You might want to add a cheap Oscilloscope to your kit list. They make things like finding video pins far easier (just probe each pin without the need to switch off and on, video has a distinctive shape) and can help diagnose faulty chips (distorted logic signals etc).
I 2nd this entirely. For a video signal, 50 MHz should be enough. Even a used analog scope would be a GREAT help. With the caveat that analog scopes are getting long in the tooth, and you don't want yet another thing that you have to fix.
@@harrkev standard definition video (the kind that a machine like this puts out) runs to only 5 or 6MHz (look at the spacing between UHF channel numbers), even a 10 or 20MHz scope would be plenty. Thinking back to the video above, chances are that some of the extra pins on the connector were either HSync or VSync, so the reason he was having problems with the image location was that the monitor was seeing only the picture and mistaking the first character as VSync. A scope will show these regular sync pulses clearly.
I got myself a Rigol 1054Z and it basically earned its cost the first day I used it. I confirmed that the wrong chip was in a socket from the signal behaviour.
Yes get your self a period correct Tektronix. they are very reliable, and will fit in with your collection. Having a scope will make troubleshooting a lot easier. Check the signal quality and find that IC acting up, check clock and power signals etc. or like in this case just probe for the video out. Giveaway of the video out on this and many other boards is some discrete components. here the transistor and resistors. Video normally has an output impedance of 75 ohm, so look for resistors with a value close to that. in this case there is a 100 ohm to the output.
From Byte magazine 1983-12 page 576: Insight Enterprises EQ-4 The single-board EO-4 from Insight Enterprises is compatible with CP/M 2.2 and 3.0. It has virtual memory-mapping circuitry that lets the Z80A central processor and the DMA controller directly access 128K bytes of RAM, 2K bytes of EPROM, and 4K bytes of video memory in 8K-byte blocks. Interfaces incorporated into the EQ-4 include SASI, four serial RS-232C channels with independently programmable data rates ranging from 110 to 76,800 bps, a Centronics parallel printer, and floppy disk ports. The floppy-disk controllers can handle single- and double-density 5V4- and 8-inch drives si multaneously. CTC, DART, and PIO peripheral controllers are standard. The parallel keyboard input accommodates 7- or 8-bit ASCII-encoded boards with jumper-selectable active high and low strobes. Horizontal and vertical sync signals and composite video output compose EQ-4's video features. Standard Microsystems' 8002 video-display attributes controller provides the EQ-4 with an on-chip character generator, 128 characters in a 7- by 1 1-dot matrix, and character oriented, wide- and thinline graphics. Attributes supported for each character are reverse video, character blank, blink, underline, and strike-through. The single-unit price for the EQ-4 is S 750, which includes CBIOS, utilities, and source codes. Complete specifications are available from Insight Enterprises Corp., Suite 12, 373 North Western Ave., Los Angeles, CA 90004, (213) 461-3262. Circle 613 on inquiry card.
Wow ! A trip down memory lane for me. I was designing and building CPM based single board computers using the Z80 and the Z80A back in late 1970's. At the time I worked for a private company that was purchased by Exxon Enterprises. Exxon Enterprises also owned Zilog back then. So I downloaded your BIN file. But I'm going to have to find my "software tools" for reverse assembly. Just maybe we can make some sense out of this. Thanks for the video. Don
@@TechTimeTraveller I may not be the best person to work on this as I have not been into Z80 opcode since 1983. However: Looks like the EPROM starts at E000 with the stack around F980 and later moved to FCFF. The "main" routine is quite small at only 347 bytes. There are many subroutines. I have created a I/O reference list. I'll see if I can upload this somewhere. The code is somewhat reminiscent of the code required to run CP/M, where you ORG it into high memory. But I don't see the "vector" table required for CP/M, the list of vectors for the various routines that CP/M requires to run. More digging to follow.
@@dri50 Fantastic! Yeah personally I kind of wonder if this is a finished work or not. That's why I halted my efforts with the keyboard until I acquired for info on what exactly it is doing. It didn't make it into the video, but I did probe the FDC to see if it was trying to reach out to a floppy drive anywhere.. but nothing as far as I could determine.
It's interesting to note that the original design goals of the Big Board were very similar to the Arduino and Raspberry Pi projects of today, trying to put a computer in the hands of all sorts of experimenters. That's why it has the big prototyping area onboard.
If an I/O and memory map could be obtained for the board it would make it easier to determine what the disassembled ROM code is doing. The chip enable lines could be traced back to decoder chips and then see what address lines are fed to those chips.
I really hope someone does. I searched in vain for the names of company principals or designers hoping to reach out to them, but that info wasn't to be found. Have to hope someone with knowledge stumbles across this video and says 'Hey! I know that machine!'
In the early days of computing sometimes the keyboard had only 16 keys and a few extra. What was very comon back then was a matrix 8 by 8 wires and some pull-up resistors. Real ASCI keyboards came later.
I love the Z80. I think I might still have a disassember and compiler for it. I'll have to look. I have written a bit of Z80 assembly back on the '90s for a CNC machine tool. Managed to get it booting from a serial port instead of a cassette tape.
