Old mystery motherboard and Bios hacking – followup

Last Updated or created 2023-05-31

The board seems to be a X Golden Board, except for the missing logo on the motherboard.

Downloaded pcxtbios and compiled the eproms native in linux. So i don´t have to use dosbox any more.

cd pcxtbios
edit make_linux.sh if needed

and you should end up with

I didn’t have enough 28C64, but the 28C256 has the same pinout. It just lacks A14 and A13

So I flashed the compiled ROMs for basic to different Eeproms

minipro -w ./2764/basicfc.rom -p AT28C64
minipro -w ./2764/basicf6.rom -p AT28C64
minipro -w ./27256/basicfa.rom -p AT28C256
minipro -w ./27256/basicf8.rom -p AT28C256

These roms need to be placed in sockets ROM6,5,4,3

ROM7 (BIOS)fe00:0-ffff:ffff
ROM6 Basicfc00:0000-fdff:ffff
ROM5 Basicfa00:0000-fbff:ffff
ROM4 Basicf800:0000-f9ff:ffff
ROM3 Basicf600:0000-f7ff:ffff

Machine Code monitor/editor

I tried to find a machine code monitor for 8088 rom, but did not have any luck there.

I tried mumon88, but that didn´t work.

Shaders using Bonzomatic

Last Updated or created 2024-03-04

Saw some demo-scene shader showdowns on YT the other day.

Two guys live programming shaders in less than a hour!

Fun to play with .. bonzomatic.
This shader program is realtime being compiled and the effect is shown on the background.

Below version I made using an example is changing to the music being played. (Fast Fourier transform function, see my other post about this)

PCem and bootdisks.

Last Updated or created 2023-07-21

PCem (short for PC Emulator) is an IBM PC emulator for Windows and Linux that specializes in running old operating systems and software that are designed for IBM PC compatibles. Originally developed as an IBM PC XT emulator, it later added support for other IBM PC compatible computers as well.

The big difference with PCem and Dosbox is the fact that you can configure many systems from 8088 to pentium, soundcards and graphic cards (like hercules, CGA, EGA VGA and alike)
You won’t start in MS-DOS, you can boot from a virtual floppy, just what i needed!

Update : Typing boot disk.img in dosbox works

I’ve installed PCem using:

cd pcem/
sudo apt-get install libsdl2-dev
sudo apt-get install libopenal-dev
tar xzvf ../PCemV17Linux.tar.gz 
make clean
# first start (complains about roms, but creates ~/.pcem/...
cd ~/.pcem/roms
# git clone roms
git clone https://github.com/BaRRaKudaRain/PCem-ROMs.git
mv PCem-ROMs/* ./
rm -rf PCem-ROMs

Below a simple example, booting a floppy with a custom made bootsector.
I’m still searching for our bootblock demo, which uses VGA graphics and a music loader using Soundblaster.
We made this around the 90’s, and i have never seen a demo then booting a demo without dos.
Scrollers, music, starfields etc.

NOTE: Dos calls can’t be used, that’s not loaded. So NO int 21h software functions!

Running a bootblock program, there is NO ms-dos being loaded.

The disk image I created using my real original 5.25″ floppy, and converted this with my Fluxengine.

One of the other bootblock thingy’s I made, An amiga guru meditation error. (below a old capture)
When a corrupted disk or faulty software was booted using a amiga you often could see an error like this, now you could have it on you PC!

Original screen capture of a Guru Meditation.
You can see, mine is a little different, because of the font spacing and color.

