My journey with the Book 8088: swapping CGA/VGA cards, broken CF slot, and USB booting
Out of curiosity, I purchased two Book 8088 units from AliExpress, one with CGA and the other with VGA, hoping to play with my favourite DOS software on the 8088 processor. The VGA unit worked well out of the box; however the CGA unit booted up to a BIOS beep but no video. At first I could apply pressure on the CGA card at one of its corners to make the video work, but eventually nothing I tried could make it display anything. Two weeks after informing the seller about the problems, I received a replacement CGA card, a spare VGA card, and what looked like a controller board for the display panel, all for free:
This photo shows the back of the CGA and VGA cards:
I swapped the CGA card and my Book 8088 CGA unit came to life, with CGA video, apparently just like the average 8088 back in the day. However, after just a few minutes of testing, I soon realised the limitations of this CGA implementation, with constant display artifacts and screen flickering. As CGA emulation on VGA was good enough for my usage, I removed the CGA card and used VGA instead.
Unfortunately this was where my trouble started. On my unit, the plastic access panel (most likely 3D printed) did not align very well with the video card slot on the PCB and swapping the video card required opening the case. Although I had done this a few times before, it was a bit difficult to open the case this time and I had to use some force. Upon reassembly, the Book 8088 no longer detected the CF card. Examining the PCB closely, I saw that several traces had been lifted off the PCB. Most likely, I had forgotten to remove the card while opening the case, and my attempts at forcing it open might have destroyed the CF socket.
For a moment, I thought that my Book 8088 was gone as the default BIOS did not boot from USB. It was a relief when I located a custom XTIDE BIOS for the Book 8088 here which allows the device to boot from a USB disk, if a floppy disk image (1.44MB or 2.88MB) has been written to it. This BIOS also fixed several weird issues with keyboard scan code mappings. After swapping the original EPROM with a Winbond W27C512, flashed with XTIDE using MiniPro v6.85, the machine was able to boot normally, with the USB disk emulating a 2.88MB floppy disk via the CH375 USB controller:
I upgraded the processor to an NEC v20 but did not bother with a 8087 as very few 8088-compatible programs actually used the math co-processor. On my unit, the 8087 would get very hot after just a few minutes, while the NEC v20 would remain at normal temperature. Eventually, the system would hang with a persistent beep. A similar behaviour was also observed when the battery was low. I removed the 8087 and my system became stable once again.
The System Information tool from Norton Utilities (SI.EXE) correctly reported the presence of an NEC v20. The floppy disk drive was detected as 1.44MB, yet the emulated 2.88MB disk worked fine.
DOS Controller, a lightweight Norton Commander clone, worked fine. Here it showed the contents of my 2.88MB disk image, including QBASIC, Turbo Pascal, A86 compiler and some games:
Adlib Jukebox sounded great too. Listening to the songs it played reminded me of the good old days:
I eventually copied my complete DOS software collection and Windows 3.0 on the other unit with a functional 2GB CF card, while using this unit for occasional hardware tinkering with the serial port and ISA adapter. Hopefully one day I will be able to repair the CF slot on this unit, or perhaps write some custom DOS drivers to make full use of the full space on the USB thumb drive, once the machine has booted in floppy emulation mode.
Of note, at one point my Book 8088 refused to boot from USB regardless of BIOS settings, despite correctly detecting the USB thumb drive at the POST screen. Reprogramming the 24C256 EEPROM solved the issue. There might have been data corruptions on the EEPROM higher data bits affecting the USB handling logic in the BIOS. The 3.7V lithium battery it came with was also of very poor quality, became swollen after just two months and had to be replaced. Otherwise, the overall build quality seems to be quite good and I hope my unit will last for a while.
You can download a ZIP file with the user manual, schematic, original BIOS image and source code, modified XTIDE BIOS, as well as the 2.88MB bootable floppy image here. The archive also contains the user manuals for Hand386, a 80386 clone. The latest version of the XTIDE BIOS can be found here. For other modification ideas for the Book 8088, see this VCFed discussion.
See also:
USB flash drives on 8-bit ISA bus using CH375 ISA to USB adapter