Just watched your video. Interesting board. In reading through the comments I did not see any reference to using a serial terminal connected to one of the DARTs. My Big Board I allows me to use the on board video with a parallel keyboard or attaching a serial terminal, like a DEC VT220, to serial port 0. I have built/assembled several Z80 based boards and the Z80 variants (example:HD64180) in the past. In some cases, a serial terminal was the only way to communicate with the board. In fact I have 5 Big Board I and 2 Xerox 820-I and 2 Xerox 820-II sitting around. I have my mystery board to work on as well. My son's friend was cleaning out an old business and uncovered a Z80 based machine. Several days after the discovery, he told my son. He called me immediately and I went over to the location. Sadly, they had pulled the boards out of the machine and put them in a box. The rest they tossed into the dumpster. So, I do not have any info except what is on the boards. The info on the boards is "Molecular Computer". Ever hear of them??? I haven't done much with them yet but they are on my list. Serial terminal will be my only choice.
G'day, I think a hunt for serial console on the nice obvious RS232 line drivers (1488/89) would have been my first point of call, then go down the hard path of the parallel keyboard etc. Love the stuff in your collection. Cheers.
So... being a little bored in Covid lockdown I started disassembling the eprom contents you linked to. I have the DART configuration code, found the Dart 1 channel A,B tx routines, initial relocation and setup of the interrupt mode 2 vector table etc. If I find anything really exciting I'll let you know. Pity you are on the other side of the world! Cheers.
23:28 that's why I love the Testofon - it converts measuring current to audio frequency in real time (since it's an ancient, super simple circuit). If I hold one probe to the pin in question and then check continuity, in a worst-case scenario I'd take 5 minutes to go through every pin on the entire board - I didn't count pins here, but I can measure 4-10 pins per second).
A counterpoint: embedded industrial controllers is a "hidden market" for which the Z80 was ideal, with the STD bus. Today's single chip systems are the evolution started with those single board computers running automation, highway signs, etc.
Thank you for mentioning that!! It didn't do it there the first couple times I ran through the video. They advertise that it'll do it at 'natural breakpoints'. Sigh. But thankfully I can adjust/remove it, and have. Appreciate the tip!
The meat of the Blue Kazak camel has a nutty cheesy flavour and is highly prized. It is usually dry aged in the desert for at least 60 days before consumption. Boiled in fermented mare's milk it is reserved for special occasions. Brutal wars have been fought to gain acquisition of the animal.
I had one of those, sold it and I'm glad I did. I never found any software that used the 128k due to non-standard bank switching. Maybe there was an MP/M but it was not included. You're on the mark with the decline of kit-computing. That was the reason Heathkit died: there was no savings to build-it-yourself.
I am not sure someone already said this in comments but I recommend a decent bench power supply like a siglent 3303. Not only can you dial in your bipolar voltages you can limit current its output making it less likely to smoke parts. Also you can very quickly spot bus power shorts right after power up. You may want to add a dedicated 5v supply with current display such as siglent 1168. Together these cost maybe $500 us but combined with a decent scope will probably become your most used bench tools. Along w a dvm They are for me.
So the keyboard input is just like a Centronics printer port going the other direction. Back then I built a very simple Centronics port with a 74257 because I thought a big PIA chip was overkill.
'data lines go to a missing 20 pin chip' screams 74ls244 or 245. check the pinoit of those to see which one makes sense. it also should match the surrounding logic families, probably. if everything else is 74HCxx, then use an HC244 or whatever
In marketing you never ask a question that’s probably why the ad did not work. You wanna tell them why they want this product. Give them a point of purchasing.
The First computer I ever got to play with was a Sinclair ZX80! in 1980, and a ZX81 the next! Timex/Sinclair was a British Timex offshoot or Sinclair used their PC under license... The ZX80 was named after the Zilog Z80 processor with the 'X' meaning "the mystery ingredient".
Thank you you the high compliment! I personally haven't reached a comfort level with asking people directly for money. I've no problems taking Google's money but I feel like the channel (ie. Me) has to prove itself before any steps towards direct funding are taken. Right now it is an enjoyable diversion for me - a way to connect with my creative side. If it turns into something larger then who knows. For now getting nice comments like these is reward enough.
I would love to know if you connected the SASI interface to a SCSI-1 hard drive whether it would work, as SCSI-1 was supposed to be backwards compatible with SASI
I looked thru the comments. there is a link in there going to a Google drive with a lot of documentation. including the keyboard Pinot and configuration. so are we going to see and update on this board. it's been a year?
It is in the pipeline. I was sent a full manual and I do plan to do a followup.. I have just been struggling to find a EQU CPM boot disk. Without that it still won't do much.
Great video! Subscribed now and will check out your other content. If a guy had a blank Big Board, do you suppose it's possible to build it at this point in history? When checking voltages, I might have pulled the socketed chips and checked power/ground at each socket before putting power to it.
A blank Big Board should be easy. There's nothing it uses that, to my knowledge is unobtainable today. I sort of thought about pulling the socketed chips but I figured I'd only be saving a few while frying the many anyway. :) Thanks for subscribing! Really appreciate it!
I don't know whether you noticed, but we are also seeing different prices. I believe we are seeing two different generations and capabilities... three counting yours.
Please invest in an oscilloscope. You can get good older ones on eBay for next to nothing, and the decent (i.e. with a real front end, not some $5 PC based thing) Chinese scopes are pretty respectable nowadays too. (Just noticed this video is from over a year ago, apologies if you already have.)
The letters and numbers you're seeing is because the values are counting up continuously in the EPROM contents. Looks like that was their choice of fill data most likely, so just unused space.
