Finding an intermittent fault on the Book8088 & adding external CGA output

This is the Book8088, an interesting "modern" take on an old 8088 IBM PC compatible machine. This particular unit was sent in and was broken, so it's time to try to figure out what's wrong with it and get it working. Along the way, I want to add proper external CGA output to this computer to make it more useful.

0:00 Intro
1:01 Fixing the dead computer
42:58 Adding CGA output

-- Links

Mail Call episode 0078 where I first test the Book8088:

Book8088 and also the new Book386 seller:

Adrian's Digital Basement Merch store:

Adrian's Digital Basement ][ (Second Channel)

Support the channel on Patreon:

My GitHub repository:

-- Tools

Deoxit D5:

O-Ring Pick Set: (I use these to lift chips off boards)

Elenco Electronics LP-560 Logic Probe:

Hakko FR301 Desoldering Iron:

Rigol DS1054Z Four Channel Oscilloscope:

Head Worn Magnifying Goggles / Dual Lens Flip-In Head Magnifier:

TL866II Plus Chip Tester and EPROM programmer: (The MiniPro)

TS100 Soldering Iron:

EEVBlog 121GW Multimeter:

DSLogic Basic Logic Analyzer:

Magnetic Screw Holder:

Universal ZIP sockets: (clones, used on my ZIF-64 test machine)

RetroTink 2X Upconverter: (to hook up something like a C64 to HDMI)

Plato (Clone) Side Cutters: (order five)

Heat Sinks:

Little squeezy bottles: (available elsewhere too)

--- Instructional videos

My video on damage-free chip removal:

--- Music

Intro music and other tracks by:
Nathan Divino
@itsnathandivino

[FabioBattaglia]

Hey, my recreated CGA schematics! Glad all that work helped someone :)

[wolvesone]

i like the fact that its boot up sound is a version of the old intel jingle

It's great when you suggest "...this video could be a complete failure...", I immediately check the timeline length... cool! Over 1 hour... I'm in, with popcorn ready! 🍿

[chrissalch]

Bodge wire? Bodge wire! How about a whole bodge forest!

Seriously though, nice work!

[Loki-]

I was sad for a second thinking I didn't have anymore Adrian to watch, only to realize I had to sleep halfway through this! I have the rest to enjoy now!

[rzerobzero]

After seeing this thing on Aliexpress a year ago I had so many questions. Leave it to you to answer all of them and more! The mod was amazing too!

[repatch]

There aren't many creators on Youtube that can post an > 1hr video and have a guarantee I'll watch it. Obviously Adrian you're one of them, and you never disappoint. Thanks!

[electronics]

As others already pointed out: the beep beep bop boop boop. Is actually the "in tel inside" that was in those older intel cpu advertisements but in beeps

[bitwiz_]

[53:46] high quality bodge! I love it when you can fit pin positions right over stuff, and it's rare that you can bodge a whole chip like that!
[54:44] yeah, that's a nice little nest you've got there
[58:49] Be careful with the wire dangling like that. I used to do Sega Saturn switch mods with the switch dangling out the back on ribbon cable wires, and the wires would wear out at the bend and fail open. Hot glue may not be enough strain relief because there will still be a bend point. The D connector itself would need to be glued down.
[1:07:45] even just having unused pads on the board for the chip would have been fine, at basically no extra cost

[thirstyCactus]

74244 not only provides a barrier from outside world, but also has a higher current sourcing ability than standard 7400 logic (IIRC). This helps with signal integrity through cable capacitance and whatever termination circuitry is in the monitor. In this case, the 74244 also provides 3.3v to 5v level-shift.

[decidedly_retro]

The ALE line is "Address Latch Enable". Without that signal nothing was getting an address on the multiplexed bus.

[jandjrandr]

Still a pretty neat little 8088 notebook, but having an external video does make it cooler!

[ChristopherHailey]

I remember writing software for old MDA and CGA, instead of using the really bad BIOS and DOS stuff for the displays I wrote my own. The CGA would show static if you didn't wait before writing which slowed it down a LOT. When a CGA would scroll the screen would blink in the most annoying way. A little bit of snow was better than the blink. I mostly used MDA video as CGA was so bad. It was fun writing PC software back in the days where there was almost no software for it so you had to write everything. I hope people can use these modern 8088 type machines to get a feel what it was like back then!

[LozzoAmiga]

The best kind of repair, whereyou identify the exact fault instead of just swapping parts. Awesome! Nice bodge mod too, reminds me of my homebrew c64/1541 JiffyDOS rom switcher. :)

[richym]

The box is magic! It deserves its own channel where you out random broken hardware in it and leave it for 2 weeks.

[elfenmagix]

An excellent video.

Shows how much one faulty chip can take down a whole PC.

[cpu_duke]

Wow you made it again down into that rabbit hole ! Amazing work, thanks. This external monitor feature definitely is missing and it is sooo funny we see already repair videos on retro projects released in 2022/2023!

[parrottm]

Adrian created his own 'glop top'. Loved the entire video. Very informative and just plain fun.

[GraceMcClain]

It was very cool literally getting to see that chip fail on boot up. You get so used to seeing things in nondescript boxes, and you forget how complex they are on the inside, and then you get to see literal signals moving along pins. It's awesome!

[adagioleopard]

We had an issue on a dead channel on our pick and place machine. When I pulled out the card and desoldered the shift register, some of the pins were also dodgy like that.

It was clear someome changed it, and reused some chips.