PCem info

Systems / motherboards emulated :

    AMI XT clone
    Atari PC3
    Compaq Portable Plus
    DTK Clone XT
    (c)Anonymous Generic Turbo XT BIOS
    IBM PC
    IBM PCjr
    IBM XT
    Juko XT clone
    NCR PC4i
    Phoenix XT clone
    Schneider Euro PC
    Tandy 1000
    Tandy 1000HX
    Thomson TO16 PC
    Toshiba T1000
    VTech Laser Turbo XT
    Zenith Data SupersPort


    Amstrad PC1512
    Amstrad PC1640
    Amstrad PC2086
    Amstrad PC3086
    Amstrad PC5086
    Amstrad PPC512/640
    Compaq Deskpro
    Olivetti M24
    Sinclair PC200/Amstrad PC20
    Tandy 1000SL/2
    Toshiba T1200
    VTech Laser XT3


    AMI 286 clone
    Award 286 clone
    Bull Micral 45
    Commodore PC30-III
    Compaq Portable II
    Dell System 200
    Epson PC AX
    Epson PC AX2e
    GW-286CT GEAR
    IBM AT
    IBM PS/1 Model 2011
    IBM PS/2 Model 30-286
    IBM PS/2 Model 50
    IBM XT Model 286
    Samsung SPC-4200P
    Samsung SPC-4216P
    Toshiba T3100e
    Tulip AT Compact


    Acermate 386SX/25N
    AMI 386SX clone
    Amstrad MegaPC
    DTK 386SX clone
    Epson PC AX3
    IBM PS/1 Model 2121
    IBM PS/2 Model 55SX
    Packard Bell Legend 300SX
    Samsung SPC-6033P


    AMI 386DX clone
    Compaq Deskpro 386
    IBM PS/2 Model 70 (type 3)
    IBM PS/2 Model 80
    MR 386DX clone
    Samsung SPC-6000A


    AMI 486 clone
    AMI WinBIOS 486 clone
    Award SiS 496/497
    Elonex PC-425X
    IBM PS/2 Model 70 (type 4)
    Packard Bell PB410A

Socket 4/5/7 (Pentium)

    ASUS P/I-P55TVP4
    ASUS P/I-P55T2P4
    Award 430VX PCI
    Epox P55-VA
    Intel Advanced/EV (Endeavor)
    Intel Advanced/ZP (Zappa)
    Intel Premiere/PCI (Batman's Revenge)
    Packard Bell PB520R (Robin LC)
    Packard Bell PB570 (Hillary)

Super Socket 7 (K6-2/III)

    FIC VA-503+

Socket 8 (Pentium Pro)

    Intel VS440FX

Slot 1 (Pentium II)

    Gigabyte GA-686BX

Graphics cards emulated :

    3DFX Voodoo Graphics
    3DFX Voodoo 2
    ATI Graphics Pro Turbo (Mach64 GX)
    ATI Video Xpression (Mach64 VT2)
    ATI VGA Edge-16 (ATI-18800)
    ATI VGA Charger (ATI-28800)
    Cirrus Logic CL-GD5429
    Cirrus Logic CL-GD5430
    Cirrus Logic CL-GD5434
    Compaq CGA
    Diamond Stealth 32 (Tseng ET4000/w32p)
    Diamond Stealth 3D 2000 (S3 ViRGE/325)
    Hercules InColor
    MDSI Genius
    Number Nine 9FX (S3 Trio64)
    OAK OTI-037
    OAK OTI-067
    Olivetti GO481 (Paradise PVGA1A)
    Paradise Bahamas 64 (S3 Vision864)
    Phoenix S3 Trio32
    Phoenix S3 Trio64
    Plantronics ColorPlus
    S3 ViRGE/DX
    Sigma Color 400
    Trident TVGA8900D
    Trident TGUI9400CXi
    Trident TGUI9440
    Trigem Korean VGA (Tseng ET4000AX)
    Tseng ET4000AX
    Wsye 700

Sound cards emulated :

    AdLib Gold
    Ensoniq AudioPCI
    Gravis UltraSound
    Sound Blaster v1.0
    Sound Blaster v1.5
    Sound Blaster MCV
    Sound Blaster v2.0
    Sound Blaster Pro v1
    Sound Blaster Pro v2
    Sound Blaster Pro MCV
    Sound Blaster 16
    Sound Blaster AWE32
    Sound Blaster PCI128
    Windows Sound System

Old mystery motherboard and Bios hacking

Last Updated or created 2023-05-24

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


SDK-85 Cassettes

Last Updated or created 2023-10-24

Started drawing a Cassette interface in Kicad.
This so i can read back my old cassettes with programs.
(And write some new stuff)

I’m planning to buy a small micro cassette player.
With schematic below, I’m going to use it as save/load device.
But also with the same player, I’m going to convert the tape to a wave file, and try to decode the program using python.