Cetronics typically only had 25 pins and usually only used about 20, as well. Willing to bet J1, J2, J4, and J7 are diskette drive controllers (By 1983 the Shugart interface was pretty well known), and that J6 and J8 are expansion bus headers. J5 is almost certainly the parallel port connector. J10, J11, J12, and J13 are all going to be serial ports. Considering I don't see another connector for a keyboard, it's possible they expect you to have a terminal connected to one of the serial ports and stick the video display on J9. Another heads up, ALL of these connectors will have at least one or two ground pins. A voltage is just a difference, and without a ground (0 volts), the 5 volts means nothing. Hunting for a video signal would be GREATLY aided with an oscilloscope. You should really consider one, it doesn't have to be perfect or even good, just enough to show you something. It will tell you immediately if you've got a clock signal, if your voltages are clean, and with a little bit of know how, it can trace out a video signal on a header like that in seconds with power applied. Another heads up, in the 1970s and 1980s, -12 volts was extremely common for memory! It was a very necessary bias voltage. When testing for composite video like this, ALWAYS put a capacitor in line with your video signal! This will prevent any DC bias getting to your display, which even at 5 volts would most likely damage it or the computer with a bang and a puff of smoke. God forbid at 12 or -12 volts! Composite video is generally
I would find it fascinating to take one of these and give it a thorough study to reverse engineer the schematic, though that would not. Be a quick or easy task.
@@TechTimeTraveller I would start by taking high-resolution photos of the top and bottom of the board, which might have to be stitched together from multiple shots with a large board like this. Import those into a drawing program that lets you draw on multiple layers, align them with each other. Mark out the position of all the components, pins, and thru vias, and then trace out all of the connections on each copper layer. The fact that this board has more than two layers will make this difficult, you may need to use a multimeter to verify the connections on the internal layers, but at least it doesn't seem to have much in the way of large opaque copper pours. Once you have the connectivity worked out you can start reorganizing that into a more legible schematic, broken down by functional blocks. The fact that this board seems to be made entirely from standard logic parts and is probably very similar in design to the Big Boards it was designed to compete with will help.
I do not think reverse engineering would be that hard as the chips are off the shelf. The main things to work out are the IO addresses and the how the RAM is bank switched.
As it happens, a fellow emailed me and he had a pretty complete set of docs he made available. I am going to review them and then will do a followup video hopefully with the machine running. Many thanks for these links though.. everything seems to point to this being a regular production board.. Hopefully I can get it running!
The EQ Equaliser comments suggest that it may have been used as an embedded device of some kind. May be it never expected to use a lot of the on board HW?
With all the info uploaded by Pablo at the below link, are you going to be revisiting this machine soon?drive.google.com/drive/folders/1Inx8MxXN1q8k6H118Yw6VNZvcsR2E5Mx
I believe it was CA. In the event.. someone had documentation for the board or at least a similar model and they sent it along. So hopefully soon I'll be able to do a followup video based on what I've found in there. I'm surprised so far at how much I got right. The only thing I'm missing now is a boot disk.
I Assume these 8 Outputs of the 74LS373 go to the Databus of the Z80CPU - and any other Device on the same Databus. /OE of 74LS373 connected to an Address-Decoder for IO-Reads of the Address.
It's a 374 in this case.. but I have followed the traces directly to one of the DARTs on board. I am told by a former hardware designer that this was not an uncommon way to have parallel ASCII keyboard input handled. At some point I will probably try to trace it out further. But first I want to find out if the ROM even accepts keyboard input in the first place.
Try to take a look here: Insight Enterprises EQ-4 The single-board EO-4 from Insight Enterprises is compatible with CP/M 2.2 and 3.0. It has virtual memory-mapping circuitry that lets the Z80A central processor and the DMA controller directly access 128K bytes of RAM, 2K bytes of EPROM, and 4K bytes of video memory in 8K-byte blocks. Interfaces incorporated into the EQ-4 include SASI, four serial RS-232C channels with independently programmable data rates ranging from 110 to 76,800 bps, a Centronics parallel printer, and floppy disk ports. The floppy-disk controllers can handle single- and double-density 5V4- and 8-inch drives si multaneously. CTC, DART, and PIO peripheral controllers are standard. The parallel keyboard input accommodates 7- or 8-bit ASCII-encoded boards with jumper-selectable active high and low strobes. Horizontal and vertical sync signals and composite video output compose EQ-4's video features. Standard Microsystems' 8002 video-display attributes controller provides the EQ-4 with an on-chip character generator, 128 characters in a 7- by 1 1-dot matrix, and character oriented, wide- and thinline graphics. Attributes supported for each character are reverse video, character blank, blink, underline, and strike-through. The single-unit price for the EQ-4 is S 750, which includes CBIOS, utilities, and source codes. Complete specifications are available from Insight Enterprises Corp., Suite 12, 373 North Western Ave., Los Angeles, CA 90004, (213) 461-3262. Circle 613 on inquiry card. From Byte 1983-12 page 576
Nice!! Okay so now we know what this product was.. the question now is, was it actually mass produced or did they just do a run of prototypes/pilot units before the whole company crashed in 84. Need to find a company principal!
@@TechTimeTraveller The name of the (main?) developer of the EQ4 firmware was Ralph Nicovich. His name appears in some pieces of source code I still have. According to Facebook, Mr. Nicovich has 71 years old and is still related to computer science in the San Francisco area (telephone number available on Google). Maybe he has saved sources. I am also trying to obtain the source code from a guy in NY I was in contact in 1985; he donated his EQ-4 to a computer museum... which is now closed due to Covid...
please note: commercial entities (corps) are only looking to make money, not have nice ideas, those dont combine, unless you have a nice idea and you are interested in it, truly, not for money, money makes/has different goals than interested hobbyists or free scientists (not bowing to money, and money dont think for them, as other people's rulings)
corporate interest stops at the money fulfilment, then move to next money making stuff, whatever that is, ie doing work for no reason / in-vain (money is no reason)
From the disassembly, I don't see the keyboard being read the usual way (e.g. 7 data bits + strobe), which might explain why your experiment didn't work. P.S. my previous comment marked as spam?
