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Book 8088 discovery and modification thread

Betamax80 said:
I'll try the QBasic route, but I'm quite sure there is something goofy going on - many have put it down to the small Realtek firmware in the LCD display.... with the book8088, I think we all expect things to be a bit goofed up (its hard to say that as a buyer).
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"Normal" 70hz 320x200 VGA and MCGA seems to work just fine, but the display really doesn't like 60hz VGA-modes (such as 320x240).
 
Curious if you can remove the CF card and put it into a XTIDE on another retro system (5150?) and if it would likely boot to dos?
 
Nama said:
Curious if you can remove the CF card and put it into a XTIDE on another retro system (5150?) and if it would likely boot to dos?
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I think you could. You can even boot the CF card under VirtualBox (although I did find some corruption doing it directly) I'm sure it would work in another XTIDE card.
 
britelite said:
"Normal" 70hz 320x200 VGA and MCGA seems to work just fine, but the display really doesn't like 60hz VGA-modes (such as 320x240).
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I suspect that this might be the problem - the 60Hz modes. I'm guessing Win3.0 is obsessed about 60Hz too?
 
Betamax80 said:
I'm guessing Win3.0 is obsessed about 60Hz too?
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“obsessed”? 60hz is what 640x480 VGA runs at. If the monitor in these machines can’t sync to that they’re fundamentally broken. Windows running at 320x200x256 colors, the only “official” vga-specific graphics mode that runs at 70hz, wouldn’t exactly be useful.

The original IBM VGA monitors have fixed 31.5khz line rates, and use different combinations of h/vsync polarity to tell the monitor to size the picture properly depending on if they’re pumping out 350 (EGA high res) or 400 (text and double-scanned CGA/EGA low res)@70hz or 480 (VGA square-pixel high res)@60hz modes. Any VGA->LCD scaler chip should be able to handle this, if the board they built for this can’t they seriously screwed up. What is the physical pixel resolution of the panel? Because… yeah, this is a hard fail.

So when you display the EGA high res mode (640x350) does it display it “letterboxed” (black lines above and below) or scale it? On a real VGA monitor it’s the changed sync priority that tells the monitor to stretch those 350 lines to cover the full vertical compared to the 400 line text/200 line graphics modes, I’m going to guess that’s another nicety this thing ignores.
 
Eudimorphodon said:
“obsessed”? 60hz is what 640x480 VGA runs at. If the monitor in these machines can’t sync to that they’re fundamentally broken. Windows running at 320x200x256 colors, the only “official” vga-specific graphics mode that runs at 70hz, wouldn’t exactly be useful.

The original IBM VGA monitors have fixed 31.5khz line rates, and use different combinations of h/vsync polarity to tell the monitor to size the picture properly depending on if they’re pumping out 350 (EGA high res) or 400 (text and double-scanned CGA/EGA low res)@70hz or 480 (VGA square-pixel high res)@60hz modes. Any VGA->LCD scaler chip should be able to handle this, if the board they built for this can’t they seriously screwed up. What is the physical pixel resolution of the panel? Because… yeah, this is a hard fail.

So when you display the EGA high res mode (640x350) does it display it “letterboxed” (black lines above and below) or scale it? On a real VGA monitor it’s the changed sync priority that tells the monitor to stretch those 350 lines to cover the full vertical compared to the 400 line text/200 line graphics modes, I’m going to guess that’s another nicety this thing ignores.
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In what windows calls EGA (which I think visually looks like x350) the chip scales it fully - as in it literally fills the display (unlike the V1 - mine was scaling the CGA output in textmode too but not graphics). Its almost like the output was tested for EGA mode... I don't really get it, as it feels like the developer didn't do full testing with a VGA so I wonder what happened. I was thinking the 60hz was the issue until PC Paintbrush refused on me too.
 
I should add Windows dosen't need that EGA TSR installed to load fine on here.
 
@sergey - would you give me a hand?
Yesterday i've tried to redo board hack and accidentally broke pin 19 on SN74HC245D U17 chip. To the worst extent, right at the body. Tried to power on it this way: it gave memory error beep pattern. Unsoldered the chip - apparently it now works (blinks, boots) but surely gives card not found beep pattern. I've ordered the chip, but if i did a short between pin 19 and 20 (that pins/legs are really small for my eyes) - what chips could it damage too? I really not good at soldering and microelectronics :(
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As for video - my V1 device has 10 pin (2 row, 2mm step) connector point and i planned to solder a connector there and test RGB2HDMI by hoglet with it, to understand kind of signal it outputs. Judging from the fact that seller now offers ISA CGA card (and i clearly see those CLPD chips there) it might output true CGA frequencies. So Realtek chip was programmed to work with that frequencies first, and as V2 now offers swappable video cards (and VGA has a real chip) devs could make kind of sacrifice (or simply skip some frequencies not knowing they are there)
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If i couldn't repair the book, i will wait for next version with at least PS/2 keyboard connector, or go with Mister FPGA (btw it's PC XT implementation uses Sergey's BIOS too)
 
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If it's any interest @n0p I did see an ISA PS/2 + Serial card, I think on AliExpress.
I also think we might find a voltage problem on the V2 RS232 port - I tried a PS/2 convertor and a PS/2 optical mouse (Genius Netscroll 120) but it wasn't having it at all. I will try one more time but I suspect not enough voltage for an optical sensor. I was lucky enough to find an old Logitech Kidz serial mouse (ball, ofc) and that works very well.