While I’m at it, reading the old manuals, a RS-232 interface would be nice also!

UPDATE 20231016

This is the final version

Information about the 7655A.
A eprom WITH IO ports! Amazing piece of history hardware.

Testing some sims on Linux and Android

RFID music playlist genre selector.

Last Updated or created 2023-05-24

Just a proof of concept for a friend.

This one works with Logitech Media Server and Spotify playlists, but also works with generic LMS playlists when you change the url)

Selecting music using the RFID reader module in my game.
(i didn´t have a spare reader)

Cardboard box with rfid tags inside.

Looks nicer using laser lettering.

Maybe a tetrahedron for play,next,previous and stop?
And another with volume settings?

Simple node-red switcher

URL being called:


JiffyDos notes (work in progress)

Last Updated or created 2023-05-23

JiffyDOS is an enhanced DOS for the C64. The software is programmed onto ROM chips that replace the Kernal ROM chip on the motherboard and the DOS ROM chip in the disk drive. JiffyDOS is intended to provide greater speed, commands and convenience than on stock systems.

The 1541 drive is a computer on its own, using a 6502 and VIA chips.
(See other pages) (C64 uses a 6510, that is the same slightly modified version of the 6502)
A cool example of the drive being an OS/computer on its own:

Some notes:

  • I want to use a larger rom and using the higher address lines as kernal selector. Address line A13 and A14 can be used as selector
  • There is a schematic out there using runstop at boottime to do de selection of the rom part

Did I misspell kernel? NO
(Below from Wikipedia)

The KERNAL was known as kernel inside of Commodore since the PET days, but in 1980 Robert Russell misspelled the word as kernal in his notebooks. When Commodore technical writers Neil Harris and Andy Finkel collected Russell’s notes and used them as the basis for the VIC-20 programmer’s manual, the misspelling followed them along and stuck.

Original Kernal: 901227-03
8-kilobyte 2364 ROM 4K * 8 bits PROM

28C265 = 32K * 8bits

Diffference in ROM size AND there are some other pin placements.

Romselect should be /(a15 * a14 * a13) depending on ram/rom switch.


$E000-$FFFF – ROM

KERNAL ROM or RAM area (8192 bytes); depends on the value of bits #0-#2 of the processor port at memory address $0001
$FFFA-$FFFF – hardware vectors

%x0x: RAM area.


Converting png images to composite pixels (6502)

Last Updated or created 2023-05-22

Using searle’s design, i can draw pixels using composite video out.

Converting b/w png to hex include files, for usage in vasm I did the following.

#Python script to convert black levels to pixels
from PIL import Image
i = Image.open("fash.png")

pixels = i.load() # this is not a list, nor is it list()'able
width, height = i.size

all_pixels = []
for x in range(width):
    for y in range(height):
        cpixel = pixels[x, y]
        if cpixel[1] == 255:
            s = '\t.db 0x05,' + hex(int(x)) + ',' + hex(int(y))
            print (s)

Running and output example

python3 image.py > out

head out
	.db 0x05,0x1,0x16
	.db 0x05,0x1,0x18
	.db 0x05,0x1,0x19
	.db 0x05,0x2,0x7
	.db 0x05,0x2,0x8
	.db 0x05,0x2,0xc
	.db 0x05,0x2,0xd
	.db 0x05,0x2,0x17
	.db 0x05,0x3,0x5

Control codes and vasm include

01 (01) - Cursor home (Standard ASCII)
04 (04) - Cursor solid
05 (05) - Set graphics pixel (next two bytes = x,y) 
0C (12) - Clear screen (Standard ASCII)
0D (13) - Carriage return (Standard ASCII)
0E (14) - Set column 0 to 79 (2nd byte is the column number) or 0 to 39 for a 40 char line
0F (16) - Set row 0 to 24 (2nd byte is the row number)
1B (27) - ESC - reserved for ANSI sequences

vasm include part:

	.db 0x01,0x0c   ; home and clear
	.db 0x1b,0x2d   ; disable ansi translation
	include "out"   ; include hex "png"
	.db 0x00        ; end with 0 (part of message print routine)

Forgot a password on a webform?