Weird.. yeah your comment about posting on github got taken out.. I gotta figure out what happened.. I saw it in my email notification and assumed it was OK. Maybe the link? Thanks so much for doing this! Programming is not my strong suit.. and I like hearing that my failure to get any input may not have been my usual incompetence!
Certainly it was the link. So for those who want to contribute to the disassembly, look on Github for "insight-enterprises-z80-eprom" by nippur72. The code is quite intricate, I just found a big and mostly useless jump table that makes things a lot harder. I'll let you know if I find something about the keyboard. P.S. since the character generator is definitely not in the EPROM, are there any other ROM on board? Perhaps something like the Signetics 2513 ?
@@TechTimeTraveller I’ll try to download it this evening and decompile it. It’ll probably take a little while to make sense of it. But if I can figure out what it’s doing I/O wise that should help. I write z80 assembly for my own projects. So I have a good grasp on it. Also, the empty socket that goes from the DART appears to just be the serial connection. Much like on a IMSAI front panel, it connects through a dip socket and special cable.
gist.github.com/einstein95/dc0c8bb4bd88ee26d4bf8abd371e02d5 This is an EQ4, a different model than the one in the advert, not a prototype, however it might have been an uncompleted kit build, the missing chip worries me.
Crude way to test the video port. Every hear of an oscilloscope? Trying to connect keyboard, might try to disassemble the rom code. You know where to start, location zero. On the big board, the rom copied itself into ram, and then disappeared from the memory map.
Yes I have a Rigol DS1052e, but I am still learning how to use that. I know shotgunning is frowned upon but in this situation we didn't have to worry about blowing anything up, and knew to 95% certainty where the video connector was. It was simply quicker to go about it that way. If no signal had been found, an investigation with scope was possible - although between my inexperience with that and all the unknowns with this board, it might not have helped any. :) Another viewer has downloaded the ROM and suggested that the IE ROM seems to be doing the same thing the BB ROM does. Others that have also looked think it may be unfinished as I suspected.
It's his computer. He can test it how ever he likes. Here is this guy taking his time to make amazing content and here is you bitching because you don't like how he tested HIS computer.
@@thomasparks1943 Thank you! I cannot understand these armchair quarterback, strike that, hecklers. If he's better off just not watching if he's gonna hate.
"This looks like new Jersey"
>another world
God damn it, that caught me off guard. Good one xD
I lived in Hackettstown so I poke fun at NJ now and again. :)
You might want to add a cheap Oscilloscope to your kit list. They make things like finding video pins far easier (just probe each pin without the need to switch off and on, video has a distinctive shape) and can help diagnose faulty chips (distorted logic signals etc).
I 2nd this entirely. For a video signal, 50 MHz should be enough. Even a used analog scope would be a GREAT help. With the caveat that analog scopes are getting long in the tooth, and you don't want yet another thing that you have to fix.
@@harrkev standard definition video (the kind that a machine like this puts out) runs to only 5 or 6MHz (look at the spacing between UHF channel numbers), even a 10 or 20MHz scope would be plenty.
Thinking back to the video above, chances are that some of the extra pins on the connector were either HSync or VSync, so the reason he was having problems with the image location was that the monitor was seeing only the picture and mistaking the first character as VSync. A scope will show these regular sync pulses clearly.
I got myself a Rigol 1054Z and it basically earned its cost the first day I used it. I confirmed that the wrong chip was in a socket from the signal behaviour.
Yes get your self a period correct Tektronix. they are very reliable, and will fit in with your collection.
Having a scope will make troubleshooting a lot easier.
Check the signal quality and find that IC acting up, check clock and power signals etc. or like in this case just probe for the video out.
Giveaway of the video out on this and many other boards is some discrete components. here the transistor and resistors.
Video normally has an output impedance of 75 ohm, so look for resistors with a value close to that. in this case there is a 100 ohm to the output.
From Byte magazine 1983-12 page 576:
Insight Enterprises EQ-4
The single-board EO-4 from Insight Enterprises is compatible with CP/M 2.2 and 3.0. It has virtual memory-mapping circuitry that lets the Z80A central processor and the DMA controller directly access 128K bytes of RAM, 2K bytes of EPROM, and 4K bytes of video memory in 8K-byte blocks. Interfaces incorporated into the EQ-4 include SASI, four serial RS-232C channels with independently programmable data rates ranging from 110 to 76,800 bps, a Centronics parallel printer, and floppy disk ports. The floppy-disk controllers can handle single- and double-density 5V4- and 8-inch drives si multaneously. CTC, DART, and PIO peripheral controllers are standard. The parallel keyboard input accommodates 7- or 8-bit ASCII-encoded boards with jumper-selectable active high and low strobes. Horizontal and vertical sync signals and composite video output compose EQ-4's video features. Standard Microsystems' 8002 video-display attributes controller provides the EQ-4 with an on-chip character generator, 128 characters in a 7- by 1 1-dot matrix, and character oriented, wide- and thinline graphics. Attributes supported for each character are reverse video, character blank, blink, underline, and strike-through. The single-unit price for the EQ-4 is S 750, which includes CBIOS, utilities, and source codes. Complete specifications are available from Insight Enterprises Corp., Suite 12, 373 North Western Ave., Los Angeles, CA 90004, (213) 461-3262. Circle 613 on inquiry card.
