviously because no keyboard is connected. I would assume if I probed the OC pin on 374 it should be high, disabling outputs.

So the question is, does this work like I think it might: you would have your parallel ascii keyboard set up to bring KP/strobe low when you press a key, that would bring OC low, and then take whatever ASCII code the keyboard is outputting for that key and bounce it through the flipflop to whatever (probably a PIO chip) that interprets it for the computer?

I should note that on this same header J5 I have also found a ground pine, as well as +12V and +5V. I don't see -12V which would have been used in some parallel keyboard designs, but I'm guessing by 83 maybe they were down to single voltages? Anyway, seems coincidental that we've got all of these things lining up on this header.
 
Think I found the strobe pin.

I followed pin 5 from the J5 header to pin 13 of a 74LS86. I then followed pin 12, the other input of this ExOR gate, to a jumper marked T2. T2 is 3 pins. The top pin is connected to Ground. The bottom pin is connected to 5V.

If I understand how ExOR gates work, I think this jumper would sort of make sense as a means of determining if the type of strobe the keyboard is configured for is high going or low going. If you've got input A4 on the 7486 held low, the output Y4 will go high only if the input on B4 (pin 13,which is connected to suspected keyboard header J5 at pin 5) is high. Vice versa if T2 is connected to +5V. So depending what sort of strobe your keyboard uses, you set the jumper accordingly.

I think... I have a hard time explaining this stuff aloud but it sort of makes sense in my head.
 
Hello ! It is very nice to find that still there are some EQ4 computers out there. I still have my EQ4 Z-80 SBC, I bought it from Insight Enterprises on June 1983 (Serial Number IE-142) and used it for some years. For all those vintage hobbysts in this thread: I have the full original documentation from Insight Enterprises, including schematics in perfect condition, part list, and I also can provide the source code for the BIOS I wrote, and worked perfectly to boot with CP/M 2.2. No need to reverse engineer !! I Can post all this information for free on some shared folder.
 
Hello again. As I have posted yesterday, I have scanned the full EQ-4 documentation, including:

- EQ-4 Schematics (4 images)
- EQ-4 Brochure
- EQ-4 Hardware Configuration Guide (2 versions)
- EQ-4 Software Configuration Guide
- EQ-4 Update Sheet (like an errata)
- EQ-4 Chip list
- Disk Driver jumper configuration guide
- A firmware folder including some BIOS and ROMs I have written in 1984 for the EQ-4 to boot CP/M 2.2

All the documentation will be available for a few weeks at this Google Drive link:
https://drive.google.com/drive/folders/1Inx8MxXN1q8k6H118Yw6VNZvcsR2E5Mx?usp=sharing
In case of trouble downloading this material, please post here a comment.

As a return favor, please post at this forum your advances. Example: if you could boot CP/M on your EQ-4s. Thank you.
 
paggps said:
Hello again. As I have posted yesterday, I have scanned the full EQ-4 documentation, including:

- EQ-4 Schematics (4 images)
- EQ-4 Brochure
- EQ-4 Hardware Configuration Guide (2 versions)
- EQ-4 Software Configuration Guide
- EQ-4 Update Sheet (like an errata)
- EQ-4 Chip list
- Disk Driver jumper configuration guide
- A firmware folder including some BIOS and ROMs I have written in 1984 for the EQ-4 to boot CP/M 2.2

All the documentation will be available for a few weeks at this Google Drive link:
https://drive.google.com/drive/folders/1Inx8MxXN1q8k6H118Yw6VNZvcsR2E5Mx?usp=sharing
In case of trouble downloading this material, please post here a comment.

As a return favor, please post at this forum your advances. Example: if you could boot CP/M on your EQ-4s. Thank you.
Click to expand...

Thanks so much for doing this!! I have been tied up with work but definitely am going to have a look through this asap. Much appreciated!
 
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