Tag Archives: 8088

Multiple computer systems in a carrying case.

Test picture of a multiprocessor computer setup.
Using buttons on the right, I want the possibility to change between systems and keyboard settings.
Also, multiple software/OS slots for SDCards will be on the right.

Mockup using a laptop display (eeepc) a bought display controller and a pi2 with Faux86

The lid containing the keyboard has a handle!

After laser cutting a nice front, it could become a nice road warrior hacking station.

I’m going to replace the wireless keyboard, probably with a touch display and a programmable layout for keyboards.
Something like below

Some layouts:

I’ll probably buy this one from waveshare

Info about Faux86

  • 8086/8088, V20, 80186 and limited 286 instruction set.
  • Configurable CPU speeds from 5Mhz up to 100Mhz.
  • Custom Hardware BIOS’s supported.
  • Supports bootable disk images in .img and .raw file format.
  • CGA / EGA / VGA Colour Video emulation, with most modes supported.
  • PC Speaker, Adlib, Soundblaster and Disney SoundSource.
  • UART Com Ports.
  • Standard PC XT Keyboard.
  • Serial Port 2-Button mouse.

Checking faulty chips/hardware

When I fix old hardware I often use a flir camera.

My brother gave me his CAT S60 mobile phone. Which has a flir camera, he used it when he was a voluntary fireman.

Forward-looking infrared (FLIR) cameras, typically used on military and civilian aircraft, use a thermographic camera that senses infrared radiation

Soo .. when testing hardware. I do the following.

  • Clean the motherboard
  • Check chip pins
  • Press all chips/ic’s in their sockets
  • Test the power supply disconnected. ( Most will give a higher voltage when nothing is connected )
  • Measure the resistance of the board (sometimes)
  • Check if the machine can be started.

Now it gets interesting. Sometimes nothing happens. Sometimes the machine runs like it suppose to do.

But old hardware can be faulty or connections are bad. IC’s run hot and they stop working. ( Untill they are cooled enough or they stop forever 🙁 )

So I start monitoring the temperature when I boot the machine. Sometimes components heat up very fast. I use my finger and the flir camera.

These are pictures from my 8088. Nothing runs hot

Old mystery motherboard and Bios hacking

When selling a large part of my computer collection I kept a few odd pieces.

Amongst those was a 8088 DIY machine.

It is a 50PTX3 motherboard with a 8088 compatible CPU

  • Power light (Not LED) and connected to power adaptor, not motherboard
  • Reset button??? not connected
  • Power switch
  • Mid center, 5v gnd and 12v
  • 5.25″ drive not connected

Tested the power adapter first, a nice 5V and 12V.
Then I plugged the power in the Motherboard add plugged a test ISA card in the slot.
After turning the machine on I saw the Address leds flashing

A NEC D70108C from 1984, which is 8088 pin compatible with Intel 8088 but faster, and has some extra functionality.
The empty socket is for the 8087 Co-processor.

Nec V20 versus 8088

Everything pretty dirty

Rom 2764 (8Kb) and a disconnected speaker wire.

Adding an 8bit Isa hercules/CGA card.

It starts! .. But there is no Floppy controller (yet)

I’ve dumped the Bios to a file and used a hexeditor to play around.
So that’s why there is a bad checksum.

Installing a ZIF socket (Zero Insertion Force) to make things easier to modify.

Burned GlaBios on the Eprom and now I can continue to play around.

So why? Why this all ..

I want to play around with old 8088 assembly code again, but not as I did before using a Dos machine, but hardcoded into Eproms.
I’ve got 8 banks for ROMs and the source code for GlaBios is available.

In the past Edk and me wrote a boot demo, so it was not utilizing Ms-Dos functions. Maybe i can get some graphical and sound stuff working straight from the Bios.

Some commands:

# Dump the bios to file
minipro -w original.rom -p AT2764A@DIP28

xxd and hexdump to view the dump

I've used ghex to alter the ROM

# Write a new bios to a 28C64 (same Eeprom i've used for the C64 Cartridges)
minipro -w /home/henri/Downloads/MYROM -p AT28C64

GlaBios source code:

I was planning to disassemble the Phoenix Bios, but it’s quite hard to differentiate between code and data, there are no named pointers and you have to interpret every line of code.

So GlaBios it is ..

First code to look at:

This is after the whole post reset.
There is a reset pointer at ffff:fffe
Which points to the bootstrap routine, which ends in below machine code.
I'm going to plug my own code over here.

(See the funny remark about Monster as being displayed in one of above pictures)

; INT 18 - Unbootable IPL
; Display a disk boot failure message and wait for a key to cold reboot.
; This may be re-vectored to ROM BASIC, if present.
; Size: 18 bytes
	PRINT_SZ  BOOT_FAIL			; print boot failure string
	XOR	AX, AX				; AH = 0 (wait for key)
	MOV	DS, AX				; DS = 0000
	MOV	WARM_FLAG_ABS, AX			; do a cold boot
	INT	16H					; wait for key press
	JMP	BOOT					; reboot



; Banner Strings

			DB	'Starting GLaDOS...'
NL2_Z			DB	LF				; two NL's, null term'd
NL_Z			DB	CR, LF, 0			; one NL, null term'd
BOOT_FAIL		DB	'Disk Boot Fail.'
			DB	' You monster.'
ANY_KEY		DB	'Press the Any Key'
			DB	'...'

Assembly stuff

I’ve got Dosbox installed on my machine.

git clone https://github.com/640-KB/GLaBIOS.git
I copied MASM.EXE and LINK.EXE in the GLaBios src directory.

edit make.bat


start dosbox

mount c: /home/henri/projects/


cd glabios/src