Wow ! A trip down memory lane for me. I was designing and building CPM based single board computers using the Z80 and the Z80A back in late 1970's. At the time I worked for a private company that was purchased by Exxon Enterprises. Exxon Enterprises also owned Zilog back then. So I downloaded your BIN file. But I'm going to have to find my "software tools" for reverse assembly. Just maybe we can make some sense out of this.
Thanks for the video. Don
Awesome! I was hoping someone might do that. Please let us know what you find out!
@@TechTimeTraveller I may not be the best person to work on this as I have not been into Z80 opcode since 1983. However:
Looks like the EPROM starts at E000 with the stack around F980 and later moved to FCFF.
The "main" routine is quite small at only 347 bytes. There are many subroutines.
I have created a I/O reference list. I'll see if I can upload this somewhere.
The code is somewhat reminiscent of the code required to run CP/M, where you ORG it into high memory. But I don't see the "vector" table required for CP/M, the list of vectors for the various routines that CP/M requires to run.
More digging to follow.
@@dri50 Fantastic! Yeah personally I kind of wonder if this is a finished work or not. That's why I halted my efforts with the keyboard until I acquired for info on what exactly it is doing. It didn't make it into the video, but I did probe the FDC to see if it was trying to reach out to a floppy drive anywhere.. but nothing as far as I could determine.
With the music and the witty humour, this is like This Old Tony but for electronics.
Stunning quality content. Thank you and keep up the excellent work.
I think a good first step would be for you to disassemble the ROM and see what it does. :)
haha I'm crazy enough in lockdown to have started :-)
@@ingmarm8858 \o/
I love watching these old boards come back to life, even in a limited capacity.
Thanks for sharing. 😉👌🏻
It's interesting to note that the original design goals of the Big Board were very similar to the Arduino and Raspberry Pi projects of today, trying to put a computer in the hands of all sorts of experimenters. That's why it has the big prototyping area onboard.
If an I/O and memory map could be obtained for the board it would make it easier to determine what the disassembled ROM code is doing. The chip enable lines could be traced back to decoder chips and then see what address lines are fed to those chips.
Thanks for the video! It's good to see another interesting piece of the history.
Would be cool if someone turned out to have more information on this.
I really hope someone does. I searched in vain for the names of company principals or designers hoping to reach out to them, but that info wasn't to be found. Have to hope someone with knowledge stumbles across this video and says 'Hey! I know that machine!'
I like how you hooked it up to a period appropriate display 😀
In the early days of computing sometimes the keyboard had only 16 keys and a few extra. What was very comon back then was a matrix 8 by 8 wires and some pull-up resistors. Real ASCI keyboards came later.
I love the Z80. I think I might still have a disassember and compiler for it. I'll have to look. I have written a bit of Z80 assembly back on the '90s for a CNC machine tool. Managed to get it booting from a serial port instead of a cassette tape.
Another really cool video with a super interesting computer. Thanks!
Watching your videos makes me feel like i really stumbled upon something special. Keep it going man!
It's so cool that this board works after all these years. Nice one. :)
As a lifelong NJ resident I can confirm that def was NJ!
I lived in Hackettstown briefly. Definitely felt appropriate. :)
Just watched your video. Interesting board. In reading through the comments I did not see any reference to using a serial terminal connected to one of the DARTs. My Big Board I allows me to use the on board video with a parallel keyboard or attaching a serial terminal, like a DEC VT220, to serial port 0. I have built/assembled several Z80 based boards and the Z80 variants (example:HD64180) in the past. In some cases, a serial terminal was the only way to communicate with the board. In fact I have 5 Big Board I and 2 Xerox 820-I and 2 Xerox 820-II sitting around. I have my mystery board to work on as well. My son's friend was cleaning out an old business and uncovered a Z80 based machine. Several days after the discovery, he told my son. He called me immediately and I went over to the location. Sadly, they had pulled the boards out of the machine and put them in a box. The rest they tossed into the dumpster. So, I do not have any info except what is on the boards. The info on the boards is "Molecular Computer". Ever hear of them??? I haven't done much with them yet but they are on my list. Serial terminal will be my only choice.
G'day, I think a hunt for serial console on the nice obvious RS232 line drivers (1488/89) would have been my first point of call, then go down the hard path of the parallel keyboard etc. Love the stuff in your collection. Cheers.
So... being a little bored in Covid lockdown I started disassembling the eprom contents you linked to. I have the DART configuration code, found the Dart 1 channel A,B tx routines, initial relocation and setup of the interrupt mode 2 vector table etc. If I find anything really exciting I'll let you know. Pity you are on the other side of the world! Cheers.
23:28 that's why I love the Testofon - it converts measuring current to audio frequency in real time (since it's an ancient, super simple circuit). If I hold one probe to the pin in question and then check continuity, in a worst-case scenario I'd take 5 minutes to go through every pin on the entire board - I didn't count pins here, but I can measure 4-10 pins per second).
"Shugart Associates System Interface" - That's a new one on me!
A lot of effort went into this video, thank you.
very interesting computer
A counterpoint: embedded industrial controllers is a "hidden market" for which the Z80 was ideal, with the STD bus. Today's single chip systems are the evolution started with those single board computers running automation, highway signs, etc.