Last Updated or created 2023-05-20

Use inspect in your webbrowser and change password into input.
Just search in the form part.
(No you can’t copy paste the ******* field. But you can when you changed this to input)

Hint: Some browsers will highlight the part you are hovering over.

Mikrotik RB4011 Vlan Guest Wifi (IOT) devices

Last Updated or created 2023-05-19

See inline comments:

# Add vlan bridge
/interface bridge
add name=bridge_vlan5

# add security profile for wifi
/interface wireless security-profiles
set [ find default=yes ] supplicant-identity=MikroTik
add authentication-types=wpa2-psk eap-methods="" mode=dynamic-keys name=iot supplicant-identity=""

# add virtual wifi to 2.4G and 5G APs
/interface wireless
set [ find default-name=wlan2 ] band=2ghz-g/n country=netherlands disabled=no distance=indoors frequency=auto installation=indoor mode=ap-bridge security-profile=xxxxxxxxxxx ssid=MYSSID station-roaming=enabled wireless-protocol=802.11 wps-mode=\
set [ find default-name=wlan1 ] band=5ghz-a/n/ac channel-width=20/40mhz-Ce country=netherlands disabled=no distance=indoors frequency=auto installation=indoor mode=ap-bridge name=wlan5 security-profile=xxxxxxxxxxxxx skip-dfs-channels=all ssid=\
    MYSSID station-roaming=enabled wireless-protocol=802.11 wps-mode=disabled
add disabled=no keepalive-frames=disabled mac-address=4A:8F:5A:48:A4:69 master-interface=wlan2 multicast-buffering=disabled name=wlan_iot2 security-profile=iot ssid=IOT vlan-id=5 vlan-mode=use-tag wds-cost-range=0 wds-default-cost=0 \
add disabled=no keepalive-frames=disabled mac-address=4A:8F:5A:80:CE:1D master-interface=wlan5 multicast-buffering=disabled name=wlan_iot5 security-profile=iot ssid=IOT vlan-id=5 vlan-mode=use-tag wds-cost-range=0 wds-default-cost=0 \

# Add vlans to virtual Wifi
/interface vlan
add interface=wlan_iot2 name=vlan5_iot-2 vlan-id=5
add interface=wlan_iot5 name=vlan5_iot-5 vlan-id=5

# add ip range for dhcp
/ip pool
add name=dhcp_pool5_iot ranges=

# add dhcp server with above range
/ip dhcp-server
add address-pool=dhcp_pool5_iot interface=bridge_vlan5 name=dhcpiot

# add vlans and interfaces to vlan  bridge
/interface bridge port
add bridge=bridge interface=wlan_iot2
add bridge=bridge interface=wlan_iot5
add bridge=bridge_vlan5 interface=vlan5_iot-5
add bridge=bridge_vlan5 interface=vlan5_iot-2

# add vlan to existing bridge (Not really needed) is for inter vlan traffic
/interface bridge vlan
add bridge=bridge_vlan5 vlan-ids=5

# add interfaces to LAN list (firewall needs this)
/interface list member
add interface=vlan5_iot-2 list=LAN
add interface=bridge_vlan5 list=LAN
add interface=vlan5_iot-5 list=LAN

# Add gateway/dhcpserver ip address
/ip address
add address= comment="IOT (vlan5)" interface=bridge_vlan5 network=

# dhcp server network
/ip dhcp-server network
add address= dns-server= gateway= netmask=24

# generic NAT rule
/ip firewall nat
add action=masquerade chain=srcnat comment="defconf: masquerade" ipsec-policy=out,none out-interface-list=WAN