And I think you are right, I think the Realtek chip is still programmed for CGA frequencies, and "whatever works" from the VGA is what happens.
 
Retroplayer said:
I have one of these coming any day now. After reading more about it, it appears to be only one or the other, not both.
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Oh, fair enough. I hope it works.
I wonder what the deal is with the Hand386 breakout for those. It's using a PC104 header I gather.

I have ordered an SDLPT out of sheer curiosity. It's the last one of 90 (with case) and I didnt want it to disappear for good without me.
 
While the Book8088 is on my list of projects right now, it is not at the very top. But I do have an ISP programmer coming for the keyboard microcontroller in the hopes of dumping it. I should already have all the tools needed to talk to the RTD2662 LCD controller, but have not had experience doing it before. I have an LCD controller with this chip coming soon to practice with. I have a 12.1" panel I am going to use it with and wouldn't mind making it CGA or RGBI compatible for my other toys.

The normal method for doing so is to go through the I2c DDC pins on the VGA port. These are normally connected to pins 58 & 59 of the RTD chip. The eeprom with the settings/firmware is usually connected to 69/70

58 SCL
59 SDA

69 SCL
70 SDA

These need a 4.7K pullup if not present and a 100 ohm series resistor (for the pins 58 & 59).

Attached is a schematic for a reference design.

I do have an RGB2VGA converter that I plan to test out the 10 pin header on the V1. I just have not gotten around to it yet. I don't see any reason it would not work. The circuitry looks like it is right out of the datasheet for the old CRT controller. The question is, could we fit a DB9 connector into the body?

Switching to an 8 inch panel would be a huge improvement. There should be plenty of room in the bezel, but I am not sure I am really prepare to hack mine up just yet. Maybe if replacement injection molded top halves were available.
 

Attachments

  • RTD2662_Sch.pdf
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@Betamax80, yes, i've seen those cards, but they don't help with keyboard :(
@Retroplayer, so V2 has that connector point too? I planned using BH2-10R + IDC2-10 + DB9 connectors for that.
Good luck working on controller chips. I would love to see kbd and display connections.
 
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Eudimorphodon said:
a VGA card should support graphics modes 1, 2, 7, 8, 9, 11, 12, and 13. If any of these don’t work there’s something goofy going on.
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Tested the screen modes in QBasic just for fun and the result was that all modes except 11 and 12 show up just fine, as expected. 640x350 also gets stretched to full screen.
 
britelite said:
Tested the screen modes in QBasic just for fun and the result was that all modes except 11 and 12 show up just fine, as expected. 640x350 also gets stretched to full screen.
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So do modes 11 and 12 cause some kind of error attempting to set them, or does the screen go black or... ?
 
@britelite good work. I've looked up what those modes represent, and that sounds exactly the same as my (more "layperson") findings.
On my particular panel, the screen goes black - backlight turns off, like a power save mode, and a soft-reset seems to generate a kind of "buffer clean-up" on the screen at the start of POST.

Mode Resolution Colors T/G CharBlock AlphaRes
------------------------------------------------
0,1 360x400 16 T 9x16 40x25
2,3 720x400 16 T 9x16 80x25
4,5 320x200 4 G 8x8 40x25
6 640x200 2 G 8x8 80x25
7 720x400 mono T 9x16 80x25
D 320x200 16 G 8x8 40x25
E 640x200 16 G 8x8 80x25
F 640x350 mono G 8x14 80x25
10 640x350 16 G 8x14 80x25
11 640x480 2 G 8x16 80x30
12 640x480 16 G 8x16 80x30
13 320x200 256 G 8x8 40x25

Source: https://cs.lmu.edu/~ray/notes/pcvideomodes/
 
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What a goofy mistake/omission/whatever. I'd have guessed that the "default" out-of-the-box firmware for that scaler chip would know how to deal with this; only thing I can think of is maybe they tweaked it to do a better job with the 70hz modes and somehow broke it.

Retroplayer said:
I should already have all the tools needed to talk to the RTD2662 LCD controller, but have not had experience doing it before. I have an LCD controller with this chip coming soon to practice with. I have a 12.1" panel I am going to use it with and wouldn't mind making it CGA or RGBI compatible for my other toys.
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If you figure this out be sure to fulsomely document it. A few years ago I started digging into the rabbit hole of custom firmware for these LCD controller boards hoping for a clear answer on the a similar thing, IE, if it's possible with a custom firmware to get these boards to handle 15khz input, but I gave up because of how scattered the info was. (And much of it not being in English.) The datasheet seemed to imply that the RGB input bottomed out at 31.5khz, which doesn't make a ton of sense given it supports 15khz composite, but, well, said datasheet just generally was unclear when it came to distinguishing what were limits of the hardware vs. the reference firmware.
 
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