These boards were sold as _Z-80 development systems._ I'm sure that there's an EPROM burning capability on the board.
Google put a mid-roll ad right in the middle of your joke at 26:43! Such AI.
Thank you for mentioning that!! It didn't do it there the first couple times I ran through the video. They advertise that it'll do it at 'natural breakpoints'. Sigh. But thankfully I can adjust/remove it, and have. Appreciate the tip!
geat video !! lots of history and research.
The meat of the Blue Kazak camel has a nutty cheesy flavour and is highly prized.
It is usually dry aged in the desert for at least 60 days before consumption.
Boiled in fermented mare's milk it is reserved for special occasions.
Brutal wars have been fought to gain acquisition of the animal.
I had one of those, sold it and I'm glad I did. I never found any software that used the 128k due to non-standard bank switching. Maybe there was an MP/M but it was not included. You're on the mark with the decline of kit-computing. That was the reason Heathkit died: there was no savings to build-it-yourself.
You know, that logo looks like a time-traveling refrigerator. Excellent.
I am not sure someone already said this in comments but I recommend a decent bench power supply like a siglent 3303. Not only can you dial in your bipolar voltages you can limit current its output making it less likely to smoke parts. Also you can very quickly spot bus power shorts right after power up. You may want to add a dedicated 5v supply with current display such as siglent 1168. Together these cost maybe $500 us but combined with a decent scope will probably become your most used bench tools. Along w a dvm They are for me.
Taking a dump (of an EPROM)
All right, I like your sense of humor.
So the keyboard input is just like a Centronics printer port going the other direction. Back then I built a very simple Centronics port with a 74257 because I thought a big PIA chip was overkill.
'data lines go to a missing 20 pin chip' screams 74ls244 or 245. check the pinoit of those to see which one makes sense. it also should match the surrounding logic families, probably. if everything else is 74HCxx, then use an HC244 or whatever
In marketing you never ask a question that’s probably why the ad did not work. You wanna tell them why they want this product. Give them a point of purchasing.
Character generator is on CRT Video Display Attributes Controller chip CRT8002.
The First computer I ever got to play with was a Sinclair ZX80! in 1980, and a ZX81 the next! Timex/Sinclair was a British Timex offshoot or Sinclair used their PC under license...
The ZX80 was named after the Zilog Z80 processor with the 'X' meaning "the mystery ingredient".
Time used Sinclairs design under licence.
Still looking for you to cover the KIM-1.....
One day. I have one.. but it doesn't work.. seems to be a possible ROM issue.
Definitely my favourite channel. Any thoughts of using Patreon?
Thank you you the high compliment! I personally haven't reached a comfort level with asking people directly for money. I've no problems taking Google's money but I feel like the channel (ie. Me) has to prove itself before any steps towards direct funding are taken. Right now it is an enjoyable diversion for me - a way to connect with my creative side. If it turns into something larger then who knows. For now getting nice comments like these is reward enough.
I would love to know if you connected the SASI interface to a SCSI-1 hard drive whether it would work, as SCSI-1 was supposed to be backwards compatible with SASI
I looked thru the comments. there is a link in there going to a Google drive with a lot of documentation. including the keyboard Pinot and configuration. so are we going to see and update on this board. it's been a year?
It is in the pipeline. I was sent a full manual and I do plan to do a followup.. I have just been struggling to find a EQU CPM boot disk. Without that it still won't do much.
Will you do a video on the Ferguson Big Board in the future?
Yeah... I just missed the classic era and spent the entire retro era with this huge false-nostalgia for a time I hasn't seen but wished I had.
CP/M did not... not... go the way of the Dodo .... you monster!!!! Loving your vids. Cool board.
Really enjoyed this video. Learned a lot. Subscribed!
Any update on this thing I really wish I had the technical expertise to help you
Make a fan of wires like a brush to a fast continuity meter. Boom fast tracing
That’s a pretty good idea, I wonder if there is something like a carbon filament brush available?
By the way, this is very interesting computer archaeology.
Hard to say, might not be a Monitor it's booting into but a Bootloader. However it should pop up an error if no bootable media is found.
Perhaps it's not a disk bootloader, maybe it's a serial paper tape reader/terminal one, although I'll admit that would look a bit ancient even in '83.
Many 1980s CP/M systems just waited forever for the user to insert a diskette without ever printing a message of any kind.
Great video! Subscribed now and will check out your other content.
If a guy had a blank Big Board, do you suppose it's possible to build it at this point in history?
When checking voltages, I might have pulled the socketed chips and checked power/ground at each socket before putting power to it.
A blank Big Board should be easy. There's nothing it uses that, to my knowledge is unobtainable today. I sort of thought about pulling the socketed chips but I figured I'd only be saving a few while frying the many anyway. :) Thanks for subscribing! Really appreciate it!
@@TechTimeTraveller I learned a lot about how to investigate connections to an old board. No problem sitting through a 40 minute video.
Can we get these today?
Great video!
I don't know whether you noticed, but we are also seeing different prices. I believe we are seeing two different generations and capabilities... three counting yours.
Sphere ads were great for vaporware in their later lifetime like lines on the CRT being white drafting tape
Please invest in an oscilloscope. You can get good older ones on eBay for next to nothing, and the decent (i.e. with a real front end, not some $5 PC based thing) Chinese scopes are pretty respectable nowadays too. (Just noticed this video is from over a year ago, apologies if you already have.)
This is all well and good but I will never wire up another data or address bus again. God bless microcontrollers !!!
Wow nice Falcon!
The letters and numbers you're seeing is because the values are counting up continuously in the EPROM contents. Looks like that was their choice of fill data most likely, so just unused space.
Cetronics typically only had 25 pins and usually only used about 20, as well.
Willing to bet J1, J2, J4, and J7 are diskette drive controllers (By 1983 the Shugart interface was pretty well known), and that J6 and J8 are expansion bus headers. J5 is almost certainly the parallel port connector. J10, J11, J12, and J13 are all going to be serial ports. Considering I don't see another connector for a keyboard, it's possible they expect you to have a terminal connected to one of the serial ports and stick the video display on J9.
Another heads up, ALL of these connectors will have at least one or two ground pins. A voltage is just a difference, and without a ground (0 volts), the 5 volts means nothing.
Hunting for a video signal would be GREATLY aided with an oscilloscope. You should really consider one, it doesn't have to be perfect or even good, just enough to show you something. It will tell you immediately if you've got a clock signal, if your voltages are clean, and with a little bit of know how, it can trace out a video signal on a header like that in seconds with power applied.
Another heads up, in the 1970s and 1980s, -12 volts was extremely common for memory! It was a very necessary bias voltage.
When testing for composite video like this, ALWAYS put a capacitor in line with your video signal! This will prevent any DC bias getting to your display, which even at 5 volts would most likely damage it or the computer with a bang and a puff of smoke. God forbid at 12 or -12 volts! Composite video is generally
Extremely interesting sorta reverse engineering video, though!
great channel. subbed :)
Many thanks! Appreciate the vote of confidence!
@@TechTimeTraveller you're welcome :)
I would find it fascinating to take one of these and give it a thorough study to reverse engineer the schematic, though that would not. Be a quick or easy task.
I've always kind of wanted to do that.. but I don't really know how to organize it on something this complicated.
@@TechTimeTraveller I would start by taking high-resolution photos of the top and bottom of the board, which might have to be stitched together from multiple shots with a large board like this. Import those into a drawing program that lets you draw on multiple layers, align them with each other. Mark out the position of all the components, pins, and thru vias, and then trace out all of the connections on each copper layer. The fact that this board has more than two layers will make this difficult, you may need to use a multimeter to verify the connections on the internal layers, but at least it doesn't seem to have much in the way of large opaque copper pours. Once you have the connectivity worked out you can start reorganizing that into a more legible schematic, broken down by functional blocks. The fact that this board seems to be made entirely from standard logic parts and is probably very similar in design to the Big Boards it was designed to compete with will help.
I do not think reverse engineering would be that hard as the chips are off the shelf. The main things to work out are the IO addresses and the how the RAM is bank switched.
There are a few tantalum capacitors on that board. I would replace them all.
Plenty of close up pictures of the predecessor 128-I machine, but not much on the EQ4
As it happens, a fellow emailed me and he had a pretty complete set of docs he made available. I am going to review them and then will do a followup video hopefully with the machine running. Many thanks for these links though.. everything seems to point to this being a regular production board.. Hopefully I can get it running!
The EQ Equaliser comments suggest that it may have been used as an embedded device of some kind. May be it never expected to use a lot of the on board HW?
Really well done video! I'm glad The Almighty Algorithm suggested this for me.
Thank you! I'm glad you (and the algorithm) enjoyed it! :)
This video had 555 likes. I gave it a like, and now I feel bad..
Great now we're two timers.. :)
With all the info uploaded by Pablo at the below link, are you going to be revisiting this machine soon?drive.google.com/drive/folders/1Inx8MxXN1q8k6H118Yw6VNZvcsR2E5Mx
Nice 4layer board. Loader maybe just that. no monitor or basic.
In what State was that company Incorporated in?
You can find the filing paperwork and contact the owners.
I believe it was CA. In the event.. someone had documentation for the board or at least a similar model and they sent it along. So hopefully soon I'll be able to do a followup video based on what I've found in there. I'm surprised so far at how much I got right. The only thing I'm missing now is a boot disk.
@@TechTimeTraveller
You clearly knew your stuff.
It's always the last one you try, eh?
Often not even that. :)
Steve Wozniak and Chuck Peddle were easy for me to identify at 30:47, but I'd like to know who the third guy is.
Don Lancaster
@@TechTimeTraveller Thanks! I knew about his TV Typewriter but didn't know what he looked like.
I Assume these 8 Outputs of the 74LS373 go to the Databus of the Z80CPU - and any other Device on the same Databus. /OE of 74LS373 connected to an Address-Decoder for IO-Reads of the Address.
It's a 374 in this case.. but I have followed the traces directly to one of the DARTs on board. I am told by a former hardware designer that this was not an uncommon way to have parallel ASCII keyboard input handled. At some point I will probably try to trace it out further. But first I want to find out if the ROM even accepts keyboard input in the first place.
@@TechTimeTraveller TRay to disassemble the EPROM to check for initialization routines for dart like Also PFM ROM makes in the bigboard i
Try to take a look here:
Insight Enterprises EQ-4
The single-board EO-4 from Insight Enterprises is compatible with CP/M 2.2 and 3.0. It has virtual memory-mapping circuitry that lets the Z80A central processor and the DMA controller directly access 128K bytes of RAM, 2K bytes of EPROM, and 4K bytes of video memory in 8K-byte blocks. Interfaces incorporated into the EQ-4 include SASI, four serial RS-232C channels with independently programmable data rates ranging from 110 to 76,800 bps, a Centronics parallel printer, and floppy disk ports. The floppy-disk controllers can handle single- and double-density 5V4- and 8-inch drives si multaneously. CTC, DART, and PIO peripheral controllers are standard. The parallel keyboard input accommodates 7- or 8-bit ASCII-encoded boards with jumper-selectable active high and low strobes. Horizontal and vertical sync signals and composite video output compose EQ-4's video features. Standard Microsystems' 8002 video-display attributes controller provides the EQ-4 with an on-chip character generator, 128 characters in a 7- by 1 1-dot matrix, and character oriented, wide- and thinline graphics. Attributes supported for each character are reverse video, character blank, blink, underline, and strike-through. The single-unit price for the EQ-4 is S 750, which includes CBIOS, utilities, and source codes. Complete specifications are available from Insight Enterprises Corp., Suite 12, 373 North Western Ave., Los Angeles, CA 90004, (213) 461-3262. Circle 613 on inquiry card.
From Byte 1983-12 page 576
Nice!! Okay so now we know what this product was.. the question now is, was it actually mass produced or did they just do a run of prototypes/pilot units before the whole company crashed in 84. Need to find a company principal!
@@TechTimeTraveller The name of the (main?) developer of the EQ4 firmware was Ralph Nicovich. His name appears in some pieces of source code I still have. According to Facebook, Mr. Nicovich has 71 years old and is still related to computer science in the San Francisco area (telephone number available on Google). Maybe he has saved sources. I am also trying to obtain the source code from a guy in NY I was in contact in 1985; he donated his EQ-4 to a computer museum... which is now closed due to Covid...
Great. but does it play Doom? 😅
It might be Doomed.. but playing Doom is probably a stretch. :)
direct mechanical optical gates, photonic momentum computer/copmuting
optical does not need "ground", just light or no light signal, at some threshold
also optical signals can cross over at single plane, without messing things up, unlike electric voltage signals
ie optical signals have a directional conduction pipes, that can cross over, no collision
please note: commercial entities (corps) are only looking to make money, not have nice ideas, those dont combine, unless you have a nice idea and you are interested in it, truly, not for money, money makes/has different goals than interested hobbyists or free scientists (not bowing to money, and money dont think for them, as other people's rulings)
corporate interest stops at the money fulfilment, then move to next money making stuff, whatever that is, ie doing work for no reason / in-vain (money is no reason)
From the disassembly, I don't see the keyboard being read the usual way (e.g. 7 data bits + strobe), which might explain why your experiment didn't work. P.S. my previous comment marked as spam?
Weird.. yeah your comment about posting on github got taken out.. I gotta figure out what happened.. I saw it in my email notification and assumed it was OK. Maybe the link? Thanks so much for doing this! Programming is not my strong suit.. and I like hearing that my failure to get any input may not have been my usual incompetence!
Certainly it was the link. So for those who want to contribute to the disassembly, look on Github for "insight-enterprises-z80-eprom" by nippur72. The code is quite intricate, I just found a big and mostly useless jump table that makes things a lot harder. I'll let you know if I find something about the keyboard. P.S. since the character generator is definitely not in the EPROM, are there any other ROM on board? Perhaps something like the Signetics 2513 ?
The chargen chip it's the CRT8002
35:51 how did you get george lucas on this?
I had some dirt on him and Linda Ronstadt. Shhhhh. 😀
If you want to shoot me a copy of the dumped binary, I’d be willing to decompile it and see what I can make of it.
It is linked in the description for the video. Much appreciated.. very interested to learn more!
@@TechTimeTraveller I’ll try to download it this evening and decompile it. It’ll probably take a little while to make sense of it. But if I can figure out what it’s doing I/O wise that should help. I write z80 assembly for my own projects. So I have a good grasp on it.
Also, the empty socket that goes from the DART appears to just be the serial connection. Much like on a IMSAI front panel, it connects through a dip socket and special cable.
way too clean to be Jersey .
gist.github.com/einstein95/dc0c8bb4bd88ee26d4bf8abd371e02d5
This is an EQ4, a different model than the one in the advert, not a prototype, however it might have been an uncompleted kit build, the missing chip worries me.
I think this board is called the "bigboard", it was a "hobby" board, you could assemble yourself, it was quite famous in its time.
Yes to be outdone, Seagate introduced the
Crude way to test the video port. Every hear of an oscilloscope?
Trying to connect keyboard, might try to disassemble the rom code. You know where to start, location zero. On the big board, the rom copied itself into ram, and then disappeared from the memory map.
Yes I have a Rigol DS1052e, but I am still learning how to use that. I know shotgunning is frowned upon but in this situation we didn't have to worry about blowing anything up, and knew to 95% certainty where the video connector was. It was simply quicker to go about it that way. If no signal had been found, an investigation with scope was possible - although between my inexperience with that and all the unknowns with this board, it might not have helped any. :)
Another viewer has downloaded the ROM and suggested that the IE ROM seems to be doing the same thing the BB ROM does. Others that have also looked think it may be unfinished as I suspected.
It's his computer. He can test it how ever he likes. Here is this guy taking his time to make amazing content and here is you bitching because you don't like how he tested HIS computer.
@@thomasparks1943 Thank you! I cannot understand these armchair quarterback, strike that, hecklers. If he's better off just not watching if he's gonna hate.
I am dropping you. Not because of you, but because I will not support UA-cam and its fascist policies. Thank you for your content I have enjoyed.....
What does this even mean?